Dr. Andrew A. Snelling

Education

PhD, Geology, University of Sydney, Sydney, Australia, 1982

BSc, Applied Geology, The University of New South Wales, Sydney,

Australia, First Class Honours, 1975

Professional Experience

Field, mine, and research geologist, various mining companies,

Australia

, Australian Nuclear Science and Technology Organisation

(ANSTO), Consultant researcher and writer , Australia, 1983–1992

Geological consultant, Koongarra uranium project, Denison Australia PL, 1983–1992

Collaborative researcher and writer, Commonwealth Scientific and Industrial Organisation

(CSIRO), Australia, 1981–1987

Professor of geology, Institute for Creation Research, San Diego, CA, 1998–2007

Staff member, Creation Science Foundation (later Answers in Genesis–Australia), Australia, 1983–

1998

Founding editor, Creation Ex Nihilo Technical Journal (now Journal of Creation), 1984–1998

Researcher and editor, Radioisotopes and the Age of The Earth (RATE), 1997–2005

Editor-in-chief, Proceedings of the Sixth International Conference on Creationism, 2008

Director of Research, Answers in Genesis, Petersburg, KY, 2007–present

Professional Affiliations

Geological Society of Australia /Geological Society of America /Geological Association of Canada/

Mineralogical Society of America /Society of Economic Geologists /Society for Geology Applied to Mineral

Deposits / Creation Research Society /Creation Geology Society

Dr. Andrew A. Snelling is perhaps one of the world's leading researchers in flood geology.He worked for a number of years in the mining industry throughout Australia undertaking mineral exploration surveys and field research. He has also been a consultant research geologist for more than a decade to the Australian Nuclear Science and Technology Organization and the US Nuclear Regulatory Commission for internationally funded research on the geology and geochemistry of uranium ore deposits as analogues of nuclear waste disposal sites..His primary research interests include radioisotopic methods for the dating of rocks, formation of igneous and metamorphic rocks, and ore deposits. He is one of a controlled number permitted to take rock samples from the Grand Canyon.He was also a founding member of the RATE group (Radioisotopes and the Age of The Earth). Andrew completed a Bachelor of Science degree in Applied Geology with First Class Honours at The University of New South Wales in Sydney, and graduated a Doctor of Philosophy (in geology) at The University of Sydney, for his thesis entitled A geochemical study of the Koongarra uranium deposit, Northern Territory, Australia. Between studies and since, Andrew worked for six years in the exploration and mining industries in Tasmania, New South Wales, Victoria, Western Australia and the Northern Territory variously as a field, mine and research geologist. Full-time with the Australian creation ministry from 1983 to 1998, he was during this time also called upon as a geological consultant to the Koongarra uranium project (1983–1992). Consequently, he was involved in research projects with various CSIRO (Commonwealth Scientific and Industrial Research Organisation), ANSTO (Australian Nuclear Science and Technology Organisation) and University scientists across Australia, and with scientists from the USA, Britain, Japan, Sweden and the International Atomic Energy Agency. As a result of this research, Andrew was involved in writing scientific papers that were published in international scientific journals.Andrew has been involved in extensive creationist research in Australia and overseas, including the formation of all types of mineral deposits, radioactivity in rocks and radioisotopic dating, and the formation of metamorphic and igneous rocks, sedimentary strata and landscape features (e.g. Grand Canyon, USA, and Ayers Rock, Australia) within the creation framework for earth history. As well as writing regularly and extensively in international creationist publications, Andrew has travelled around Australia and widely overseas (USA, UK, New Zealand, South Africa, Korea, Indonesia, Hong Kong, China) speaking in schools, churches, colleges and universities, particularly on the overwhelming scientific evidence consistent with the Global Flood and the Creation.

HOW OLD IS EARTH – 10 BEST EVIDENCES THAT CONFIRM A YOUNG EARTH………………………………………...4

EVIDENCES FROM THE RADIOHALOS

Radiohalos—Mysterious Bullet Holes in Rocks………………………………………………………………………….11

Radiohalos—The Mysterious Vanishing Bullets…………………………………………………………………………12

Radiohalos—Solving the Mystery of the Missing Bullets……………………………………………………………….15

Radiohalos in Multiple, Sequentially Intruded Phases of the Bathurst Batholith, NSW, Australia…………………17

Radiohalos and Diamonds………………………………………………………………………………………………....38

Radiohalos in the Cooma Metamorphic Complex……………………………………………………………………… 43

Radiohalos in the Shap Granite, Lake District, England Evidence that Removes Objections to Flood Geology.. 52

Radiohalos—A Tale of Three Granitic Plutons….…………………………………………………………………….…62

Implications of Polonium Radiohalos in Nested Plutons of the Tuolumne Intrusive Suite, Yosemite, California…73

Testing the Hydrothermal Fluid Transport Model for Polonium Radiohalo Formation………………………………84 EVIDENCES FROM THE MAGNETIC FIELD

More Evidence of Rapid Geomagnetic Reversals Confirms a Young Earth……………………………………….…89

The “Principle of Least Astonishment”!... ………………………………………………………………………………..93

The Earth’s Magnetic Field and the Age of the Earth….…………………………………………………………….…94

Fossil Magnetism Reveals Rapid Reversals of the Earth's Magnetic Field………………………………………….96 ***

Rocks Around the Clock: Do Zircons Contain Reliable Time Stamps and Early Earth’s Secrets?.......................98

Journey to the Center of the Earth………………………………………………………………………………………101

Giant’s Causeway Northern Ireland…………………………………………………….………………………………102

The Devils Marbles………………………………………………………………………………………………….……104

Arches of Utah……………………………………………………………………………………….……………………104

Hawaii’s Volcanic Origins—Instant Paradise……………………………………………………………………..……105

The Florida Sinkhole Tragedy …………………………………………………………………………….…… ……….108

Volcanoes—Windows Into Earth’s Past………………………………………………………………………. ...……. 110

Does Sand Prove Long Ages? …………………………………………………………………………………… ……112

Thirtieth Anniversary of a Geologic Catastrophe………………………………………………………………………113

The Cooling of Thick Igneous Bodies on a Young Earth……………………………………………………………...115

Catastrophic Granite Formation…. ……………………………………………………………………..………………123

Conflicting ‘Ages’ of Tertiary Basalt and Contained Fossilised Wood……………………………………………….132 RAPID ROCKS

Granites … They Didn’t Need Millions of Years of Cooling….………………………………………………………..150

“Rapid” Granite Formation?....... ………………………………………………………………………………...………152

Towards a Creationist Explanation of Regional Metamorphism…..………………………………………………….153

Australia’s Burning Mountain….………………………………………………………………………………………….166

When Was the Ice Age in Biblical History?... …………………………………………………………………….……169 ASTRO GEOLOY

Moon Dust and the Age of the Solar System………………………………………………………… ……….………172

Solar Neutrinos—The Critical Shortfall Still Elusive……………………………………………………………...……197

Galaxy-Quasar ‘Connection’ Defies Explanation………………………………………………………………………198

Saturn’s Rings—Short-Lived and Young……………………………………………………………………………….198

That Matter of the Shrinking Sun………………………………………………………………………………..……….199 GOLD

A Little Bit of Heaven on Earth….……………………………………………… ………………………………………200 CRYSTALS

Shape-Shifting Silicon………………………………………………………………………….…………………………202

Rubies & Sapphires…………………………………………………………………………….…………………………205

Microscopic Diamonds Confound Geologists………………………………………………………………………….207

Creating Opals ……………………………………………………………………………………..……………………..208

Diamonds—Evidence of Explosive Geological Processes……………………………………………………………209

Growing Opals—Australian Style….…………………………………………………… ………………………………211

HOW OLD IS EARTH – 10 BEST EVIDENCES THAT CONFIRM A YOUNG EARTH

#1 Very Little Sediment on the Seafloor

by Dr. Andrew A. Snelling on October 1, 2012 If sediments have been accumulating on the seafloor for three billion years, the seafloor should be choked with sediments many miles deep.Every year water and wind erode about 20 billion tons of dirt and rock debris from the continents and deposit them on the seafloor.1 (Figure 1). Most of this material accumulates as loose sediments near the

continents. Yet the average thickness of all these sediments globally over the whole seafloor is not even 1,300 feet (400 m).2Some sediments appear to be removed as tectonic plates slide slowly (an inch or two per year) beneath continents. An estimated 1 billion tons of sediments are removed this way each year.3 The net gain is thus 19 billion tons per year. At this rate, 1,300 feet of sediment would accumulate in less than 12 million years, not billions of years.This evidence makes sense within the context of the Flood cataclysm, not the idea of slow and gradual geologic evolution. In the latter stages of the year-long global Flood, water swiftly drained off the emerging land, dumping its sediment-chocked loads offshore. Thus most seafloor sediments accumulated rapidly about 4,300 years ago.4 Where Is All the Sediment?

Figure 1: Every year, 20

billion tons of dirt and rock debris wash into the ocean and accumulate on the seafloor. Only 1 billion tons (5%) are removed by tectonic plates. At this rate, the current thickness of seafloor sediment would accumulate in less than 12 million years. Such sediments are easily explained by water draining off the continents towards the end of the Flood. Rescuing Devices

Those who advocate an old earth insist that the seafloor sediments must have

accumulated at a much slower rate in the past. But this rescuing device doesn’t “stack up”! Like the sediment layers on the continents, the sediments on the continental shelves and margins (the majority of the seafloor sediments) have features that unequivocally indicate they were deposited much faster than today’s rates. For example, the layering and patterns of various grain sizes in these sediments are the same as those produced by undersea landslides, when dense debris-laden currents (called turbidity currents) flow rapidly across the continental shelves and the sediments then settle in thick layers over vast areas. An additional problem for the old-earth view is that no evidence exists of much sediment being subducted and mixed into the mantle.

#2 Bent Rock Layers

by Dr. Andrew A. Snelling on October 1, 2012 In many mountainous areas, rock layers thousands of feet thick have been bent and folded without fracturing. How can that happen if they were laid down separately over hundreds of millions of years and already hardened?Hardened rock layers are brittle. Try bending a slab of concrete sometime to see what happens! But if concrete is still wet, it can easily

be shaped and molded before the cement sets. The same principle applies to sedimentary rock layers. They can be bent and folded soon after the sediment is deposited, before the natural cements have a chance to bind the particles together into hard, brittle rocks.1The region around Grand Canyon is a great example showing how most of the earth’s fossil-bearing layers were laid down quickly and many were folded while still wet. Exposed in the canyon’s walls are about 4,500 feet (1,370 meters) of fossil-bearing layers, conventionally labelled Cambrian to Permian.2 They were supposedly deposited over a period lasting from 520 to 250 million years ago. Then, amazingly, this whole sequence of layers rose over a mile, around 60 million years ago. The plateau through which Grand Canyon runs is now 7,000–8,000 feet (2,150–3,450 meters) above sea level. Layers Laid Down Quickly and Bent While Soft

Figure 1: The Grand Canyon

now cuts through many rock layers. Previously, all these layers were raised to their current elevation (a raised, flat region known as the Kaibab Plateau). Somehow this whole sequence was bent and folded without fracturing. That’s impossible if the first layer, the Tapeats Sandstone, was deposited over North America 460 million years before being folded. But all the layers would still be relatively soft and pliable if it all happened during the recent, global Flood. Figure 2: This phenomenon was

not regional. The Tapeats Sandstone spans the continent, and other layers span much of the globe. Think about it. The time between the first deposits at Grand Canyon (520 million years ago) and their bending (60 million years ago) was 460 million years! Look at the photos of some of these layers at the edge of the plateau, just east of the Grand Canyon. The whole sequence of these hardened sedimentary rock layers has been bent and folded, but without fracturing (Figure 1).3 At the bottom of this sequence is the Tapeats Sandstone, which is 100–325 feet (30–100 meters) thick. It is bent and folded 90° (Photo 1). The Muav Limestone above it has similarly been bent (Photo 2).

Photo courtesy Andrew A. Snelling Photo 1: The whole sequence of

sedimentary layers through which Grand Canyon cuts has been bent and folded without fracturing. This includes the Tapeats Sandstone, located at the bottom of the sequence. (A 90° fold in the eastern Grand Canyon is pictured here.) Photo courtesy Andrew A. Snelling Photo 2: All the layers through which

Grand Canyon cuts—including the Muav Limestone shown here—have been bent without fracturing. However, it supposedly took 270 million years to deposit these particular layers. Surely in that time the Tapeats Sandstone at the bottom would have dried out and the sand grains cemented together, especially with 4,000 feet

(1,220 m) of rock layers piled on top of it and pressing down on it? The only viable scientific explanation is that the whole sequence was deposited very quickly—the young age model indicates that it took less than a year, during the global Flood cataclysm. So the 520 million years never happened, and the earth is young. Rescuing Devices

What solution do old-earth advocates suggest? Heat and pressure can make hard rock layers pliable, so they claim this must be what happened in the eastern Grand Canyon, as the sequence of many layers above pressed down and heated up these rocks. Just one problem. The heat and pressure would have transformed these layers into quartzite, marble, and other metamorphic rocks. Yet Tapeats Sandstone is still sandstone, a sedimentary rock! But this quandary is even worse for those who deny recent creation and the Flood. The Tapeats Sandstone

and its equivalents can be traced right across North America (Figure 2),4 and beyond to right across northern Africa to southern Israel.5 Indeed, the whole Grand Canyon sedimentary sequence is an integral part of six megasequences that cover North America.6 Only a global Flood cataclysm could carry the sediments to deposit thick layers across several continents one after the other in rapid succession in one event.7

#3 Soft Tissue in Fossils

by Dr. David Menton on October 1, 2012 Ask the average layperson how he or she knows that the earth is millions or billions of years old, and that person will probably mention the dinosaurs, which nearly everybody “knows” died off 65 million years ago. A recent discovery by Dr. Mary Schweitzer, however, has given reason for all but committed evolutionists to question this assumption.Bone

slices from the fossilized thigh bone (femur) of aTyrannosaurus rex found in the Hell Creek formation of Montana were

studied under the microscope by Schweitzer. To her amazement, the bone showed what appeared to be blood vessels of the type seen in bone and marrow, and these contained what appeared to be red blood cells with nuclei, typical of reptiles and birds (but not mammals). The vessels even appeared to be lined with specialized endothelial cells found in all blood vessels.Amazingly, the bone marrow contained what appeared to be flexible tissue. Initially, some skeptical scientists suggested that bacterial biofilms (dead bacteria aggregated in a slime) formed what only appear to be blood vessels and bone cells. Recently Schweitzer and coworkers found biochemical evidence for intact fragments of the protein collagen, which is the building block of connective tissue. This is important because collagen is a highly distinctive protein not made by bacteria. (See Schweitzer’s review article in Scientific American [December 2010, pp. 62–69] titled “Blood from

Stone.”)Some evolutionists have strongly criticized Schweitzer’s conclusions because they are understandably reluctant to concede the existence of blood vessels, cells with nuclei, tissue elasticity, and intact protein fragments in a dinosaur bone dated at 68 million years old. Other evolutionists, who find Schweitzer’s evidence too compelling to ignore, simply conclude that there is some previously unrecognized form of fossilization that preserves cells and protein fragments over tens of millions of years.1 Needless to say, no evolutionist has publically considered the possibility that dinosaur fossils

are not millions of years old. Tyler Lyson, Associated Press A Little Skin: A largely intact dinosaur mummy,

named Dakota, was found in the Hell Creek Formation of the Western U.S. in 2007. Some soft tissue from the long-necked hadrosaur was quickly preserved as fossil, such as the scales from its forearm shown here.An obvious question arises from Schweitzer’s work: is it even remotely plausible that blood vessels, cells, and protein fragments can exist largely intact over 68 million years? While many consider such long-term preservation of tissue and cells to be very unlikely, the problem is that no human or animal remains are known with certainty to be 68 million years old. But if creationists are right, dinosaurs died off only 3,000–4,000 years ago. So would we expect the preservation of vessels, cells, and complex molecules of the type that Schweitzer reports for biological tissues historically known to be 3,000–4,000 years old?The answer is yes. Many studies of Egyptian mummies and other humans of

this old age (confirmed by historical evidence) show all the sorts of detail Schweitzer reported in her T. rex. In addition to Egyptian mummies, the Tyrolean iceman, found in the Alps in 1991 and believed to be about 5,000 years old, shows such incredible preservation of DNA and other microscopic detail.We conclude that the preservation of vessels, cells, and complex molecules in dinosaurs is entirely consistent with a young-earth creationist perspective but is highly implausible with the evolutionist’s perspective about dinosaurs that died off millions of years ago.

#4 Faint Sun Paradox

by Dr. Danny Faulkner on October 1, 2012 Evidence now supports astronomers’ belief that the sun’s power comes from the fusion of hydrogen into helium deep in the sun’s core, but there is a huge problem. As the hydrogen fuses, it should change the composition of the sun’s core, gradually increasing the sun’s temperature. If true, this means that the earth was colder in the past. In fact, the

earth would have been below freezing 3.5 billion years ago, when life supposedly evolved.The rate of nuclear fusion depends upon the temperature. As the sun’s core temperatures increase, the sun’s energy output should also increase, causing the sun to brighten over time. Calculations show that the sun would brighten by 25% after 3.5 billion years. This means that an early sun would have been fainter, warming the earth 31°F (17°C) less than it does today. That’s below freezing.

But evolutionists acknowledge that there is no evidence of this in the geologic record. They even call this problem the faint young sun paradox. While this isn’t a problem over many thousands of years, it is a problem if the world is billions of years old. Rescuing Devices

Over the years scientists have proposed several mechanisms to explain away this problem. These suggestions require changes in the earth’s atmosphere. For instance, more greenhouse gases early in earth’s history would retain more heat, but this means that the greenhouse gases had to decrease gradually to compensate for the brightening sun. None of these proposals can be proved, for there is no evidence. Furthermore, it is difficult to believe that a mechanism totally unrelated to the sun’s brightness could compensate for the sun’s changing emission so precisely for billions of years.

#5 Rapidly Decaying Magnetic Field

by Dr. Andrew A. Snelling on October 1, 2012; last featured November 6, 2012 Shop Now

The earth is surrounded by a magnetic field that protects living things from solar radiation. Without it, life could not exist. That’s why scientists were surprised to discover that the field is quickly wearing down. At the current rate, the field and thus the earth could be no older than 20,000 years old.

Several measurements confirm this decay. Since measuring began in 1845, the total energy stored in the earth’s magnetic field has been decaying at a rate of 5% per century.1Archaeological measurements show that the field was 40% stronger in AD 1000.2 Recent records of the International Geomagnetic Reference Field, the most accurate ever taken, show a net energy loss of 1.4% in just three decades (1970–2000).3 This means that the field’s energy has halved every 1,465 years or so.Creationists have proposed that the earth’s magnetic field is caused by a freely-decaying electric current in the earth’s core. This means that the electric current naturally loses energy, or “decays,” as it flows through the metallic core. Though it differs from the most commonly accepted conventional model, it is consistent with our knowledge of what makes up the earth’s core.4 Furthermore, based on what we know about the conductive properties of liquid iron, this freely decaying current would have started when the earth’s outer core was formed. However, if the core were more

than 20,000 years old, then the starting energy would have made the earth too hot to be covered by water. Figure 1: Creationists have proposed that the earth’s

magnetic field is caused by a freely decaying electric current in the earth’s core. (Old-earth scientists are forced to adopt a theoretical, self-sustaining process known as the dynamo model, which contradicts some basic laws of physics.) Reliable, accurate, published geological field data have emphatically confirmed this young-earth model. Reliable, accurate, published geological field data have emphatically confirmed the young-earth model: a freely-decaying electric current in the outer core is generating the magnetic field.5 Although this field reversed direction several times during the Flood cataclysm when the outer core was stirred (Figure 1), the field has rapidly and continuously lost total energy ever since creation (Figure 2). It all points to an earth and magnetic field only about 6,000 years old.6 Figure 2: The earth’s magnetic field has rapidly and

continuously lost total energy since its origin, no matter which model has been adopted to explain its magnetism. According to creationists’ dynamic decay model, the earth’s magnetic field lost more energy during the Flood, when the outer core was stirred and the field reversed direction several times. Rescuing Devices

Old-earth advocates maintain the earth is over 4.5 billion years old, so they believe the magnetic field must be self-sustaining. They propose a complex, theoretical process known as the dynamo model, but such a model contradicts some basic laws of physics. Furthermore, their model fails to explain the modern, measured

electric current in the seafloor.7 Nor can it explain the past field reversals, computer simulations notwithstanding.8

To salvage their old earth and dynamo, some have suggested the magnetic field decay is linear rather than exponential, in spite of the historic measurements and decades of experiments confirming the exponential decay. Others have suggested that the strength of some components increases to make up for other components that are decaying. That claim results from confusion about the difference between magnetic field intensity and its energy, and has been refuted categorically by creation physicists.9

#6 Helium in Radioactive Rocks

by Dr. Andrew A. Snelling on October 1, 2012 Shop Now During the radioactive decay of uranium and thorium contained in rocks, lots of helium is produced. Because helium is the second lightest element and a noble gas—meaning it does not combine with other atoms—it readily diffuses (leaks) out and eventually escapes into the atmosphere. Helium diffuses so rapidly that all the helium

should have leaked out in less than 100,000 years. So why are these rocks still full of helium atoms?While drilling deep Precambrian (pre-Flood) granitic rocks in New Mexico, geologists extracted samples of zircon (zirconium silicate) crystals from different depths. The crystals contained not only uranium but also large amounts of helium.1 The hotter the rocks, the faster the helium should escape, so researchers were surprised to find that the deepest, and therefore hottest, zircons (at 387°F or 197°C) contained far more helium than expected. Up to 58% of the helium that the uranium could have ever generated was still present in the crystals.The helium leakage rate has been determined in several experiments.2 All measurements are in agreement. Helium diffuses so rapidly that all the helium in these zircon crystals should have leaked out in less than 100,000 years. The fact that so much helium is still there means they cannot be 1.5 billion years old, as uranium-lead dating suggests. Indeed, using the measured rate of helium diffusion, these pre-Flood rocks have an average “diffusion age” of only 6,000 (± 2,000) years.3These experimentally determined and repeatable results, based on the well-understood physical process of diffusion, thus emphatically demonstrate that these zircons are only a few thousand years old. The supposed 1.5-billion-year age is based on the unverifiable assumptions of radioisotope dating that are radically wrong.4Another evidence of a young earth is the low amount of helium in the atmosphere. The leakage rate of helium gas into the atmosphere has been measured.5 Even though some helium escapes into outer space, the amount still present is not nearly enough if the earth is over 4.5 billion years old.6 In fact, if we assume no helium was in the original atmosphere, all the helium would have accumulated in only 1.8 million years even from an evolutionary standpoint.7But when the catastrophic Flood upheaval is factored in, which rapidly released huge amounts of helium into the atmosphere, it could have accumulated in only 6,000 years.8 Rescuing Devices

So glaring and devastating is the surprisingly large amount of helium that old-earth advocates have attempted to discredit this evidence.One critic suggested the helium didn’t all come from uranium decay in the zircon crystals but a lot diffused into them from the surrounding minerals. But this proposal ignores measurements showing that less helium gas is in the surrounding minerals. Due to the well-established diffusion law of physics, gases always diffuse from areas of higher concentration to surrounding areas of lower concentration.9Another critic suggested the edges of the zircon crystals must have stopped the helium from leaking out, effectively “bottling” the helium within the zircons. However, this postulation has also been easily refuted because the zircon crystals are wedged between flat mica sheets, not wrapped in them, so that helium could easily flow between the sheets unrestricted.10 All other critics have been answered.11 Thus all available evidence confirms that the true age of these zircons and their host granitic rock is only 6,000 (± 2,000) years. Helium in Radioactive Rocks Quick Escape of Helium

Figure 1: Radioactive elements in rocks produce a lot of helium as they decay; and this gas quickly slips away into the

atmosphere, especially when the rocks are hot. Yet radioactive rocks in the earth’s crust contain a lot of helium. The only possible explanation: the helium hasn’t had time to escape!

#7 Carbon-14 in Fossils, Coal, and Diamonds

by Dr. Andrew A. Snelling on October 1, 2012; last featured November 20, 2012

Carbon-14 (or radiocarbon) is a radioactive form of carbon that scientists use to date fossils. But it decays quickly.

Carbon-14 (or radiocarbon) is a radioactive form of carbon that scientists use to date fossils. But it decays so quickly—with a half-life of only 5,730 years—that none is expected to remain in fossils after only a few hundred thousand years. Yet

carbon-14 has been detected in “ancient” fossils—supposedly up to hundreds of millions of years old—ever since the earliest days of radiocarbon dating.1Even if every atom in the whole earth were carbon-14, they would decay so quickly that no carbon-14 would be left on earth after only 1 million years. Contrary to expectations, between 1984 and 1998 alone, the scientific literature reported carbon-14 in 70 samples that came from fossils, coal, oil, natural gas, and marble representing the fossil-bearing portion of the geologic record, supposedly spanning more than 500 million years. All contained radiocarbon.2Further, analyses of fossilized wood and coal samples, supposedly spanning 32–350 million years in age, yielded ages between 20,000 and 50,000 years using carbon-14 dating.3 Diamonds supposedly 1–3 billion years old similarly yielded carbon-14 ages of only 55,000 years.4

A sea creature, called an ammonite, was discovered near Redding, California, accompanied by fossilized wood. Both fossils are claimed by strata dating to be 112–120 million years old but yielded radiocarbon ages of only thousands of years.Even that is too old when you realize that these ages assume that the earth’s magnetic field has always been constant. But it was stronger in the past, protecting the atmosphere from solar radiation and reducing the radiocarbon production. As a result, past creatures had much less radiocarbon in their bodies, and their deaths occurred much more recently than reported!So the radiocarbon ages of all fossils and coal should be reduced to less than 5,000 years, matching the timing of their burial during the Flood. The age of diamonds should be reduced to the approximate time of creation—about 6,000 years ago.5 Rescuing Devices

Old-earth advocates repeat the same two hackneyed defenses, even though they were resoundingly demolished years ago. The first cry is, “It’s all contamination.” Yet for thirty years AMS radiocarbon laboratories have subjected all samples, before they

carbon-14 date them, to repeated brutal treatments with strong acids and bleaches to rid them of all contamination.6 And when the instruments are tested with blank samples, they yield zero radiocarbon, so there can’t be any contamination or instrument problems.The second cry is, “New radiocarbon was formed directly in the fossils when nearby decaying uranium bombarded traces of nitrogen in the buried fossils.” Carbon-14 does form from such transformation of nitrogen, but actual calculations demonstrate conclusively this process does not produce the levels of radiocarbon that world-class laboratories have found in fossils, coal, and diamonds.7

#8 Short-Lived Comets

A comet spends most of its time far from the sun in the deep freeze of space. But once each orbit a comet comes very close to the sun, allowing the sun’s heat to evaporate much of the comet’s ice and dislodge dust to form a beautiful tail. Comets have little mass, so each close pass to the sun greatly reduces a comet’s size, and eventually comets fade away. They can’t survive billions of years.Two

other mechanisms can destroy comets—ejections from the solar system and collisions with planets. Ejections happen as comets pass too close to the large planets, particularly Jupiter, and the planets’ gravity kicks them out of the solar system. While ejections have been observed many times, the first observed collision was in 1994, when Comet Shoemaker-Levi IX slammed into Jupiter.Given the loss rates, it’s easy to compute a maximum age of comets. That maximum age is only a few million years. Obviously, their prevalence makes sense if the entire solar system was created just a few thousand years ago, but not if it arose billions of years ago. Rescuing Devices

Evolutionary astronomers have answered this problem by claiming that comets must come from two sources. They propose that a Kuiper belt beyond the orbit of Neptune hosts short-period comets (comets with orbits under 200 years), and a much larger, distant Oort cloud hosts long-period comets (comets with orbits over 200 years). Yet there is no evidence for the supposed Oort cloud, and there likely never will be. In the past twenty years astronomers have found thousands of asteroids orbiting beyond Neptune, and they are assumed to be the Kuiper belt. However, the

large size of these asteroids (Pluto is one of the larger ones) and the difference in composition between these asteroids and comets argue against this conclusion. #9 Very Little Salt in the Sea

by Dr. Andrew A. Snelling on October 1, 2012; last featured December 4, 2012 Shop Now If the world’s oceans have been around for three billion years as evolutionists believe, they should be filled with vastly more salt than the oceans contain today.Every year rivers, glaciers, underground seepage, and atmospheric and volcanic dust dump large amounts of salts into the oceans (Figure 1). Consider the influx of the

predominant salt, sodium chloride (common table salt). Some 458 million tons of sodium mixes into ocean water each year,1 but only 122 million tons (27%) is removed by other natural processes2 (Figure 1).If seawater originally contained no sodium (salt) and the sodium accumulated at today’s rates, then today’s ocean saltiness would be reached in only 42 million years3—only about 1/70 the three billion years evolutionists propose. But those assumptions fail to take into account the likelihood that the saltwater ocean was created for all the sea creatures. Also, the year-long global Flood cataclysm must have dumped an unprecedented amount of salt into the ocean through erosion, sedimentation, and volcanism. So today’s ocean saltiness makes much better sense within the young age timescale of about six thousand years.4 Salt in the Sea

The Numbers Just Don’t Add Up Figure 1: Every year,

the continents, atmosphere, and seafloor add 458 million tons of salt into the ocean, but only 122 million tons (27%) is removed. At this rate, today’s saltiness would be reached in 42 million years. Rescuing DevicesThose who believe in a three-billion-year-old ocean say that past sodium inputs had to be less and outputs greater. However, even the most

generous estimates can only stretch the accumulation timeframe to 62 million years.5 Long-agers also argue that huge amounts of sodium are removed during the formation of basalts at mid-ocean ridges,6 but this ignores the fact that the sodium returns to the ocean as seafloor basalts move away from the ridges.7 #10 DNA in “Ancient” Bacteria

by Dr. Georgia Purdom on October 1, 2012; last featured January 15, 2013 Scientists were surprised to find that DNA was still intact after a supposed 250 million years.

In 2000, scientists claimed to have “resurrected” bacteria, named Lazarus bacteria, discovered in a salt crystal conventionally dated at 250 million years old. They were shocked that the bacteria’s DNA was very similar to modern bacterial DNA. If the modern bacteria were the result of 250

million years of evolution, its DNA should be very different from the Lazarus bacteria (based on known mutation rates). In addition, the scientists were surprised to find that the DNA was still intact after the supposed 250 million years. DNA normally breaks down quickly, even in ideal conditions. Even evolutionists agree that DNA in bacterial spores (a dormant state) should not last more than a million years. Their quandary is quite substantial.However, the discovery of Lazarus bacteria is not shocking or surprising when we base our expectations on the young age accounts. For instance, the Flood likely deposited the salt beds that were home to the bacteria. If the Lazarus bacteria are only about 4,500 years old (the approximate number of years that have passed since the worldwide flood), their DNA is more likely to be intact and similar to modern bacteria. Rescuing Devices

Some scientists have dismissed the finding and believe the Lazarus bacteria are contamination from modern bacteria. But the scientists who discovered the bacteria defend the rigorous procedures used to avoid contamination. They claim the old age is valid if the bacteria had longer generation times, different mutation rates, and/or similar selection pressures compared to modern bacteria. Of course these “rescuing devices” are only conjectures to make the data fit their worldview.

EVIDENCES FROM THE RADIOHALOS

Radiohalos—Mysterious Bullet Holes in Rocks Part One

by Dr. Andrew A. Snelling on April 1, 2012; last featured April 1, 2014

The tiny black flecks found in granite testify to a powerful and recent worldwide Flood. But you have to look closely. Shop Now Radiohalos—The Flood’s Smoking Gun Part One: Mysterious Bullet Holes in Rocks

Part Two: The Mysterious Vanishing Bullets Part Three: Solving the Mystery of the Missing Bullets

Most people are familiar with granite. Several famous cliffs are made of granite, such as the sheer towering cliffs on either side of the Yosemite Valley—El Capitan and Half Dome (Figure 1). In other places granites cover the ground with large rounded boulders, such as the Devil’s Marbles in central Australia (Figure 2). We also see granites used for countertops in many home kitchens. Their colorful, interlocking crystals give the rock an elegant, sought-after flecked appearance (Figure 3). Along with glassy, pink, and cream crystals, granites usually contain scattered flakes of a dark, shiny mineral called biotite.

WORLDWIDE TESTIMONY TO THE FLOOD—LOCKED IN GRANITE.Granite is one of the most

common rocks on the planet, seen in places like Half Dome in Yosemite (Figure 1) and the Devil’s Marbles in central Australia (Figure 2). Inside the granite is radioactive damage, called radiohalos, which is best explained by granite forming quickly during a recent, worldwide catastrophe.These are more than just pretty rocks. They have amazing stories to tell. Just one of those stories has to do with the flakes of biotite. Sometime during the

Flood, these flakes were damaged at the atomic level. If we can piece together their story, these flakes can tell us more about the forces during the Flood—and to form new granites from molten conditions in only hours or days, not millions of years.But to investigate that story requires a bit of background on that tiny black mineral found in granite. The first article in this three-part series explains a few things we can learn about a rock’s history by looking at it under a microscope. WHAT ARE RADIOHALOS? (Figures 3 and 4) Granite is filled with tiny black specks, which give the granite its beauty in countertops. These black specks are the mineral called biotite.Creationists are interested in something mysterious within this black mineral. Under a microscope, they find something that looks like “bullet holes”—round places where the mineral has been damaged. What caused this damage?Within the biotite are small radioactive crystals, called zircons. When the radioactive elements in zircons decay, they shoot out particles in all directions. These “bullets,” known as alpha particles, cause damage to the surrounding material. This damaged area looks like a

sphere around the zircon, called a “radioactive halo,” or simply radiohalo. Biotite Flakes and Zircon Crystals

To the unaided eye, the flat surfaces of the biotite flakes in granites look polished and smooth. However, under a microscope, the brown or green biotite flakes often contain impurities, tiny crystals of other types of minerals. It is as if biotite crystals grew around previous minerals, like a tree might grow around a nail. One of these minerals, which is of special interest to us, is zirconium silicate (ZrSiO4). Crystals of zirconium silicate are called zircons, named after the distinctive atom of the mineral.Biotite flakes consist of layers and layers of ultra-thin crystal sheets, stacked on top of one another like the pages of a book. Wedged between these sheets are tiny zircons (like bookmarks between pages of a book).An additional characteristic of zircons is that they are radioactive. None of the atoms of pure zirconium silicate are radioactive. However, uranium atoms (which are radioactive) are so similar in size and electric charge to zirconium atoms

that they can “play the part” of zirconium atoms. When zircon crystals form, any uranium atoms in the vicinity can replace zirconium atoms in the zircon’s crystal structure.Once the zircons form, the trapped uranium atoms start breaking apart or releasing pieces because the uranium nucleus is very large and highly unstable. The nuclear binding forces can’t hold together all 238 of the particles in the nucleus. When they release pieces, this is called radioactive decay. Two protons (particles with a positive electric charge) and two neutrons (particles with no electric charge) are ejected from the nucleus of each uranium atom. Alpha ParticlesThe two protons and two neutrons are “clumped” together when ejected, behaving as a single unit. This unit, called an alpha particle, is itself the very stable nucleus of another atom, helium. The type of radioactive decay that produces alpha particles (helium) is called alpha decay. These are the particles that cause the “clicking” sound in a Geiger counter, the familiar instrument for detecting radioactivity.Once ejected from uranium atoms, the alpha particles leave the zircon crystals entirely. They are so energetic they “shoot” out like little “bullets,” moving at a whopping speed of 9,300 miles/second (15,000 km/sec)—more than 45,000 times faster than a typical bullet from a gun.As a result, the alpha particles damage the surrounding biotite flakes, the same way bullets would leave holes in the walls of a house. Millions of these alpha particle “bullets” shoot out in all directions creating a zone of damage a specific distance away from each tiny zircon.As the alpha particle bullets “crash” their way through the biotite flakes, leaving trails of damage in the biotite’s structure, they slow down until they eventually stop. The most damage occurs where the alpha particles stop. All of this bombardment by millions of alpha particles produces a narrow band of dark discoloration in the biotite flakes at a certain distance in every direction away from the zircon. Radiohalos

The spherical zone of damage around a zircon looks like a halo around the zircon (Figure 4). That’s why these zones of radiation damage are called radioactive halos, or radiohalos for short. The tiny zircon crystal at the center of each halo is called a radiocenter. (These terms will become very important later in the discussion.)When the alpha particle bullets shoot out from the tiny zircon crystals, they pass through and damage multiple biotite crystal sheets (book pages) until they stop. The resulting discoloration thus affects many “pages” of the biotite “book.”In order for geologists to study these radiohalos under a microscope, they have to pull apart the biotite sheets and view them in two dimensions. So the radiohalos appear circular on the flat surface of the biotite sheet, much like a slice through a golf ball might look (Figure 5).

HOW CAN YOU STUDY RADIOHALOS? (Figures 5 and 6) The biotite specks in granite are made of thin flakes, which are stacked on top of each other, like the pages of a book. If the flakes are pulled apart, you can look at the pages of the book. The sphere damaged by radioactive decay looks like a halo.Creationists are most interested in the slice

through the middle of the sphere. The center, where the destructive particles originated, is called the radiocenter. In many cases a zircon is there, but in some cases the source is missing. Why do we find a radiohalo but not the source?The best view, though, is the slice through the center of the radiohalo. That’s where the tiny zircon crystal, the radiocenter, can be seen. We know when we are looking at the central slice when the radiocenter is seen and the discoloration is the same distance all the way around the radiocenter.If you look at Figure 6, you will see that the outer edge of the discoloration halo looks like a dark line. This shows where the most damage was caused as the alpha particles stopped. A Reminder of the Flood

Far from being an oddity, radiohalos are a record of radioactive decay during the Flood. The sequence of events that produced this discoloration is locked into biotite flakes for us to see today, in a sense like pre-Flood animals and plants were locked into mud and sand layers that hardened into fossils. Just like the fossils, these halos of “fossilized” radioactivity serve.Once you finish this series, every sighting of this ubiquitous rock, granite, will become another opportunity to share your faith and the historical truth of the Flood.

Radiohalos—The Mysterious Vanishing Bullets Part Two

Geologists have uncovered a great mystery in granite rocks. They find tiny black circles, known as radiohalos. They were caused by radioactive decay of polonium, but the source has disappeared. Where did it come from, and where did it go? The only answer is a global Flood. Radiohalos—The Flood’s Smoking Gun

Part One: Mysterious Bullet Holes in Rocks Part Two: The Mysterious Vanishing Bullets

Part Three: Solving the Mystery of the Missing Bullets Part one of this three-part series described the mysterious “halos” found inside granite (the common speckled rocks used for kitchen countertops and tombstones). These microscopic halos look a lot like “bullet holes.” Why are they of interest to creationists?Once you learn more about these features, you will see why they mystify geologists. They are hard to explain if granite formed slowly over millions of years, but they make perfect sense if molten material rose near the earth’s surface during the worldwide Flood and quickly hardened into granite.But first, you will need to understand a bit more about radioactive decay and its effects on rocks. The Well-Understood Radioactive Decay of Uranium

Geologists have a clear understanding of the radioactive decay of uranium atoms and the decay’s effects on surrounding rocks. We can observe this process today. It is not a mystery.As explained in the first article, the nuclei of uranium atoms are so large that they are very unstable. As the atoms decay, subatomic alpha particles fly out like bullets, damaging the surrounding material. These bullets produce spherical halos called radiohalos (an abbreviation for “radioactive halos”). After the first set of these particles is ejected, the smaller nucleus is still unstable. So more particles are ejected from the nucleus. This happens repeatedly until the atom is stable and no longer decays. In what is known as the uranium decay

chain, the nucleus of the original uranium-238 atom typically undergoes eight alpha-particle changes until it becomes the stable lead-206 atom (see “The Uranium Decay Chain—The Source of Radiohalos” below). The Uranium Decay Chain—The Source of Radiohalos

All the intermediate steps during the radioactive decay of uranium-238 are shown, resulting in the final, stable element lead-206. Where the arrows point downward, those changes result from alpha decay. The arrows pointing upward indicate beta decay. (Alpha decay involves the loss of two protons and two neutrons; beta decay involves splitting of a neutron, the loss of an electron, and the gain of a proton.)The original (or parent) uranium nucleus contains 92 protons. That’s why uranium is element number 92 on the periodic chart. However, after two protons are ejected in an alpha particle, the nucleus then has only 90 protons, so the uranium has changed into element number 90, which is thorium.The nucleus of thorium is still unstable, so it decays radioactively. However, it decays by successively splitting and ejecting two electrons, known as beta particles, while gaining two extra protons, giving it a total of 92 again. So the thorium has changed back into the element number 92, uranium.But this uranium is now four neutrons lighter. Whereas the original parent uranium atom had 146 neutrons and 92 protons in its nucleus (called uranium-238), this uranium atom has only 142 neutrons and 92 protons (called uranium-234).The nucleus of this uranium-234 atom is still unstable, so it decays. The process continues through what is known as the uranium decay chain, until the stable lead-206 atom is reached, the final end product.The picture is a little more complicated at the bottom end of this decay chain. At polonium-218 there is “branching,” but most polonium-218 atoms decay to lead-214. Then they quickly decay to bismuth-214, then polonium-214. The main decay path is depicted with solid red arrows. And the main eight alpha-decaying atoms are shown in red.Figure 1 shows a sample radiohalo that resulted from this process. Notice the eight dark rings. Why eight and not just

one? As each of the alphaparticles is “fired” from the nucleus, it has a different energy. Consequently each bullet travels a different distance into the surrounding material before it stops to leave a black mark. The Mystery of Polonium Radiohalos

The origin of eight-ring radiohalos is not a mystery for geologists. They must have formed from uranium-238 decay. The mystery is the source of the one-ring, two-ring, and three-ring radiohalos that are found in the same rock specimens (Figures 2–4). Geologists find four types of radiohalos in granite. One was caused by the decay of uranium, and the others came from the decay of another radioactive element, polonium.We can see the source of the eight-ring radiohalos because it is still there—a zircon crystal that still hosts uranium. But nothing is usually visible at the center of the other types of radiohalos. The source has vanished!Fortunately, it is still possible to determine the source of the rings. By carefully measuring the distance from the center of the radiohalo to each ring, we can identify which type of nucleus formed each ring (Figure 5).1In

each case, the “smoking gun” was a variation of the radioactive element polonium.2 Polonium-218, polonium-214, and polonium-210 generate exactly the right amount of energy to produce the three-

ring, two-ring, and one-ring radiohalos.The problem is that polonium is never found alone in rocks. It is a rare, unstable element that appears quickly during the decay of uranium and then decays into stable elements, such as lead. The only

possible source of the polonium was the decay of uranium. But we do not find a uranium source at the center of the one-, two-, and threering radiohalos! The crucial clue is the appearance of polonium during the uranium-238 decay chain. As the uranium atom’s nucleus becomes progressively smaller, three variations of polonium appear briefly in sequence at the end of the chain. FIGURE 5—Composite schematic

drawing of the four types of radiohalos: (a) a uranium-238 radiohalo, (b) a polonium-218 radiohalo, (c) a polonium-214 radiohalo, and (d) a polonium-210 radiohalo. Different types of atoms (nuclides) cause each ring in the radiohalos, and the particles that they send out have different energies (MeV). A Possible Source of the Polonium Radiohalos

We can be certain that no other radioactive element appeared at the center of the polonium radiohalos. If any other elements had been there, such as

uranium or radon, they would have formed other rings as they decayed. So where did the polonium atoms come from?The best possible answer is that the polonium traveled from a nearby source where uranium atoms were decaying. Is there such a nearby uranium source? Absolutely! The same flakes that host the polonium radiohalos usually contain uranium radiohalos, usually less than a fraction of an inch from polonium radiohalos (Figure 6). Finding the Source of Polonium Radiohalos

The source of uranium radiohalos still survives in granite rocks: tiny zircon crystals. But geologists are mystified because the source of polonium radiohalos is missing. The answer lies only a tiny way up the biotite sheet . . . the zircons! Photo courtesy Andrew Snelling Biotite flakes often have numerous polonium radiohalos, in addition to uranium radiohalos. FIGURE 7—Diagram of a cross-section through a biotite flake

where radiohalos are found. The uranium-238 in the zircon crystal generated the uranium-238 radiohalo. Water flowing past the crystal carried decaying atoms along the same sheet to a nearby location, where a polonium-210 radiohalo developed. Nothing remains at the center of this radiohalo, however, because it dissolved quickly. Yet under normal conditions, like those we see in the earth today, that migration would be impossible. To understand the magnitude of the problem, you need to understand how many polonium atoms had to migrate and how quickly they had to travel.Scientists have estimated that each radiohalo’s discoloration initially develops after 100 million alpha-particles have been emitted from its center. It does not become dark until

500 million particles, and it does not become very dark until one billion alpha particles have been ejected.3 This means that each polonium radiohalo needs at least 500 million polonium atoms. And many polonium radiohalos often appear in the same specimen, so many billions of polonium atoms had to move into position to explain the radiohalos we see.Then there is the problem of how fast they must be moved. Polonium-214 atoms decay so quickly they are gone in the blink of an eye! Polonium-218 has a half-life (decay rate) of only 3.1 minutes, while polonium-214 decays in 164 microseconds!4 By comparison polonium-210 atoms are long-lived, with a half-life of 138 days. What unusual forces could have carried so many atoms away from the uranium source so quickly?Another possibility is to

move another element in the uranium-238 decay chain that appears before polonium. For example, the element immediately before the polonium-218, polonium-214, polonium-210 sequence is radon-222. If radon-222 moved into place, then the polonium would not have to be transported. But this presents two problems. First, the travel time is still short: the half-life of radon-222 is only 3.8 days. The radon would still have to be transported from the zircons to the

polonium halo sites in only days.Second, we don’t find a radon-222 decay halo in the polonium radiohalos. Somehow the polonium had to separate from the radon-222 and then concentrate in what would become the polonium radiohalo centers. The location of radiohalos and the different chemical properties of radon and polonium suggest a solution to these problems. How Polonium Radiohalos Likely Formed

When uranium and polonium radiohalos are observed under the microscope, their radiocenters are actually on the same sheet.5 As explained in the first article, radiohalos are found in the dark flecks within granites, called biotite. These biotite flakes consist of layers and layers of crystal sheets, which can be pulled apart and examined under a microscope.Water can easily travel down the spaces between these sheets (Figure 7). Changes in the biotite’s color are often evidence that water has seeped between the sheets. That’s the key to the creationist explanation for polonium radiohalos.When granites crystallize and are cooling, hot waters are left over. This water is capable of seeping along the spaces between the stacked sheets of biotite. As they pass by the zircon, these waters could dissolve any radon-222 atoms that had leaked out of the zircon crystals and transport them between the sheets of the biotite flake.Radon-222 atoms are chemically inert (they do not combine with other atoms). But once they decay, the newly formed polonium-218 atoms would readily combine with other atoms, such as chlorine or sulfur atoms that had dissolved in the hot water and were flowing between the biotite sheets. Polonium chlorides and polonium sulphides don’t dissolve well in water, so as soon as the polonium combines with these other atoms, the molecules drop out of the water. There the polonium would start forming polonium radiohalos.The water would continue to move many radon-222 atoms past the forming radiocenters, providing a continual supply of new polonium atoms.Ever since a geologist dismissed this evidence of the Flood, calling it “a very tiny mystery” at a 1981 trial on teaching creationism in Arkansas schools,6 scientists have ignored this mystery. The problem is that secular geologists believe the host granites took millions of years to form, but the process had to be much faster—only hours or weeks—for polonium radiohalos to appear. They shouldn’t exist, according to conventional wisdom! The next and final article will look at the profound implications for all of geology.Though they are very tiny, polonium radiohalos have a huge message that cannot be ignored. These amazing testimonies to the Flood are found in granites all around the world. And they point to a catastrophic origin for granites, consistent with the timeframe for earth history.Though they are very tiny, polonium radiohalos have a huge message that cannot be ignored. These amazing testimonies to the Flood are found in granites all around the world. And they point to a catastrophic origin for granites, consistent with the young age timeframe for earth history.

Radiohalos—Solving the Mystery of the Missing Bullets Part Three

by Dr. Andrew A. Snelling on October 1, 2012; last featured April 9, 2014

Granite rocks exhibit mysterious black spheres, known as radiohalos. The only reasonable explanation for their origin is a recent, worldwide Flood. Indeed, the unique conditions required to form such spheres show us that radioactive decay—and granite formation—was extremely rapid in the past.

Shop Now Radiohalos—The Flood’s Smoking Gun

Part One: Mysterious Bullet Holes in Rocks Part Two: The Mysterious Vanishing Bullets Part Three: Solving the Mystery of the Missing Bullets

The only reasonable explanation for their origin is a recent, worldwide Flood. Indeed, the unique conditions required to form such spheres show us that radioactive decay—and granite formation—was extremely rapid in the past.Part two of this series explained why old-earth geologists are baffled by evidence of radioactive damage from polonium in certain kinds of granite crystals, called biotite. These damaged areas, called radiohalos, look like dark “halos.” To the evolutionist, their existence is a mystery.Why the mystery? The source of these halos, polonium, is an unstable, radioactive element that does not survive long in nature (only milliseconds, in some cases). It appears only briefly during the decay of another element, uranium. But no uranium source is found at the center of these polonium radiohalos! Where did the polonium come from?The cataclysmic, worldwide Flood provides the answer. Uranium-238 is found a short distance away from the polonium radiohalos. Hot water seeping through the granite during the Flood could easily explain how products of the uranium’s decay could be transported to the site of the polonium radiohalos.As will be explained in this article, this whole process must have occurred rapidly. Otherwise, not enough polonium would be produced to form each radiohalo, which requires hundreds of millions of polonium atoms in a short amount of time.The rapid formation of polonium radiohalos has astounding implications for earth history and physics. It means that radioactive decay must have occurred at a much faster rate in the recent past, and it also means that the earth’s granites must have formed under catastrophic conditions (e.g., at Creation and again during the world-wide Flood). Accelerated Radioactive Decay

Two basic kinds of radiohalos are found in biotite: some come from uranium and others come from polonium. Something very unusual must have taken place for both kinds of radiohalos to appear together.According to standard estimates, uranium must eject at least 500 million alpha particles to form a single dark radiohalo.1 At their current very slow rate of radioactive decay, parent uranium-238 atoms would need nearly 100 million years to produce that many alpha particles. So each uranium radiohalo would require 100 million years to form.In contrast, the polonium radiohalos had to form very, very quickly. While the reasons are complex (see previous article), basically the only way to transport polonium is as its precursor, a radioactive gas called radon. But this presents a huge problem. The only reasonable way to transport the radon is hot water, water so hot that it would destroy any polonium halos that formed! That makes the polonium radiohalos “a very tiny mystery” for long-age geologists.2This means that all the radon had to be transported first, while things were hot, and then the polonium halos had to form later, after things got “cooler.” But since both radon and polonium have short half-lives, the entire process had to occur in days. Radon-222 has a half-life (decay rate) of only 3.8 days, and polonium-218 and polonium-214 have half-lives of 3.1 minutes and 164 microseconds, respectively. At least

500 million radon atoms had to be produced, be transported, decay, and then be deposited as polonium. This would require 100 million years’ worth of decay in just a few days.Expressed another way, rare conditions were required to form the polonium radiohalos, and those conditions had to remain in place for more than 100 million years. The hot waters would have to keep seeping into and through the biotite flakes for more than 100 million years at current rates of uranium decay, and this had to happen in granites all over the globe (Figure 1). Such a scenario is impossible.The only viable alternative is that all the needed polonium was available very quickly, before it could decay away. That is, it had to be transported to the various points within the biotite flakes within hours, or days at the very most (Figure 1).3 Figure 1: Two Essential Conditions to Form Polonium Radiohalos In granites all over the earth’s surface, we find polonium-210 radiohalos near uranium-238 sources at the centers of uranium radiohalos. Two rare conditions were required to form these polonium radiohalos. First, a constant flow of hot water within forming granites had to rapidly transport millions of decaying atoms from the uranium to the sites of the polonium radiohalos. Second, molten granite magma, where the radiohalos formed, had to crystallize and cool quickly—in a matter of days. Only a global, cataclysmic Flood could explain these unique conditions. (a) The uranium-238 in the zircon crystal generated the

uranium-238 radiohalo. Water flowing past the crystal carried along decaying radon and polonium atoms between the same biotite sheets to a nearby location, where a polonium-210 radiohalo developed. Nothing remains at the center of this radiohalo, however, because whatever was there has been dissolved away. Constantly Flowing Hot Water

(b) The crystallizing granite magma included zircon crystals containing radioactive uranium-238 atoms that emitted alpha-particles. The cooling residual magma then released hot water, which flowed through the minerals. The hot water dissolved any products of the uranium decay (radon and polonium atoms) and then carried them a slight distance away. These radioactive products also emitted alpha-particles. Falling Temperatures (c) To dissolve and transport radon gas requires high

temperatures, but such high temperatures would remove any evidence of alpha-particle decay. (In essence, the minerals were so hot the tracks left by alpha decay were erased.) (d) The hot, mineral-rich water also carried sulfur atoms,

which lodged in the mineral’s cleavages. As temperatures dropped near 150°C (302°F), the polonium in the hot water combined with the sulfur and was removed from the water flow. The uranium in the zircon continued to decay and replenish the supply of radon and polonium to the hot flowing water. (e) Once the temperature dropped below 150°C (302°F), the

alpha particles started to leave trails, discoloring the mineral. As the polonium decayed to lead, more polonium flowed in. Both uranium and polonium radiohalos formed at the same time. (f) Once the granite cooled completely, the hot water flow

ceased, leaving behind the polonium radiohalos we find in granites today.The implications are astounding. At least 500 million uranium-238 atoms had to alpha decay within a few hours or days. The equivalent of “100 million years” of uranium-238 decay had to occur within hours!Thus, the decay rate of uranium had to be nearly a billion times faster in the past than it is today! And if uranium decayed at such an accelerated rate, then other radioactive elements, which are even less stable, must have also decayed much faster.Yet long-age dating methods assume that the radioactive decay rates have never changed. The very existence of the polonium radiohalos is evidence that the radioactive rates were accelerated in the past. This means that dates for rocks of billions of years must be questioned, as the rocks are in fact only thousands of years old. This means that all the rocks we know of—meteorites, rocks brought back from the moon, and the “oldest” rocks on the earth—are in fact only thousands of years old. This gives us good scientific reasons to believe that the earth, the moon, and all the objects of the solar system are only thousands of years old. The Rapid Origin of Granites

The rapid formation of polonium radiohalos has another astounding implication for earth history.The granite masses that contain the radiohalos are typically cubic miles in size and originally formed under ground from molten magmas at temperatures between 650°C and 705°C (1200–1300°F). It is usually claimed that they thus take millions of years to

crystallize and cool.4 Since radiohalos can survive only at and below 150°C (302°F), based on observed evidence,5 the radiohalos had to be generated very late in the granite formation process (Figure 2). By this time, though, most of the polonium would have decayed away. Any polonium halos that might have formed would be destroyed by the heat. Figure 2: The Right Conditions Lasted Only 6–10 Days This diagram shows the only possible timescale that could produce radiohalos from cooling granite magma. The magma must first be hot enough to produce water and transport the radon and polonium, but then it must be cool enough for the decaying polonium to leave behind radiohalos. The only way to explain these radiohalos is if the granites were deposited and cooled in less than two weeks . . . during a global Flood!

So unless the granites cooled quickly, no polonium radiohalos could be present. Thus, the existence of the polonium radiohalos implies that granites crystallized and cooled within just six to ten days, not millions of years!Uranium and polonium radiohalos found together in the same biotite flakes thus provide startling evidence of past catastrophic geological processes acting on a young earth. During Creation (about six thousand years ago) and again during the year-long Flood (about 4,300 years ago) sediments were eroded and deposited catastrophically on a global scale.6 Rapid earth movements pushed up mountains and melting of rocks formed granite bodies quickly.7 Inside these granites, super-fast radioactive decay generated uranium and polonium radiohalos rapidly.Though the radiohalos are so microscopic they could easily be overlooked, their abundance in granites all around the world cannot be ignored. They are exciting confirmation that the earth and its rocks are not millions and billions of years old as usually claimed. Instead, they are only thousands of years old.

Radiohalos in Multiple, Sequentially Intruded Phases of the Bathurst Batholith, NSW, Australia: Evidence for Rapid Granite Formation during the Flood

by Dr. Andrew A. Snelling on March 5, 2014 Abstract

The Bathurst Batholith west of Sydney, Australia, consists of an enormous pluton (the Bathurst Granite) and numerous smaller related satellite plutons and dikes. The major pluton cuts east-west across the prevailing north-south strike of the fossiliferous sedimentary strata, unequivocal evidence that the intrusion of the batholith structurally disrupted the regional fabric of the host strata sequence. Sedimentary rocks in the contact zone were metamorphosed by the hot magma. The major dike-like Evans Crown granite cuts across the Bathurst Granite and the surrounding host strata. This dike’s central portions are coarse and even grained like the Bathurst Granite, but the margins are chilled, testimony to intrusion of the dike as hot granite magma. Many minor granite dikes cut across the margins of the Bathurst Granite and also across the Evans Crown dike out into the surrounding strata. Alteration zones marginal to the sharp contacts of the dikes with the wallrocks indicate the magma was still hot when injected. Abundant 238U and 210Po radiohalos are present in biotite flakes of all samples of the Bathurst Granite and Evans Crown dike. 214Po and 218Po radiohalos are present only in some samples of the Bathurst Granite. A few 210Po and 238U radiohalos are also present in biotite flakes within some samples of the dikes that cut across the Bathurst Granite or the Evans Crown dike. Field and textural data have established that these granite phases were sequentially intruded while still hot. That these granitic phases were intruded as hot magma is also confirmed by analytical and experimental data. All this had to occur within the Flood year, so these multiple granite phases were not created cold by fiat. Instead, the Po radiohalos indicate they were formed rapidly below 150°C via hydrothermal fluid transport of Rn and Po from the zircon grains embedded in the biotite flakes that are often the radiocenters of the U radiohalos. Furthermore, their presence in all three sequentially intruded granite phases is evidence that all this intrusive activity, and the cooling of all three granite phases to 150°C, must have occurred within a week or two so that these Po radiohalos in them formed subsequently within days to weeks. Shop Now

Keywords: granite, Bathurst Batholith, magma, contact metamorphism, dikes, alteration zones, host fossiliferous

sediments, chemical analyses, experimental data, biotite, 238U radiohalos, Po radiohalos, hydrothermal fluids, the Flood Introduction

Over 50 years ago there was intense debate in the conventional scientific community on the origin and formation of granites (Pitcher 1993). For most geologists it has now been conclusively resolved that granitic magmas formed by partial melting of deep crustal (continental) rocks or of subducted sediments at temperatures of around 630–730°C. The hot granitic magmas, being less dense than the surrounding source rocks, then ascended through fractures and feeder zones to intrude into upper crustal rocks, including fossiliferous sedimentary strata. Often, the heat and hydrothermal fluids released by the cooling granitic magmas baked and/or altered the host rocks around the contact zones (contact metamorphism and/or metasomatism).However, there are still some unresolved issues. On one hand, there is the issue of the time involved for such a process, because the conventional geologic community generally regards the time necessary from partial melting to intrusion, crystallization and cooling of granites to have taken millions of years (Pitcher 1993; Young and Stearley 2008). On the other hand, a potential solution to the time issue and an alternative model for the origin of granites was presented by Gentry (1973, 1974, 1986, 1988). He argued that because the polonium (Po) radiohalos within biotite grains in granites appeared to be “orphaned” (there apparently being no precursor or parent atoms in situ), and they thus had to form extremely rapidly (due to the fleeting existence of two of the polonium isotopes), the Po radiohalos and the granites hosting them had to have been created in a fiat manner .He concluded the granites are primordial rocks and termed the Po radiohalos as “fingerprints of creation.”The observation that many granite bodies intrude fossil-bearing sedimentary rocks which were deposited during the Flood is not considered an obstacle to this proposal for the instantaneous origin of granites. Instead, Gentry (1986, 1988, 1989) proposed and insisted that primordial granite bodies were tectonically intruded during the Flood while they were cold, and any thermal effects surrounding the margins of these granite bodies was due to frictional heating during tectonic emplacement. His argument was aided by the observational fact that limited exposures of the contact zones at the margins of granite bodies are difficult to find. However, this is because outcrops of the contact zones are often not fully exposed or are absent due to the alteration effects facilitating deeper weathering of both the margins of the granite bodies and their adjacent host rocks.A number of previous studies have sought to establish the case for Po radiohalos having formed rapidly from Po atoms sourced from nearby decaying uranium (U) atoms and transported by hydrothermal fluids during the cooling phase of granite bodies (Snelling 2005a, 2008a, d; Snelling and Armitage 2003; Snelling and Gates 2009). Only one of these studies included an investigation of the contact zone around a granite body. Also, no previous studies examined discrete, separate granite bodies that had intruded into one another sequentially. The present study encompasses these two aspects in the investigation of a major granite body, two generations of dikes intruding into it, and their contained radiohalos.Fieldwork was conducted in July–September 1974 as the focus of a B.Sc. (Honors) dissertation at The University of New South Wales, Sydney, Australia, in an area located about 185 km (115 mi.) west of the city of Sydney (fig. 1). Detailed field observations were made of the contact zone along the margins of the Bathurst Granite where it intruded the host fossil-bearing sedimentary strata, and where it was itself intruded by two generations of late-stage granitic dikes. The resulting unpublished dissertation (Snelling 1974) was a description and discussion of the geology of the field area, accompanied by the compiled geological map. Further fieldwork in the region was undertaken in July 1999 to acquire a regional perspective in the investigation of radiohalos in the granite and the dikes. This subsequent radiohalos study used samples collected in 1999 and archived samples from the 1974 dissertation fieldwork. The results provide convincing evidence that this granite and its ancillary phases were indeed intruded rapidly as a hot magma into the surrounding host fossiliferous sedimentary strata during the Flood. Furthermore, the radiohalos in these sequentially intruded phases had to have been produced rapidly from Po atoms sourced from decaying U atoms in these granitic rocks.

Fig. 1. Location of the Bathurst

Batholith (red) in relation to other granite batholiths (pink) in south-eastern Australia. The Bathurst Batholith Geologic Setting The Bathurst Batholith, named after the city which sits on top of it, outcrops over an area of about 1600 km2 (620 sq. mi.) (fig. 1). It consists of an enormous pluton (the Bathurst Granite) and numerous smaller related satellite plutons and dikes. Though often deeply weathered, the granite is well exposed in road and railroad cuts, and in the hills around its margins which have been mapped in detail. At the contact with the granite the host fossiliferous sedimentary strata have been metamorphosed and in this instance have thus been more resistant to weathering (Joplin 1936; Snelling 1974; Vallance 1969).Previous studies by

Chaffer (1955) and Mackay (1959) included geological mapping and investigations, as well as the measuring of the type section for the Lambie Group at Mt. Lambie in the map area and identifying the fossil assemblages.Outcrops are poor over much of the Bathurst Plains and little is known of the granite in that region. However, early fieldwork by Joplin (1931, 1933, 1935, 1944) dealing with the eastern part of the batholith has contributed much to our knowledge of the batholith as a whole as a composite body, concluding the batholith consists of multiple plutons with variable compositions ranging from minor gabbroic phases to dominant adamellite (Chappell et al. 1991; Joplin 1931; Knutson and Flood 1988; Vallance

1969). The main plutonic rock types in the eastern part of the batholith, as elsewhere in the batholith, are pinkish, even-grained, biotite-granite/adamellite, gray biotite-granite/adamellite with large pink phenocrysts of potassium feldspar, hornblende-biotite granite/adamellite, and hornblende and biotite granodiorites (Joplin 1931). All are medium- to coarse-grained and massive with gradational contacts between the several varieties. Biotite granites with large potassium feldspar phenocrysts outcrop, for example, near Sodwalls and Tarana in the area studied by Snelling (1974). The satellite stock-like body at Yetholme, which appears to be related to the main mass of the batholith, also carries similar large K-feldspar phenocrysts.In general, age relations between the various granitic units in the batholith are not clear. An obvious exception to this rule is the major dike-like granite body 12.8 km (8 mi.) long and often 0.8 km (0.5 mi.) wide that forms the Evans Crown ridge near Tarana and extends north-north-eastwards cutting across the Bathurst Granite and the surrounding host sedimentary strata. Numerous minor granitic dikes cut across the margins of the Bathurst Granite and out into the surrounding host strata. Good exposures of these dikes are seen in the many railroad cuts between Sodwalls and Tarana. Up to 45 m (about 150 ft.) wide, these granitic dikes have the same composition as both the Bathurst Granite and the Evans Crown dike, often with the same porphyritic texture (Snelling 1974).Recent airborne magnetic and radiometric surveys have enabled the separate bodies with different compositions to be identified within the main outcrop of the batholith (Branagan and Packham 2000). The individual intrusive phases are well expressed on modern detailed aeromagnetic maps and in radiometric data. Detailed mapping using such data combined with petrology has enabled their improved depiction on geological maps (Raymond et al. 1998). The emplacement of these granitic plutons caused thermal metamorphism (hornfels and skarns) and metasomatism to the surrounding strata.Earlier K-Ar dating (Facer 1979) on an adamellite from Dunkeld just east of the city of Bathurst, yielded a total rock age of 304±4 Ma and a biotite age of 301±6 Ma for the western part of the Bathurst Granite, has proved unreliable. Radioisotope dating using the K-Ar, Rb-Sr, and Re-Os methods has been interpreted as indicating a mean time of emplacement of the Bathurst Batholith at 310 Ma (Scheibner and Basden 1998). However, Shaw and Flood (1993) have suggested that these ages are too young. Shaw’s unpublished data (Scheibner and Basden 1998) consists of more extensive Rb-Sr age dating of biotite/bulk rock pairs, and show that all plutons are older, with the mafic intrusions being the oldest at 340 Ma (Knutson and Flood 1988). This is within the range of 338–349 Ma from biotite in the regionally metamorphosed Merrions Formation (Cas, Flood, and Shaw 1976). The youngest intrusives dated are the felsic north-south dikes cross-cutting the Bathurst Batholith, with the Evans Crown dike dating at 312 Ma. Shaw and Flood’s (1993) histogram of 33 biotite ages from all major plutons of the batholith suggests an intrusive maximum around 325–330 Ma.In its structural setting the Bathurst Batholith is clearly discordant along much of its margin. Apart from radiometric dating, the evidence that the granite intruded later than the folding can be seen in the shape of the granite body which trends east-west, cutting across the “grain” of the folded host sedimentary rocks (fig. 2). The western part of the batholith lies against well-cleaved or foliated lower Paleozoic rocks. In places, the host country rocks have been shoved locally into concordances with the trend of the contact. Important structural features such as the thrust fault systems to the north of the batholith are intersected by the intrusive body which is clearly younger than the thrust faults.

Fig. 2. Simplified geological map of the Lachlan Fold Belt in the region of the Bathurst Batholith (after Branagan and

Packham 2000). Click image for larger view. The granitic bodies making up the batholith invade host country rocks as young as upper Devonian, and on the eastern margin are overlapped by Permian sediments. The available evidence from the thickness of the overlapping Permian sediments suggests that the depth of cover at the eastern margin, at least, was not great, perhaps not more than 1.5 km (0.93 mi.). The distribution of the thermal aureole indicates that the contacts between the granites and the host sedimentary strata are often rather shallowly dipping, as can clearly be recognized in the Tarana area. The numerous stocks, including those at Yetholme and Meadow Flat, which are lithologically similar to the rocks of the main granite mass of the batholith, yet separated from it at today’s land surface, suggest that the granite is not deeply eroded.With the folding and regional metamorphism of the sedimentary strata in what is now the Lachlan Fold Belt, numerous post-kinematic, massive, orogenic granites were intruded into these host strata, including the Bathurst Granite. These granites cut across the structural zones, and individual granitic stocks and batholiths show a marked preference for zones of crustal weakness, such as pre-existing lineaments and fracture zones. For example, the transverse Bathurst Batholith was emplaced along the Lachlan River Lineament (Scheibner and Stevens 1974). Aeromagnetic data indicate the importance of some additional lineament directions for the emplacement history of the Bathurst Batholith (Raymond et al. 1998). Also, the individual plutons, their often concentric structure and the numerous late north-south trending dikes, which are also very common in the surrounding country rocks, are all well displayed in the aeromagnetic images. Host Rocks the Batholith Intrudes

The Bathurst Batholith and related satellite bodies and dikes intrude into folded Silurian-Devonian marine sediments and pyroclastics. Two tectonically distinct zones are recognized in the local region—the Hill End Trough and the Capertee High (fig. 2). The Hill End Trough was the site of thick active sedimentation—almost 7500 m (24,600 ft.) of turbidites, flysch, and pyroclastics (Scheibner and Basden 1998). These sediments thin and wedge out as they onlap the Capertee High, which is believed to have been the site of the active volcanism responsible for much of the pyroclastic material and lava flows in the sedimentary sequence.

Fig. 3. The local stratigraphic column

(approximately 6100 m [20,000 ft.] thick), showing the order of deposition of the sedimentary rock units that host the Bathurst Granite in the Tarana-Sodwalls area. At the base of the stratigraphic section in the mapped area is the Silurian Chesleigh Group (Scheibner and Basden 1998) (fig. 3) which crops out sparsely south and east of Meadow Flat (fig. 4) and in its type area is 1050 m (3445 ft.) thick (Packham 1968). It consists of turbidites, primarily graywackes (well-sorted with small angular quartz and feldspar fragments scattered throughout a clay matrix) with interbedded shales (typically composed of extremely small grains of quartz and occasional feldspar set in a clay matrix). Up-sequence the amount of feldspar increases, and these turbidites are interbedded with felsic tuffs, characterized by quartz, orthoclase and plagioclase fragments in an ultra-fine groundmass. Among the tuffs is a porphyritic rhyodacite lava, consisting of fragmented quartz, orthoclase and plagioclase phenocrysts in a flow-banded groundmass.

Fig. 4. Geological map of the Tarana-Sodwalls-Mt. Lambie-Meadow Flat area, west of Sydney, New South Wales,

Australia (from Snelling 1974). Click image for larger view. There is a sharp change in the conformably overlying lower Devonian Crudine Group from quartz-rich sedimentation into volcanogenic deposition of felsic tuffs, tuffaceous breccias, banded tuffs interbedded with graywackes, siltstones, and shales. Then followed the accumulation of the widespread, grossly tabulated volcanogenic Merrions Formation (fig. 3), which consists of sheet-like to lobate horizons of dacite lavas and volcaniclastics. These two lower Devonian stratigraphic units are together about 1600 m (5250 ft.) thick in the study area (Snelling 1974)In the middle Devonian the sediments deposited in the Hill End Trough and on adjoining highs were deformed regionally into north-south trending folds with an axial slaty cleavage. This was followed by onset of upper Devonian molassic sedimentation with deposition of the Lambie Group (fig. 3). In the type section on Mt. Lambie, Mackay (1959, 1961) measured 3405 m (11,170 ft.) of reddish shales, siltstones, sandstones, conglomerate and massive quartzites. Upper Devonian fossils recorded in the area include brachiopods (including four species of Cryptospirifer), clams and clam fragments. The Bathurst Granite is in direct intrusive contact with the upper Devonian Lambie Group strata, so the granite is clearly younger. However, unconformably overlying all these Silurian-Devonian sedimentary units and the Bathurst Granite on its eastern flank is the Permian Megalong Conglomerate, a massive cobble conglomerate which is the basal unit of the western Sydney Basin (fig. 2). Metamorphism in the Host Rocks

Exogenetic metamorphic products associated with the batholith are variable. Many previously cleaved or foliated rocks have retained traces of original structures after static recrystallization. Thus in the Newbridge area, on the extreme southwestern margin of the batholith (Benson 1907), and to the north of the batholith (Vallance 1969), slates develop porphyroblasts of andalusite or chiastolite. On the southern margin of the batholith, some reaction between foliated rocks and the granite has led locally to the formation of banded quartzofeldspathic rocks described as migmatites by Binns (1958).To the east, the batholith comes into contact with less deformed rocks, and massive granoblastic hornfelses are typical in the aureole. Similar products have been examined in detail at Hartley (Joplin 1935), where the upper Devonian sediments include quartz-rich sandstones, shales and impure calcareous rocks. Among the sandstone and shale hornfelses, the most common minerals are quartz, biotite, andalusite, and cordierite. More calcareous rocks include plagioclase, diopside, hornblende, wollastonite, grossular, or vesuvianite. Local variations in grade are common and not

all hornfelses carry equilibrium assemblages. Andalusite-biotite-potassium feldspar hornfelses (indicating pyroxene hornfels facies conditions) and hornblende-diopside-plagioclase rocks (hornblende-hornfels facies) both occur at Hartley (Joplin 1935, 1936). At granite contacts near Tarana, calcsilicate rocks are derived from limestones. Silicated hornfelses (andradite-wollastonite) occur between recrystallized pure limestone and granite suggesting transfer of material across the contact. Andradite-hedenbergite skarns occur at various localities, such as at Yetholme where a satellite stock has invaded a succession containing limestones and conglomerates with limestone pebbles (Vallance 1969). History and Significance of U and Po Radiohalos

When radiohalos were first reported between 1880 and 1890, they remained a mystery until the discovery of radioactivity. Now they are recognized as any type of discolored radiation-damaged region within a mineral, resulting from the α-emissions from a central radioactive inclusion or radiocenter (Gentry 1973). Radiohalos when viewed in rock thin sections usually appear as concentric rings that were initiated by the α-decay in the 238U or 232Th series (Gentry 1973, 1974). Radiohalos are usually found in igneous rocks, most commonly in granitic rocks in which biotite is a major mineral. However, more recently radiohalos have also been reported as common in biotite in some metamorphic rocks (Snelling 2005a, 2008b, c). Thus biotite is the major mineral in which the radiohalos occur. While initially observed mainly in Precambrian rocks (Gentry 1968, 1970, 1971; Henderson and Bateson 1934; Henderson, Mushkat, and Crawford 1934; Iimori and Yoshimura 1926; Joly 1917a, b, 1923, 1924; Kerr-Lawson 1927, 1928; Owen 1988; Wiman 1930), radiohalos have since been shown to exist in rocks stretching from the Precambrian to the Tertiary (Holmes 1931; Snelling 2000, 2005a; Stark 1936; Wise 1989). Within the 238U decay series, the three Po isotopes have been the only α-emitters observed to form radiohalos other than 238U itself (fig. 5). These isotopes and their respective half-lives are 218Po (3.1 minutes), 214Po (164 microseconds), and 210Po (138 days), respectively. Their very short half-lives constrain the formation of the granites in which they are found to a short time frame because the Po radiohalos can only form after the granites have crystallized and cooled (Gentry 1986, 1988; Snelling 2000, 2005a). Thus, if granite magma emplacement and pluton cooling are not extremely rapid, then these Po isotopes would not have survived to form the Po radiohalos (Snelling 2008a). This is consistent with, and in support of, a young earth model.

Fig. 5. Composite schematic drawing of (a) a

218Po halo, (b) a 238U halo, (c) a 214Po halo, and (d) a 210Po halo, with radii proportional to the ranges of the α-particles in air. The nuclides responsible for the α-particles are listed for the different halo rings (after Gentry 1973). Because the rings which should be produced by the Po precursors are missing in many Po radiohalos (fig. 5) (Snelling, Baumgardner, and Vardiman 2003), the source of the Po for the radiohalos has been an area of contention (Snelling 2000). Was it primary, or did a secondary process transport it? Gentry (1986) proposed that the Po radiohalos had been produced by primordial Po, having an origin independent of any U, suggesting all granites and granitic rocks were formed by fiat creation. In contrast, based on all the available evidence, Snelling (2000) suggested a possible model for transporting the Po via hydrothermal fluids

during the latter stages of cooling of granite plutons to sites where the Po isotopes would have been precipitated and concentrated in radiocenters that then formed the respective Po radiohalos in the granites.Subsequently, Snelling and Armitage (2003) investigated the radiohalos in biotite within three granite plutons, demonstrating that these granite plutons had been intruded and cooled during the Flood. They found that the biotite grains contained both fully formed 238U and 232Th radiohalos around zircon and monazite inclusions (radiocenters) respectively, thus providing a physical, integral, historical record of at least 100 million years’ worth (at today’s rates) of accelerated radioactive decay during the recent year-long Flood. However, Po radiohalos were also often found in the same biotite flakes as the U radiohalos, usually less than 1 mm (0.04 in) away. Thus, they argued that the source of the Po isotopes must have been the U in the zircon grains within the biotite flakes, the same zircon inclusions that are the radiocenters to the U radiohalos.Because the precursor to 218Po is the inert gas 222Rn, which is produced by 238U decay in the zircon grains and is then capable of diffusing out of the zircon crystal lattice, Snelling and Armitage (2003) reasoned that the evidence confirmed the tentative model suggested by Snelling (2000). Concurrently, as the emplaced granite magma crystallizes and cools, the water dissolved in it is released below 400°C, causing hydrothermal fluids to begin flowing around the constituent minerals and through the granite pluton, including along the cleavage planes within the biotite flakes. Snelling and Armitage (2003) and Snelling (2005a) argued these hydrothermal fluids were capable of transporting 222Rn (and its daughter Po isotopes) from the zircon inclusions to sites where new radiocenters were formed by Po isotopes precipitating in lattice imperfections containing rare ions of S, Se, Pb, halides or other species with a geochemical affinity for Po. Continued hydrothermal fluid transport of Po would have also replaced the Po atoms in the radiocenters as they α-decayed to produce the Po radiohalos, thus progressively supplying the 5×109 Po atoms needed to form fully registered Po radiohalos. Significantly, none of the radiohalos (Po or U) could form or be preserved until the biotite crystals had formed and cooled below the thermal annealing temperature for α-tracks of 150°C (Laney and Laughlin 1981). Yet hydrothermal fluids probably started transporting Rn and the Po isotopes immediately after they were expelled from the crystallized granite at temperatures below 400°C. This implies that cooling of the Po-radiohalo-containing granite plutons had to be extremely rapid, in only 6–10 days (Snelling 2008a). Snelling, Baumgardner, and Vardiman (2003) and Snelling (2005a) have summarized this model for hydrothermal fluid transport of U-decay products (Rn, Po) in a six-step diagram. The final step concludes with the comment: With further passing of time and more α-decays both the 238U and 210Po radiohalos are fully formed, the granite cools completely and hydrothermal fluid flow ceases. Note that both radiohalos have to form concurrently below 150°C. The rate

at which these processes occur must therefore be governed by the 138 day half-life of 210Po. To get 218Po and 214Po radiohalos these processes would have to have occurred even faster. (Snelling 2005a) If the U and Po radiohalos both formed during the 6–10 days while the granite plutons cooled during the Flood, then this implies 100 million years’ worth of accelerated 238U decay occurred in a time frame of a few days. Thus the U-Pb isotopic systematics within the zircons in these granite plutons are definitely not providing absolute “ages” as conventionally interpreted. Field and Laboratory Methods Mapping and Sampling

July–September 1974 was spent geological mapping an area of almost 95 km2 (almost 37 sq. mi.) straddling the margins of the Bathurst Granite and the adjoining fossil-bearing sedimentary host rocks (figs. 2 and 6). The study area embraces the villages of Sodwalls and Tarana in the southeastern and southwestern corners respectively, and the village of Meadow Flat in the northwest corner (fig. 4). Access to much of the area was facilitated by the major western railroad from Sydney, and the Great Western Highway traverses across the northern boundary and passes through Meadow Flat.

Fig. 6. Regional outline of the

Bathurst Batholith, showing the location of the area mapped and sampled in July–September 1974 and locations of the regional samples collected in July 1999. Mapping was accomplished by using 1964 air-photo coverage of the Bathurst district (Bathurst Run Numbers 10 and 11, Photo Numbers 5162-5167 and 5057-5062, respectively). Pairs of aerial photos were closely examined through a stereoscopic viewer and the tentative boundaries between various rock units were annotated on the photos, along with the locations of outcrops. A tentative geologic map was then compiled from this air-photo interpretation by transferring it to a composite

overlay. The geological map produced (fig. 4) was originally at the air-photo scale of 1:38,000.This tentative geological map was field checked along the boundaries between the different strata, recording geologic details at different outcrops. Traverses were done on foot along the railroad, along creeks and their tributaries, and across ridges and hills. Various outcrops were appropriately sampled and significant features photographed, with the locations of these being carefully recorded on the geological map being compiled. Samples were named and numbered appropriately according to the various rock types. Where appropriate, strike and dip measurements were made on bedding planes in the outcrops of the sedimentary rock units, and such details were also recorded on the geological map being compiled.Further fieldwork was undertaken in the region in July 1999. The aim was to give a regional perspective to the previously mapped and sampled area, which represented only a small fraction of the margins of the Bathurst Batholith (fig. 6). Several outcrops were sampled along the highways and minor roads that skirt around and cross the batholith, the chosen samples being representative of the margins of the batholith for comparison with similar samples in the earlier intensely mapped area. Chemical Analyses

Seven samples collected during the 1974 fieldwork were selected for further chemical analyses. These included two from the Bathurst Granite, three from the Evans Crown dike (one from a feeder dike, one from the coarse-grained phase, and one from the chilled margin), and two samples of porphyry dikes that cross-cut both the Bathurst Granite and the Evans Crown dike. These samples were sent to the Perth (Western Australia) laboratories of Associated Laboratories of Australia Pty Ltd for whole-rock analyses. Laboratory Methods

Samples were crushed and pulverized. The following methods were then used to analyze the chemical compositions of these rocks: X-ray Fluorescence (XRF) fusion analysis was used to determine Si, Al, Fe, Ti, Ca, and K concentrations, as well as the loss on ignition (H2O±). To accomplish this, the pulverized samples were heated in a platinum crucible to 1000°C, fused with a lithium tetraborate based flux, and quenched quickly. A counting precision of ± 2% was obtained by accumulating more than 2500 counts per element peak. Detection limits were rather less than 500 ppm, depending on the matrix.Atomic Absorption Spectroscopy (AAS) was used to analyze for Mg, Mn, Na, Cu, and Mo following total acid attack of the pulverized samples. While Mg and Mn were included in the XRF fusion determination, the AAS method allows a 100-fold reduction in the detection limit. Precision, based on the measuring of light intensities, was better than 5%. Detection limits were all routinely 5 ppm.X-ray Fluorescence (XRF) pressed powder pellet analysis was used to determine S concentrations, assuming levels not much higher than 1%. Precision depended to a large extent on particle size, but a precision of ± 5% or ± 50 ppm has been consistently demonstrated at this laboratory.Once all the results were obtained the weight percents of the major elements were calculated, followed by distribution of oxygen proportionally to the various oxides in order to recalculate the oxide percentages. Trace elements were reported as ppm concentrations.Samples selected for radiohalos counting were thin-sectioned in order to characterize the mineralogy and textures of the different rock types, particularly the granites from the main batholith mass and satellite stocks, the granitic rocks from the dikes, and the host rocks adjoining the margins of the granite where metamorphism had occurred. Furthermore, an accurate assessment of the mineral content of several samples of the Bathurst Granite and the Evans Crown dike were obtained by point counting of thin sections for statistical analyses. Counting of Radiohalos

Twenty-four samples of granitic rocks were selected from those collected in 1974, and four granite samples collected in 1999. Of these 28 samples, twelve were of the Bathurst Granite, eight were from the Evans Crown dike (seven of coarse-grained granitic dike rock and one from the dike’s chilled margin), four were from granitic dikes intruded across the Bathurst Granite, two were from granitic dikes intruding through the Evans Crown dike, and two were from granitic dikes

cross-cutting the host sedimentary rocks.Portions of the 28 samples were crushed to liberate the biotite grains. Biotite flakes were then handpicked with tweezers from each crushed sample and placed on a piece of Scotch tape™ fixed to the flat surface of a laminated board on a laboratory table with its adhesive side up. Once numerous biotite flakes had been mounted on the adhesive side of this piece of tape, a fresh piece of Scotch tape™ was placed over them and firmly pressed along its length so as to ensure the two pieces were stuck together with the biotite flakes firmly wedged between them. The upper piece of tape was then peeled back in order to pull apart the sheets composing the biotite flakes, and this piece of tape with thin biotite sheets adhering to it was then placed over a standard glass microscope slide so that the adhesive side and the thin mica flakes adhered to it. This procedure was repeated with another piece of Scotch tape™ placed over the original tape and biotite flakes affixed to the board, the adhering biotite flakes being progressively pulled apart and transferred to microscope sides. As necessary, further handpicked biotite flakes were added to replace those fully pulled apart. In this way tens of microscope slides were prepared for each sample, each with many (at least 20) thin biotite flakes mounted on it. This is similar to the method pioneered by Gentry (1988). A minimum of 50 microscope slides was prepared for each sample (at least 1000 biotite flakes) to ensure good representative sampling statistics.Each slide for each sample was then carefully examined under a petrological microscope in plane polarized light and all radiohalos present were identified, noting any relationships between the different radiohalo types and any unusual features. The numbers of each type of radiohalo in each slide were counted by progressively moving the slide backwards and forwards across the field of view, and the numbers for each slide were then tallied and tabulated for each sample. Results Mapping and Sampling

The geological map resulting from the intense fieldwork is shown in Fig. 4 (Snelling 1974). Marked on the map are the interpreted boundaries between the various outcropping rock units in the area, the creek drainages, the villages, the major roads, and the railroad. The strike and dip measurements of the bedding in the host sedimentary units are recorded on the map in the locations they were obtained, and the numbered black dots represent the sample collection sites. Only those samples used in this radiohalos study are marked on the map. And around the borders of the map not only are the longitude east and latitude south coordinates marked, but there is also a one kilometer by one kilometer grid coordinates system marked and annotated for ease of referencing map locations.

Fig. 7. Panoramic view looking southwest

and west from the summit of Mt. Lambie (from Snelling 1974). To the left in the distance the Evans Crown dike is easily recognized with its prominent granite tors on the middle. Moving right the topographic hollow of the Solitary Creek valley is seen, as marked on Fig. 4. The Evans Crown dike crosses that valley and

forms the ridge (Evans Crown) in the middle of the view (center and right). The Deadman’s Creek valley separates the latter ridge and Mt. Lambie (just beyond the foreground). The Tarana Range looms in the background (middle right). Fig. 8. The local

composite stratigraphic cross-section, drawn approximately east-west through the summit of Mt. Lambie (from Snelling 1974). Fig. 9. View of the Solitary

Creek valley with the railroad from Sydney west to Parkes on the extreme right (from Snelling 1974). Bald Ridge (marked on fig. 4) lies in the center of the

view, with the Evans Crown dike cropping out along the ridge to the left. In the railroad cuts to the immediate right of Bald Ridge the Evans Crown dike is found to split into a multitude of coalescing smaller dikes. The margins of the Bathurst Granite occupy the low-lying land along Solitary Creek because the granite is more weathered. Fig. 10. Prominent outcrop of the Bathurst Granite in

the Meadow Flat stock at grid reference 928693 in Fig. 4 (from Snelling 1974). Fig. 11. Outcrop of the granitic Evans Crown dike at

grid reference 939636 in Fig. 4 (from Snelling 1974). Mineral variations within this dike parallel the jointing, which can be seen prominently running through the

crest of the outcrop. The host sedimentary rocks and stratigraphic sequences and relationships are shown in Fig. 3. Because they have been regionally metamorphosed, they are more resistant to weathering and erosion, so they form the higher ground in the panoramic view in Fig. 7. This view is looking west and southwest from the summit of Mt. Lambie, at 1284 m (4213 ft.) the highest point in the map area (fig. 4). The next ridge to the west (center and right in fig. 7) is the Evans Crown dike. These topographic variations according to the rock types can also be seen in the geological cross-section in Fig. 8, which cuts approximately east-west across Fig. 4 through the summit of Mt. Lambie. Because the Bathurst Granite is more weathered, it occupies the lower ground along Solitary Creek in the southern portion of the map area (fig. 4), as observed in Figs. 7 and 9. Adjacent to the margins of the Bathurst Granite in the west and north of the map area are outlying stocks of the same granite—the Eusdah and Meadow Flat stocks respectively (figs. 4 and 10). Cross-cutting the margin of the Bathurst Granite near Tarana and then through the surrounding host sedimentary rocks roughly northwards to form Bald Ridge

(figs. 4 and 9) and Evans Crown (fig. 7) is the granitic Evans Crown dike (fig. 11), which is estimated to be 12.8 km (8 mi.) long and often 0.8 km (0.5 mi.) wide. In the railroad cuts beside Solitary Creek to the immediate south of Bald Ridge within the Bathurst Granite the Evans Crown dike was found to split into multiple, coalescing smaller dikes. In the same area several granitic (acid) dikes are found within the Evans Crown dike, following and paralleling jointing. A few basaltic (basic) dikes (fig. 12) and numerous minor granitic dikes (similar to those that are within the Evans Crown dike) also cut across the margins of the Bathurst Granite, also following and paralleling jointing, and extend out into the surrounding host sedimentary strata (fig. 13). Good exposures of these dikes are seen in the many railroad cuts between Sodwalls and Tarana (fig. 4). Up to 45 m (about 150

ft.) wide, these granitic dikes have the same mineral composition as both the Bathurst Granite and the Evans Crown dike, often with the same porphyritic texture.The regional context of the mapped area in relation to the whole Bathurst Batholith is shown in Fig. 6. The sites from which the regional samples of the Bathurst Granite were collected are marked. These chosen samples were representative of the batholith and very similar in appearance and composition to the Bathurst Granite in the mapped area. Fig. 12. A basaltic (basic) dike cutting across the Bathurst granite in a railroad cut at grid reference 948587 in Fig. 4 (from

Snelling 1974). Notice the parallel jointing in both the dike and the granite, due to the basaltic magma having intruded along the jointing in the granite. Fig. 13. View of the weathered Bathurst Granite along the Solitary Creek valley at grid reference 958584 in Fig. 4 (from

Snelling 1974), showing the linear outcrops of cross-cutting dikes which can be traced across the fields.

Chemical Analyses

The whole-rock chemical analyses for the selected granitic rocks are listed in Table 1. Included in this table is a sample of the Bathurst Granite from the Sodwalls area (sample 2) whose chemical analysis was reported by Joplin (1963). Photomicrographs representative of some of the samples of the Bathurst Granite, the Evans Crown dike and the minor granitic dikes are provided in Fig. 14. The mineral contents of selected

samples of the Bathurst Granite and the Evans Crown dike obtained by point counting of thin sections, the modal analyses, are listed in Table 2.

Fig. 14. Photomicrographs

representative of some of the samples of the Bathurst Granite, Evans Crown dike, and granitic dikes intruding them used in this study, as seen under the microscope. Their locations are plotted on Fig. 4. All photomicrographs are at the same scale (20× or 1 mm = 40μm) and the granites are as viewed under crossed polarized light. Bathurst Granite:–

(a) Sample RBG-4: K-feldspar (plain mid gray), quartz (light color), biotite (bright colors partly extinguished). (b) Sample ASI-32: plagioclase (striped gray), K-feldspar (plain dull gray), biotite (bright colors), sphene (prismatic crystal), quartz (light color). (c) Sample ASI-32: quartz (light yellowish color), biotite (bright colors partly extinguished), sphene (prismatic crystal), K-feldspar (plain mid and dull gray), magnetite (black). (d) Sample ASI-31: plagioclase (striped gray), K-feldspar (plain mid gray), biotite (bright colors), magnetite (black). (e) Sample ASI-23: plagioclase (striped gray), quartz (light yellowish color), biotite (bright colors), K-feldspar (plain mid gray). (f) Sample ASI-23: plagioclase (striped gray), quartz (light yellowish color), K-feldspar (plain mid gray), biotite (bright colors). Evans Crown dike:–

(g) Sample ASI-46: biotite (bright colors), K-feldspar (plain mid gray), plagioclase (speckled gray due to alteration to sericite). (h) Sample ASI-46: K-feldspar (plain mid gray), plagioclase (remnant striping and speckled gray due to alteration to sericite). (i) Sample ASI-17: biotite (dark brown due to alteration), altered plagioclase (right, striped speckled mid gray) and K-feldspar (left, speckled mid gray). (j) Sample ASI-17: altered plagioclase and K-feldspar (speckled mid gray and black), minor quartz (light yellowish color). Granite dikes:–

(k) Sample ASI-57: minor quartz (light yellowish color), altered plagioclase (crystal shape right, speckled mid gray) and K-feldspar (speckled mid gray and black). (l) Sample ASI-109: minor quartz (light yellowish color), altered plagioclase (crystal shape top, speckled mid gray) and K-feldspar (speckled mid gray and black). (m) Sample ASI-110: plagioclase (speckled gray and brown due to alteration to sericite and iron oxides), K-feldspar (plain mid gray), biotite (bright colors). (n) Sample ASI-110: plagioclase (speckled gray and brown due to alteration to sericite and iron oxides), biotite (bright colors), K-feldspar (plain mid gray). Table 1. Whole-rock chemical analyses, expressed in oxide percent,

of Bathurst Granite and granitic dikes of the Tarana-Sodwalls area (from Snelling 1974).

1. Granite, Sodwalls. Analyst—Associated Laboratories of Australia 2. Granite, Sodwalls. Analyst—W. G. Stone (Joplin 1963) 3. Porphyry dike, between Sodwalls and Tarana. Analyst—Associated Laboratories of Australia 4. Dikes of the Evans Crown dike Railway Cuttings. Analyst—Associated Laboratories of Australia 5. Chilled Margin, Evans Crown dike. Analyst—Associated Laboratories of Australia 6. Coarse-grained phase, Evans Crown dike. Analyst—Associated Laboratories of Australia 7. Porphyry dike near Sodwalls. Analyst—Associated Laboratories of Australia 8. Granite, Meadow Flat. Analyst—Associated Laboratories of Australia Click table to view larger version. Counting of Radiohalos

Fig. 15. Photomicrographs of some representative 238U and 210Po radiohalos in biotite flakes in samples of the Bathurst

Granite, Evans Crown dike, and granitic dikes intruding them, as seen under the microscope. All the biotite grains are as viewed in plane polarized light, and the scale bars are all 50 μm (microns) long. Bathurst Granite: samples ASI-32 (a), (b) (c) and (d); ASI-23 (e) and (f). Bathurst Granite: samples ASI-31 (g); RBG-3 (h) and (i); ASI-68 (j) and (k); and ASI-37 (l). Evans Crown dike: samples ASI-46 (m); and ASI-44 (n). Granitic dike intruding Bathurst Granite: sample ASI-57 (o) and (p). Granitic dike intruding Evans Crown Dike: sample ASI-110 (q) and (r). Photomicrographs of some representative radiohalos are shown in Fig. 15. The statistics of the counted radiohalos in the 28 chosen granitic samples are listed in Table 3. The number of radiohalos per slide was calculated by adding up the total number of all radiohalos found in each sample, divided by the number of slides made and viewed for counting of radiohalos. The number of Po radiohalos per slide was calculated in a similar way, except it was the total number of Po radiohalos divided by the number of slides examined for that sample. And finally, the ratio in the last column was calculated by taking the number of 210Po radiohalos and dividing by the number of 238U halos. Table 2. Modal analyses of the mineral contents of the Bathurst Granite and the Evans Crown dike of the Tarana-Sodwalls area obtained by point counting of thin sections.

1. Bathurst Granite, Sodwalls. (Mackay 1959) 2. Bathurst Granite, Sodwalls. (Mackay 1959) 3. Bathurst Granite, Sodwalls. 4. Bathurst Granite, Sodwalls. 5. Evans Crown dike. (Mackay 1959) 6. Evans Crown dike. (Mackay 1959) 7. Evans Crown dike. 8. Evans Crown dike. Click table to view larger version. Table 3. Radiohalos count statistics for samples of the Bathurst Granite and granitic dikes of the Tarana-Sodwalls area.

Click table to view larger version. Discussion Results of the Present Study

In the mapped area there is a definite sequence for the formation of the granitic rocks. The fossil-bearing sedimentary rocks were first intruded by the major pluton of the Bathurst Granite. Fig. 16 shows the contact of the Bathurst Granite (right) with the host fossil-bearing Lambie Group sedimentary strata in a railroad cut at grid reference 993589 in Fig. 4 (from Snelling 1974). Notice the vein-like apothyses of granite protruding into the sedimentary strata from the granite to the left of the line of contact. Also notice that the bedding of the sedimentary layers has been disturbed near the contact. Both these observations indicate the granite had the constituency of a hot magma that flowed as it forced its way up and into the host sedimentary strata, rather than being a cold, solid body that was tectonically emplaced. Fig.16. The contact of the Bathurst Granite (right) with

the host Lambie Group sedimentary strata in a railroad cut at grid reference 993589 in Fig. 4 (from Snelling

1974). Notice the vein-like apothyses of granite protruding into the sedimentary strata from the granite to the left of the line of contact. Further observations to answer this question of whether the granite was hot or cold when intruded are readily available. The granite at the contact and in the apothyses in Fig. 16 is coarse-grained and is the same as the granite outcropping elsewhere in the pluton, so the intruding granite body appears to have been at a uniform temperature. If the pluton had been tectonically emplaced there should be evidence in the contact zone either of melting and recrystallization or of mechanical crushing of the granite. If melting and recrystallization had occurred, then the granite at the contact with the sedimentary strata and in the apothyses could be expected to be of a noticeably different grain size than the granite in the main body, contrary to what is observed. Alternately, if any mechanical crushing had occurred at the margin of the granite body, then the granite and the host sedimentary layers at the contact should exhibit signs of mylonitization, which is not evident. Also, no vein-like apothyses would be expected, as those indicate fluid flow, and not mechanical crushing. Additionally the hot granite intrusion would have impacted the adjacent host fossil-bearing sedimentary strata, creating the observable contact metamorphic aureole. As already noted (Fig. 16), it is evident that the sedimentary layering very close to the granite contact has been disturbed, not crushed, likely both by intrusion of the main granite body and of the apothyses. This would have been due to the mechanics of fluid flow of a hot magma, rather than tectonic emplacement of a cold body. Nevertheless, the definitive observation that is consistent with intrusion of a hot granitic magma is the contact metamorphism of the host sedimentary strata adjacent to the granite margin. Fig. 17. ACF-A′KF diagrams for the contact metamorphism of the sedimentary strata in the aureole adjoining the margin

of the Bathurst Granite in the Tarana-Sodwalls area (from Snelling 1974). (A) The albite-epidote-hornfels facies. (B) The hornblende-hornfels facies. Both Mackay (1959) and Snelling (1974) cataloged the contact metamorphic mineral assemblages in the aureole adjacent to the margins of the Bathurst Granite in the Sodwalls-Tarana area (fig. 4). These mineral assemblages are summarized in the ACF-A′KF diagrams in Fig. 17. The depicted mineral assemblages of the albite-epidote-hornfels facies are found in the host sedimentary rocks in the outer fringes of the contact aureole where the temperatures of contact metamorphism were very low. Furthermore, many of these same minerals characterize the assemblages typical of the greenschist facies produced by the regional burial metamorphism of these sedimentary strata. However, the mineral assemblages of the

hornblende-hornfels facies in the aureole closer to the contact with the Bathurst Granite stand out in clear contrast to the regional burial metamorphism of the surrounding host sedimentary strata. This facies embraces the majority of rocks that form the obvious contact aureole. It is also significant that sillimanite, which is characteristic of the even higher temperature pyroxene-hornfels facies, is not present in the aureole even closer to the contact, but is found in the granite right at the boundary (Snelling 1974).

Fig. 18. Diagram showing the pressure-

temperature (P-T) fields of the four facies of low-pressure contact metamorphism (after Turner 1968). The pressure-temperature (P-T) conditions in the contact aureole can be determined by the experimental calibration curves for the mineral reactions. Fig. 18 depicts the P-T fields of these facies of contact metamorphism (Turner 1968). The position of the minimum melting curve for quartz-orthoclase-albite (Qz-Or-Ab) implies the highest temperature at the least pressure (that is, the shallowest depth) at which the hornblende-hornfels facies would be produced in this aureole against the molten Bathurst Granite is 700°C and 2 kb pressure, approximately equivalent to a depth of less than 5 km (3 mi.) (Bucher and Fry 2002).

Confirmation that the depth of granite emplacement was shallow is indicated by the observations of jointing and flow banding in the granite consistent with those outcrops near the roof of the pluton (Snelling 1974), and confirmed by measurements of the stratigraphic thicknesses above the granite. Independent confirmation that the granite would have been molten at 700°C (or more) is consistent with experimental work on granite formation (Johannes and Holtz 1996; Tuttle and Bowen 1958).Field relationships clearly indicate that the Evans Crown dike intruded into a major fracture through the Bathurst Granite and also penetrated across into the surrounding sedimentary strata. The dike’s central portions are coarse and even-grained like the Bathurst Granite, but the margins are chilled against the host granite. These relations indicate the dike intruded as a hot granitic magma similar to that of the Bathurst Granite (and likely even from the same magma source). Other observations indicate the Bathurst Granite had cooled considerably prior to this dike’s intrusion. Some of the chilled margins in the dike exhibit pronounced flow-banding texture parallel to the contact (Snelling 1974). Furthermore, the development of graphic quartz-feldspar intergrowths, myrmekitic outgrowths and reaction-rimmed grains in the dike also suggest the Bathurst Granite had cooled prior to the dike’s intrusion.

Fig. 19. A typical granitic (acid) dike within the Bathurst Granite in a railroad cut at grid reference 963586 in Fig. 4 (from

Snelling 1974). Notice the jointing in the dike and the alteration zones in the Bathurst Granite marginal to the dike due to the heat and fluids during its intrusion. Following intrusion of the Evans Crown dike, residual granitic magma intruded as smaller dikes that cut across the Bathurst Granite. These dikes follow joints and fractures within and parallel to the Evans Crown dike, and they also continue out into and across the host sedimentary strata. Both reaction textures and mineral intergrowths within these granitic dikes suggest the phenocrysts crystallized prior to the injection of the dikes into the Bathurst Granite, and also across the Evans Crown dike (Snelling 1974). Alteration zones marginal to the sharp contacts of the dikes with the wall-rocks indicate the magma was still hot when injected, and the dikes are frequently flow-banded parallel to these contacts (fig. 19).Whole-rock chemical analyses of the granitic rocks are listed in Table 1 in order of

increasing silica (SiO2) content. Note that the Bathurst Granite samples have the lowest silica content, and that in the later dike phases (both the Evans Crown dike and the smaller dikes that intrude it and the Bathurst Granite) the silica content is increased. This silica trend somewhat parallels the time sequence of intrusion, which is consistent with the interpretation that later granitic dike phases were derived from residual magma of the Bathurst Granite. This relationship is well-recognized and characterized in the literature (Hall 1996). The exception is the Meadow Flat Granite in the satellite stock, north of the mapped area (fig. 4), which is lithologically similar to the Bathurst Granite, but has the highest silica content of the samples (table 1). This may suggest that because the stock was intruded peripherally to the main body of the batholith, it intruded laterally as a residual magma from the main Bathurst Granite pluton. Fig. 20. Triangular plot of modal plagioclase, orthoclase and quartz in 260 thin sections of granites from the eastern

United States (after Chayes 1951; Tuttle and Bowen 1958). The contours from the outside inwards are more than 0, 2, 5, and 7% respectively (0.25% counter). The pioneering experimental work of Tuttle and Bowen (1958) led to the development of graphical schemes for the classification of granitic rocks based on both modal and normative analyses. Modal analyses are obtained by direct point counting of the observed mineral contents of the rocks in thin sections, whereas normative analyses rely on calculating the ideal mineral contents from the oxides obtained in whole-rock chemical analyses. Once obtained, the modal and normative analyses were recast or normalized so that the three components quartz, orthoclase and plagioclase, and quartz, orthoclase and albite respectively totalled 100% for each rock. These were then plotted on triangular composition diagrams with the respective minerals at their apices (figs. 20 and 21). The surprising results were that both schemes plotted around the same point, the point representing one third of each mineral component, and corresponded exactly with the results

of their laboratory work on artificial silicate systems. Fig. 21. Contoured triangular diagram showing the distribution of normative albite, orthoclase and quartz in all 1269

analyzed rocks in Washington’s (1917) tables containing 80% or more combined albite + orthoclase + quartz (after Tuttle and

Bowen 1958). The internal triangle labeled abc indicates the compositions considered to be granites (or rhyolites) in the present classification of sialic (acid) rocks. Fig. 22. Paths of crystallization in the three component (quartz + orthoclase + albite) “magma” towards the point of lowest

temperature, 660–700°C (point M) (after Tuttle 1955; Tuttle and Bowen 1958).

Tuttle (1955), Tuttle and Bowen (1958) and Johannes and Holtz (1996) discuss the magmatic origin of granite based on experimental work on artificial silicate systems. Tuttle and Bowen (1958) demonstrated that the path of crystallization in the three component system quartz-orthoclase-albite reaches its minimum temperature of 660–700°C when the components are in equal proportions (fig. 22). This point coincides with the clustering of the modal and normative analyses of the same three components on the same triangular compositional diagram (figs. 20 and 21), thus leading to the overwhelming conclusion that the analyzed granites were truly of magmatic origin. Tuttle and Bowen (1958) went on to show that sediments at 37 km (23 mi.) depth could melt to form a granitic magma at 630°C if sufficient water were present. Johannes and Holtz (1996) have subsequently shown that at the pressure and temperature conditions indicated for the contact metamorphism of the host sediments at the granite contact (2 kb and 700°C), the Bathurst Granite would have to have been intruded with a water content of 4–5 wt % in the magma, which has been found to be a common water content for granitic magmas (Hall 1996; Johannes and Holtz 1996). Table 4. Normative analyses of orthoclase, albite (plagioclase) and quartz in the Bathurst Granite and Evans Crown dike of the Tarana-Sodwalls area derived from the chemical analyses in Table 1. (A) The raw normative proportions. (B) The adjusted proportions, normalized to 100%.

1. Bathurst Granite, Sodwalls. (Mackay 1959) 2. Bathurst Granite, Sodwalls. (Mackay 1959) 3. Bathurst Granite, Sodwalls. Analyst—W. G. Stone (Joplin 1963) 4. Bathurst Granite, Sodwalls. Analyst—Associated Laboratories of Australia 5. Evans Crown dike. (Mackay 1959) 6. Evans Crown dike. (Mackay 1959) 7. Evans Crown dike. Analyst—Associated Laboratories of Australia 8. Evans Crown dike. Analyst—Associated Laboratories of Australia Table 5. Modal analyses of the Bathurst Granite and Evans Crown dike of the Tarana-Sodwalls area adjusted to only their quartz, orthoclase and plagioclase contents.

1. Bathurst Granite, Sodwalls. (Mackay 1959) 2. Bathurst Granite, Sodwalls. (Mackay 1959) 3. Bathurst Granite, Sodwalls. 4. Bathurst Granite, Sodwalls. 5. Evans Crown dike. (Mackay 1959) 6. Evans Crown dike. (Mackay 1959) 7. Evans Crown dike. 8. Evans Crown dike. The results of both the modal and normative analyses of the granitic rocks of Bathurst Batholith in the Tarana-Sodwalls area (Tables 1 and 4A) can thus be recast or normalized so that their three components quartz, orthoclase, and plagioclase, and quartz, orthoclase, and albite respectively totalled 100% for each rock (tables 4B and 5). These compositions were then plotted on the three component triangular diagrams in Figs. 23 and 24. Not surprisingly the Bathurst Batholith granitic rock values cluster in much the same way as Tuttle and Bowen’s (1958) data (figs 20 and 21). Furthermore, a quick comparison of the modal and normative values of the Tarana-Sodwalls granitic rocks (plotted in figs. 23 and 24, respectively) with the path of magmatic crystallization to its minimum temperature of 660–700°C when the quartz-orthoclase-albite components are in equal proportions (fig. 22), demonstrates that they also coincide to Tuttle and Bowen’s (1958) data (figs. 20 and 21). This suggests that the granitic rocks of the Bathurst Batholith also have a magmatic origin.

Fig. 23. Triangular plot of the modal quartz, orthoclase and plagioclase in the samples of the Bathurst Granite and the

Evans Crown dike in the Tarana-Sodwalls area as recorded and numbered in Table 4. All samples plot within the adamellite field. Fig. 24. Triangular plot of the normative quartz, orthoclase and albite in the

samples of the Bathurst Granite and the Evans Crown dike in the Tarana-Sodwalls area as recorded and numbered in Table 5. All samples plot within the triangle abc indicating the compositions are granites as formally classified.. Abundant 238U and 210Po radiohalos are present in biotite flakes of all samples of the Bathurst Granite and Evans Crown dike (table 3 and fig. 15a–l and m–n respectively). 214Po and 218Po radiohalos are only present in some samples of the Bathurst Granite (table 3), but in one sample (RBG-4) they are present in comparatively large numbers, especially the 218Po radiohalos. A few 210Po and 238U radiohalos are also present in biotite flakes within some samples of the dikes that cut across the Bathurst Granite or the Evans Crown dike (table 3 and fig. 15o–p and q–r, respectively).The 238U radiohalos in Fig. 15 are “over exposed,” meaning there has been so much rapid 238U decay that the resultant heavy discoloration of the biotite has blurred all the inner rings (compare with fig. 5). Often only holes remain in the centers of the 238U radiohalos where the tiny zircon radiocenters have been lost during the peeling apart of the biotite flakes to tape them to the microscope slides. In Fig. 15g a visible zircon radiocenter is so large it has distorted the radiohalo’s shape. In Fig. 15 there are also numerous examples of incomplete radiohalos stains. These are due to the biotite sheets not peeling apart through the radiocenters of these (spherical) radiohalos during preparation of the microscope slides. These stains usually represent 238U radiohalos, but sometimes 210Po radiohalos. Nevertheless, only the visible complete radiohalos where the radiocenters were visible are recorded in Table 3. The 210Po radiohalos are easily identified by their single

outer ring about 39 μm (microns) in diameter (fig. 5). Usually their radiocenters are hollow “bubbles” or empty holes where former “bubbles” were destroyed, which is consistent with hydrothermal fluids having deposited the 210Po atoms there, which then α-decayed to discolor the biotite and form the radiohalos. Sometimes the 210Po radiocenters are only about 100 μm from the nearby 238U radiocenters in the same biotite flake (fig. 15c, d, l, and m). The hydrothermal fluids thus did not have far to transport 222Rn and Po from the 238U radiocenters to form and supply the 210Po radiocenters. This likely occurred within weeks so that the 238U and 210Po radiohalos formed concurrently. Fig. 15 (a, e, l, m, n, and r) shows “over-exposed” 210Po radiohalos. This is indicative of a lot of 210Po atoms having been in the radiocenters that then decayed. Spreading of the radiation damage is often due to the large sizes of many radiocenters, which appear to now be empty “holes” that may originally have been fluid-filled “bubbles.” There are also remnants of much larger fluid inclusions in several biotite flakes (fig. 15b, e, f, h. i, q, and r). And finally, in Fig. 15e, k, o, and q are 210Po radiohalos consisting of 210Po radiation staining around elongated radiocenters that appear to have been fluid inclusions. The data for all the samples from each rock unit are listed in Table 3 and summarized in Table 6. All granitic rock units contain more 210Po radiohalos than 238U radiohalos (except the dikes which intrude the sedimentary rocks and contain no radiohalos at all). There is a distinct pattern in the radiohalo abundances according to the sequence of intrusion of the different granitic rocks. Table 6. Summary of the radiohalos data for the different granitic rock units of the Tarana-Sodwalls area, including several regional samples of the Bathurst Granite (see table 3).

The radiohalo abundance for the Bathurst Granite are highly inflated by one sample, RBG-4, which comes from just on the edge of the main study area near Tarana (fig. 6). This sample comes from near a small prospector’s mine where there was copper and gold mineralization found in hydrothermal veins (Raymond et al. 1998; Snelling 1974). Snelling (2005a) found that there were higher numbers of radiohalos in granites associated with hydrothermal ore veins and lodes, such as those hosted by the Land’s End Granite in Cornwall, UK, and in and around the Mole Granite in the New England area of eastern Australia. Thus this solitary anomalous Bathurst Granite sample with high numbers of radiohalos (2270210Po radiohalos, 23 214Po radiohalos, 520 218Po radiohalos, 1694 238U radiohalos, and 31 232Th radiohalos—see RBG-4 in table 3) would appear to be consistent with its proximity to an area of higher hydrothermal fluid flows, which lends support to the hydrothermal fluid flow model for Po transport to form Po radiohalos (Snelling 2000, 2005a; Snelling and Armitage 2003). Excluding sample RBG-4, the Bathurst Granite has on average 2.22 210Po radiohalos and 2.7 total radiohalos per microscope slide, with a ratio of 1.6 210Po radiohalos for every 238U radiohalo (table 6). As expected, the Meadow Flat stock, which is an outlying extension of the Bathurst Granite, has similar radiohalo statistics to the Bathurst Granite, with an average of 1.98 210Po radiohalos and 2.64 total radiohalos per microscope slide, with a ratio of 3 210Po radiohalos for every 238U radiohalo. In contrast, the coarse-grained inner section of the Evans Crown dike has on average 0.65 210Po

radiohalos and 0.74 total radiohalos per microscope slide, but a ratio of 6.6 210Po radiohalos for every 238U radiohalo (see the samples in brackets in table 6, compared to the total figures that include the sample from the fine-grained margin). Similarly, radiohalo numbers are low in the dikes cutting through the Bathurst Granite and Evans Crown dike, with averages of 0.03 210Po radiohalos and 0.03 total radiohalos per microscope slide and 0.07210Po radiohalos and 0.08 total radiohalos per microscope slide, respectively. But the ratio at seven 210Po radiohalos for every 238U radiohalo in the dikes cutting through the Evans Crown dike is higher. Results Compared to Previous Models

In conventional thought, the Po radiohalos observed in the Bathurst Granite are “a very tiny mystery” (G. Brent Dalrymple, as quoted by Gentry, 1988, p. 122) that can be conveniently ignored because they have little apparent significance. However, the reality is that the mystery of the Po radiohalos is often ignored because it constitutes a profound challenge to conventional wisdom.Comprehensive reviews of what these Po radiohalos are and how they may have formed are provided by Gentry (1973, 1974, 1986, 1988) and Snelling (2000). Gentry (1974) has established that all the observed Po radiohalos are generated exclusively from the Po radioisotopes in the 238U decay series, namely, 218Po, 214Po, and 210Po, with contributions from none of the other species in the 238U α-decay chain. Furthermore, it has been estimated that, like the 238U radiohalos, each visible Po radiohalo requires between 500 million and 1 billion α-decays (Gentry 1988), equating to a corresponding number of Po atoms in each radiocenter. Yet the half-lives of these Po radioisotopes are only 3.1 minutes (218Po), 164 microseconds (214Po), and 138 days (210Po), so how did so many Po atoms get concentrated into these radiocenters, before they decayed, to then generate the Po radiohalos?Gentry (1986, 1988, 1989) insists that the Po must be primordial, that is, the Po radioisotopes was created instantaneously in place in the radiocenters in the biotite flakes in the granites, and thus the granites are also created rocks. In other words, he argues that granites did not form from the crystallization and cooling of magmas, but rather are the earth’s original foundation rocks.Moreover, where granites such as the Bathurst Granite have intruded into fossiliferous Flood-deposited strata, Gentry (1989) insists that these granites also represent originally created rocks. He argues that during the Flood they were tectonically intruded as cold bodies, and that the contact metamorphic aureoles were produced by the heat and pressure generated during tectonic emplacement, augmented in some cases by hot fluids from depth. Thus, in the case of the Bathurst Granite, he would surmise it was tectonically emplaced during the Flood, but he would have to also argue that the Evans Crown dike and the dikes intruding it and the Bathurst Granite were subsequently and sequentially emplaced tectonically. Alternately he would argue the Bathurst Granite was created then tectonically emplaced during the Flood, yet somehow the Evans Crown and the other dikes were then sequentially intruded into the Bathurst Granite and the host sediments.Such interpretations are inconsistent with the field and petrological evidence from the Bathurst Granite and the dikes, and with the experimental evidence discussed above. The contact between the Bathurst Granite and the regionally metamorphosed fossiliferous (Flood-deposited) host rocks it intruded is a sharp, knife-edge boundary, with none of the fracturing, brecciation, or mylonization that should be evident in either the granite or host rocks if the granite had been intruded tectonically as a cold body (fig. 16). Instead, there are apothyses or veins of granite intruding into the host sedimentary layers, and a contact metamorphic aureole with mineralogy consistent with the temperatures of the granite magma when it intruded (figs. 18 and 22). Furthermore, the mineralogy and textures of the Evans Crown dike and the dikes which intrude into it and the Bathurst Granite are very similar to and identical with those of the Bathurst Granite (fig. 14). This is entirely consistent with a magmatic origin for all these granitic phases from the same magma source, but is not in any way consistent with the Bathurst Granite being created cold and the subsequent granitic dikes being a result of local melting of the Bathurst Granite during its cold tectonic emplacement during the Flood. The chilled margin of the Evans Crown dike against the Bathurst Granite and the host sedimentary rocks is also consistent with its intrusive magmatic origin.Gentry (1989) postulated hot fluids augmented the heat and pressure during tectonic emplacement of cold granite bodies to produce the contact aureoles, and presumably the local melting of the granite at its margin to produce veins and apothyses, and in the case of the Bathurst Granite, also the formation of the granitic magma that then intruded as the Evans Crown dike and subsequent dikes. However, if the theorized accompanying hot fluids from depth had a temperature of >150°C, as likely they would have to locally melt granite, then they would have left evidence of their passage within the Bathurst Granite and annealed all the radiohalos in it (Laney and Laughlin 1981). There is no observable evidence of any pervasive alteration produced by hydrothermal fluids, either macroscopically or microscopically, in the Bathurst Granite. In fact, the only evidence of extensive hydrothermal fluid flows in the Bathurst Granite is in the one sample (RBG-4) in proximity to hydrothermal ore veins, showing an increase in the numbers of Po radiohalos, consistent with the hydrothermal fluid model for transport of the Po atoms as a requirement to form the Po radiohalos (Snelling 2005a; Snelling and Armitage 2003). Evidence Supporting the Hydrothermal Fluid Transport Model

We conclude that the presently observed Po radiohalos in the Bathurst Granite and its associated granitic dikes could only have been generated after the granite had cooled below 150°C (Laney and Laughlin 1981). Thus the Po radiohalos were formed after the Bathurst Granite was intruded as magma and after it and its contact metamorphic aureole in the host rocks had cooled. The only other model at present that explains the formation of the Po radiohalos is the hydrothermal fluid transport model (Snelling 2005a; Snelling and Armitage 2003). In that model it is postulated that the Po isotopes, as well as the 222Rn parent of 218Po, were produced from 238U decay in the zircons which are the radiocenters of nearby 238U radiohalos located in the same biotite flakes as the Po radiohalos. The hydrothermal fluids released by the crystallizing and cooling granite magma flowed along the biotite cleavage planes and transported the222Rn and Po isotopes from the zircon radiocenters (fig. 25). The Po isotopes, including the 218Po produced by 222Rn α-decay (half-life of 3.8 days), likely precipitated in lattice defects along the same biotite cleavage planes where S, Cl, and other atoms chemically attractive to Po were located, remaining within about a millimeter of the zircon radiocenters. These Po precipitation sites became the subsequent radiocenters for the Po radiohalos. As the Po in the radiocenters α-decayed, new Po atoms were supplied from hydrothermal fluids flowing through the biotite lattice (fig. 25). Thus, provided the supply of Po isotopes was sufficient and the hydrothermal fluid flows were sustained and rapid, the required Po concentrations could have been supplied to the radiocenters to produce the 500 million–1 billion Po α-decays to generate the Po radiohalos within hours or days, consistent with the very short half-lives of the Po isotopes.

Fig. 25. Time sequence of diagrams to show schematically the formation of 238U and 210Po radiohalos concurrently as a

result of hydrothermal fluid flow along the biotite flakes within a cooling granite mass (after Snelling 2005a). (a) Diagrammatic cross-section through a biotite flake showing the sheet structure and perfect cleavage. A tiny zircon

crystal (left) has been included between two sheets and its 238U content has generated a 238U radiohalo. A 210Po radiohalo (right) has also developed around a tiny radiocenter between the same two sheets. Its radiocenter contains no visible inclusion, being just a bubble-like “hole” left behind by loss of the original inclusion, probably by dissolution of the solid phases. (b) Enlarged diagrammatic cross-section through a biotite flake that has crystallized from a granite magma to 300°C. The

radioactive 238U in an included zircon crystal is emitting α-particles, while hydrothermal fluids released from the cooling magma are flowing along the cleavage planes dissolving the U decay products—222Rn and Po isotopes—that have diffused out of the tiny zircon crystal and carrying them downflow a short distance where they also emit α-particles. (c) However, at temperatures >150°C the α-tracks are annealed, so no radiohalos form and there is no α-track record of

the hydrothermal fluids containing Rn and Po flowing at a rate of up to 5 cm (2 in) per day along the cleavage plane. A few S atoms also transported in the hydrothermal fluids become lodged in lattice defects downflow of the zircon crystal. (d) As the temperatures approach 150°C and 222Rn decays to 218Po, the Po isotopes in the hydrothermal fluids which

have a geochemical affinity for S precipitate to form PoS as the fluids flow by the S atoms in the lattice defects. The 238U in the zircon continues to decay and replenish the supply of Rn and Po isotopes in the fluids. (e) Once the temperature drops to below 150°C, the α-tracks produced by continued decay of both the 238U in the zircon

and the Po in the PoS are no longer annealed and so start discoloring the biotite sheets, forming both 238U and 210Po radiohalos concurrently. More Po isotopes in the flowing hydrothermal fluids replace the Po in the PoS after it decays to Pb, the “freed” S atoms scavenging yet more Po from the passing fluids. (f) With further passing of time and more α-decays both the 238U and 210Po radiohalos are fully formed, the granite cools

completely and hydrothermal fluid flow ceases. Note that both radiohalos have to form concurrently below 150°C, and that the original content at the center of the 210Po radiohalo has been dissolved and carried away. The rate at which these processes occur must therefore be governed by the 138 day half-life of 210Po. To get 218Po and 214Po radiohalos the processes would have to have occurred even faster. Click image to view larger version. Because hydrothermal fluid flows are crucial to this Po radiohalos formation model, it might be expected that the greater the volume and flow of hydrothermal fluids, the greater the probability that more Po radiohalos would be generated. This prediction has shown to hold true in several situations. First, in granites where hydrothermal ore deposits have formed in veins due to large, sustained hydrothermal fluid flows, there are huge numbers of Po radiohalos (for example, the Land’s End Granite, Cornwall [Snelling 2005a]). Second, where hydrothermal fluids were produced by mineral reactions, at a specific pressure-temperature boundary during regional metamorphism, four to five times more Po radiohalos were generated, precisely at that specific metamorphic boundary (Snelling 2008b). Third, the Po radiohalos numbers also progressively decreased where the hydrothermal fluids generated in the central granite at the highest grade within a regional metamorphic complex flowed and decreased outwards into that complex (Snelling 2008c). Fourth, in a granite pluton which has an atypically wide contact metamorphic and metasomatic aureole around it due to the high volume of hydrothermal fluids it released during its crystallization, Po radiohalos numbers were shown to be higher than in other granite plutons (Snelling 2008d). Fifth, in a sequentially intruded suite of nested granite plutons where the hydrothermal fluid content of the granites correspondingly increased, so that the last intruded central pluton was connected to coeval explosive, steam-driven volcanism, the numbers of Po radiohalos generated increased inwards within the nested suite of

granite plutons (Snelling and Gates 2009). Such evidence provides confirmation that the hydrothermal fluid transport model can explain the generation of the Po radiohalos. Suggested Model for the Bathurst Granite

The hydrothermal fluids generated by the crystallization and cooling of the Bathurst Granite produced several effects indicating a large volume of sustained fluid flow was involved. Hydrothermal fluids dispersed the heat released by the crystallizing granite by convection into the host rocks. The heat from these fluids likely helped to generate the contact metamorphic aureole around the granite (Mackay 1959; Snelling 1974). Additionally, in one location near Tarana, the hydrothermal fluids penetrated along fractures in the host rocks, beyond the aureole, to deposit ore veins of copper and gold (Raymond et al. 1998; Snelling 1974). Then, within the granite itself, the numbers of Po radiohalos are consistent with sustained hydrothermal fluid flows. The tiny zircon grains that are still at the centers of the many 238U radiohalos in the Bathurst Granite would have been the source of the Po isotopes transported by the hydrothermal fluids to generate the Po radiohalos. However, the general absence of 214Po and 218Po radiohalos in the Bathurst Granite and the granitic dikes implies both a generally reduced supply of hydrothermal fluids and a slow rate of hydrothermal fluid transport, restricting the formation of those radiohalos due to their very short half-lives. It also implies that 222Rn was likely absent in the hydrothermal fluids. Therefore, Po was most likely transported primarily as210Po in the fluids to the nucleation sites where the 210Po radiohalos formed.A constraining factor on the preservation of the Po radiohalos is that the damage left by the α-particles is retained in the biotite flakes only below 150°C (Laney and Laughlin 1981). Above this α-particle annealing temperature the damage either doesn’t register or is obliterated. Thus all the radiohalos now observed in the Bathurst Granite had to form below 150°C, late in the cooling history of the granite. Granite magmas intrude at temperatures of 650–750°C, and the hydrothermal fluids are released at temperatures of 370–410°C, after most of the constituent minerals have crystallized (fig. 26). However, the accessory zircon grains, containing the 238U, crystallize very early at higher temperatures, and likely were already formed in the magma before and during intrusion. Thus the 238U decay producing the Po isotopes had begun well before the granite had fully crystallized, and before the hydrothermal fluids had begun flowing. Furthermore, by the time the temperature of the granite and the hydrothermal fluids had cooled to 150°C, the heat energy driving hydrothermal fluid convection would have likely begun to wane and the vigor of the hydrothermal flow would also have begun to diminish (fig. 26). If the processes of magma intrusion, crystallization and cooling required 100,000–1 million years, as is conventionally claimed (Pitcher 1993; Young and Stearley 2008), most of the Po would have already decayed and thus been lost from the hydrothermal fluids by the time the granite and fluids had cooled to 150°C, leaving no Po isotopes left to generate the Po radiohalos (Snelling 2008a). Fig. 26. Schematic, conceptual, temperature versus time cooling curve diagram to show the timescale for granite

crystallization and cooling, hydrothermal fluid transport, and the formation of polonium radiohalos (after Snelling 2008a). The data in Tables 3 and 6 show that Po radiohalos greatly outnumber 238U radiohalos in the Bathurst Granite. There are likely two reasons for this. First, many of the 238U radiohalos are dark and overexposed with blurred inner rings (fig. 15), which indicates that there has been an enormous amount of 238U decay, much more than the 500 million–1 billion atoms needed to produce a radiohalo with distinct inner rings. This implies that there likely would have been enough Po generated to form multiple Po radiohalos in the vicinity of each 238U radiohalo. Second, as noted above, much evidence suggests that the greater the volume and flow of hydrothermal fluids, the greater the number of Po radiohalos generated. A reasonably large volume of hydrothermal fluids

apparently flowed within and through the Bathurst Granite and the associated dikes. Thus, there was a great capacity for hydrothermal fluid transport of Po atoms to supply the observed Po radiohalos. Rapid Formation of the Bathurst Granite

Conventional thinking on the timescale for the granite intrusion, crystallization, and cooling processes used to claim granite formation took more than a million years (Pitcher 1993; Young and Stearley 2008). However, it is now recognized that granite formation is a rapid, dynamic process operating on timescales as short as thousands of years (Clemens 2005; Petford et al. 2000). Various studies have shown that emplacement of a melt is rapid via dikes and fractures, and assisted by tectonics (Clemens and Mawer 1992; Coleman, Gray, and Glazner 2004). Other studies have shown that melt cooling is aided by hydrothermal fluids and groundwater flow (Brown 1987; Burnham 1997; Cathles 1977; Hardee 1982; Hayba and Ingebritsen 1997). Formation of these granites, from emplacement to cooling, therefore had to have been on a timescale that previously has been considered impossible. The processes of magma generation, segregation, ascent,

emplacement, crystallization, and cooling are now being viewed even as catastrophic (Snelling 2008a, Snelling and Woodmorappe 1998; Vardiman, Snelling, and Chaffin 2005). Catastrophic Granite Formation and Accelerated Decay

Both catastrophic granite formation and accelerated radioisotope decay are relevant to the hydrothermal fluid transport model for Po radiohalo formation (Vardiman, Snelling, and Chaffin 2005). Halo formation provides constraints on the rates of both those processes (Snelling 2005a). If 238U in the zircon radiocenters supplied the Po isotopes required to generate the Po radiohalos, the 238U and Po radiohalos must have formed in hours or days, as required by the Po isotopes’ short half-lives. This requires 238U production of Po to be grossly accelerated. The 500 million–1 billion α-decays necessary to generate each 238U radiohalo, equivalent to at least 100 million years’ worth of238U decay at today’s decay rates, had to have taken place in hours to days to supply the required concentration of Po for producing Po radiohalos. However, because accelerated 238U decay in the zircons would have occurred as the zircons crystallized at 650–750°C (fig. 26), the granite magma must have fully crystallized and cooled to below 150°C very rapidly. If not, the 238U in the zircons would have rapidly decayed away, as would have also the daughter Po isotopes, before the biotite flakes were cool enough for the 238U and Po radiohalos to form and survive without annealing. Furthermore, the hydrothermal fluid flows needed to transport the Po isotopes along the biotite cleavage planes from the zircons to the Po radiocenters are not long sustained, even in the conventional framework, but decrease rapidly due to cooling of the granite (fig. 26) (Snelling 2008a). Therefore, Snelling (2005a) concluded that granite intrusion, crystallization, and cooling processes occurred together over a timescale of only about 6–10 days.Thus sufficient Po had to be transported quickly to the Po radiocenters to form the Po radiohalos while there was still enough energy at and below 150°C to drive the hydrothermal fluid flows rapidly enough to get the Po isotopes to the deposition sites before they decayed. This is the time and temperature “window” depicted schematically in Fig. 26. It would thus simply be impossible for the Po radiohalos to form slowly over many thousands of years at today’s groundwater temperatures and chemistries in cold granites. Hot chemically enriched hydrothermal fluids are needed to dissolve and carry the Po atoms, and heat is needed to drive rapid hydrothermal convection to move Po transporting fluids fast enough to supply the Po radiocenters to generate the Po radiohalos. Furthermore, the required heat cannot be sustained for the 100 million years or more while sufficient 238U decays at today’s rates to produce the 500 million–1 billion Po atoms needed for each Po radiohalo.One consequence of accelerated 238U decay is that the decay of the Po isotopes might also be similarly accelerated, and thus there would not have been enough time for hydrothermal fluid transport of the radioactive Po atoms within the biotite flakes. However, Austin (2005) and Snelling (2005b) have shown that in an accelerated α-decay episode the parent isotopes which today have the slowest decay rates (and thus yield the oldest ages on the same rock samples) had their decay accelerated the most. The implication of this observation is that in an accelerated α-decay episode, the Po isotopes which decay at extremely high rates today should have experienced almost no acceleration of their decay. This inverse relationship of decay rate to accelerated decay would, therefore, have allowed enough time for hydrothermal fluid transport of the Po atoms to generate the Po radiohalos.However, what requires the hydrothermal fluid flow interval to be so brief? Surely, because the zircon radiocenters and their 238U radiohalos are near to (typically within only 1 mm [0.04 in] or so) the Po radiocenters in the same biotite flakes, could not the hydrothermal flow have indeed carried each Po atom from the 238U radiocenters to the Po radiocenters within minutes, but the interval of hydrothermal fluid flow persist over many thousands of years during which the billion Po atoms needed for each Po radiohalo are transported that short distance? In this case the 238U decay and the generation of Po atoms could be stretched over that longer interval. However, as already noted above, by the time a granite body and its hydrothermal fluids cool to below 150°C, most of the energy to drive the hydrothermal convection system and fluid flow has already dissipated (Snelling 2008a). The hydrothermal fluids are expelled from the crystallizing granite and start flowing at between 410 and 370°C (fig. 26), so unless the granite cooled rapidly from 400°C to below 150°C, most of the Po transported by the hydrothermal fluids would have been flushed out of the granite by the vigorous hydrothermal convective flows as they diminished. Simultaneously, much of the energy to drive these fluid flows dissipates rapidly as the granite temperature drops. Thus, below 150°C (when the Po radiohalos start forming) the hydrothermal fluids have slowed down to such an extent that they cannot sustain protracted flow. Moreover, the capacity of the hydrothermal fluids to carry dissolved Po decreases dramatically as their temperature decreases.In summary, for there to be sufficient Po to produce Po radiohalos after the Bathurst Granite cooled to 150°C, the timescales of the decay process as well as the cooling both must be on same order as the lifetimes of the Po isotopes. The hydrothermal fluid flows had to be rapid, as the convection system was short-lived while the granite crystallized and cooled rapidly within 6–10 days, and as they transported sufficient Po atoms to generate the Po radiohalos within hours to a few days.Furthermore, if the formation of the large volume, Bathurst Granite was rapid in order for the radiohalos present in it to exist, it follows that the formation of the intruded granitic dikes in this field area which also contain Po radiohalos had to be likewise rapid. The numbers of Po radiohalos in these subsequent granitic dikes decrease in order of their intrusion, with the narrower granitic dikes containing fewer Po radiohalos intruded after the Evans Crown dike (table 6). On the other hand, the ratio of 210Po radiohalo numbers per each 238U radiohalo increases according to the time sequence in which these units were intruded, from around 4:1 in the Bathurst Granite to 6.6:1 in the Evans Crown dike to 7:1 in the granitic dikes intruding the Evans Crown dike. This is consistent with an increase in hydrothermal fluids being progressively released with each subsequent granitic intrusion. This is further corroborated by the evidence of increased hydrothermal alteration observed in the Evans Crown dike and the subsequently intruded granitic dikes (fig. 14), and is consistent with all these granitic rocks being sourced from the same magma body late in its “life.” Thus the granitic magma that was intruded as the Evans Crown dike was likely residual magma from the Bathurst Granite, while the remaining residual magma then intruded into the Evans Crown dike. Such an increase in the volume of hydrothermal fluids in a sequence of granitic intrusions has already been documented by Snelling and Armitage (2003) in the zoned La Posta Pluton in the Peninsular Ranges Batholith east of San Diego, and by Snelling and Gates (2009) in the nested plutons of the Tuolumne Intrusive Suite of Yosemite, California.Thus the significance of the progressively increasing Po radiohalo numbers relative to 238U radiohalos numbers in granitic intrusions within the Bathurst Batholith (table 6), according to the order in which they were intruded, implies that there were progressively more hydrothermal fluids per volume with each successive intrusion from the Bathurst Granite pluton to the large Evans Crown dike to the narrow granitic dikes intruding them both. The increase in the hydrothermal fluids in the later stages of the intrusive sequence is likely due to the water released as the intrusive phases crystallized and cooled building up in the later residual intrusive phases; particularly if the hydrothermal fluids are not readily escaping out into the surrounding host rocks. Whereas many other granite plutons intruded into sedimentary rocks containing connate and ground waters that assisted rapid granite cooling by convection outwards from the plutons (Snelling and Woodmorappe 1998), the large Evans Crown dike intruded into the Bathurst Granite pluton, and then narrower granitic dikes subsequently intruded into them both. Consequently, since granites have poor connective porosities and therefore poor permeabilities, the successively generated hydrothermal fluids would have been essentially “trapped” in the later intrusive phases.Since these granitic intrusions in the Bathurst Batholith were

successively intruded into one another, there were severe constraints, due to the 150°C thermal annealing temperature of the radiohalos. The lapse of time between the intrusion of each phase of the batholith had to be extremely short, as each phase had to be rapidly emplaced, crystallized and cooled before the next phases were injected, so that the entire intrusion sequence of pluton and dikes was in place before the radiohalos began forming below 150°C. Otherwise, the heat given off by each successively emplaced phase, which intruded its predecessors, would have annealed all radiohalos in them. Confirmation that each phase had crystallized and cooled before the next phase was intruded is demonstrated by the lack of contact metamorphic effects where the Evans Crown dike intrudes the Bathurst Granite and where the smaller dikes cut into the Bathurst Granite and the Evans Crown dike, by the chilled margin of the Evans Crown dike, and by alteration zones marginal to the smaller dikes (Snelling 1974). It can therefore be concluded that the successive development of the batholith was a relatively rapid emplacement process. However, so that annealing of the radiohalos would not occur above 150°C, all the phases of the batholith had to have intruded so rapidly that the Bathurst Granite pluton, and the stocks, satellite bodies, and subsequent large and small dikes making up the batholith cooled below 150°C more or less at the same time. Furthermore, because of the short half-life of 210Po and the need for the hydrothermal fluids within the cooling granite masses to rapidly transport sufficient 210Po to supply the radiocenters to form the 210Po radiohalos before the 210Po decayed, the successive emplacement and cooling of this successive series of intrusions could not have taken more than a week or two.Survival of the Po radiohalos as a result of the rapid sequential emplacement of these intrusions also implies that there could not have been a “heat problem” due to accelerated radioactive decay (Snelling 2005a). The mechanisms that dissipated the heat from these crystallizing and cooling magmas (Snelling 2008a; Snelling and Woodmorappe 1998) did so rapidly and efficiently without annealing the Po radiohalos in the surrounding earlier intruded phases of this suite of intrusions. Thus this entire intrusive event that lasted only a week or two, consisting of successive pulses of granite magma emplacement and cooling, fits easily within the time frame of the year-long Flood event. Extension of Model to Other GranitesThe Bathurst Granite does not appear to be unique, but rather is typical of other granites, in terms of its mineralogy, chemistry, texture, and the hydrothermal fluids it generated. Thus this model for its rapid formation and cooling can be extended to other granite bodies, as has been done by Snelling (2005a, 2008a, d), Snelling and Armitage (2003), and Snelling and Gates (2009). Many other granites are surrounded by aureoles, though many are often larger. Almost all granites show evidence of the hydrothermal fluids they generated as they crystallized and cooled. The ubiquitous presence of Po radiohalos (Snelling 2005a) is also testimony to these hydrothermal fluids. In those granites where fewer Po radiohalos suggest less hydrothermal fluids were produced, the presence of Po radiohalos indicates there were still sufficient hydrothermal fluids to cool them rapidly. The volume of the Bathurst Batholith is very large. Yet, the volume of the nested granite plutons of the Tuolumne Intrusive Suite of Yosemite, California, is comparable to that of the Bathurst Batholith, and Snelling and Gates (2009) built a strong case that each of those plutons also formed and cooled rapidly. Because this model of rapid formation and cooling has been applied successfully to other granite bodies, it can be concluded that each of the plutons, stocks, satellite bodies and subsequent large and small dikes making up the Bathurst Batholith likewise formed and cooled rapidly. Conclusions

The Bathurst Granite intruded Flood-deposited, fossiliferous sedimentary strata, disrupting them and producing a contact metamorphic zone. It was then itself intruded by the Evans Crown dike, which has a chilled margin. Finally, smaller granite dikes intruded both the Bathurst Granite, Evans Crown dike and the host sedimentary strata, producing adjacent alteration zones. Field and textural data have established that these granite phases were sequentially intruded while still hot. Analytical and experimental data confirm that these granitic phases were intruded rapidly as hot magma, contradicting Gentry’s concept of their cold creation and tectonic emplacement during the Flood. Evidence suggests all granitic phases were intruded from the same magma source, with the release of hydrothermal fluids as the magmas crystallized and cooled. All three granite phases contain 238U and Po radiohalos. The Po radiohalos indicate rapid formation after all the granites cooled below 150°C via hydrothermal fluid transport of Po from 238U decay in the zircon grains in the biotite flakes that are usually in the radiocenters of the 238U radiohalos. Their presence in all three, sequentially intruded, granite phases is evidence that all this intrusive activity, and the cooling of all three granite phases to below 150°C, must have occurred within a week or two so that the Po radiohalos in them subsequently formed within days to weeks during the Flood year.

Radiohalos and Diamonds Are Diamonds Really for Ever?

by Dr. Andrew A. Snelling and Mark Armitage on September 9, 2009

Abstract We offer an explanation for the radiohalos and for the “tubes” in these diamonds in terms of a hydrothermal fluid transport model for Po radiohalo formation. Keywords: radiohalos, diamonds, diamond

inclusions, zircons, polonium, kimberlite, hydrothermal fluids, cleavagesThis paper was originally published in the Proceedings of the Sixth International Conference on Creationism, pp. 323–334 (2008) and is

reproduced here with the permission of the Creation Science Fellowship of Pittsburgh and the Institute for Creation Research, Dallas. Abstract

Radiohalos were first reported in diamonds more than a decade ago. Since that time little work has been done to locate other radiohalo-bearing diamonds, to explain the origin of the radiohalos, or evaluate their significance. We conducted a search for such diamonds secured from a variety of sources and identified radiohalos containing one, three and four rings, as well as strange features in the form of twisted crystalline “tubes.” New data suggest a radiohalo annealing temperature in diamond above 620ºC. We offer an explanation for the radiohalos and for the “tubes” in these diamonds in terms of a hydrothermal fluid transport model for Po radiohalo formation. Introduction

Diamonds are probably the most intensely sought after of all the mineral gems known to man. India was the earliest producer of diamonds in the sixth century, with monarchs as their primary customers. Diamonds remained very rare and

only a privileged few had them, until the first commercial diamond mine was opened in the late 1860s in South Africa.1 It was Marilyn Monroe who in 1953 immortalized the phrase, “Diamonds are a girl’s best friend” in a song from the movie Gentlemen Prefer Blondes. Of course, it had already become accepted practice for a marriage proposal to be

secured with a diamond ring. It was DeBeers, a privately owned commercial enterprise, and still the largest seller of diamonds in the world with revenues of US$65 billion in 2005 alone, who in 1947 launched the successful “A Diamond is Forever” marketing campaign.2 The unmatched brilliance of the sparkle of diamonds, their sizes and colors make them desirably attractive, but it is their unique hardness and resistance to physical weathering that give them their durability. Today, over 130 million carats (US$10–13 billion) of diamonds are mined annually.3Tiny, microscopic radioactive halos (or radiohalos for short,) were first reported in diamonds only a decade ago.4, 5 This discovery elicited some brief discussion,6, 7, 8 but little has been done since to elucidate their enigma. The purpose of this study was to find additional diamonds containing radiohalos and to investigate in greater depth how they might have formed. Diamonds

Diamonds are classified into two major categories—Type I, which contain nitrogen, and Type II, which do not.9 There are four generally recognized sub-categories based on the form and placement of the nitrogen, and the presence or absence of boron. Type Ia diamonds, for example, which may comprise over 98% of the world’s natural diamonds, contain from 200 ppm up to a maximum of 5500 ppm nitrogen distributed in small clusters or aggregates of nitrogen atoms through the diamonds.10 Diamonds in this category are normally colorless, light yellow or brown. Type Ib diamonds, which comprise around 1% of natural diamonds, are yellow and contain lesser atoms (150–600 ppm) of nitrogen in individual carbon substitution sites. Normal colors of this type range from light to bright yellow or even amber. Type IIa diamonds comprise less than 1% of all diamonds and contain very small concentrations of nitrogen atoms in the range of 4–40 ppm (undetectable or barely detectable by infrared spectroscopy). These diamonds are generally colorless or brown. Some of the world’s very large diamonds are in this category. Type IIb diamonds, the rarest and purest type, contain up to around 20 ppm boron and even less nitrogen. These are usually blue or grey in color, and are electrically conductive.The origin and formation of diamonds is not yet completely understood, but it is generally accepted that diamonds crystallized from a liquid melt in the earth’s upper mantle at depths of between 150 and 300 km.11 At these depths the temperatures range from 1100–2900° C and the pressures range from 50–100 kilobars, as calculated and confirmed by laboratory studies of the minerals in rock fragments brought up from the earth’s upper mantle with the diamonds in volcanic rocks.12 Some diamonds may even have formed at depths of 450 km below the earth’s surface, because of the great temperatures and pressures required for certain mineral inclusions in them to form.13Most natural diamonds so far discovered are thought to have crystallized between 1 and 3 billion years ago in mantle rock containing relatively high concentrations of magnesium and iron.14, 15 The processes of diamond formation are inferred on the basis of what is known of conditions in the earth’s upper mantle at 150–300 km depth.16, 17, 18 The origin of the carbon source for diamonds is also still very much debated.19, 20, 21 Once formed, the diamonds seemed to have resided for hundreds of millions up to 2 billion years in the upper mantle beneath the Archean keels of the continental Precambrian cratons. The diamond phase of carbon, once crystallized, remains stable there, because of the high temperatures and pressures.It is generally postulated that localized melting of the mantle subsequently occurred to produce a magma rich in CO2and H2O, either a kimberlite or lamproite. This volatile-rich magma then began rising explosively through the mantle areas containing the diamonds and transported the diamonds through the crust to the earth’s surface at speeds of 10–30 km per hour via propagating cracks in the mantle and the crust above.22, 23 The kimberlite and lamproite magmas cooled as they approached the earth’s surface and therefore hardened, so the resultant explosive eruptions often shattered the solidified magmas in what were cold volcanic eruptions. What remained in the conduit and the material that settled back into it after the eruptions contains the diamonds in pipe-like structures. If these kimberlite and lamproite magmas did not ascend catastrophically from the upper mantle to the earth’s surface within 8–24 hours, the diamond crystals would have become unstable at the changing pressure and temperature conditions during their passage and would have reverted to graphite. At the earth’s surface these kimberlite and lamproite pipes weather and are eroded so the diamonds are shed into alluvial deposits in river systems, deltas and along coastlines. The diamonds that remain in the pipes may be mined, often from great depths. For some diamond deposits no formation process has been proposed.24, 25, 26, 27Efforts to produce gem-grade synthetic diamonds, though intensive, have produced only meager results. In 1955 researchers at General Electric successfully synthesized tiny industrial-grade diamonds over several weeks of extreme laboratory temperatures and pressures over intervals of several weeks.28 Since then many small industrial-grade diamonds have been produced (some estimates are as high as 100,000 carats per year). In order to produce these diamonds, carbon must be subjected to very high pressures and temperatures in the presence of transition metals (or some other “seed”) to get the reaction started.29, 30, 31 Although gem quality diamonds as large as 5 carats have been produced, the cost of production generally remains prohibitively high. DeBeers claims that their equipment can detect the difference between synthetic and natural diamonds; but that claim is highly disputed. Synthetic gemstones larger than 1 carat are not readily produced or available.Diamonds, along with other gemstones, were present in and on the earth, so if diamonds are really as “old” as claimed, then they may date back to the original creation. Their presence in the earth’s crust today and at the earth’s surface may then largely be due to the subsequently eruption of kimberlite and lamproite magmas during the Flood. Diamonds and their origin have occasionally featured in creationist news reports and literature.32, 33, 34, 35, 36, 37, 38, 39 Inclusions in Diamonds

Natural diamonds (and many other crystalline materials) often encase smaller grains or crystals of other minerals within their crystalline matrices, and these are known as inclusions. Twenty to thirty different minerals have been described as inclusions inside natural diamonds, along with 58 different types of impurities, including uranium and thorium.40 Synthetic diamonds also suffer from inclusions, but these are mostly metal fragments introduced in the manufacturing process.41 In the case of the natural diamonds, these included minerals must have been present at the time the diamonds formed to be incorporated within the diamond matrix. As far as has been ascertained, diamonds are almost completely chemically inert and extremely resistant to any contamination or chemical exchange within their crystal lattice. This means they would have traveled from the earth’s upper mantle and through the crust to the earth’s surface carrying these inclusions completely intact and unchanged during the 150–300 km ascent.42, 43, 44, 45, 46Therefore, these inclusions represent tiny “capsules” of mantle materials captured under mantle conditions that have been safely delivered from the upper mantle to the earth’s surface. Yet there are some as yet unexplained mysteries concerning the types of inclusions found in diamonds. For example, it is well known that sulfides represent the most common inclusions in diamonds, implying that these sulfides formed in the mantle. Yet many mantle xenoliths brought from the upper mantle to the earth’s surface by volcanic eruption contain only small quantities of sulfides.47Furthermore, it is puzzling as to how saline liquids and water, plus gases, are often encapsulated as fluid inclusions within diamonds at such depths (and pressures).Inclusions consist of, but are not limited to, apatite, calcite, carbonates, chromite, smaller diamonds, garnet, hematite, iron, mica, pyrite, pyroxene, silicates, sulfides, zircon, and, as mentioned, liquids (such as liquid CO2, water and even brine) and

gases.48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58Frequently mineral inclusions contain radioactive nuclides such as uranium or thorium incorporated within the crystalline lattice of the inclusion. These radioactive nuclides eject alpha particles as a normal part of the radioactive decay process. Alpha-particles travel some distance in the mineral (and then into the surrounding host) depending on the energy at which they were ejected from the nucleus of the nuclide as well as the characteristics of the crystalline material(s). The crystalline lattice structure of inclusions, including zircons, may tend to become somewhat amorphous over time if sufficient self-irradiation takes place.59, 60The presence of zircons in diamonds is considered rare, but they have been previously reported.61, 62 It may be that few reports of zircon inclusions have appeared because zircons are not expected to be at depths in the mantle where diamonds are thought to form.63 The consensus is that zircons exist predominately in the earth’s crust. Because of their extreme hardness, it is unlikely that diamonds can incorporate zircons from the crust during their ascent from the mantle to the earth’s surface (J. Baumgardner, pers. comm., April 2, 2007). Nevertheless, zircon inclusions occur within diamonds and have been reported.64, 65 Furthermore, there have even been reports of diamond inclusions within zircons,66, 67, 68 but these are microdiamonds formed under ultrametamorphic conditions in the earth’s crust.69, 70Zircons are known to contain radioactive nuclides (such as described above) and they are also well known in their role as radiocenters for 238U radiohalos, which have been observed in biotite, chlorite, cordierite, fluorite, sapphire, quartz, and other minerals.71, 72, 73, 74, 75, 76, 77, 78 One well-known researcher commented, however, that he was not aware of any report describing uranium in diamond (K. N. Bozhilov, pers. comm., June 16, 2006). Nevertheless, zircon inclusions in sapphires are known to contain uranium, the parent radionuclide for polonium79 and others have described such radioactive elements in other rocks from diamond-bearing kimberlites.80Radiohalos are minute circular areas (in cross-section) of discoloration and darkening caused by damage from α-particle radiation emanating from a tiny central inclusion containing radioactive elements such as U and Th.81, 82 The damage is mostly from point vacancies produced in the crystal lattice of the host mineral by the α-particles. The identity of the isotopic species responsible for a given ring in the darkened region can be determined from the ring’s diameter, which is proportional to the energy of the alpha particles emitted by the isotopic species. The rare element polonium (Po) is momentarily produced as three isotopes in the 238U decay chain—218Po, 214Po and 210Po. Whereas a 238U radiohalo consists of eight rings, radiohalos are also found with only three, two, and one rings, resulting from, respectively, the α-decay of these three Po isotopes. Such 218Po, 214Po, and 210Po radiohalos had to have been produced with the respective Po isotopes exclusively present in their radiocenters. It has been estimated that each radiohalo requires between 500 million and 1 billion α-particles to form it.83Doubts have been raised concerning whether radiohalos interpreted as polonium radiohalos have been correctly identified. For example, Moazed, Spector, and Ward84 and Moazed, Overbey, and Spector85 claim that single-, double-, triple- and quadruple-ring radiohalos can clearly and unambiguously be shown to have been generated by the 238U and 232Th decay chains, rather than by “parentless” polonium isotopes as proposed by Gentry.86, 87, 88, 89 This claim is based partly on the issue of potential uncertainties in the ion microprobe analyses of the halo radiocenters. However, Gentry90, 91 and Gentry, Hulett, Cristy, McLaughlin, McHugh, and Bayard92 have refuted this claim, demonstrating that due care was taken in these analyses, and other techniques were employed for comparison to rule out such uncertainties. Furthermore, most of the many others that disagree with Gentry’s model for the formation of these polonium radiohalos have accepted their correct identification (for example, Damon,93 Dutch,94 Wakefield,95Wilkerson,96 York97). Indeed, Collins98 goes further and specifically includes the Moazed, Overbey, and Spector99claim in his list of attempts to explain Gentry’s conundrum that are not fully satisfactory. In any case, Meier and Hecker100 have conclusively shown that polonium radiohalos are sometimes associated with polonium bands generated by the polonium being transported by hydrothermal fluids along fractures. Thus the overwhelming consensus is that the polonium radiohalos have been correctly identified.The formation of Po radiohalos has thus been somewhat enigmatic, given the short half-lives of the three Po isotopes—3.1 minutes, 164 microseconds and 138 days, respectively. Conventionally the Po radiohalos have been called “a very tiny mystery” without further explanation (Dalrymple, as quoted by Gentry101). The mystery in question is how these polonium isotopes could have been derived and separated from a nearby source of 238U to then be concentrated in radiocenters to produce the Po radiohalos, all within ten half-lives of these Po isotopes, corresponding to their effective life-spans (1.64 milliseconds in the case of 214Po). Therefore, Gentry102, 103, 104, 105 proposed that the polonium had to have been primordial, created in place in the radiocenters and then nearly instantaneously produce the Po radiohalos. Furthermore, he maintained, if the Po was primordial, then the host crystals and rocks (for example, biotite flakes and their host granites) also had to have been created at the same time. However, as pointed out by Wise106 and Snelling,107 many granites that contain Po radiohalos appear from their geologic contexts to have been formed during the Flood, and therefore cannot have been primordial (that is, created) granites. This in turn implies that the Po which generated the Po radiohalos in those granites could not have been primordial Po. Indeed, Snelling and Armitage108 studied three specific Po-radiohalo–bearing granite plutons that they demonstrated had to have been generated and formed during the Flood. Therefore, Snelling and Armitage109 and Snelling110 proposed a hydrothermal fluid transport model for Po radiohalo formation, which has been tested and verified by subsequent studies (Snelling,111, 112, 113 Snelling and Gates114).Mendelssohn, Milledge, Vance, Nave, and Woods115 reported finding radiohalos on the outer surfaces of opaque diamonds using cathodoluminescence. Armitage,116, 117 however, was the first to report optically-visible, multiringed internal radiohalos in a Type Ia diamond. Despite the fact that exact size matching with the radiohalos observed in biotites was difficult because of the greater density of the diamond’s carbon structure reduces the penetration distance of the α-particles, these radiohalo rings were nevertheless identified as produced by 218Po, 214Po, 210Po, and 222Ra. Furthermore, these radiohalos were found along rod-like structures and at the termini of strange hollow tubes that were bent repeatedly at right angles within the diamond. Wise118 suggested that these structures represented fluid conduits along which the radioisotopes responsible for parenting these radiohalos had been transported into the diamond, but both Armitage119 and Gentry120 maintained that this interpretation was not viable due to the diamond’s unfractured internal crystal structure. They insisted instead that the short half-lives of the radioisotopes responsible for the rings in the radiohalos suggested a primordial origin for the radioisotopes and thus the diamond. Nevertheless, Vicenzi, Heaney, Snyder, and Armstrong121 reported radiation halos 25 micrometers in diameter in alluvially deposited polycrystalline diamonds (carbonados) from the Central African Republic, which they maintained were generated as a result of uranium deposition from a single pulse of fluids infiltrating the diamonds following their formation. Furthermore, whereas J. W. Harris (pers. comm., May, 2007) has claimed, “over decades of looking at millions of diamonds I have only once seen a green set of haloes inside a stone,” jewelers and gemologists in southern California testify to having regularly seen radiohalo inclusions in diamonds and other gemstones (Armitage, pers. comm. with jewelers in southern California, April, 2007; May, 2007). Diamonds Examined

Sixty-nine small diamonds and diamond chips from diamond mines in Kimberley (South Africa), Jwaneng (Namibia), and Orapa (Botswana), and from alluvial diamond deposits in Namibia and Guinea, were examined for radiohalos. These

diamonds were in the possession of Dr. John Baumgardner at the Institute for Creation Research in Santee, California. The two diamonds with radiohalos in them examined in this study were on loan from the Gemological Institute of America laboratory (GIA), Carlsbad, California, courtesy of Dr. John Koivula and Thor Strom. The first of these diamonds was a 0.06 carat, faceted stone from an unknown source. The other was described as a 0.11 carat diamond macle (or oddly shaped crystal) from the Diamantina mines, Gerias, Brazil.The diamonds of interest were photographed with film on a Zeiss Jena dissecting light microscope configured with multiple fiber optic illuminators and an Olympus SLR film camera body. Illumination of radiohalos proved difficult particularly since both specimens had been carbon-coated for examination with scanning electron microscopy (SEM), but SEM was not performed in this study. Prints of the negatives made were digitally scanned.Twenty different jewelry stores in three counties in southern California were visited over a period of several weeks. Jewelers and gemologists at those stores were interviewed. Half of the proprietors stated that they had seen such radiohalo inclusions in diamonds and other gemstones previously but none of the twenty had any gemstones available for examination. Results

No radiohalos were found in any of the African diamonds. However, large numbers of various inclusions (including possible zircons) were found in them and some in the Orapa diamond were photographed (fig. 1).

Fig. 1. Small inclusions in diamond from Orapa mine, Africa.

Magnification 250×. Scale bar = 300 microns. Radiohalos with one, three, and four rings were found in the GIA diamonds. The round brilliant cut 0.06 carat diamond from an unknown source contained dozens of radiohalos and “etch trails” (figs. 2–4). Documentation was provided with this diamond. It described “etch trails” which intersected with the radiocenters of each halo sharply bent at differing angles (see fig. 4). These “etch trails” did not extend to the surface. Therefore, the diamond girdle was ground away by GIA personnel until contact with the etch trails was made (see ground girdle on figs. 4–5). The text stated that inclusions were solid (crystalline?) and that “they appear to have a hexagonal outline.” These radiohalos (both 3

and 4 ring varieties) were measured with a calibrated ocular micrometer to 50 micrometers diameter.The diamond macle (oddly shaped crystal) from Brazil (figs. 7–8) contained dozens of radiohalos, but only of the single ring variety. This documentation supplied with this specimen stated “this 0.11 carat diamond macle is from Diamantina mines, Gerais, Brazil. Its radiation spots with central ‘cores’ are from some unknown substance. These spots started out green and changed to brownish orange when the diamond was heated to 620°C. The first change in spot color was noticed at 590–600°C.” These radiohalos (single ring only) were measured with a calibrated ocular micrometer to 30 micrometers diameter.DiscussionThe crucial factor in the occurrence of the radiohalos within these two diamonds is the temperature at which radiohalos are annealed. At the annealing temperature the vibrations of the atoms in the crystal structure have increased sufficiently to repair the point vacancies caused by the previous α-particle bombardment, such that the

darkening, and thus the radiohalos, are erased. In biotites, radiohalos are erased above 150°C.122 This annealing temperature was determined using samples taken from a drill-hole in which present in situ temperatures had been measured, and so could be interpreted as having been determined under natural conditions. In contrast, Armitage and Back123 placed biotite flakes containing radiohalos in an oven, heating them at temperatures up to 700°C for up to five hours. They found

erasure of radiohalos occurred after only an hour of heating at temperatures of 250–550°C. However, it is not known whether radiohalos in diamonds are annealed at 150–250°C. The Brazilian macle diamond was reported to have been heated to 620°C without complete loss of radiohalos. This would seem to imply that the annealing temperature of radiohalos in diamonds is higher than 620°C. Fig. 2. Round, brilliant cut diamond. Note radiohalos at 12 o’clock position. Scale bar = 0.3 mm

Fig. 3. Radiohalos in round diamond. Magnification 80×. Scale bar = 450 micrometers.

Fig. 4. Radiohalos in round diamond. Note right and sharp angles made by crystalline tubes. Magnification 80×. Scale bar

= 450 micrometers. Fig. 5. Radiohalos in round diamond. Magnification 100×. Scale bar = 160 micrometers.

Fig. 6. Radiohalos in

round diamond. Magnification 200×. Scale bar = 75 micrometers. Fig. 7. Radiohalos in

macle diamond from Brazil. Magnification 200×. Scale bar = 1 mm. The temperatures at the 150–300 km depths in the upper mantle where

diamonds are inferred to have formed are 1100–2900°C. Of course, any radiohalos would only be generated in diamonds after the diamonds formed at those temperatures. If the annealing temperature of radiohalos in diamonds is higher than 620°C, there is a greater temperature window (compared with the 150°C annealing temperature of radiohalos in biotites) in which magmatic and hydrothermal fluids could transport 238U and its decay products into and within diamonds. This assumes that238U, its decay products, or tiny crystals of a mineral such as zircon hosting them, had not been included in diamonds when they formed. Zircon inclusions in diamonds are considered to be rare, but at the upper mantle temperatures at which diamonds have supposedly resided for hundreds of millions of years, before transport to the earth’s surface by kimberlite and lamproite magmas, it is highly unlikely radiohalos would have formed around any zircon

inclusions.Instead, it is far more likely that 238U and its decay products infiltrated the diamonds during and after their ascent to the earth’s upper crust. However, while kimberlite and lamproite magmas are volatile-rich, particularly with respect to CO2, they contain very little water and so produce dry volcanic eruptions. Thus, as water is the likely transporter of238U and its decay products, the infiltration of water transporting 238U and its decay products to form the radiohalos in diamonds would need to occur after the emplacement of the host kimberlite or lamproite at and near the earth’s surface. Indeed, even though the kimberlite and lamproite magmas are considered dry, they are nonetheless very hot (>1,000°C) when emplaced, and their interaction with the ground waters in the immediately surrounding intruded strata would generate in situ hydrothermal fluids.124 That such fluids are generated is confirmed by the ubiquitous hydrothermally produced minerals such as serpentine in kimberlites and lamproites. Such fluids would scavenge, dissolve, and concentrate 238U and its decay products from both the intruded strata and the congealed, rapidly cooled, and explosively fragmented intruding magmas.The next question has to be whether magmatic and hydrothermal fluids can infiltrate into diamonds. Both Armitage125and Gentry126 insisted that fluid infiltration was not possible due to the unfractured, tight internal crystal structure of diamonds. However, Vicenzi et al127 maintained the radiohalos they found in alluvially deposited carbonados were generated as a result of uranium deposition from a single pulse of fluids having infiltrated those microcrystalline diamonds after their formation. The crystal structure of diamonds is cubic, and even though diamonds fracture conchoidally, they exhibit cleavage in four directions (octahedral) with one perfect cubic cleavage.128 As in the case of the radiohalos in the diamond documented by Armitage,129 many of the radiohalos in one of the diamonds in our study are centered along thin darkened straight lines within the diamond. These lines appear to follow the directions of the cleavages (figs. 3–5). Other radiohalos are at the termini of strange darkened tubes that turn and twist at right angles (fig. 4). Wise130 interpreted all these features as conduits along which fluids must have transported the 238U and its decay products responsible for the radiohalos. This interpretation is supported by the observations made by Armitage and Back131 and in our study that the darkening along these linear features and twisted tubes is due to radiation staining. Furthermore, these linear features and the linear sections of the twisted tubes appear to follow the perfect cleavages within the diamonds. These cleavages are the natural weaknesses of the diamond crystal lattice along which infiltrating fluids might be expected to flow. Fig. 8. Radiohalos in macle diamond. Magnification 90×. Scale bar = 0.5 mm.

This interpretation raises several issues. Again, the intact crystal structure of diamonds, without clearly developed fracture surfaces along cleavages, would seem not to be capable of providing open avenues for fluid infiltration. However, this concern is based on observations of diamonds at ambient temperatures. By contrast, at the temperatures of 300–400°C at which magmatic and hydrothermal fluids might have infiltrated, the heat would likely have expanded the diamond crystal structure, thus opening cleavage planes to provide the necessary pathways for these fluids. Yet how are these darkened linear features and “tubes” produced by fluid infiltration when cleavage planes are two-dimensional surfaces? Given that the diamond crystal structure is normally tight (close-packed), if the cleavages within it are opened by heat and fluid pressures, the easiest, most open, pathways for fluids to infiltrate would be at the linear intersections of cleavage planes. It then follows that because there are essentially five cleavage planes in diamonds, the lines of intersection between them run in numerous directions, which would account for the twisted tubes.It would also be precisely because of the tight crystal structure of diamonds that some of these tubes are twisted at right angles. Because all the cleavages are at varying angles only a few right angles would seem possible, but the cubic cleavage plane is regarded as perfect.132 Armitage133 described these strange twisted tubes as solid inclusions, rather than being hollow as previously thought.134 A few of these twisted tubes were found to extend to the surface of the diamond,135 and not all of them terminated at a radiohalo. Furthermore, in both the Armitage136 diamond and the cut diamond in our study, both the darkened linear tubes with radiohalos centered along them, and the twisted tubes terminating in radiohalos, usually do not reach the surfaces of these faceted stones. This would seem to argue against these tubes having been formed by fluid infiltration. However, the character of these tubes, and their containment of solid mineral inclusions, suggest their formation as mineral inclusions via precipitation from infiltrating fluids. These would have to have been trapped in the diamond crystal structure long enough for the mineral matter dissolved in them to precipitate.It is thus envisaged that with the emplacement of the host kimberlite pipe, connate water in the surrounding intruded strata was heated by the cooling kimberlite, and the hydrothermal fluids thus generated infiltrated the still warm diamonds within the kimberlite, carrying 238U and its decay products scavenged from the intruded strata. Heated diamonds expanded sufficiently to

facilitate fluid infiltration along cleavage planes; but because of the tight diamond crystal structure, where the fluids met resistance within the diamonds because the cleavages would not open further, the fluids instead exploited any weakness along the intersections between other cleavage directions. Thus some of the linear fluid pathways became twisted repeatedly at right angles as the fluids infiltrated where cleavage intersections were sufficiently open to them. As the diamonds first cooled at their outer surfaces, the cleavages infiltrated by the fluids would contract and close first at their outer surfaces, locking the fluids into those cleavages where the contained elements and minerals then precipitated. Because 238U and its decay products were dissolved in these infiltrating fluids, α-radiation tracks would be left along the cleavage pathways traversed by the fluids. The 238U decay products in the fluids apparently became concentrated in nucleation or precipitation centers, where trace atoms such as Cl (present in diamonds) chemically attracted Po. These precipitated Po atoms then “parented” the now observed radiohalos. The half-lives of these radioisotopes are short (210Po 138 days, 218Po 3.1 minutes, and 214Po 164 microseconds); but isolated 214Po radiohalos may be accounted for by retention in the infiltrating fluid of the 27-minute half-life parent 214Pb and the 20-minute half-life parent 214Bi. Similarly, isolated 210Po radiohalos may be accounted for by retention of the 22-year half-life parent 210Pb and the 5-day half-life parent 210Bi. A satisfactory explanation for the observed density ratios of polonium radiohalos awaits further study.The single ring radiohalos in the Brazilian macle diamond, most probably 210Po radiohalos, are dispersed randomly and sometimes apparently in clusters, and do not seem to be along any radiation-stained linear features (figs. 7–8). This does not mean the 210Po was not transported into this diamond by fluid infiltration along cleavages. Rather, it suggests that the 210Po transport was so rapid there was insufficient time for radiation staining to develop along the cleavages infiltrated by the fluids. Furthermore, the oddly shaped nature of this macle diamond has two other implications. First, its contraction accompanying cooling after emplacement would have been very rapid due to its likely less orderly crystalline structure; and thus fluid infiltration to produce these 210Po radiohalos also needed to be very rapid. And second, the packing of its crystal structure would mean that its cleavages are not as well defined, and the infiltrating fluids would have more readily dispersed around the constituent components of its crystal lattice rather than along cleavages. This is consistent with its distribution pattern of 210Po radiohalos. However, since only 210Po radiohalos are present in this macle diamond, the infiltrating fluids likely only transported 210Po scavenged from the host kimberlite and the intruded strata. The fluids which infiltrated the other diamond we studied had to have carried radioisotopes higher up the 238U decay chain, at least up to 1,000 year half-life 226Ra, which is readily soluble in most fluids.All these considerations indicate time limits on the fluid infiltration process to generate the polonium radiohalos is the order of hours or weeks. This is consistent with the evidence of the rapid speed (within hours) at which diamond-bearing kimberlite pipes are explosively emplaced. Additionally, once emplaced, complete cooling of the fragmented congealing kimberlite magma is also rapid (within days or weeks) at the surface, and in the near-surface environment beneath where heated meteoric waters containing Ra, Rn, and Po scavenged from the host strata would rapidly penetrate into the kimberlite and mix with any magmatic and hydrothermal fluids. Rapid hydrothermal fluid transport of 210Po in the natural environment has been documented.137 Hussain, Church, Luther, and Moore138 found that the residence time of 210Po in hydrothermal fluids venting on the ocean floor was of the order of only a few minutes, and that the residence time of the hot fluids in the hydrothermal system was no more than 30 days. Furthermore, the hydrothermal fluids in geothermal and mid-ocean ridge vent systems are estimated to circulate through rock volumes of several cubic kilometers over distances of several kilometers,139, 140 transporting 210Po within 20–30 days. Given the explosive emplacement of the hot kimberlite pipes and the rapid penetration into them of hydrothermal fluids transporting Ra, Rn, and Po, infiltration of hydrothermal fluids carrying Po into the diamonds within the hot fragmented kimberlite would have needed to be rapid to deposit the Po in time to generate the Po radiohalos before the whole system cooled rapidly, the diamond cleavages “closed,” and hydrothermal fluid circulation ceased. Conclusions

Even though the available data suggest the erasure temperature of radiohalos in diamonds may be above 620°C, the 1100–2900°C conditions in the mantle where diamonds form would be too severe for radiohalos to form there. Furthermore, the temperature of the kimberlite and lamproite magmas that transported diamonds to the upper crust, the short transit times, and the lack of water to transport radioisotopes into diamonds, would militate against radiohalos being formed during the ascent of diamonds from the mantle. Thus the radiohalos in the diamonds examined in this study must have formed after emplacement of their host kimberlite/lamproite pipes at or near the earth’s surface.The emplacement of the hot, dry kimberlite/lamproite magmas in pipes would result in heating of the connate water in the surrounding intruded (host) strata. The hydrothermal fluids thus produced would then scavenge and concentrate trace amounts of 238U and its decay products, transporting them into the kimberlite/lamproite pipes via convective flow. Due to expansion of the still hot diamonds, these fluids would have infiltrated the diamonds along the cleavages within them. Where resistance was sometimes encountered because of the diamonds’ tight crystal structure, the fluids exploited other cleavage directions, resulting in fluid pathways, which twisted repeatedly at right angles. The α-decay of the radioisotopes in the fluids often left dark radiation stains along these linear and twisted fluid pathways. Contraction of the outer surfaces of the diamonds would have closed termination of cleavages there, thus trapping the infiltrated fluids to precipitate the mineral matter that forms the observed tubes. Precipitation of 238U decay products in nucleation centers along, and sometimes at the end of, these fluid infiltrated cleavages where chemical conditions were conducive produced concentrations that generated the observed polonium radiohalos. All considerations indicate severe time limits on the fluid infiltration process—on the order of hours or weeks. Radiohalos in diamonds can be explained by the hydrothermal fluid transport model for Po radiohalo formation; but they cannot answer the question: are diamonds really for ever? Acknowledgments

The authors gratefully acknowledge the kind loan of diamonds from the collection of Dr. John Koivula and Thor Strom at the Gemological Institute of America (Carlsbad, CA). We also thank Dr. John Baumgardner of the Institute for Creation Research for allowing us access to his collection of diamonds. Additionally, we thank the anonymous reviewers and the editor of the manuscript for their helpful comments and suggestions that considerably improved the final paper.

Radiohalos in the Cooma Metamorphic Complex, New South Wales, Australia The Mode and Rate of Regional Metamorphism

by Dr. Andrew A. Snelling on September 2, 2009 Abstract The Cooma granodiorite was generated as a consequence of the regional metamorphism that resulted from the catastrophic large-scale emplacement during the catastrophic plate tectonics of the Flood. Keywords: regional metamorphism, Cooma, southeastern Australia, Po radiohalos, 238U radiohalos, granodiorite,

metamorphic zones, hydrothermal fluids, catastrophic granite generation, creationist model for regional metamorphism

This paper was originally published in the Proceedings of the Sixth International Conference on Creationism, pp. 371–387 (2008) and is reproduced here with the permission of the Creation Science Fellowship of Pittsburgh and the Institute for Creation Research, Dallas. Abstract

The Cooma metamorphic complex in southeastern Australia is a classical example of regional metamorphic zones centered on a granodiorite generated by partial melting at the highest metamorphic grade. Samples collected along a traverse from the low-grade biotite and then andalusite zone schists through the high-grade K-feldspar and migmatite zone gneisses into the central granodiorite contain increasing numbers of Po radiohalos with increasing metamorphic grade. The highest Po radiohalo numbers are in the high-grade zones and the granodiorite. These radiohalo patterns correlate with the Po radiohalos being generated by the hydrothermal fluids flowing out of the central granodiorite as it crystallized and cooled, their numbers diminishing as the hydrothermal fluid flow decreased outwards. This is further evidence consistent with the hydrothermal transport model for Po radiohalo formation. Furthermore, generation of the regional metamorphic complex only required 12–20 days, based on the catastrophic granite formation of the adjacent Murrumbidgee Batholith whose heat and hydrothermal fluids generated the regional metamorphic zones of the complex from the mineral constituents of the original fossiliferous sediment layers, then the central granodiorite as a consequence. This sequence of outcomes is consistent with creationist models for catastrophic granite formation and regional metamorphism driven by catastrophic plate tectonics during the year-long Flood. Introduction

The Cooma granodiorite was first mapped by Browne1 and is a small, elliptical pluton centered approximately on the township of Cooma in southern New South Wales, 300 km south-southwest of Sydney (fig. 1 inset). The pluton is about 8 km in maximum dimension and has a surface exposure of 14–20 km2, depending on where its gradational contact with the surrounding migmatites is placed.2 When mapped, the pluton was found to be central to a sequence of roughly concentric prograde regional metamorphic zones.3,4,5 In fact, the Cooma metamorphic complex is considered to be a classic geological area for regional metamorphic zones, because it is one of the first localities where andalusite-sillimanite type regional metamorphism was described.6,7 Furthermore, the Cooma granodiorite itself is also regarded as a classic geological example of a pluton produced by a low degree of partial melting of the metasediments at the heart of a regional metamorphic complex (fig. 1).8The Cooma metamorphic complex has a mapped outcrop area exceeding 300 km2, and probably extends over a similar area beneath the local cover of Tertiary basalt. Isograds can be traced over 30 km northwards adjacent to the Murrumbidgee Batholith.9 Based mainly on the work of Joplin10,11 and Hopwood,12,13 Chappell and White14recognized a series of metamorphic zones delineated by the appearance of chlorite, biotite, andalusite, sillimanite, and granitic veining, respectively. Approximate equivalents are chlorite zone–greenschist facies; biotite and andalusite zones–amphibolite facies; sillimanite and migmatite zones–granulite

facies.15 Some additional metamorphic zones have been distinguished by subdividing the andalusite and sillimanite zones on the basis of the first appearances of cordierite, andalusite, and K-feldspar.16 The zoning is markedly asymmetric. The belt of highest grade rocks and the enclosed Cooma granodiorite are located towards the eastern margin of the complex (fig. 1), with the regional aureole extending approximately 3 km to the east, but nearly 10 km to the west. At least four,17 and possibly seven,18 separate deformation fabrics can be distinguished in the metasediments of the Cooma complex. The exception is the Cooma granodiorite, which preserves only the last foliation, suggesting that it was emplaced late in the development of the complex.19,20 Cooma Metamorphic Complex

Fig. 1. The Cooma metamorphic complex, southeastern Australia,

showing the zones of regional metamorphism of increasing grade surrounding a central granodiorite, coinciding with the town of Cooma. The marked area is enlarged in Fig. 2. The stratigraphic sequence that transitions into the higher grade zones of the Cooma metamorphic complex has been estimated at approximately 3,000 meters thick, as measured from beyond the western edge of the low grade zones eastward into the complex.21,22Four units have been mapped, none of which are completely free of low grade metamorphic effects. The lowest unit, to the east stratigraphically above the high grade zone rocks of the central complex, is a sequence of regularly bedded sandstones and shales. The sandstones are thinly bedded, averaging 10–45 cm thick, and the shaly units are often characterized by finely laminated alternating units of grey shale and white sandy shale. About halfway up this unit 1, which is at least 915 m thick, is an 18 m thick massive sandstone bed. Otherwise, gradually towards the top of this formation massive clayey shales and lenses of black shales appear. The overlying unit 2 is a sequence of massive thickly bedded sandstones, averaging 2.5–3.5 m thickness per bed, and often separated by thin layers of sandy shale. These shale layers appear regularly throughout the sequence, but together make up no more than one fifth of the total 425 m thickness of unit 2. Above this is unit 3, a 950 m thick sequence of green and grey shales, with occasional lenticular black shales and very thinly laminated siliceous bands. At the base of the unit is a massive black shale layer, over which lies a fine-grained grey siltstone, while towards the top, the monotonous sequence of shales is broken by a thin quartz-rich sandstone layer. The top of the unit 3 shale succession then grades by interlayering into the volcanic sequence of unit 4, which is at least 455 m thick. At the base are a few small limestone lenses, and clay shales. The

volcanics, now greenschists, are strongly foliated, and porphyritic in quartz. They probably were originally trachytic or andesitic lava flows and their detrital equivalents. The top of this unit 4 volcanic sequence is not exposed. Abundant fossilized graptolites have been recorded still preserved in the shale layers within these lowest grade zone rocks, approximately 8 km west of the Cooma granodiorite, in the outer area of the metamorphic complex.23 Biostratigraphically these graptolites equate to upper Ordovician fossil zones elsewhere in the Lachlan Fold Belt of New South Wales.24,25 Thus the volcanics at the top of this strata sequence could be lower Silurian. Otherwise, the other units are typical of other upper Ordovician turbidite strata sequences of shales and subgreywacke sandstones found elsewhere in the Lachlan Fold Belt. Furthermore, detrital zircon and monazite grains with inherited U-Pb ages have been found in both these metamorphosed sediments of the Cooma metamorphic complex, at least as far out as the low grade biotite zone, and in the Cooma granodiorite which was derived from those sediments by partial melting.26 The U-Pb ages of these detrital zircon grains ranged from 450 Ma to 3538 Ma, with 50% of the grains in the 450–600 Ma range and 30% in the 800–1250 Ma range. The detritral monazite grains yielded similar U-Pb ages, with most grains in the 410–650 Ma range. Similar detrital zircon grains are also found in graptolite fossil-bearing upper Ordovician turbidite sediments elsewhere in the Lachlan Fold Belt.27 The U-Pb ages of those zircon grains were similarly in the ranges of 480–630 Ma (60% of grains in one sample) and of 470–600 Ma (50% of grains in a second sample), with 20% and 25% of grains (respectively) yielding 1000–1300 Ma ages.The metamorphism in the Cooma complex (fig. 1) is classified as low-P, high-T (LPHT),2829 the metamorphic assemblages resembling those in the Abukuma andalusite-sillimanite metamorphic belt of Japan:30 Chlorite zone

The metapelites are characterized by the mineral assemblage chlorite + muscovite + quartz, with minor albite, calcite, and opaque (iron oxide) minerals.31,32,33 Muscovite is generally far more abundant than chlorite, and both minerals occur as highly elongate grains rarely longer than 0.1 mm. The metapsammites contain the same minerals, with local detrital K-feldspar grains sometimes partly altered to muscovite, whereas former detrital biotite and plagioclase grains have been altered to chlorite and albite respectively. Biotite zone

This zone is differentiated from the chlorite zone by the first appearance of biotite in metapelites, resulting in the characteristic mineral assemblage quartz + albite + biotite + muscovite ± chlorite, with minor tourmaline and opaque (iron oxide) minerals. The first biotite to appear is green and weakly pleochroic, but this variety gives way to a more strongly pleochroic brown biotite further into the zone.34 Grain sizes differ little from those in the chlorite zone, except the mica grains range up to 0.2 mm in length, and biotite porphyroblasts can be as long as 0.7 mm.35 Andalusite zone

This zone is defined on the presence of andalusite alone, without accompanying sillimanite. Its characteristic mineral assemblage is andalusite + cordierite + biotite + muscovite + quartz + albite, with minor tourmaline, opaque (iron oxide) minerals and zircon. Andalusite porphyroblasts range widely in size from approximately 0.5 to 5.0 mm in their longest dimension. Johnson, Vernon, and Hobbs36 inserted an extra zone between the biotite and andalusite zones, basing its identification on the first appearance of cordierite. Named the cordierite zone, it has the same mineral assemblage as the andalusite zone, but minus andalusite, whereas cordierite is still present in the andalusite zone. In this cordierite zone the cordierite porphyroblasts range from 1.0 to 10.0 mm in longest dimension, but are extensively replaced by retrogressive aggregates of sericite, biotite and chlorite. On the other hand, in the andalusite zone some andalusite is intimately related with replaced cordierite porphyroblasts. K-feldspar zone

This zone is defined by the first appearance of metamorphic K-feldspar (orthoclase), which marks the onset of grain coarsening into a gneissic texture. The characteristic mineral assemblage is K-feldspar + cordierite + andalusite + biotite + plagioclase + quartz ± sillimanite, with minor tourmaline, zircon and opaque (iron oxide) minerals. Muscovite is commonly present as relatively large grains, which appear though to be of retrograde origin. Migmatite zone

This zone is vaguely defined by the presence of abundant granitic “veins” in a sillimanite-andalusitebiotite gneiss. The “veins” consist chiefly of quartz, K-feldspar and lesser plagioclase, and vary in thickness from a few millimeters to a few centimeters. Overall, the metasedimentary rocks of this zone are commonly divided into mottled metapelitic gneisses and banded metapsammitic gneisses.37,38 The mottling in the metapelitic gneisses is due to intergrowths of green-brown biotite, quartz and andalusite pseudomorphing cordierite porphyroblasts. The banded metapsammitic gneisses are composed of a dark/light compositional layering. These metapelitic and metapsammitic migmatites are found all the way around the granodiorite in gradational contact with it. The more pelitic rocks have leucosomes of granitic material surrounded by coarse-grained mesosomes. The leucosomes are composed of quartz, K-feldspar and plagioclase, and range in width from 2 mm to 5 cm. Some leucosomes have distinct biotite-rich selvedges and may contain fresh cordierite crystals up to 5 mm across.39Major and trace element abundances suggest that the high-grade metapelitic and metapsammitic gneisses of the migmatite and K-feldspar zones surrounding the granodiorite are the geochemical equivalents of the more distant, low-grade pelitic and psammitic schists.40 However, the minor variation in the orthoclase-albiteanorthite ratio between the low-grade schists and high-grade gneisses would suggest otherwise.41 Nevertheless, for the purpose of this study it was noted as significant that biotite is always present throughout the metamorphic complex from the biotite zone inwards through the migmatite zone into the granodiorite, while accessory zircons are similarly distributed.42,43 Williams also reported 238U and 232Th radiohalos surrounding tiny zircon and monazite grains respectively within biotite flakes from the K-feldspar and migmatite zones, as well as in the granodiorite, the latter confirmed by Snelling and Armitage,44 along with abundant Po radiohalos. Furthermore, Snelling45,46 had reported finding Po radiohalos in metamorphic rocks, including through the zones within a regionally metamorphosed sequence of sandstone.47 Thus, because Snelling48 had proposed a model for regional metamorphism involving hydrothermal fluids, and the hydrothermal fluid transport model for the formation of Po radiohalos involves the required Po isotopes being sourced from zircons in biotites,49,50 it was predicted that Po radiohalos would be found in all the biotite bearing schists and gneisses of the Cooma metamorphic complex. Cooma granodiorite

The Cooma granodiorite contains the same minerals as the gneisses and migmatites, and lies within the cordierite-andalusite-K-feldspar zone. It is extremely quartz-rich (50%), and contains plagioclase, K-feldspar and biotite, with andalusite, sillimanite, cordierite and muscovite, some or all of the latter appearing to be secondary.51,52,53 The biotite is crowded with 238U and 232Th radiohalos around inclusions of zircon and monazite respectively,54 while Snelling and Armitage55 have reported Po radiohalos are also prevalent. The granodiorite contains abundant xenoliths of the surrounding migmatites and, less commonly, the high-grade gneisses, quartz veins and pegmatites. This is consistent with the granodiorite having been derived by partial melting of a metasedimentary source, presumably the high-grade

gneisses surrounding the granodiorite.56 Thus the granodiorite has been classified as S-type57 with normative corundum values of 5.82%,58 indicating that it is strongly peraluminous. It is also very low in Na2O and CaO, which has been attributed to its derivation from the surrounding metamorphosed Ca-poor Ordovician sediments.59 This origin is supported by isotopic data.60,61,62,63,64 The Cooma granodiorite is thus typical of “regional aureole” granites described by White, Chappell, and Cleary,65 and Chappell and White.66Radioisotopic data suggests that the Cooma granodiorite and the related metamorphic rocks thus cooled through the blocking temperature for most geochronological systems in the mid to late Silurian.67 Pidgeon and Compston68obtained an Rb-Sr mineral isochron age for the granodiorite of 406 ± 12 Ma. The age of the high-grade gneisses was found to be similar to the granodiorite, but the low grade metasediments yielded a significantly older age of 450 ± 11 Ma (recalculated by Munksgaard69). Based on these results it was concluded that the granodiorite formed in situ by partial melting of the surrounding metasediments, the high-grade gneisses being associated with the emplacement of the granodiorite, whereas the higher ages in the low-grade metasediments perhaps indicated the original age of deposition, or the age of regional metamorphism predating the high-grade metamorphism. Tetley70 obtained a Rb-Sr whole-rock isochron age for the granodiorite of 410.0 ± 19.0 Ma, thus supporting the previously determined granodiorite age. However, Munksgaard obtained whole-rock Rb-Sr ages of 362 ± 77 Ma for the granodiorite, 375 ± 55 Ma for the high-grade gneisses, and 386 ± 25 Ma for the low-grade metasediments. He suggested these results implied the metasediments and the granodiorite were not fully equilibrated on a regional scale with respect to their Sr isotope composition at the time of metamorphism, and thus whole-rock samples would not give meaningful ages for the Cooma complex. Nevertheless, he showed that the Cooma granodiorite is similar in major- and trace-element composition to a calculated mixture of the surrounding schists and gneisses.Preliminary results of ion-probe zircon U-Pb studies71 yielded ages from zircon about 30 Ma greater than the 410 Ma age recorded by hornblende K-Ar and whole-rock Rb-Sr.72 More detailed results have now been published.73 Both monazite and zircon grains from the Cooma granodiorite and from the metasediments in each of the surrounding regional metamorphic zones were analyzed. Monazite in the migmatite and granodiorite were found to have recorded only metamorphism and granite genesis at 432.8 ± 3.5 Ma, whereas detrital zircon grains in the original sediments were unaffected by metamorphism until the inception of partial melting, when platelets of new zircon precipitated on the surfaces of the grains. These new growths of zircon crystals, although maximum in the leucosome of the migmatites, were best dated in the granodiorite at 435.2 ± 6.3 Ma. Thus the best combined estimate for the U-Pb age of the metamorphism and granite genesis is 433.4 ± 3.1 Ma. Because the detrital zircon U-Pb ages were found to have been preserved unmodified throughout metamorphism and magma genesis, Williams74 concluded that this indicated the Cooma granodiorite was derived from lower Paleozoic source rocks with the same protolith as the Ordovician sediments found outcropping adjacent to the metamorphic complex in the same region. These U-Pb ages for the detrital zircon and monazite grains preserved in the metasediments and the granodiorite from the original Ordovician sediments were dominated by composite populations dated at 500–600 Ma and 900–1200 Ma, although almost 10% of the grains analyzed yielded apparent ages scattered from 1450 Ma to 2839 Ma, one grain even yielding an apparent age of 3538 Ma.The general consensus is that the Cooma granodiorite is an integral part of the regional metamorphic sequence, having formed by the in situ, or virtually in situ, partial melting of high-grade metasediments identical to those surrounding it.75, 76, 77, 78, 79, 80, 81, 82, 83, 84 However, Flood and Vernon85 pointed out that an origin for the Cooma granodiorite from essentially in situ anatexis of the adjacent metasedimentary rocks was in apparent conflict with the surrounding low-pressure metamorphic environment, unless unrealistically high and localized geothermal gradients were invoked. They suggested that subsequent to the granodiorite forming by partial melting of the adjacent high-grade migmatitic rocks, the granodiorite moved upwards as a diapiric intrusion, the high-grade envelope surrounding it having been dragged up to higher crustal levels with the intruding granitic diapir. Support for this model includes evidence for vertical movement along a transition zone between the andalusite zone schists and the K-feldspar zone gneisses (fig. 1), a step in metamorphic pressures at the sillimanite isograd, coinciding with the boundary between the gneisses and migmatites, and a steady pressure rise thereafter towards higher metamorphic grades.86 All the metamorphism is regarded as part of the same relatively intact sequence, the thermal aureole having contracted towards the granodiorite during the later stages of the deformation associated with the regional metamorphism and the emplacement of the granodiorite.87 Finally, Vernon, Richards, and Collins88 have demonstrated that in situ partial melting of metapsammitic leucosome would have produced a magma of suitable composition to form the Cooma granodiorite, but this locally produced magma appears to have only contributed to the rising pluton of magma formed by deeper, more extensive accumulation of similarly derived magma, a model consistent with the U-Pb zircon data.89 Field Work

A field trip to the Cooma area was undertaken in late December, 2004. A west-east traverse was made through the metamorphic complex into the central granodiorite along major roads (fig. 2). Representative samples were collected from the biotite, andalusite, K-feldspar, and migmatite zones, as well as from the granodiorite, from outcrops in road cuts and on a small hill in Cooma itself. All nine sample locations are marked in Fig. 2. Views of some of the outcrops are shown in Fig. 3.

Fig. 2. Enlargement of the area marked in Fig. 1, showing an enlarged view of the regional metamorphic zones west of

the Cooma granodiorite centered on the town of Cooma. The sample locations are shown along major roads. Fig. 3. Typical views of

the outcrops sampled (see fig. 2). (a) Sample site RMC-3, a low-grade biotite zone schist. (b) Sample site RMC-4, a low-grade andalusite zone schist (c) Sample site RMC-7, high-grade migmatite zone gneiss (d) Sample site RGC-1, the Cooma granodiorite on Nanny Goat Hill Experimental Procedures A standard petrographic thin section was obtained for each sample. In the laboratory, a scalpel and tweezers were used to

pry flakes of biotite loose from the sample surfaces, or where necessary portions of the samples were crushed to liberate the constituent mineral grains. Biotite flakes were then hand-picked and placed on the adhesive surface of a piece of clear Scotch™ tape fixed to a bench surface with its adhesive side up. Once numerous biotite flakes had been mounted on the adhesive surface of this piece of clear Scotch™ tape, a fresh piece of clear Scotch™ tape was placed over them and firmly pressed along its length so as to ensure the two pieces of clear Scotch™ tape were stuck together with the biotite flakes firmly wedged between them. The upper piece of clear Scotch™ tape was then peeled back in order to pull apart the sheets composing the biotite flakes, and this piece of clear Scotch™ tape with thin biotite sheets adhering to it was then placed over a standard glass microscope slide, so that the adhesive side which had the thin mica flakes adhered to it became stuck onto the microscope slide. This procedure was repeated with another piece of clear Scotch™ tape placed over the original Scotch™ tape and biotite flakes affixed to the bench, the adhering biotite flakes being progressively pulled apart and transferred to microscope slides. As necessary, further hand-picked biotite flakes were added to replace those fully pulled apart. In this way tens of microscope slides were prepared for each sample, each with many (at least 20–30) thin biotite flakes mounted in them. This is similar to the method pioneered by Gentry. A minimum of 30 (usually 50) microscope slides was prepared for each sample to ensure good representative sampling statistics. Thus there was a minimum of 1,000 biotite flakes mounted on microscope slides for each sample.Each thin section for each sample was then carefully examined under a petrological microscope in plane polarized light and all radiohalos present were identified, noting any relationships between the different radiohalo types and any unusual features. The numbers of each type of radiohalo in each slide were counted by progressively moving the slide backwards and forwards across the field of view, and the numbers recorded for each slide were then tallied and tabulated for each sample. Only radiohalos whose radiocenters were clearly visible were counted. Because of the progressive peeling apart of many of the same biotite

flakes during the preparation of the microscope slides, many of the radiohalos appeared on more than one microscope slide, so this procedure ensured each radiohalo was only counted once.

Fig. 4. Representative photo-micrographs

of the schists, gneisses, and granodiorite samples of the Cooma metamorphic complex, collected from the outcrops plotted on Fig. 2. All photo-micrographs are at the same scale (20× or 1 mm = 40 μm) and the rocks are as viewed under crossed polars. (a) RMC-3 biotite zone schist: quartz, biotite, muscovite (b) RMC-4 andalusite zone schist: quartz, biotite (with halos), muscovite (c) RMC-5 K-feldspar zone gneiss: quartz, K-feldspar, biotite (with halos), muscovite (d) RMC-6 K-feldspar zone gneiss: quartz, K-feldspar, biotite (with halos), muscovite (e) RMC-7 migmatite zone gneiss: quartz, plagioclase, K-feldspar, biotite (with halos) muscovite (f) RLG-2 Cooma granodiorite: quartz, plagioclase, K-feldspar, biotite (with halos), zircon (g) RGC-1 Cooma granodiorite: quartz, plagioclase, K-feldspar, biotite (with halos), zircon, muscovite Results Fig. 4 provides representative photomicrographs of the samples of schists and gneisses from the Cooma regional metamorphic complex. All radiohalos results are listed in Table 1. As predicted, all samples of the low-grade schists, high-grade gneisses and the granodiorite, except one of the two samples from the low-grade biotite zone, contained Po radiohalos. However, the two samples each from the biotite and andalusite zones only contained Po radiohalos, and almost exclusively 210Po radiohalos. 238U radiohalos were only present in the samples of the K-feldspar and migmatite zones, and the granodiorite, confirming the observations of Williams,90 and 218Po and 214Po radiohalos were almost exclusively only found in those

same samples. Some representative examples of the observed radiohalos can be seen in Fig. 5. As well as the absolute numbers of each radiohalo type counted in each sample, Table 1 also shows the average total numbers of radiohalos per slide, and Po radiohalos per slide, plus abundance ratios for some pairs of radiohalo types. The total numbers of radiohalos and Po radiohalos per slide in the two biotite zone (low grade) samples averaged < 1, but were numerous at an average of 11–12 per slide in the two andalusite zone samples. The highest average total numbers of radiohalos and Po radiohalos (~26 and 18–19 respectively) were in both the K-feldspar zone and the granodiorite samples (two each), more than double the average total number in the two andalusite zone samples. In stark contrast to this, the total number of radiohalos and Po radiohalos per slide, at 6 and 5 respectively, were significantly lower in the one migmatite zone sample. Fig. 6 is a plot of the numbers of radiohalos per slide for each sample (vertical axis) along the west-east traverse across the regional metamorphic complex into the granodiorite (horizontal axis), as shown in Fig. 2. Four trends in the data are immediately evident. First, there is a rapid rise in the numbers of Po radiohalos with increasing metamorphic grade, from the biotite zone (low grade) through to the K-feldspar zone (high grade). Second, only the high grade zones (K-feldspar and migmatite) and the granodiorite have 238U radiohalos in them. Third, the average total numbers of radiohalos and Po radiohalos in the high-grade K-feldspar zone and the granodiorite are both high and approximately the same. And fourth, there is a dramatic drop in the total numbers of both radiohalos and Po radiohalos in the migmatite zone. Table 1. Data table of radiohalos numbers counted in samples from the Cooma metamorphic complex and Cooma

granodiorite.

Sample Rock type Slides

Radiohalos Total Number of Radiohalos per Slide

Number of Po Radiohalos per Slide

Ratios

210Po 214Po 218Po 238U 232Th 210Po:238U 210Po:238U

RMC-1

Biotite zone schist 50 0 0 0 0 0 0 0 — —

RMC-3

Biotite zone schist 50 63 0 0 0 0 1.26 1.26 — —

RMC-2

Andalusite zone schist 50 592 0 0 0 0 11.84 11.84 — —

RMC-4

Andalusite zone schist 50 557 2 0 0 0 11.18 11.18 — 278.5:1

RMC-5

K-feldspar zone schist 50 880 14 1 402 0 25.94 17.9 2.2:1 62.9:1

RMC-6

K-feldspar zone schist 50 1036 47 0 278 0 27.22 21.66 3.7:1 22:1

RMC-7 Migmatite 50 240 13 0 47 0 6.0 5.06 5.1:1 18.5:1

RLG-2 Granodiorite 41 373 44 0 418 37 21.27 10.17 0.9:1 8.5:1

RGC-1 Granodiorite 50 1175 0 81 318 0 31.48 25.12 3.7:1 —

Fig. 5. Some representative examples

of radiohalos found in biotite grains separated from the schists and gneisses of the Cooma metamorphic complex and the Cooma granodiorite. All photo-micrographs are at the same scale (40× or 1 mm = 20 μm) and the biotite grains are as viewed in plane polarized light. (a) RMC-3 biotite zone schist: two overlapping 210Po radiohalos (b) RMC-4 andalusite zone schist: a 210Po radiohalo (c) RMC-5 K-feldspar zone gneiss: two overexposed 238U radiohalos and a 210Po radiohalo (d) RMC-6 K-feldspar zone gneiss: single 210Po, 214Po and an overexposed 238U radiohalo (e) RMC-7 migmatite zone gneiss: an overexposed 238U and a 210Po radiohalo (f) RLG-2 Cooma granodiorite: four overexposed 238U and five 210Po radiohalos (g) RLG-2 Cooma granodiorite: three overexposed 238U and three 210Po radiohalos (h) RGC-1 Cooma granodiorite: two overexposed 238U and four 210Po radiohalos Discussion

The significance of so many observed Po radiohalos in these Cooma metamorphic complex and Cooma granodiorite samples depends on how they are understood to have formed. In conventional thinking they are “a very tiny mystery” (G. Brent Dalrymple, as quoted by Gentry91) that can therefore be conveniently ignored because they have little apparent significance. However, if the formation of these Po radiohalos

cannot be explained, then their significance cannot be fully comprehended. The reality is that the mystery of the Po radiohalos is ignored, because it constitutes a profound challenge to conventional wisdom. Comprehensive reviews of what these Po radiohalos are and how they may have formed are provided by Gentry92, 93,94, 95and Snelling.96 It has been established that all the observed Po radiohalos are generated exclusively from the Po radioisotopes in the 238U decay series, namely, 218Po, 214Po, and 210Po, with contributions from none of the other species in the 238U α-decay chain (Gentry97). Furthermore, it has been estimated that, like the 238U radiohalos, each visible Po radiohalo requires between 500 million and 1 billion α-decays to generate it (Gentry98), which equates to a corresponding number of Po atoms having been in each radiocenter. Thus the crucial issue is how did so many Po atoms get concentrated into these radiocenters to generate the Po radiohalos, when their half-lives are only 3.1 minutes (218Po), 164 microseconds (214Po), and 138 days (210Po)?Gentry99,100,101 insists that the Po must be primordial, that is, created instantaneously in place in the radiocenters in the biotite flakes in the granites, and thus the granites are also created rocks. In other words, he argues that granites did not form from the crystallization and cooling of magmas, but rather are the earth’s created foundation rocks. Moreover, where granites such as the Cooma granodiorite have been intruded into fossiliferous Flood-deposited strata, Gentry102 insists that these granites also represent originally created rocks. He argues that during the Flood they were tectonically intruded as cold bodies, and that the contact metamorphic aureoles were produced by the heat and pressure generated during tectonic emplacement, augmented in some cases by hot fluids

from depth.Such an interpretation is inconsistent with the field and petrological evidence from the Cooma metamorphic complex and the Cooma granodiorite. The granodiorite is in fact the product of the regional metamorphism of the fossiliferous (Flood-deposited) sedimentary rocks that host the granodiorite, with a gradational boundary of migmatites (consisting of partially melted sediments). There is no fracturing, brecciation or mylonization that should be evident in either the granodiorite or these immediately adjacent metamorphic rocks if the granodiorite had been intruded tectonically as a cold body. Indeed, the biotite flakes in the metamorphic schists and gneisses that host the Po radiohalos were not in the original fossiliferous sediments, but are the product of the regional metamorphism of the sediments which post-dated their deposition. Therefore, the Po radiohalos must have formed after the biotite flakes formed, during the regional metamorphism and the generation of the granodiorite.The four trends in the data (table 1 and fig. 6) are assumed here to be both real and significant, and thus require an attempted explanation. It was predicted that Po radiohalos would be found in these regionally metamorphosed pelitic and psammitic sediments because: The hydrothermal fluid transport model for Po radiohalo formation103,104 only requires biotite flakes which enclose tiny zircon grains containing 238U, and hydrothermal fluids to flow along the biotite cleavage planes past the zircon grains; The schists and gneisses in the Cooma metamorphic complex contain both biotite flakes and zircon grains from the biotite zone schists inwards to the migmatite zone gneisses;105,106 andA proposed young age model for regional metamorphism107,108 postulates hydrothermal fluids flowing through sediments are responsible for their regional metamorphism. Of course, this prediction was also confidently made because: 238U radiohalos had already been observed in the high grade gneisses of the Cooma metamorphic complex,109and reported in the Cooma granodiorite110 along with Po radiohalos;111 and Po radiohalos had already been observed in metamorphic rocks elsewhere.112,113,114 The increasing numbers of Po radiohalos in the schists and gneisses with increasing metamorphic grade (the first trend in fig. 5) would definitely not have been due to the increasing temperatures and pressures. It has been determined from the relevant experimental and calculated phase equilibria115,116,117 that to have produced the migmatites containing cordierite would have required temperatures of approximately 700°C at pressures of 3.5–4.0 kbar.118,119 However, radiohalos in biotite are annealed at and above 150°C,120 so all the currently observed radiohalos in both the schists and gneisses, and the granodiorite, had to form below that temperature. Thus this trend has to have been due to another factor.

Fig. 6. Plot of numbers of radiohalos per slide in each

sample along the west-east traverse shown in Fig. 2. The different metamorphic zones and the granodiorites are marked along the horizontal axis, and the relative lateral distances between sample locations are approximately to scale.Other evidence elsewhere121,122,123 would suggest that the numbers of Po radiohalos generated are primarily related to the volume and flow of hydrothermal fluids, such that more hydrothermal fluid flow produces more Po radiohalos. Of course, this assumes that there are sufficient zircon grains to supply enough Po isotopes from 238U decay, and biotite flakes to host the Po radiocenters and resultant Po radiohalos. Indeed, this relationship is a direct outworking of the hydrothermal fluid transport model for Po radiohalo formation.124 Thus, greater numbers of Po radiohalos have been reported in granites responsible for, and hosting, hydrothermal metallic ore veins—for example, the Land’s End Granite, Cornwall.125 Furthermore, where hydrothermal fluids had been produced by mineral reactions at a specific pressure-temperature boundary between zones during regional metamorphism of a sequence of sandstones, four-five times more Po radiohalos were generated at that specific

metamorphic boundary than elsewhere in that regional metamorphic complex, regardless of increasing metamorphic grade.126,127 In another example, where hydrothermal fluids flowing in narrow shear zones had rapidly metamorphosed the high-grade granulite wall rocks, Po radiohalos are now present in the resultant eclogite, a high-grade metamorphic rock that otherwise doesn’t host Po radiohalos.128 And then, in a sequentially intruded suite of nested granite plutons, where the hydrothermal fluid content of the granites correspondingly increased so that the last intruded central pluton was connected to coeval explosive, steam-driven volcanism, the numbers of Po radiohalos generated increased inwards within the nested suite of granite plutons.129 These evidences not only support the hydrothermal fluid transport model for Po radiohalo formation, but explain this first trend in the Cooma Po radiohalos data, as due to more hydrothermal fluids flowing through the metamorphic complex with increasing metamorphic grade producing more Po radiohalos.So why do only the high-grade K-feldspar and migmatite zones and the granodiorite have 238U radiohalos in them (the second trend Fig. 6), when the low-grade biotite and andalusite zone schists also contain both zircon grains and biotite flakes? It can’t be due to the 238U radiohalos being annealed in the low-grade schists because of the elevated temperatures in them, because their Po radiohalos would also have been annealed. Besides, the temperatures in the highgrade gneisses and granodiorite were presumably even higher, yet both their Po and 238U radiohalos have survived because of all being generated below 150°C. Furthermore, it can’t be due to the zircons in the lowgrade schists not having had 238U in them, because they have been “flushed” by hydrothermal fluids of the Po derived by 238U decay in them to generate the Po radiohalos in the schists’ biotites, and the zircons in these schists have yielded U-Pb ages.130 That potentially leaves only one likely explanation, namely, the zircon grains within the low-grade schists are not included in the biotite flakes. Obviously, to have 238U radiohalos form around them, the tiny zircon grains need to have been included in much larger biotite flakes, and that is the case in the high-grade gneisses and granodiorite. Neither Hopwood131 nor Johnson, Vernon, and Hobbs132 reported zircon grains being observed in the biotite zone schists, although Williams133 reported some, albeit, as grains separated from the schists, rather than being observed within biotite flakes. On the other hand, Johnson, Vernon, and Hobbs reported zircon as an accessory mineral in the andalusite zone schists, and Williams separated zircon grains from them, so again the zircon grains may not have been in the schist’s biotite flakes. The biotite flakes in the biotite zone schists can be as long as 0.7 mm,134 potentially large enough to include zircon grains only 1–2 microns wide. However, the zircon grains separated from these low-grade schists by Williams are 75–150 microns long,

too large to have 238U radiohalos form around them, but still capable of supplying Po isotopes to passing hydrothermal fluids to generate Po radiocenters and radiohalos in the biotite flakes, even if the zircon grains were not enclosed in them.Next is the third trend, namely, the numbers of 238U and Po radiohalos are large, the same, and the highest both in the high-grade K-feldspar zone gneisses and the granodiorite (table 1 and fig. 6). If the major factor influencing the numbers of Po radiohalos generated is the volume of hydrothermal fluids in these rocks, then obviously the high grade zones and the granodiorite must have experienced the same greatest hydrothermal fluid flows within the complex. It must be remembered that because of the annealing of all radiohalos at and above 150°C, these presently observed238U and Po radiohalos could only have formed after the regional metamorphism and after the granodiorite formed, as both the central granodiorite and the surrounding regional metamorphic complex together cooled below 150°C. The general consensus is that the regional metamorphism occurred first, with the granodiorite an integral part of that event, but forming late in the development of the complex135,136 by virtually in situ partial melting of the high-grade metapsammites and migmatites.137,138,139,140,141,142,143,144,145,146,147 Thus, if the granodiorite formation, crystallization, and cooling were the last to occur, then it was this that produced the last flux of hydrothermal fluids as the granodiorite and the surrounding metamorphic complex finally cooled below 150°C. Because the granodiorite is central, then the hydrothermal fluids it produced when crystallizing and cooling flowed through it and then out from it. Thus the major impact of these hydrothermal fluids to generate Po radiohalos would have been in the granodiorite and in the surrounding high-grade gneisses, their effect rapidly waning with distance out to the low-grade zones as their passage slowed and temperatures fell.Williams148 also noted that in the low-grade biotite and andalusite zone schists the zircon grains are rounded and are thus totally detrital. On the other hand, in the high-grade K-feldspar and migmatite zone gneisses, and the granodiorite, there has been progressively more metamorphic and magmatic growth of the new zircon crystal faces over the original detrital zircon grains with increasing temperatures in the migmatite and granodiorite, and even the crystallization of new zircon grains. He concluded that below the K-feldspar isograd metamorphic conditions, zircon remained inert. However, at, or just before, the point of incipient partial melting, new zircon began to grow, implying some zircon had been dissolved in the partial melts. Because peraluminous melts and magmas, such as the Cooma migmatite leucosomes and the granodiorite, become zircon-saturated at relatively low Zr contents,149 and zircon crystallization and new growth is controlled mainly by the degree of zircon supersaturation of the melt,150 it was likely inevitable that some new zircon crystals grew. This may perhaps have been another factor in why there are 238U radiohalos only in the high-grade K-feldspar and migmatite zone gneisses and the granodiorite.Given these considerations, why then is there a dramatic drop in the numbers of both 238U and Po radiohalos in the high-grade migmatite zone gneisses, the fourth trend noted in Table 1 and Fig. 6? If the generation of Po radiohalos is dependent on hydrothermal fluid flow, and the greater the fluid volume the more Po radiohalos are generated, then it follows that in the migmatite zone there must have been another factor operating to reduce the hydrothermal fluid flows, and/or their effectiveness in generating Po radiohalos. It has already been concluded above that the major impact of the hydrothermal fluids, produced by this last-stage granodiorite crystallizing and cooling to generate Po radiohalos as the whole complex cooled, would have been in the granodiorite and in the surrounding high-grade gneisses. That major impact is observed in the greatest numbers of Po radiohalos in the granodiorite and in the K-feldspar zone gneisses, but not in the migmatite zone gneisses.This apparent enigma is resolved when the conditions under which partial melting occur are understood. It has long been known experimentally that apart from temperature and pressure, the major factor involved in partial melting is the presence and availability of water.151 The temperatures required for partial melting are significantly lowered by increasing water activity up to saturation, and the amount of temperature lowering increases with increasing pressure.152 At the temperatures of 650–700°C and pressures of 3.5–4.0 kbar required to produce the Cooma migmatites containing cordierite,153 the partial melting involved would have been under conditions of water saturation (Flood & Vernon, 1978). Furthermore, the water aids the partial melting process by dissolving in the melt, the water solubility in granitic melts increasing with pressure (and thus depth), so whereas at 1 kbar (equivalent to 3–4 km depth) the water solubility is 3.7 wt%,154 at 30 kbar (up to 100 km depth) it is approximately 24 wt%.155 Thus the partial melting in the migmatite zone would have, in effect, largely used up whatever water was available in the rocks, and the water dissolved in the melt, when the latter crystallized, would have partitioned into mineral lattices, such as the biotite in selvedges around some leucosomes. There would, therefore, have been less hydrothermal fluids available during the cooling of the migmatite zone to generate Po radiohalos.Three of the four trends in the radiohalo abundance data (table 1 and fig. 6), therefore, appear to be primarily related to the availability and volume of the hydrothermal fluids that were released from the central granodiorite after crystallization as it cooled to below 150°C, and then flowed out from the granodiorite into the surrounding metamorphic complex. Thus the presently observed Po radiohalos in the metamorphic complex appear to be a consequence of the intrusion, crystallization, and cooling of the granodiorite, rather than due to the processes that formed the regional metamorphic complex. Indeed, as previously discussed, the general consensus is that the formation of the granodiorite by in situ partial melting was a consequence of the regional metamorphism and not its cause. This is supported by the isotopic uniqueness of this granodiorite compared to the many other granitic rocks in the Lachlan Fold Belt—the highest initial 87Sr/86Sr values (0.7195), the greatest negative initial Nd values (eNd = –9.2), and the highest d18O values (12.9)156,157,158—all suggestive of a different origin for this granodiorite compared to the many other granitic rocks in the Lachlan Fold Belt.Therefore, it has been suggested that the heat which caused the regional metamorphism was probably introduced to the lower crust of this region by large-scale mantle processes due to a major shift in the patterns of asthenospheric (upper mantle) convection.159 Such large-scale mantle processes are also credited with the initiation of the large-scale lower crustal partial melting to generate the tens to hundreds of granitic plutons in regional batholiths, so it has also been suggested that the Cooma regional metamorphism was related to emplacement of the adjacent Murrumbidgee Batholith.160 Indeed, Richards and Collins161 provide evidence to support their claim that the Cooma complex represents a regional metamorphic aureole developed around the Murrumbidgee Batholith.Snelling162,163 has reviewed the mounting evidence in conventional thinking that granite magma generation, intrusion, crystallization, and cooling are rapid dynamic processes requiring only tens to hundreds of years within a uniformitarian time framework, compared to the 100,000 to 1 million years originally claimed. Conventional plate tectonics at uniformitarian slow rates is postulated to be responsible for the large-scale upper mantle convection that delivered heat to partially melt the lower crust and thereby generate granite batholiths. However, in the context of the Flood event in the framework for earth history, these processes are postulated to have occurred at catastrophic rates during catastrophic plate tectonics.164 The catastrophic large-scale generation of a granite batholith, such as the Murrumbidgee Batholith in the Lachlan Fold Belt, would have resulted in the many constituent intruded plutons all emanating heat with the released convecting hydrothermal fluids as they crystallized and cooled, thus producing a regional metamorphic aureole around the batholith. This is consistent with a catastrophic model for regional metamorphism in which the heat and hydrothermal fluids acting on the mineral constituents of the original sediment layers rapidly produced the regional metamorphic zones with their index minerals designating the different metamorphic grades, as in the Cooma complex.165 Based on the catastrophic rate for granite formation of 6–10

days,166,167 this regional metamorphic complex would thus have been produced during this same timescale of 6–10 days over which the granite batholith was emplaced and cooled.However, this regional metamorphic event reached its climax within that 6–10 days timescale with the partial melting that generated the Cooma granodiorite, which is thus, in effect, a secondary product of the emplacement of the Murrumbidgee Batholith. According to Flood and Vernon,168 the large-scale partial melting at depth to produce the Cooma granodiorite as a consequence of the generation of this regional metamorphic aureole would have resulted in the melt segregating and being emplaced within the center of the regional metamorphic complex, attenuating the metamorphic zoning to leave the asymmetric zonal pattern observed today. The further 6–10 days timescale for the formation and cooling of the secondary Cooma granodiorite169,170 would have commenced within the 6–10 days timescale for the formation of the granite batholith, so the total timescale for the formation of this regional metamorphic complex with its central granodiorite would have been on the order of 12–20 days. This is consistent with the Po radiohalos produced by the hydrothermal fluids released by the cooling central granodiorite in the latter part of this period, because the 214Po and 210Po radiohalos in the schists and gneisses would have formed within hours and days respectively,171 after the granodiorite and the metamorphic complex both cooled below 150°C.It might be argued that alternately the temperature fall in both the granite and the metamorphic complex could have been gradual over thousand of years, and when the temperature reached 150°C the continued outflow of hydrothermal fluids at lower temperatures over further decades provided the necessary conditions for Po radiohalo generation in different loci at different times. However, Snelling172 has shown that the Po radiohalos in granites could only have been generated within hours to a few days concurrently while the 238U radiohalos were also forming, and while the 238U decay in their zircon radiocenters to provide the necessary Po (before it decayed) was grossly accelerated. Furthermore, Snelling173 has argued that below 150°C the hydrothermal fluid flows cannot be long sustained, because most of the heat energy to drive the needed convection system174 that both cools the granite and transports the Po has already been dissipated while the temperature in the granite rapidly falls from 400°C to 150°C. Thus, these evidences combined are consistent with the emplacement and cooling of these granite plutons within 6–10 days.Apparent U-Pb, Rb-Sr, Kr-Ar, and Ar-Ar ages of minerals from the Cooma granodiorite and metamorphic complex175,176,177 can be used to construct a cooling history curve for the Cooma granodiorite and metamorphic complex,178,179,180,181 based on the effective closure temperatures of those minerals. According to this curve, the granodiorite and metamorphic complex supposedly took 45 million years to cool from 735 to 150°C. However, if as has been shown from several lines of evidence, radioisotope decay rates were grossly accelerated during the Flood event,182 while catastrophic plate tectonics were operating to produce catastrophic granite formation, then this cooling would have occurred within days, which is consistent with the timescales for granite formation183,184 and Po radiohalos generation.185 Conclusions

The Cooma granodiorite was generated as a consequence of the regional metamorphism that resulted from the catastrophic large-scale emplacement of the Murrumbidgee Batholith during the catastrophic plate tectonics of the year-long Flood event. The Cooma metamorphic complex was generated as a regional aureole by the heat and hydrothermal fluids released by the batholith interacting with the mineral constituents of the original, fossil-bearing, Flood-deposited sediments it intruded within 6–10 days to produce the regional metamorphic zones. At the peak of this regional metamorphism, partial melting at depth at the center of the complex formed the granodiorite, which was then emplaced within the complex. As the granodiorite crystallized and cooled, the hydrothermal fluids emanating from it generated Po radiohalos within the granodiorite and within the surrounding metamorphic complex in hours to days as the terrain cooled below 150°C. This would have occurred towards the end of the further 6–10 days in which the granodiorite formed and cooled. Thus this regional metamorphic complex and its centrally-generated granodiorite with the contained Po radiohalos only took 12–20 days in total to form and cool. The observed patterns of Po radiohalos are consistent with the availability and volume of the hydrothermal fluids responsible for transporting the necessary Po isotopes from the source zircons in the granodiorite, gneisses and schists to form the Po radiocenters that generated the Po radiohalos. Thus, where there was a high volume of hydrothermal fluids in the granodiorite and the immediately surrounding gneisses of the high-grade zones, large numbers of Po radiohalos were generated, except in the migmatite zone where the water aided partial melting, was dissolved in the melt, and then was partitioned into minerals as they crystallized. Where the volume of hydrothermal fluids progressively diminished further out in the low-grade schists, the numbers of Po radiohalos rapidly diminished outwards through the andalusite and biotite zones. In conclusion, not only do the radiohalos in the Cooma metamorphic complex support the hydrothermal fluid transport model for Po radiohalos generation,186 but they and their context are consistent with young age models for catastrophic granite formation187,188 and catastrophic regional metamorphism189 during the catastrophic plate tectonics190 of the year-long Flood. Acknowledgments

This research would not have been achieved without the help and support of numerous people. First, there was the forbearance and support of my wife Kym and family in allowing the necessary field work and sampling during travel on family vacations. Second, Mark Armitage assisted with the processing of samples and the counting of radiohalos. Third, the Institute for Creation Research funded Mark’s help and my time on this project. hide="true" hide="true"

Radiohalos in the Shap Granite, Lake District, England Evidence that Removes Objections to Flood Geology

by Dr. Andrew A. Snelling on August 26, 2009 Abstract The Po radiohalos and other evidence associated with this granite thus remove objections to Flood geology and any need to place the Flood/post-Flood boundary in the lower Carboniferous. Keywords: Shap granite, northern England, contact metamorphic aureole, hydrothermal fluids, Po radiohalos, orthoclase

feldspar megacrysts, catastrophic granite formation, hydraulic fracturing, rapid unroofing, overlying basal conglomerate, Flood/post Flood boundary This paper was originally published in the Proceedings of the Sixth International Conference on Creationism, pp. 389–405 (2008) and is reproduced here with the permission of the Creation Science Fellowship of Pittsburgh and the Institute for Creation Research, Dallas. Abstract

The Shap Granite in the Lake District of northern England intruded the surrounding host rocks as a magma that released hydrothermal fluids as it crystallized and cooled. These hot fluids in turn produced an atypically wide contact metamorphic and metasomatic aureole around the intrusion. There is no evidence at the boundary for tectonic emplacement of a primordial cold granite body. This study documents an abundance of Po radiohalos in the Shap Granite. These Po

radiohalos had to have been produced in the granite after the hydrothermal fluids released in the granite had assisted in the formation of the granite’s distinctive orthoclase feldspar megacrysts, and after the crystallized granite had subsequently cooled below the 150°C annealing temperature of radiohalos. The abundance of Po radiohalos is consistent with the hydrothermal fluid transport model for Po radiohalo formation and with catastrophically rapid granite formation. These features imply that the Shap Granite formed in 6–10 days and its Po radiohalos within hours to days once the granite cooled below 150°C. Hydraulic fracturing of the host rocks overlying the pluton facilitated rapid unroofing of the granite. Continued rapid erosion then deposited granite pebbles in the basal conglomerate of the overlying limestone. It is, therefore, conceivable that the Shap Granite formed, was unroofed, and the basal conglomerate with granite pebbles was deposited, all within 2–3 weeks during the early-middle part of the Flood year. The Po radiohalos and other evidence associated with this granite thus remove objections to Flood geology and any need to place the Flood/post-Flood boundary in the lower Carboniferous. Introduction

An oft-repeated claim is that a timescale of a million years or more for the formation and cooling of molten granite bodies unequivocally disproves Flood geology and its young age chronological framework.1 But many lines of current research are dispelling this misguided thinking.2, 3, 4, 5 Nevertheless, there exist granite bodies whose geological contexts place very tight time constraints on their formation and cooling histories, so much so, that some Flood geologists feel compelled for this and other reasons to place the end of the Flood well down in the geologic record, even as low as the so-called lower Carboniferous (or Mississippian) (for example, Robinson6). An example of such a granite body is the middle Devonian Shap Granite of the Lake District, England. However, an investigation of radiohalos in this granite provides evidence that further dispels these objections to Flood geology and alleviates the need to place the end of the Flood so far down in the geologic record. Geology of the Lake District, England

The Lake District in northwest England contains a small dome of Lower Paleozoic (Ordovician and Silurian) sedimentary and volcanic strata, an inlier protruding from beneath a cover of Carboniferous and Permo-Triassic sedimentary strata.7 Fig. 1 is a generalized geological map of the area, while fig. 2 shows the generalized geological succession of strata.8

Fig. 1. Geology of the Lake District, northern England,

showing the location of the Shap Granite. The oldest rocks in the district (the lowermost in the exposed strata sequence) are Skiddaw Group greywackes, siltstones, and mudstones (now slates in some cases), with sandstones. These appear to have been deposited almost entirely by turbidity currents in relatively deep water. Even though these sedimentary strata are more than 3,000 meters thick, their accumulation via turbidity currents need not have taken the oft-claimed millions of years. Instead, such a thick strata sequence could have accumulated very rapidly early in the Flood year as catastrophic global tectonic upheavals triggered an abundance of turbidity currents, at intervals as short as minutes. Such a catastrophic depositional environment has been confirmed by recognition of large blocks hundreds of meters in diameter which slid downslope as the sediments accumulated.9 The burial of such large blocks indicates that each cycle of these turbidite sediments had to be tens to hundreds of meters thick, so that the whole 3,000 meters thick sequence was deposited within days during the Flood. One source of this huge thickness of sediments would have been the sediments on the pre-Flood ocean floor.10 The conventional Ordovician age assigned to these Skiddaw Group sediments is based mostly on graptolites, but acritarchs and other microfossils have lately been used.Overlying the Skiddaw Group sediments are the Eycott Group volcanic strata. These likely erupted partly in submarine conditions, as some of the last Skiddaw Group sediments are interbedded with them. They consist primarily of basalt and basaltic andesite lavas that preceded the main large-scale catastrophic explosive volcanism of the overlying Borrowdale Volcanic Group. Dominating the landscape over 800 km2 of the Lake District, the Borrowdale

Volcanic Group consists of about 6,000 meters of calc-alkaline basalt, basaltic andesite, and andesite lavas followed by the catastrophic explosive eruption of widespread and voluminous dacitic and rhyolitic pyroclastic deposits (tuffs and ignimbrites), and lavas, associated with volcano-tectonic faulting.11 Garner12 has discussed the evidence for subaqueous, rather than the oft-claimed subaerial, eruption of these volcanics and has shown how the rapid, catastrophic accumulation of the entire volcanic succession during the Flood is consistent with all the field data and what is known about explosive volcanism. For example, in the AD186 Taupo, New Zealand, eruption hot ash-flows or ignimbrites traveled for 80 km in all directions with an initial speed of 250–300 m/sec, so that 30 km3 of rhyolitic volcanic ash was erupted in less than 10 minutes!13

Fig. 2. Time-stratigraphic chart showing the strata sequence in the Lake District, northern England, including the relative

time position of the Shap Granite. Unconformably overlying both the Skiddaw Group and Borrowdale Volcanic Group strata are the predominantly sedimentary strata of the 3,000 meter thick Windermere Group. Deposition commenced in the latest Ordovician with the thin (60–150 m) Coniston Limestone, which contains reworked volcanic ash, and occasional brachiopods and trilobites. Sedimentation was then continuous throughout the so-called Silurian, with thick turbidite sequences of sandstones, flagstones (thin, hard sandstones), gritstones, mudstones, and dark shales deposited that are quite fossiliferous (trilobites, graptolites, brachiopods, ostracods). Apart from uniformitarian assumptions about sedimentation rates, there is no evidence in these Windermere Group strata that would preclude their having been deposited rapidly, especially the thick turbidite sequences, as part of the catastrophic sedimentation during the early part of the Flood. Even the black shales in the Windermere Group, which conventionally would be interpreted as having been deposited in a quiescent, anaerobic, deep marine environment, could have been deposited catastrophically. For example, there are marine black shales in Scotland that must have been deposited as a result of a submarine earthquake induced tsunami, because the shales intertongue with large boulders.14 Furthermore, recent experiments have demonstrated that muddy sediments do accumulate rapidly, at flow velocities that transport and deposit sand.15, 16 In addition to the sediments and extruded volcanic rocks, there was also massive intrusive volcanism. Even as early as the Ordovician, the intrusion of the large Lake District Batholith17, 18 had begun, as represented by the now extensive outcrops

of the Eskdale Granite. Intrusive activity apparently continued until the early Devonian, represented by the Skiddaw and Shap Granites. The dates for the granites are based on K-Ar, Rb-Sr, and U-Pb radioisotope whole-rock and mineral, model and isochron methods.19, 20, 21, 22, 23 It has thus been suggested that the batholith may be genetically related to the Borrowdale volcanicity.24, 25 There is evidence for continuation of a large volume of intrusive activity through the Silurian to the early Devonian.26, 27 The east-west belt of relatively low gravity anomalies suggests the area is underlain by the large granite batholith, for which gravity minima coincide with the outcropping Eskdale, Skiddaw and Shap Granite plutons. These plutons are parts of the roof of the batholith that was exposed by erosion. The heat from these granite intrusives produced wide contact metamorphic aureoles, while hydrothermal fluids from the cooling granites penetrated the overlying Skiddaw, Borrowdale and Windermere Group rocks, depositing copper, lead, tungsten, and iron ores in fracture veins.28By the late Devonian all earlier formed strata were being severely eroded. As a result, the coarse-grained, poorly-sorted Mell Fell Conglomerate was deposited in what has been interpreted as a series of alluvial fans. At least 275 m thick (some estimates are as high as 1,500 m thick), this conglomerate consists of pebbles of mostly Silurian Windermere greywacke, but also some Skiddaw type and Borrowdale volcanic pebbles.29 Possible crossstratification in this conglomerate is added testimony to its rapid deposition.This severe erosion had waned by the early Carboniferous or Dinantian (equivalent to the Mississippian in the USA), giving way to deposition of a sequence of predominantly limestones that has been interpreted as a series of cyclothems.30 However, the Basement Beds to these limestones consist of conglomerates and sandstones that appear to fill irregularities in the pre-Dinantian erosion surface, and are therefore extremely variable in thickness—over 200 meters in the southwest, about 10 m in the Shap area, and completely absent in places. It is in this lower Carboniferous basal conglomerate that pebbles of, and pink feldspar crystals from, the Shap Granite are found, just over a kilometer to the east of the outcropping Shap Granite. Then during the Namurian (mid-Carboniferous) these limestones were overlain by typical cyclothem sequences consisting of sandstones, shales, and gritstones followed by limestones. These in turn were overlain by the Westphalian (upper Carboniferous, or Pennsylvanian in the USA) Coal Measures, up to more than 600 meters of cyclothems consisting of shales, sandstones, and coals, followed by several hundred meters of red beds.Finally, Permian-Triassic sedimentary strata outcrop along the southwestern, northern and northeastern margins of the Lake District. The lowest deposits (Permian) were breccias that are overlain by, and interbedded with, the Penrith Sandstone, followed by so-called evaporite deposits (mainly gypsum and anhydrite). These latter strata are usually interpreted as representing a desert environment, but can be equally well explained as precipitites, that is, they precipitated from water oversaturated in those salts due to catastrophic influxes of salt-laden hydrothermal fluids into cold ocean waters during the Flood.31, 32, 33 The Shap Granite

Fig. 3. Geologic map of the Shap Granite, showing the

atypically wide contact metamorphic and metasomatic aureole surrounding the boundary of the granite with its host rocks. Sample locations are marked. The nearby basal conglomerate to the Carboniferous limestone outcrops near the Spa Wells Hotel (right). The Shap Granite is one of the best-known and most distinctive rock types in northern England.34 With its coarse porphyritic texture and large, pink orthoclase feldspar megacrysts, it has been quarried as a building stone used in London and many other places. Although the Shap Granite only outcrops over a small area of 5.5 km2 (fig. 3), geophysical studies and field evidence have revealed that it is a steepsided stock-like intrusion with a subsurface extension to the northwest.35 This granite pluton was intruded near and at the unconformity between the Ordovician Borrowdale Volcanic Group lavas and tuffs, and the overlying Silurian Windermere Group. The heat and hydrothermal fluids from the crystallizing granite magma as it cooled generated a broad (600+ meter wide) metamorphic and metasomatic aureole around its contact with its host rocks.36, 37, 38The Shap Granite has a characteristic porphyritic texture dominated by pink orthoclase feldspar megacrysts often more than 3 cm in length with good rectangular shapes and twinning parallel to their long axes.39 The matrix is coarse and consists of glassy grey quartz, cream plagioclase feldspar, and black biotite crystals. Hornblende is occasionally a minor constituent, while accessory minerals include zircon, apatite, allanite, sphene (titanite), and magnetite.40Also present in the granite is a suite of mafic microgranular enclaves, essentially quartz

microdiorite, often incorrectly called xenoliths, typically 10–20 cm in size.41, 42 They can be angular or rounded, and may have either sharp or fuzzy boundaries with the normal granite. Furthermore, they also usually contain the same pink orthoclase feldspar megacrysts as in the granite, but they are less frequent and more rounded than in the normal granite. These observations have fueled debate about the origin of these mafic enclaves.The Shap Granite when first mapped was shown to be a composite intrusion, with three separate main stages, each containing different types of mafic enclaves, after an initial more primitive fraction of the magma represented by the early mafic enclaves.43, 44 These three granite stages show cross-cutting relationships, and show a progressive increase in both grain size and orthoclase feldspar megacryst content. The second stage represents 90% of the intrusion, and the third and last stage of the intrusion contains approximately 50% orthoclase feldspar megacrysts. Firman45demonstrated that the whole-rock geochemical data46 was consistent with a mixing hypothesis. However, textural observations,47 mixing trends,48 rare earth element patterns49 and the crystallization path50 all suggest little open system fractionation has occurred. Changes in pressure and/or fluid content, together with partial hydridization, seem to have dominated the granite magma’s chemical evolution as it was intruded, crystallized, and cooled. Indeed, the mafic (quartz microdiorite) enclaves are now regarded as the result of hydridization of the granite by co-intrusion of a mafic magma. Good evidence for this is provided by seismic reflection data for sills in the nearby related Eskdale Granite.51 There is also good observational evidence that magmatic hydrothermal fluids played a major role in the formation of the orthoclase feldspar megacrysts during granite crystallization and cooling at temperatures of 410°C and 370°C.52, 53, 54Brown et al.55 have summarized all previous attempts to date the Shap Granite.56, 57, 58 Six Rb-Sr model ages determined on biotite from the granite ranged from 364 ± 24 Ma to 403 ± 15 Ma, while 15 K-Ar model ages, also determined on biotite, ranged from 381 ± 12 Ma to 410 Ma. Subsequent U-Pb measurements on zircons from the granite yielded a discordia line with an upper intercept age of 390 ± 6 Ma.59 Wadge, Gale, Beckinsdale, and Rundle60made three further K-Ar model age determinations on biotites from the granite, which yielded ages of 394 ± 12 Ma, 394 ± 12 Ma and 403 ± 12 Ma, averaged to 397 ± 7 Ma. However, they also performed 22 Rb-Sr measurements on whole-rock granite samples, and biotite and orthoclase feldspar megacryst separates, which yielded a 21-point Rb-Sr isochron line corresponding to an age of 394 ± 3 Ma. Given this apparent agreement (concordance) between these ages for the Shap Granite obtained by three radioisotope dating methods (K-Ar, Rb-Sr, and U-Pb), it has been concluded that in conventional terms this granite is early Devonian (Emsian). The Perceived Problem

Fig. 4. Outcrops of the

conglomerate, containing the Shap Granite pebbles and pink K-feldspar crystals, at the base of the Carboniferous (Dinantian) limestone in the creek bank near the Spa Wells Hotel (fig. 3). (a) The conglomerate can be seen at the bottom of the creek bank (b) Closer view of the basal conglomerate layer with rounded pebbles clearly visible (c) Even closer view of the conglomerate showing the clasts in a course matrix (d) Another enlarged view of the conglomerate in which granite and K-feldspar clasts can be seen The Shap Granite has been convincingly dated, in

conventional terms, at 394 ± 3 Ma, or middle Devonian. Yet just over a kilometer to the east of the outcropping granite, near the Spa Wells Hotel (fig. 3), is an outcrop of the lower Carboniferous basal conglomerate to the overlying Carboniferous limestones, in which are found pebbles of, and pink orthoclase feldspar megacrysts from, the Shap Granite (fig. 4). So if this conglomerate dates to approximately 354 Ma, there are only 40 million years, in conventional terms, for complete cooling of the granite, erosion of perhaps 1–3 kilometers of host metamorphosed sediments to unroof the granite, and then erosion of the granite to deposit these granite pebbles and feldspar megacrysts in the nearby conglomerate bed.Placement of these processes during the Flood year requires 40 million years of conventional geologic time to be compressed to perhaps only 2–3 weeks! To alleviate this problem some have placed the Flood/post- Flood boundary within this interval, allowing more time in the immediate post-Flood period for the cooling and unroofing of this granite61 (Robinson, Tyler, and Garton, pers. comm.). This view makes the upper Carboniferous coal measures, which overlie the limestones and their basal conglomerate, post-Flood. It also makes the Carboniferous-Recent fossils the result of the post-Flood recolonization of the earth. Since radiohalo studies have provided evidence that granites had to crystallize and cool rapidly,62, 63 a radiohalos investigation of the Shap Granite was undertaken. Field Work

A field trip to the Shap Granite was made in early October 2002. Several sections of the boundary of the granite with its host rocks were followed and inspected in outcrop. Four samples of the granite were collected. Three of these were from the sporadically used Shap Granite Quarry, and one from an outcrop of the granite at its host rock boundary, not far from the active Shap Blue Quarry (fig. 3). Fig. 5 shows views of the granite and of the sampled outcrops. Experimental Procedures

Fig. 5. Outcrops of the

Shap Granite sampled in this study (locations indicated in fig. 3). (a) The northern end of the Shap Granite Quarry’s east-facing wall in the vicinity of where samples RUK-2 and 3 were collected (b) Close view of the Shap Granite in the quarry showing the abundance of pink K-feldspar megacrysts in the granite (c) The boundary of the pink granite (foreground) with the overlying grey contact hornfels at the site of sample RUK-4, taken from the “clean” area towards the creek. The red ribbon marks the granite/hornfels boundary, which is sharp

(d) Closer view of the granite/hornfels boundary, marked by the hand lens and red ribbon. The boundary is sharp, with no evidence of any cold tectonic emplacement of the granite A standard petrographic thin section was obtained for each granite sample. In the laboratory, a scalpel and tweezers were used to remove flakes of biotite from the sample surfaces. Where necessary portions of the samples were crushed to liberate the constituent mineral grains. Biotite flakes were then hand-picked and placed on the adhesive surface of a piece

of clear Scotch™ tape. Once numerous biotite flakes had been mounted on the adhesive surface of this tape, a fresh piece of clear Scotch™ tape was placed over them and firmly pressed along its length so as to ensure the two pieces of tape were stuck together with the biotite flakes firmly wedged between them. The upper piece of clear Scotch™ tape was then peeled back in order to pull apart the biotite flakes. This upper piece of clear Scotch™ tape with thin biot ite sheets adhering to it was then placed over a standard glass microscope slide. This procedure was repeated with another piece of clear Scotch™ tape placed over the original Scotch™ tape with biotite flakes adhering to it. These adhering biotite flakes were progressively pulled apart and transferred to microscope slides. In this way tens of microscope slides were prepared for each granite sample, each slide with many (at least 20–30) thin biotite flakes mounted on it. This is similar to the method pioneered by Gentry (Gentry, pers. comm.). Fifty microscope slides were prepared for each sample to ensure good representative sampling statistics. Thus there was a minimum of 1,000 biotite flakes mounted on microscope slides for each sample.Each slide for each granite sample was then carefully examined under a petrological microscope in plane polarized light, and all radiohalos present were identified, noting any relationships between the different radiohalo types, and any unusual features. The numbers of each type of radiohalo in each slide were counted by progressively moving the slide backwards and forwards across the field of view, and the numbers recorded for each slide were then tallied and tabulated for each sample. Because of the progressive peeling apart of many of the same biotite flakes during the preparation of the microscope slides, many of the radiohalos appeared on more than one microscope slide. Only radiohalos whose radiocenters were clearly visible were thus counted to ensure each radiohalo was only counted once. Results

Fig. 6 shows the typical mineralogy and textures of the Shap Granite under the microscope in the samples collected for this study. All radiohalos results are listed in Table 1. All four samples contained abundant 238U, 232Th, and Po radiohalos, some representative examples of which can be seen in Fig. 7. As well as the absolute numbers of each of the radiohalo types counted, Table 1 also shows the average total numbers of radiohalos and of just Po radiohalos per slide, plus abundance ratios for pairs of radiohalo types.The four samples average between 9 and 16 radiohalos per slide, and between 6 and 12 Po radiohalos per slide. This compares well to similar average numbers of radiohalos in other Paleozoic-Mesozoic granitic rocks, well above the numbers of radiohalos in Precambrian granitic rocks (see Tables 1 and 2, and Figs. 5 and 6 in Snelling64). 210Po radiohalos outnumber 238U radiohalos by between 2.3 to 1 and 8.7 to 1, and greatly outnumber 214Po and 218Po radiohalos, 35-227 to 1 and 48-571 to 1, respectively. This is also typical of other Paleozoic-Mesozoic granitic rocks. Discussion

The significance of so many observed Po radiohalos in these Shap Granite samples depends on how they are understood to have formed. In conventional thinking they are “a very tiny mystery” (G. Brent Dalrymple, as quoted by Gentry65) that can therefore be conveniently ignored because they have little apparent significance. However, if the formation of these Po radiohalos cannot be explained, then their significance cannot be fully comprehended. The reality is that the mystery of the Po radiohalos is ignored, because it constitutes a profound challenge to conventional wisdom.Comprehensive reviews of what these Po radiohalos are and how they may have formed are provided by Gentry66, 67,68, 69 and Snelling.70 It has been established that all the observed Po radiohalos are generated exclusively from the Po radioisotopes in the 238U decay series, namely, 218Po, 214Po, and 210Po, with contributions from none of the other species in the 238U α-decay chain.71 Furthermore, it has been estimated that, like the 238U radiohalos, each visible Po radiohalo requires between 500 million and 1 billion α-decay s to generate it,72 which equates to a corresponding number of Po atoms having been in each radiocenter. Thus the crucial issue is how did so many Po atoms get concentrated into these radiocenters to generate the Po radiohalos, when their half-lives are only 3.1 minutes (218Po), 164 microseconds (214Po), and 138 days (210Po)?Gentry73, 74, 75 insists that the Po must be primordial, that is, created instantaneously in place in the radiocenters in the biotite flakes in the granites, and thus the granites are also created rocks. In other words, he argues that granites

did not form from the crystallization and cooling of magmas, but rather are the earth’s created foundation rocks. Moreover, where granites such as the Shap Granite have been intruded into fossiliferous Flood-deposited strata, Gentry76 insists that these granites also represent originally created rocks. He argues that during the Flood they were tectonically intruded as cold bodies, and that the contact metamorphic aureoles were produced by the heat and pressure generated during tectonic emplacement, augmented in some cases by hot fluids from depth.Such an interpretation is inconsistent with the field and petrological evidence from the Shap Granite. The contact between the granite and the metamorphosed fossiliferous (Flood-deposited) host rocks it intruded is a sharp, knife-edge boundary, with no fracturing, brecciation or mylonization that should be evident in either the adjacent granite or host rocks if the granite had been intruded tectonically as a cold body (Figs. 5c & d). Fig. 6. Representative photo-micrographs of the

Shap Granite samples used in this study. All photo-micrographs are at the same scale (20× or 1 mm = 40 µm) and the granite is as viewed under crossed polars. (a) RUK-1: quartz, K-feldspar, plagioclase (with sericite), biotite, apatite (b) RUK-2: quartz, K-feldspar, plagioclase, biotite (c) RUK-2: quartz, K-feldspar, plagioclase, biotite

(with halos) (d) RUK-3: quartz, K-feldspar, plagioclase (with sericite), biotite, sphene (titanite)

(e) RUK-4: quartz, K-feldspar, plagioclase (with sericite), biotite (f) RUK-4: quartz, K-feldspar, plagioclase (with sericite), biotite (with halos)

Fig. 7. Some

representative radiohalos found in biotite flakes separated from the Shap Granite in this study. All photo-micrographs are at the same scale (40× or 1 mm = 20µm) and the biotite flakes are as viewed in plane polarized light. (a) RUK-1: two overexposed 238U radiohalos and a 210Po radiohalo with a zircon grain nearby (b) RUK-1: an overexposed 238U radiohalo with a tiny zircon grain in its center (c) RUK-1: a 218Po radiohalo with a faint outer ring, and an enlarged 210Po radiohalo (d) RUK-2: a 210Po radiohalo, a possible 238U radiohalo, and some fluid inclusions (e) RUK-2: a 214Po radiohalo, a 210Po radiohalo, and a fluid inclusion (f) RUK-4: a 210Po radiohalo (left), and a large zircon grain (g) RUK-4: an overexposed 238U radiohalo and a fluid inclusion (h) RUK-4: an overexposed 238U radiohalo, and a reversed overexposed 238U radiohalo Table 1. Data table of

radiohalos numbers counted in the collected Shap Granite samples.

Sample Number of Slides Radiohalos

Total Number of Radiohalos per Slide 210Po 214Po 218Po 238U 232Th

RUK-1 51 311 9 3 138 18 9.4

RUK-2 51 454 2 0 52 7 10.1

RUK-3 51 576 5 12 212 7 15.9

RUK-4 51 571 3 1 216 18 15.9

Sample Number of Po Radiohalos per Slide Ratios

210Po:238U 210Po:214Po 210Po:218Po 214Po:218Po 238U:232Th

RUK-1 6.3 2.3:1 34.6:1 104:1 3:1 7.7:1

RUK-2 8.9 8.7:1 227:1 — — 7.4:1

RUK-3 11.6 2.7:1 115:1 48:1 0.4:1 30:1

RUK-4 11.3 2.6:1 190:1 571:1 3:1 12:1

Indeed, granite sample RUK-4 was collected right at the boundary, yet it displayed no petrographic signs of cold tectonic emplacement effects and looked no different from the other samples that were collected further away from the boundary. Furthermore, if the theorized accompanying hot fluids from depth had a temperature of >150°C, as likely they would, then they would have annealed all the radiohalos.77 In fact, hydrothermal fluids were responsible for forming the pink orthoclase feldspar megacrysts within the granite at 410°C and 370°C; so the presently-observed Po radiohalos in the granite could only have been generated subsequently, after the granite had cooled below 150°C. Thus the Po radiohalos were formed after the granite was intruded and after it and its contact metamorphic aureole in the host rocks had cooled. Indeed, the rock in the contact metamorphic aureole at sample site RUK-4 consists of andesite that has been extensively recrystallized to hornfels by the intense magmatic heat and hydrothermal fluids emanating from the intruding magma.78 Furthermore, tongues and veins of granite can be seen penetrating the metamorphosed host rock, proving that the granite intruded as a magma, and is therefore not primordial (that is, created).The other competing model for the formation of the Po radiohalos is a hydrothermal fluid transport model.79, 80 In this model it is postulated that the Po isotopes as well as the 222Rn parent of 218Po were produced from 238U decay in the zircons that are the radiocenters of nearby 238U radiohalos located in the same biotite flakes as the Po radiohalos. The hydrothermal fluids released by the crystallizing and cooling granite magma flowed along the biotite cleavage planes and transported the 222Rn and Po isotopes from the zircon radiocenters. The Po isotopes, including the 218Po produced by 222Rn α-decay (half-life of 3.8 days), were then precipitated in lattice defects along the same biotite cleavage planes where S, Cl and other atoms chemically attractive to Po were located, within a millimeter or so of the zircon radiocenters. These Po precipitation sites became the radiocenters for the Po radiohalos. As the Po in the radiocenters α-decayed, new Po atoms were supplied from the hydrothermal fluids flowing through the biotite lattice. Thus, provided the supply of Po isotopes was sufficient and the hydrothermal fluid flows were sustained and rapid, the required Po concentrations would have been supplied to the radiocenters to produce the 500 million–1 billion Po α-decay s to generate the Po radiohalos within hours or days, consistent with the fleeting half-lives of the Po isotopes.Because hydrothermal fluid flows are crucial to this Po radiohalos formation model, it might be expected that the greater the volume and flow of hydrothermal fluids, the greater the probability that more Po radiohalos would be generated. This prediction has proven true in several situations. First, in granites where hydrothermal ore deposits have formed in veins due to large, sustained hydrothermal fluid flows, there are huge numbers of Po radiohalos, for example, in the Land’s End Granite, Cornwall.81 Second, where hydrothermal fluids were produced by mineral reactions, at a specific pressure-temperature boundary during regional metamorphism, four to five times more Po radiohalos were generated, precisely at that specific metamorphic boundary.82, 83 Third, where hydrothermal fluids flowing in narrow shear zones had rapidly metamorphosed the wall rocks, Po radiohalos were present in the resultant metamorphic rock, a type of metamorphic rock that otherwise does not host Po radiohalos.84 Fourth, in a sequentially intruded suite of nested granite plutons where the hydrothermal fluid content of the granites correspondingly increased, so that the last intruded central pluton was connected to coeval explosive, steam-driven volcanism, the numbers of Po radiohalos generated increased inwards within the nested suite of granite plutons.85 Such evidences provide confirmations that give confidence in this hydrothermal fluid trasnport model for forming Po radiohalos.The hydrothermal fluids generated by the crystallization and cooling of the Shap Granite produced several effects that indicate substantial volumes of sustained fluid flow were involved. The hydrothermal fluids carried the heat released by the crystallizing granite and dispersed it by convection into the host rocks. These fluids generated the 600+ meter wide contact metamorphic and metasomatic aureole around the granite.86, 87, 88 The enormous width of this aureole, nearly half the radius of the exposed Shap Granite stock itself, is most unusual compared with other granites. This large width is testimony to the large volumes of hydrothermal fluids that produced it. Additionally, the hydrothermal fluids penetrated along fractures in the host rocks well beyond the aureole to deposit ore veins of copper, lead, tungsten, and iron.89 Then within the granite itself the magmatic hydrothermal fluids played a role in the formation of the orthoclase feldspar megacrysts, which are characteristic of this granite and dominate its porphyritic texture.90, 91, 92 Thus the large numbers of Po radiohalos in the Shap Granite are consistent with these other evidences of sustained hydrothermal fluid flows through it and out into the surrounding host rocks. The tiny zircon grains that are at the centers of the many 238U radiohalos in the Shap Granite would have been the source of the Po isotopes transported by the hydrothermal fluids to generate the Po radiohalos.A constraining factor on the preservation of the Po radiohalos is that the damage left by the α-particles is retained in the biotite flakes only below 150°C. Above this α-particle annealing temperature93 the damage either doesn’t register or is obliterated. Thus all the radiohalos now observed in the Shap Granite had to form below 150°C, which is relatively late in the cooling history of the granite. Granite magmas when intruded are at temperatures of 650–750°C, and the hydrothermal fluids are released at temperatures of 370–410°C after most of the granite and its constituent minerals have crystallized. However, the accessory zircon grains with their contained 238U crystallize very early at higher temperatures, and may have even been already formed in the magma when it was intruded. Thus the 238U decay producing Po isotopes had already begun well before the granite had fully crystallized, before the hydrothermal fluids had begun flowing, and before the crystallized granite had cooled to 150°C. Furthermore, by the time the temperature of the granite and the hydrothermal fluids had cooled to 150°C, the heat energy driving the hydrothermal fluid convection would have begun to wane and the vigor of the hydrothermal flow would also have begun to diminish (fig. 8). The obvious conclusion has to be that if the processes of magma intrusion, crystallization, and cooling required 100,000–1 million years, then so much Po would have already decayed and thus been lost from the hydrothermal fluids by the time the granite and fluids had cooled to 150°C that there simply would not have been enough Po isotopes left to generate the Po radiohalos.94The data in Table 1 show that Po radiohalos greatly outnumber 238U radiohalos in the Shap Granite. There are likely two reasons for this. First, many of the 238U radiohalos are dark and overexposed with blurred inner rings (fig. 7), which indicates that there has been an enormous amount of 238U decay, much more than the 500 million–1 billion atoms needed to produce a radiohalo with distinct inner rings. This implies that there likely would have been enough Po generated to form multiple Po radiohalos in the vicinity of each 238U radiohalo. Second, as already noted above, much evidence suggests that the greater the volume and flow of hydrothermal fluids, the greater the number of Po radiohalos generated. Both the Shap Granite and its aureole indicate a large volume of hydrothermal fluids flowed within and outside of this granite. Thus there was a greater capacity for hydrothermal fluid transport of Po atoms to supply more radiocenters with the needed Po atoms to generate the observed Po radiohalos.Even conventional thinking on the timescale for the granite intrusion, crystallization, and cooling processes is changing. Whereas formerly it was claimed that granites took a million years or more to form,95 it is now recognized even in the conventional community that granite formation is a rapid, dynamic process operating on timescales as short as thousands of years.96, 97 Consequently, much evidence now favors the processes of magma generation, segregation, ascent, emplacement, crystallization, and cooling being catastrophic,98, 99, 100, 101 consistent with the catastrophic plate tectonics model for the Flood event.102 Furthermore, the concept of accelerated radioisotope decay103allows nuclear decay processes at catastrophic rates during the Flood.

Fig. 8. Schematic conceptual temperature versus time cooling curve diagram to show the timescale for granite

crystallization and cooling, hydrothermal fluid transport, and the formation of polonium radiohalos (after Snelling105). Both catastrophic granite formation and accelerated radioisotope decay are relevant to the hydrothermal fluid transport model for Po radiohalo formation. However, halo formation itself provides constraints on the rates of both those processes.104 If 238U in the zircon radiocenters supplied the concentrations of Po isotopes required to generate the Po radiohalos, the 238U and Po radiohalos must form over the same timescale of hours to days, as required by the Po isotopes’ short half-lives. This requires 238U

production of Po to be grossly accelerated. The 500 million–1 billion α-decays to generate each 238U radiohalo, equivalent to at least 100 million years’ worth of 238U decay at today’s decay rates, had to have taken place in hours to days to supply the required concentration of Po for producing an adjacent Po radiohalo. However, because accelerated 238U decay in the zircons would have been occurring as soon as the zircons crystallized in the magma at 650–750°C, unless the granite magma fully crystallized and cooled to below 150°C very rapidly, all the 238U in the zircons would have rapidly decayed away, as would have also the daughter Po isotopes, before the biotite flakes were cool enough for the 238U and Po radiohalos to form and survive without annealing. Furthermore, the hydrothermal fluid flows needed to transport the Po isotopes along the biotite cleavage planes from the zircons to the Po radiocenters are not long sustained, even in the conventional framework, but decrease rapidly due to cooling of the granite (fig. 8).106 Thus Snelling107 concluded from all these considerations that the granite intrusion, crystallization, and cooling processes occurred together over a timescale of only about 6–10 days.One apparent difficulty with this model is its requirement for α-particle energy, as indicated by radiohalo radius, to be diagnostic and also independent of parent decay rate over many orders of magnitude. However, Chaffin108 has demonstrated that if the depth of the potential energy well for α-decay is increased, with a corresponding increase in the decay constant (and therefore the decay rate), then the decay energy of the α-particle may be held the same with only a slight increase in the nuclear radius, so that the radii of radiohalos also would remain the same while the α-decay rate increased. A second apparent and related difficulty is that if the 238U decay rate was grossly accelerated by many orders of magnitude, then the decay of the Po isotopes might also be similarly accelerated, and thus there would not have been enough time for hydrothermal fluid transport to carry the Po atoms for even a millimeter within the biotite flakes. However, Austin109 and Snelling110 have documented evidence that in an accelerated α-decay episode the parent isotopes which today have the slowest decay rates (and thus yield the oldest ages on the same rock samples) had their decay accelerated the most. The implication of this observation is that in an accelerated α-decay episode, those parent isotopes which decay at extremely high rates today should have experienced almost no acceleration of their decay. Thus the decay of the Po isotopes would have hardly been accelerated at all, in stark contrast to the huge acceleration of 238U decay. This would, therefore, have allowed enough time for hydrothermal fluid transport of the Po atoms needed to generate the Po radiohalos.However, someone might inquire what requires the hydrothermal fluid flow interval to be so brief? Surely, because the zircon radiocenters and their 238U radiohalos are near to (typically within only 1 mm or so) the Po radiocenters in the same biotite flakes, could not the hydrothermal flow have indeed carried each Po atom from the 238U radiocenters to the Po radiocenters within minutes, but the interval of hydrothermal fluid flow persist over many thousands of years during which the billion Po atoms needed for each Po radiohalo are transported that short distance? In this case the238U decay and the generation of Po atoms could be stretched over that longer interval. However, as already noted above, by the time a granite body and its hydrothermal fluids cool to below 150°C, most of the energy to drive the hydrothermal convection system and fluid flow has already dissipated.111 The hydrothermal fluids are expelled from the crystallizing granite and start flowing at between 410 and 370°C (fig. 8). So unless the granite cooled rapidly from 400°C to below 150°C, most of the Po transported by the hydrothermal fluids would have been flushed out of the granite by the vigorous hydrothermal convective flows as they diminished. Simultaneously, much of the energy to drive these fluid flows dissipates rapidly as the granite temperature drops. Thus, below 150°C (when the Po radiohalos start forming) the hydrothermal fluids have slowed down to such an extent that they cannot sustain protracted flow. Moreover, the capacity of the hydrothermal fluids to carry dissolved Po decreases dramatically as the temperature becomes low.Thus sufficient Po had to be transported quickly to the Po radiocenters to form the Po radiohalos while there was still enough energy at and below 150°C to drive the hydrothermal fluid flows rapidly enough to get the Po isotopes to the deposition sites before they decayed. This is the time and temperature “window” depicted schematically in Fig. 8. It

would thus simply be impossible for the Po radiohalos to form slowly over many thousands of years at today’s groundwater temperatures in cold granites. Hot hydrothermal fluids are needed to dissolve and carry the polonium atoms, and heat is needed to drive rapid hydrothermal convection to move Po transporting fluids fast enough to supply the Po radiocenters to generate the Po radiohalos. Furthermore, the required heat cannot be sustained for the 100 million years or more while sufficient 238U decays at today’s rates to produce the 500 million–1 billion Po atoms needed for each Po radiohalo. In summary, for there to be sufficient Po to produce a radiohalo after the granite has cooled to 150°C, the timescales of the decay process as well as the cooling both must be on same order as the lifetimes of the Po isotopes. Thus, the hydrothermal fluid flows had to be rapid, as the convection system was short-lived while the granite crystallized and cooled rapidly within 6–10 days, and as they transported sufficient Po atoms to generate the Po radiohalos within hours to a few days.The Shap Granite does not appear to be unique, but rather is typical of other granites, in terms of its mineralogy, chemistry and texture, and the hydrothermal fluids it generated. Thus, this model for its rapid formation and cooling can be extended to other granite bodies, as has been done by Snelling,112, 113 Snelling and Armitage,114 and Snelling and Gates.115 Even the enormous metamorphic aureole is not unique to the Shap Granite. Many other granites are surrounded by aureoles, though often smaller. Almost all granites show evidence of the hydrothermal fluids they generated as they crystallized and cooled. The ubiquitous presence of Po radiohalos116 is also testimony to these hydrothermal fluids. Even in those granites where fewer Po radiohalos would suggest less hydrothermal fluids were produced in them, the presence of Po radiohalos indicates there were still sufficient hydrothermal fluids to cool them rapidly. The volume of the Shap Granite is small compared with that of the large Lake District Batholith to which it belongs. Yet because this model of rapid formation and cooling has been applied successfully to so many other granite bodies, there are many reasons to conclude that each of the plutons making up the batholith likewise formed and cooled rapidly. Indeed, the volume of the nested granite plutons of the Tuolumne Intrusive Suite of Yosemite, California, is comparable to that of the Lake District Batholith, and Snelling and Gates117 have built a strong case that each of those voluminous plutons also formed and cooled rapidly.The abundant 238U and Po radiohalos in the Shap Granite are, therefore, compelling evidence that this granite formed in only about 6–10 days. This is consistent with its having intruded into the fossiliferous Flood-deposited Borrowdale and Windermere Group sediments and volcanics. The enormous scale of the contact metamorphic and metasomatic aureole surrounding the Shap Granite is also testimony to the rapid rate of granite cooling and thus rapid release of heat that drove the hydrothermal fluids forcefully out of the pluton and into the surrounding host rocks. Once in the host rocks, the hydrothermal fluids combined convectively with ground waters to disperse the granite’s heat and together produce the aureole. The aureole’s size also is consistent with the granite producing, and the host rocks containing, large volumes of hydrothermal fluids and ground waters, respectively. The ground water would be a consequence of rapid sediment deposition only days and weeks before granite intrusion during the Flood. The force of the intruding granite magma inevitably weakened the surrounding host rocks, particularly above the resulting pluton because the buoyant magma had pushed its way upwards into them. Any induced fracturing of the overlying rocks would have been exploited by the ascending magma. Hydrothermal fluids released by the crystallizing and cooling magma would also tend to be forced upwards more easily than laterally. The high fluid pressures would result in acute hydraulic fracturing of the roof rocks overlying the granite pluton, and the hydrothermal fluids released upwards would produce intense hydrothermal alteration. This combination of intense hydraulic fracturing and hydrothermal alteration of the host rocks directly overlying the granite pluton (the roof) makes the roof more susceptible to subsequent weathering and erosion and thus to being stripped away rapidly to expose (or unroof) the top of the granite pluton.118 In the case of the Shap Granite, the large size of the metamorphic/metasomatic aureole compared to the width of the pluton (fig. 3) likely implies that the hydraulic fracturing and hydrothermal alteration of the roof rocks was very intense, resulting in their increased susceptibility to subsequent rapid erosion and rapid unroofing of the pluton.In regard to the relative timing of deposition of the strata sequence in the Lake District during the Flood (fig. 2), there appears to have been a depositional hiatus at the time the Shap Granite was intruded, with an unconformity at the top of the Silurian Windermere Group before later deposition of the Carboniferous limestone. This implies that when the Shap Granite intruded, its Windermere and Borrowdale Group host rocks were either being uplifted, perhaps by the ascending magma itself, or the Flood water level was dropping, or both. Thus it is entirely possible that within days of intrusion and cooling of the Shap Granite stock the overlying heavily fractured and altered roof rocks were exposed to rapidly falling water levels from their uplifted and arched-up surface, resulting in their rapid erosion to quickly expose the granite beneath. However, due to the tidal movement of the global Flood waters, repeated sediment-laden surges would have quickly eroded both the roof rocks and the granite, so that dislodged pebbles of granite and orthoclase feldspar megacrysts from the granite would soon be deposited nearby in a conglomerate. With rising water levels the subsequent sediment deposition quickly transitioned into limestone.In conclusion, therefore, the presence of abundant Po radiohalos in the Shap Granite and in the sharp granite/host rock boundary, and the large comparative width of the surrounding contact metamorphic and metasomatic aureole, together provide evidence that the granite was intruded as magma and cooled within 6–10 days and was then unroofed within a few days later. Thus, a coherent solution for the perceived time problems associated with the formation of the Shap Granite and the adjacent overlying basal conglomerate containing granite pebbles and orthoclase feldspar megacrysts appears to be available, with no compelling reason to place the Flood/post-Flood boundary between the intrusion of the Devonian Shap Granite and the deposition of the basal conglomerate to the Carboniferous limestone. These observations now show that it is plausible for the Shap Granite to have been generated, intruded, cooled, and then unroofed and eroded, to be immediately followed by deposition of the conglomerate basal to the limestone, all within the early-middle part of the Flood year. Conclusions

The Devonian Shap Granite in the Lake District, England, was intruded as molten magma into the older explosively-erupted Ordovician Borrowdale Group lavas and tuffs and the fossiliferous Flood-deposited Windermere Group sediments overlying them. There is no evidence of fracturing, brecciation and mylonization at the granite/host rocks boundary that should be present if the granite stock had been emplaced tectonically as a cold body. Instead, the heat and hydrothermal fluids from the crystallizing magma produced a 600+ meter wide contact metamorphic and metasomatic aureole. Therefore, the abundant Po radiohalos presently observed in samples of the granite could not have been generated by primordial Po, because the hydrothermal fluids also helped form orthoclase feldspar megacrysts in the granite at 370–410°C. Any pre-existing Po radiohalos in the granite would have been annealed at those temperatures that are well above the 150°C annealing temperature for radiohalos. Instead, the abundant presence of Po radiohalos is consistent with a large volume of hydrothermal fluids released by the cooling granite. These fluids are also responsible for the atypically wide contact metamorphic and metasomatic aureole. Thus, this evidence supports a hydrothermal transport model for Po radiohalos and catastrophically rapid granite formation. This evidence suggests the Shap Granite formed within 6–10 days and its Po radiohalos within hours to days once the granite cooled below 150°C. Hydraulic fracturing and hydrothermal

alteration of the host rocks above the granite intrusion would have facilitated rapid unroofing of the pluton also within days. Sediment-laden Flood waters then surging over the exposed granite would have eroded granite pebbles and orthoclase feldspar megacrysts from the granite to quickly deposit them in a conglomerate bed nearby, where sedimentation soon transitioned into a Carboniferous limestone. It is, therefore, entirely conceivable for this sequence of events from formation of the Devonian Shap Granite through to the deposition of the stratigraphically overlying Carboniferous limestone to have occurred within 2–3 weeks during the early-middle part of the Flood year. The Po radiohalos and the other evidence associated with this granite thus remove objections to Flood geology, including the timescale for granite formation, and the need to place the Flood/post-Flood boundary in the lower Carboniferous. Acknowledgments

This research would not have been achieved without the support and help of numerous people. First, Paul Garner, David Tyler, and Randall Hardy organized and provided transport for the field trip to the Shap Granite and the surrounding area. Second, the Institute for Creation Research funded my time on this project, including the travel and sample processing to count radiohalos. Third, there has been the constant patience and support of my wife Kym and my family in my research endeavors. Fourth, the reviewers and the editor of the manuscript are thanked for their helpful suggestions that improved this paper.

Radiohalos—A Tale of Three Granitic Plutons

by Dr. Andrew A. Snelling and Mark Armitage on August 19, 2009 Abstract

The origin and significance of radiohalos have been debated for almost a century, perhaps largely because their geological distribution has been poorly understood. Keywords: radiohalos, 218Po, 214Po, 210Po, 238U, 232Th, granitic plutons, biotites, zircons, monazites, hydrothermal

fluids, 222Rn, radiocenters, accelerated decay and heat flow, rapid hydrothermal fluid flows, rapid regional metamorphism, rapid pluton cooling, rapidly formed Metallic Ore Deposits This paper was originally published in the Proceedings of the Fifth International Conference on Creationism, pp. 243–267 (2003), and is reproduced here with the permission of the Creation Science Fellowship of Pittsburgh. Abstract

The origin and significance of radiohalos, particularly the 218Po, 214Po, and 210Po radiohalos, have been debated for almost a century, perhaps largely because their geological distribution has been poorly understood. In this study samples from three granitic plutons were scanned under microscopes for radiohalos as part of a larger project to investigate the geological occurrence and global distribution of all types of radiohalos. These three granitic plutons were all demonstrated to have formed during the Flood, but all contained 210Po, 214Po, and 238U radiohalos, usually with 210Po >> 214Po and 238U; 218Po radiohalos were rare, and 232Th radiohalos were abundant in one granitic pluton. Thus neither the Po radiohalos nor the granitic rocks could have been formed by fiat creation. Instead, a model is proposed in which hydrothermal fluids separated 222Rn and the Po isotopes from their parent 238U in zircons and transported them very short distances along cleavage planes in the host, and adjacent, biotites until the222Rn decayed and the Po isotopes were chemically concentrated into radiocenters, there to subsequently produce the Po radiohalos. Furthermore, the very short half-lives of these isotopes require this transport process to be rapid (within days), and the observed fully formed 238U and 232Th radiohalos imply at least 100 million years worth (at today’s rates) of accelerated radioactive decay has occurred. Other implications include: accelerated heat flow during the Flood that helped catastrophically drive global tectonic and geological processes, including metamorphism and magma genesis; and rapid convective hydrothermal fluid flows that rapidly formed and cooled regional metamorphic complexes, rapidly cooled granitic and other plutons, and rapidly formed many metallic ore deposits. Introduction

Radiohalos are minute zones of darkening surrounding tiny central mineral inclusions or crystals in some minerals. They are best expressed in certain minerals in rock thin sections, notably in the black mica, biotite, where the tiny inclusions (or radiocenters) are usually zircon crystals. The significance of radiohalos is due to them being a physical, integral historical record of the decay of radioisotopes in the radiocenters over a period of time. First reported between 1880 and 1890, their origin was a mystery until the discovery of radioactivity. Then in 1907 Joly1 and Mügge2independently suggested that the darkening of the minerals around the central inclusions is due to the alpha (a) particles produced by α-decays in the radiocenters. These α-particles damage the crystal structure of the surrounding minerals, producing concentric shells of darkening or discoloration. When observed in thin sections these shells are concentric circles with diameters between 10 and 40 µm, simply representing planar sections through the concentric spheres centered around the inclusions.3Many years of subsequent investigations have established that the radii of the concentric circles of the radiohalos in section are related to the α-decay energies. This enables the radioisotopes responsible for the α-decays to be identified.4, 5, 6, 7, 8 Most importantly, when the central inclusions, or radiocenters, are small (about 1 µm) the radiohalos around them have been unequivocally demonstrated to be the products of the α-emitting members of the238U and the 232Th decay series. The radii of the concentric multiple spheres, or rings in thin sections, correspond to the ranges in the host minerals of the α-particles from the α-emitting radioisotopes in those two decay series.9, 10, 11235U radiohalos have not been observed. This is readily accounted for by the scarcity of 235U (only 0.7% of naturally-occurring U, since large concentrations of the parent radionuclides are needed to produce the concentric ring structures of the radiohalos.Ordinary radiohalos can be defined, therefore, as those that are initiated by 238U and/or 232Th α-decay, irrespective of whether the actual halo sizes closely match the respective idealized patterns. In many instances the match is very good, the observed sizes agreeing very well with the 4He ion penetration ranges produced in biotite, fluorite and cordierite.12, 13 U and Th radiohalos usually are found in igneous rocks, most commonly in granitic rocks and in granitic pegmatites. While U and Th radiohalos have been found in over 40 minerals, their distribution within these minerals is very erratic.14, 15, 16, 17 Biotite is quite clearly the major mineral in which U and Th radiohalos occur. Wherever found they are prolific, and are associated with tiny zircon (U) or monazite (Th) radiocenters. The ease of thin section preparation and the clarity of the radiohalos in them have made biotite an ideal choice for numerous radiohalo investigations.18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33 U, Th and other specific halo types thus far have been observed mainly in Precambrian rocks, but much remains to be learned about their occurrence in rocks from other geological periods. However, some studies have shown that they do exist in rocks stretching from the Precambrian to the Tertiary.34, 35, 36 Unfortunately, in most instances the radiohalo types were not specifically identified in these studies.Some unusual radiohalo types that are distinct from those formed by 238U and/or 232Th α-decay have been observed. Of these, only the Po (polonium) radiohalos can presently be identified with known α-radioactivity.37, 38, 39, 40, 41, 42There are three Po isotopes in the 238U-decay chain. In sequence they are 218Po (halflife of 3.1 minutes), 214Po (half-life of 164 microseconds), and 210Po (half-life of 138 days). Po radiohalos contain only rings

produced by these three Po α-emitters. They are designated by the first (or only) Po α-emitter in the portion of the decay sequence that is represented. The presence in Po radiohalos of only the rings of the three Po α-emitters implies that the radiocenters which produced these Po radiohalos initially contained either only the respective Po radioisotopes that then parented the subsequent α-decays, or a non–α-emitting parent.43, 44 These three Po radiohalo types occur in biotites from granitic rocks.45, 46, 47, 48, 49, 50, 51, 52, 53, 54Joly55, 56 was probably the first to investigate 210Po radiohalos and was clearly baffled by them. Because Schilling57saw Po radiohalos located only along cracks in Wölsendorf fluorite, he suggested that they originated from preferential deposition of Po from U-bearing solutions. Henderson58 and Henderson and Sparks59 invoked a similar but more quantitative hypothesis to explain Po radiohalos along conduits in biotite. Those Po radiohalos found occurring away from the conduits, similar to those found by Gentry,60, 61 were more difficult to account for. The reason for these attempts to account for Po radiohalos by some secondary process is simple—the half-lives of the respective Po isotopes are far too short to be reconciled with the Po having been primary, that is, originally in the granitic magmas which slowly cooled to form the granitic rocks that now contain the Po-radiohalo-bearing biotites. The half-life of218Po, for example, is 3.1 minutes. However, this is not the only formidable obstacle for any secondary process that transported the Po into the biotites as, or after, the granitic rocks cooled. First, there is the need for isotopic separation of the Po isotopes, or their ß-decay precursors, from parent 238U.62 Second, the radiocenters of very dark 218Po radiohalos, for example, may need to have contained as much as 5 × 109 atoms (a concentration of more than 50%) of218Po .63 But these 218Po atoms must migrate or diffuse from their source at very low diffusion rates through surrounding mineral grains to be captured by the radiocenters before the 218Po decays.64, 65, 66Studies of some Po radiohalo centers in biotite (and fluorite) have shown little or no U in conjunction with anomalously high 206Pb/207Pb and/or Pb/U ratios, which would be expected from the decay of Po without the U precursor that normally occurs in U radiohalo centers.67, 68 Indeed, many 206Pb/207Pb ratios were greater than 21.8, reflecting a seemingly abnormal mixture of Pb isotopes derived from Po decay independent of the normal U-decay chain.69, 70Thus, based on these data Gentry advanced the hypothesis that the three different types of Po radiohalos in biotites represent the decay of primordial Po (that is, original Po not derived by U-decay), and that the rocks hosting those radiohalos, that is, Precambrian granites as he perceived them to be, must be primordial rocks produced by fiat creation, given that the half-life of 214Po is only 164 microseconds.71, 72, 73, 74, 75, 76, 77, 78As a consequence of Gentry’s creation hypothesis, the origin of the Po radiohalos has remained controversial and thus apparently unresolved. Snelling79 has thoroughly discussed the many arguments and evidences used in the debate that has ensued over the past two decades, and has concluded that there are insufficient data on the geological occurrence and distribution of the Po radiohalos for the debate to yet be decisively resolved. Of the 22 locations then known where the rocks contained Po radiohalos, Wise80 determined that six of the locations hosted Phanerozoic granitic rocks, a large enough proportion to severely question Gentry’s hypothesis of primordial Po in fiat created granitic rocks. Many of these Po radiohalo occurrences are also in proximity to higher than normal U concentrations in nearby rocks and/or minerals, suggesting ideal sources for fluid separation and transport of the Po. Furthermore, there are now significant reports of 210Po as a detectable species in volcanic gases, in volcanic/hydrothermal fluids associated with subaerial volcanoes and fumaroles, and associated with mid-ocean ridge hydrothermal vents and chimney deposits,81, 82, 83 as well as in ground waters.84, 85 The distances involved in this fluid transport of the Po are several kilometers (and more), so there is increasing evidence of the potential viability of the secondary transport of Po by hydrothermal fluids during pluton emplacement, perhaps in the waning stages of the crystallization and cooling of granitic magmas.86, 87Whereas Po radiohalos would appear to indicate extremely rapid geological processes were responsible for their production (because of the extremely short half-lives of the Po isotopes responsible), 238U and 232Th radiohalos appear to be evidence of long periods of radioactive decay, assuming decay rates have been constant at today’s rates throughout earth history. Indeed, it has been estimated that dark, fully-formed U and Th radiohalos require around 100 million year’s worth of radioactive decay at today’s rates to form.88, 89, 90, 91 Thus the presence of mature U and Th radiohalos in granitic rocks globally throughout the geological record would indicate that at least 100 million year’s worth of radioactive decay at today’s rates has occurred during earth history. As proposed by Humphreys,92 these observable data require that within the young-earth time framework radioisotopic decay therefore had to have been accelerated, but just by how much needs to be determined. If, for example, mature U and Th radiohalos were found in granitic rocks that were demonstrated to have formed during the Flood year, then that would imply about 100 million year’s worth of radioisotopic decay at today’s rates had occurred at an accelerated rate during the Flood year.93,94 Furthermore, if Po radiohalos were alongside U and Th radiohalos in the same Flood-related granitic rocks, then that would have implications as to the rate of formation and age of these granitic rocks formed during the Flood year within the young age timescale.A systematic effort to investigate radiohalo occurrences in granitic rocks throughout the geological record globally has thus been initiated.95 Initial focus has been on granitic plutons that intrude Flood strata and thus are considered to have formed during the Flood. Already Armitage96 has reported the discovery of 210Po radiohalos in the late Carboniferous Stone Mountain granite near Atlanta, Georgia. Additional suitable samples have been collected from the Stone Mountain granite pluton for more detailed assessment of the radiohalo content of this pluton. Samples have also been collected along a traverse through the large mid-Cretaceous La Posta zoned granite pluton in the Peninsular Ranges Batholith east of San Diego, California. A sample has also been collected from the Silurian Cooma granite pluton which occurs at the center of a classic regional metamorphic complex in southern New South Wales, Australia. The Stone Mountain Pluton

The Stone Mountain granite is a fine-grained, leucocratic quartz monzonite97 or monzogranite98 intruded into sillimanite-grade schist and gneiss of the Inner Piedmont geologic province of Georgia, about 15–30 km east of Atlanta (fig. 1). It forms several prominent monadnocks, the most famous of which is Stone Mountain itself at the south-western extremity of the main exposure of the pluton (fig. 1), its steep north-facing slope being the Confederate Memorial, a carving of Lee, Jackson, and Davis.99 The pluton was first mapped in detail by Hermann.100 Fig. 1 is a simplified geologic map of the main body of the pluton.The composition of the monzogranite averages about 30% quartz, 35% plagioclase (oligoclase), 25% K-feldspar (microcline), 9% muscovite, and 1% biotite, with a hypidiomorphic-granular to aplitic texture.101, 102, 103Characteristic accessories include epidote, apatite, zircon, and occasional tourmaline and garnet (almandine).104commented on the well-developed radiohalos around tiny zircon inclusions within biotite grains. The mineral grain sizes range from 1 to 4 mm, but the grain size distribution is uniform so the rock mass appears equigranular throughout the pluton, which is mineralogically quite homogeneous, with very little statistically meaningful variation throughout it.105, 106 The intrusion is also noted for 2–5 cm long tourmaline-rich pods; and pegmatite, aplite, and composite dikes are common near the western margin of the pluton, while occurring sporadically throughout the rest of the intrusion. These appear similar in mineralogy to the rest of the intrusion, except tourmaline often occurs rather than biotite or muscovite.107

The monzogranite intrudes both concordantly and discordantly into country rocks composed primarily of biotite-plagioclase gneiss, interlayered with pods of amphibolite, and minor mica schist.108, 109, 110 These rocks had been regionally metamorphosed to above the sillimanite isograd. At the monzogranite contact a slight grain-size enlargement occurs which is attributed to contact metamorphism.111 There is also some indication of contact metasomatism, which manifests itself as microcline porphyroblasts in the gneisses near the north monzogranite contact.112 The intrusion appears to cross-cut both the common isoclinal structures and more open folds in the surrounding regional metamorphosed rocks, structural evidence also suggesting that some parts of the pluton may have been forcefully intruded, deforming all previous foliations.113, 114 Thus the contact and structural data indicate that the monzogranite intrusion was late metamorphic, confirmed by the crystal growth at contacts with pre-existing metamorphic mineral assemblages.115

Fig. 1. Geologic map of the

main area of the Stone Mountain pluton, showing its location near Atlanta, Georgia, and the locations of the samples examined for radiohalos. The Stone Mountain monzogranite itself has a moderate to poor foliation defined by the orientation of biotite and muscovite. This foliation is not concordant with the regional trends in the surrounding country rocks and appears to be parallel to megascopic flow features within the pluton.116 Indeed, flow banding and flowage foliation within otherwise massive monzogranite is well documented by Grant.117Xenoliths are mostly lens-shaped mica schist fragments that show a strong orientation parallel to the flow structure. Biotite gneiss xenoliths are less common. Mapping of flow structures suggests that the pluton is a rather thin sheet, the intrusion of which was controlled by the dominant northwest-trending

fold system in the surrounding country rocks.118, 119 It is thus possible that the monzogranite was intruded through northwest-trending dikes in a number of pulses rather than a single episode.120 Supporting this contention are monzogranite dikes which cross-cut earlier-formed monzogranite autoliths contained in the main monzogranite mass, all these monzogranites being of similar composition and only recognized by these textural and structural features. The distribution of lineations contained in the xenoliths support the contention that the granitic magma grew and expanded as it intruded between thin layers of simultaneously folding country rock.121Petrologic and geochemical data suggest that the origin of this peraluminous monzogranite is best explained by the anatexis of an older peraluminous, granitic crustal material.122 The most likely source material is believed to be the Lithonia Gneiss, which has a peraluminous, granitic composition very similar to the Stone Mountain monzogranite and which underlies the area.123 The Stone Mountain intrusion thus probably originated as a lowtemperature anatectic melt formed from fractional melting of a part of the Lithonia Gneiss at a temperature of 700°C or less at depths of 22–28 km, depending on the regional geothermal gradient at the time.124 During the process the availability of water would have been an important factor in determining the degree of melting. Once generated the magma was probably intruded at a depth of around 12 km.Radioisotopic ages determined from the Stone Mountain pluton are in the range 281–325 Ma.125, 126, 127 Whitney et al. obtained an Rb-Sr isochron from 10 whole-rock and three mineral samples (plagioclase, microcline, and biotite) which yielded an age of 291±7 Ma, making the intrusion latest Carboniferous. On the other hand, Dallmeyer found that40Ar/39Ar age spectra of biotite and muscovite from the Stone Mountain monzogranite were undisturbed, both minerals recording similar total-gas ages (biotite 281±5 Ma, muscovite 283±5 Ma). These ages were regarded as anomalously younger than those recorded by biotite and hornblende within the adjacent gneisses, so it was suggested that these “ages” represent rapid post-magmatic cooling below argon retention temperatures. Thus the 291 Ma date for the Stone Mountain monzogranite is the recognized “age,” temporally relating it to a belt of other granitic plutons in the Piedmont of the southeastern Appalachians, primarily in North and South Carolina.128 The postulated source for the magma, the Lithonia Gneiss, has yielded conventional K-Ar ages from its micas of 310–315 Ma129, 130 (probably the onset of regional metamorphism), whereas zircons have yielded U-Pb ages of about 480 Ma131 (zircons probably inherited from the original sediments). Both McQueen132 and Froede133 place the formation of the Stone Mountain monzogranite pluton within the year of the Flood. Furthermore, Froede134, 135 has documented much evidence consistent with rapid emplacement and cooling of the granitic magma within the Flood year prior to the massive amounts of erosion at the end of the Flood that stripped the overlying country rocks to leave the pluton exposed today at the earth’s surface. The La Posta Pluton

The La Posta pluton is located approximately 65 km east of San Diego, California, in the Peninsular Ranges Batholith and straddles the international border with Mexico (fig. 2). The Peninsular Ranges Batholith is an elongated body of igneous rocks, consisting of hundreds of plutons, averaging about 100 km in width that extends nearly 1000 km from the transverse Ranges near Riverside, southern California, to about the 28th parallel in Baja California, Mexico. It has been

subdivided along a major discontinuity into western and eastern zones that parallel the long axis of the batholith.136, 137, 138 The western zone is characterized by small plutons that are generally less than 100 km2 in exposed area, pluton compositions ranging from peridotite to granite with tonalite being most abundant, the presence of gabbros, and moderate grades of metamorphism in the host rocks.139, 140 This contrasts with the larger plutons, typically several hundred km2 in size, with a more limited range of compositions (tonalite to monzogranite), and no gabbro in the eastern zone intruded into sillimanite-bearing and migmatitic pre-batholithic rocks. The boundary between these eastern and western zones is a major discontinuity defined by an I-S line separating I-type granitoids to the west and both I-type and S-type granitoids to the east,141 and a magnetite-ilmenite line which effectively separates magnetite- and ilmenite-bearing plutons to the west from the plutons to the east in which the only opaque phase is ilmenite.142 Additionally, Todd and Shaw143 recognized that the plutons of the western zone are synkinematically deformed and were thus syntectonically emplaced, whereas the eastern zone plutons are essentially undeformed and thus are late- to post-tectonic intrusions. Finally, there is a significant difference in the ages of the plutons either side of this discontinuity through the batholith, the western zone plutons yielding emplacement ages from 140 to 105 Ma, while the eastern zone plutons were emplaced from 98 to 89 Ma,144, 145 interpreted as two distinct periods of static-arc magmatism resulting from an eastward migration of the locus of magmatism.The largest intrusion in the eastern zone of the batholith is the La Posta pluton, with an estimated exposure area of 1400 km2. Approximately 750 km2 of this pluton have been mapped and studied in detail (fig. 2).146, 147 It has thus been established that the pluton is a single intrusive body produced by a single magmatic pulse that crystallized inward to form a lithologic succession of concentric zones ranging from a sphene-hornblendebiotite tonalite rim to a muscovite-biotite granodiorite core (fig. 2). A banded border facies up to 100 m wide, not shown in Fig. 2, consists of alternating bands rich in hornblende (± biotite) and plagioclase (± quartz) which are locally and discontinuously developed along contacts with the older igneous rocks of the western zone of the batholith.148, 149 Actually, the pluton is massive, the absence of foliation being noteworthy. It is only foliated near its margins or near metasedimentary roof pendants where the foliation is steep and parallel to contacts. The sphene-hornblende-biotite tonalite found in the outer zone (hornblende-biotite facies) consists of large (up to 1 cm), inclusion-free hornblende euhedra, pseudo-hexagonal books of biotite, and smaller (up to 0.5 cm) honey- to amber-colored prismatic sphene crystals. Plagioclase is the most abundant phase and displays mild oscillatory zoning. Quartz occurs as discrete anhedral grains with weakly developed undulatory extinction. The rock becomes progressively more enriched in interstitial K-feldspar and depleted in hornblende inwards.

Fig. 2. Geologic and location maps

for the La Posta pluton, Peninsular Ranges Batholith, southern California, showing the different facies of this zoned pluton and the sampling locations.All the contacts between these internal zones of the pluton are gradational over distances of several tens of meters.150, 151 The hornblende-biotite facies grades inwards to the large-biotite facies, a sphene-biotite granodiorite, by gradual loss of the large hornblende euhedra and increase in oikocrystic feldspar. The large-biotite facies is characterized by its abundance of large (up to 1 cm) pseudohexagonal books of biotite that impart a distinct “salt and pepper” appearance to the outcrops. The transition into the small-biotite facies is observed as a gradual loss of the large biotite books and an increase in the amount of smaller (1 to 4 mm), but still euhedral, biotite grains. There also appears to be a general

decrease in grain size in this unit, although the K-feldspar oikocrysts locally reach 5-cm widths. The muscovite-biotite facies core of the pluton (a muscovite-biotite granodiorite) is defined on the basis of visible muscovite in hand specimen, which ranges up to 1% and meets the textural criteria for being of primary magmatic origin.152 Sphene is absent in this facies. Ilmenite appears to be the sole opaque phase in all of the facies.Multiple zircon fractions from three different samples within the pluton yield an U-Pb age of 94±2 Ma, although the data obtained also possibly suggest a small inherited Pb component.153, 154 An Rb-Sr mineral isochron from one of these same samples, taken from the small biotite facies on the western side of the pluton, yielded a regression age of 92±2.8 Ma (the apatite, whole rock, and hornblende had comparable Rb-Sr and thus reduced the system to an effective two-point isochron). Nevertheless, the Rb-Sr regression age is consistent within the error margins with the average zircon U-Pb age, which indicates the placement of the pluton in the mid-Cretaceous.Intrusive into the La Posta pluton and the large sillimanite-grade metasedimentary screen, elongated north-south across the center of the pluton dividing it into two parts (fig. 2), are two small garnet-muscovitebiotite monzogranite plutons.155, 156, 157, 158 The Indian Hill pluton, the smaller and more northerly of the two plutons (fig. 2), consists of two facies—the medium-grained garnet-muscovite-biotite monzogranite and a fine-grained muscovite-biotite granodiorite.159 A sample of the garnet-muscovite-biotite monzogranite yielded a four-point Rb-Sr mineral isochron representing the crystallization age of 89.6±2.6 Ma, which is thus interpreted as the emplacement age for the pluton.160, 161, 162 Five zircon fractions from the same sample yielded discordant ages that plot on a chord with a lower concordia intercept age of 84.4±6.1 Ma and an upper concordia intercept age of 1161±430 Ma. This U-Pb upper intercept age is interpreted as representing the average age of the rocks which melted to form the Indian Hill pluton, and thus the zircons containing the Pb are also interpreted as inherited.163, 164, 165, 166 Significantly, the zircon grains within this pluton are recorded as being readily apparent as tiny inclusions surrounded by radiohalos within the biotite

flakes.167 In contrast, three zircon fractions from a sample of the larger garnet-muscovite-biotite monzogranite pluton to the south (fig. 2) yielded a concordant age of 93±1 Ma, an emplacement age that is consistent with the observed field relationships.168 Pegmatite dikes are common in the metasedimentary screen to the west of the Indian Hill pluton. This metasedimentary screen, and the Indian Hill pluton within it (fig. 2), is in fact a roof pendant within and above the La Posta pluton.169 Limited field and isotopic data suggest that these dikes are genetically related to the garnet-muscovite-biotite (S-type) monzogranite plutons, which are in turn believed to have resulted from the anatexis of the metasedimentary rocks in the roof pendant to the La Posta pluton, the heat source being likely due to the emplacement of the La Posta pluton.170, 171 During the partial melting of these metasedimentary rocks detrital zircon contained in them was incorporated in the partial melt and thus the resultant monzogranite plutons. Emplacement of the plutons is believed to have been preceded by injection of the pegmatite dikes.172The most distinctive singular geochemical characteristic of the La Posta pluton is its high Sr content, which contrasts markedly with Sr abundances in the other plutonic rocks of the batholith, and this suggests a fundamental difference in the source region for its magma.173, 174 Additionally, the rare earth element (REE) patterns of the La Posta rocks suggest that the pluton was derived by subduction-related anatexis of eclogitefacies basaltic oceanic crust.175Alternately, a source region of amphibolitic oceanic crust would also appear to satisfy the trace element and chemical constraints, provided that all plagioclase was removed from the source during the melting event to account for the high Sr abundance.176 However, the presence of zircon in the La Posta pluton and in the spatially related but compositionally distinct garnet-muscovite-biotite monzogranite plutons, with U-Pb ages older than emplacement ages of these plutons, suggests inheritance of detrital zircon from a metasedimentary source, which in turn suggests contamination of the I-type La Posta magma subsequent to its derivation by partial melting of oceanic crust.177 This would also account for the core of the pluton being S-type muscovite-biotite granodiorite. It has thus been suggested that the La Posta magmatic diapir ascended through the juncture of the older North American continental crust and oceanic lithosphere,178 with the muscovite-biotite granodiorite core representing the tail of the diapir that had interacted with the leading edge of the North American continental crust prior to intruding into the head of the ballooning (?) La Posta diapir.179, 180 Viscosity differences between the parental La Posta melt and the contaminated tail would inhibit homogenization, so that inward crystallization would still produce the observed gradational contacts between the higher temperature outer facies and the lower temperature assemblage in the core. Marked changes in plagioclase compositions, and in Fe/Mg and Fe2+/Fe3+ in biotites, between the core and outer zones181 are consistent with this emplacement and crystallization model. The Cooma Pluton

The Cooma granodiorite was first mapped by Browne182 and is a small, elliptical pluton centered approximately on the township of Cooma in southern New South Wales, 300 km south-southwest of Sydney (fig. 3). The pluton is about 8 km in maximum dimension and has a surface exposure of 14–20 km2, depending on where its gradational contact with the surrounding migmatites is placed.183 When mapped, the pluton was found to be central to a sequence of roughly concentric prograde regional metamorphic zones.184, 185, 186 In fact, the Cooma metamorphic complex is considered to be a classic geological area for regional metamorphic zones, because it is one of the first localities where andalusite-sillimanite type regional metamorphism was described.187, 188 Furthermore, the Cooma granodiorite itself is also regarded as a classic geological example of a pluton produced by a low degree of partial melting of the metasediments at the heart of a regional metamorphic complex (fig. 3).189The Cooma metamorphic complex has a mapped outcrop area exceeding 300 km2, and probably extends over a similar area beneath the local cover of Tertiary basalt. Isograds can be traced over 30 km northwards adjacent to the Murrumbidgee Batholith.190 Based mainly on the work of Joplin191, 192 and Hopwood,193, 194 Chappell and White195 recognized a series of metamorphic zones delineated by the appearance of chlorite, biotite, andalusite, sillimanite, and granitic veining, respectively. Approximate equivalents are chlorite zone—greenschist Radiohalos—A Tale of Three Granitic Plutons facies; biotite and andalusite zones—amphibolite facies; sillimanite and migmatite zones—granulite facies.196 Some additional metamorphic zones have been distinguished by subdividing the andalusite and sillimanite zones on the basis of the first appearances of cordierite, andalusite and K-feldspar.197 The zoning is markedly asymmetric. The belt of highest grade rocks and the enclosed

Cooma granodiorite are located towards the eastern margin of the complex (fig. 3), with the regional aureole extending approximately 3 km to the east, but nearly 10 km to the west. At least four,198 and possibly seven,199 separate deformation fabrics can be distinguished in the metasediments of the Cooma complex. The exception is the Cooma granodiorite, which preserves only the last foliation, suggesting that it was emplaced late in the development of the complex.200, 201 Fig. 3. Geologic and location maps for the Cooma granodiorite and the surrounding

regional metamorphic zones in southeastern Australia. The location of the sample used in this study is also shown. The Cooma granodiorite contains the same minerals as the gneisses and migmatites and lies within the cordierite-andalusite-K-feldspar zone. It is extremely quartz-rich (50%) and contains plagioclase, K-feldspar and biotite, with andalusite, sillimanite, cordierite, and muscovite, some or all of the latter appearing to be secondary.202, 203, 204 The biotite is crowded with radiohalos around inclusions of zircon and monazite.205The granodiorite contains abundant xenoliths of the surrounding migmatites and, less commonly, the highgrade gneisses, quartz veins and pegmatites, which is consistent with the granodiorite having been derived by partial melting of a metasedimentary source, presumably the high-grade gneisses surrounding the granodiorite.206 Thus the granodiorite has been classified as S-type,207 with normative corundum values of 5.82%,208 indicating that it is strongly peraluminous, and is very low in Na2O and CaO, which has been attributed to its derivation from the surrounding metamorphosed Cα-poor Ordovician sediments.209 This origin is supported by isotopic data.210, 211, 212, 213,214 The Cooma granodiorite is thus typical of “regional aureole” granites described by White, Chappell, and Cleary215 and Chappell and White.216 Radioisotopic data suggests that the Cooma granodiorite and the related metamorphic rocks thus cooled through the blocking temperature for most geochronological systems in the mid to late Silurian217, 218 obtained an Rb-Sr mineral isochron age for the granodiorite of 406±12 Ma. The age of the high-grade gneisses was found to be similar to the granodiorite, but the low grade

metasediments yielded a significantly older age of 450±11 Ma (recalculated by Munksgaard219). Based on these results it was concluded that the granodiorite formed in situ by partial melting of the surrounding metasediments, the high-grade gneisses being associated with the emplacement of the granodiorite, whereas the higher ages in the low-grade metasediments perhaps indicated the original age of deposition or the age of regional metamorphism predating the high-grade metamorphism. Tetley220 obtained a Rb-Sr whole-rock isochron age for the granodiorite of 410.0±19.0 Ma, thus supporting the previously determined granodiorite age. However, Munksgaard obtained whole-rock Rb-Sr ages of 362±77 Ma for the granodiorite, 375±55 Ma for the high-grade gneisses and 386±25 Ma for the low-grade metasediments, results which he suggested implied the metasediments and the granodiorite were not fully equilibrated on a regional scale with respect to their Sr isotope composition at the time of metamorphism, and thus whole-rock samples would not give meaningful ages for the Cooma complex. Nevertheless, he showed that the Cooma granodiorite is similar in major- and trace-element composition to a calculated mixture of the surrounding schists and gneisses.Preliminary results of ion-probe zircon U-Pb studies221 yielded ages from zircon about 30 Ma greater than the 410 Ma age recorded by hornblende K-Ar and whole-rock Rb-Sr.222 More detailed results have now been published.223 Both monazite and zircon grains from the Cooma granodiorite and from the metasediments in each of the surrounding regional metamorphic zones were analyzed. Monazite in the migmatite and granodiorite were found to have recorded only metamorphism and granite genesis at 432.8±3.5 Ma, whereas detrital zircon grains in the original sediments were unaffected by metamorphism until the inception of partial melting, when platelets of new zircon precipitated on the surfaces of the grains. These new growths of zircon crystals, although maximum in the leucosome of the migmatites, was best dated in the granodiorite at 435.2±6.3 Ma. Thus the best combined estimate for the U-Pb age of the metamorphism and granite genesis is 433.4±3.1 Ma. However, detrital zircon U-Pb ages were found to have been preserved unmodified throughout metamorphism and magma genesis, which was concluded to indicate derivation of the Cooma granodiorite from lower Paleozoic source rocks with the same protolith as the Ordovician sediments found outcropping adjacent to the metamorphic complex in the same region. These U-Pb ages for the detrital zircon and monazite grains preserved in the metasediments and the granodiorite from the original Ordovician sediments were dominated by composite populations dated at 500–600 Ma and 900–1200 Ma, although almost 10% of the grains analyzed yielded apparent ages scattered from 1450 Ma to 2839 Ma, one grain even yielding an apparent age of 3538 Ma.The general consensus is that the Cooma granodiorite is an integral part of the regional metamorphic sequence, having formed by the in situ, or virtually in situ, partial melting of high-grade metasediments identical to those surrounding it.224, 225, 226, 227, 228, 229, 230, 231, 232, 233 However, Flood & Vernon234 pointed out that an origin for the Cooma granodiorite from essentially in situ anatexis of the adjacent metasedimentary rocks was in apparent conflict with the surrounding low-pressure metamorphic environment, unless unrealistically high and localized geothermal gradients were invoked. They suggested that subsequent to the granodiorite forming by partial melting of the adjacent high-grade migmatitic rocks, the granodiorite moved upwards as a diapiric intrusion, the high-grade envelope surrounding it having been dragged up to higher crustal levels with the intruding granitic diapir. Support for this model includes evidence for vertical movement along a transition zone between the andalusite zone schists and the K-feldspar zone gneisses (fig. 3), a step in metamorphic pressures at the sillimanite isograd, coinciding with the boundary between the gneisses and migmatites, and a steady pressure rise thereafter towards higher metamorphic grades.235 All the metamorphism is regarded as part of the same relatively intact sequence, the thermal aureole having contracted towards the granodiorite during the later stages of the deformation associated with the regional metamorphism and the emplacement of the granodiorite.236 Finally, Vernon, Richards, and Collins237 have demonstrated that in situ partial melting of metapsammitic leucosome would have produced a magma of suitable composition to form the Cooma granodiorite, but this locally produced magma appears to have only contributed to the rising pluton of magma formed by deeper, more extensive accumulation of similarly derived magma, a model consistent with the U-Pb zircon data.238 Sampling and Laboratory Procedures

Each of these granitic plutons was sampled at the locations shown in Figs. 1, 2, and 3. In most instances access was available by roads and samples were collected in roadcuts where the outcrops were freshest. Fist-sized (1–2 kg) pieces of granite were collected at each location, the details of which were recorded using a Garmin GPS II Plus hand-held unit.A standard petrographic thin section was obtained for each sample. In the laboratory, a scalpel and tweezers were used to prise flakes of biotite loose from sample surfaces, or where necessary portions of the samples were crushed to liberate the constituent mineral grains. Biotite flakes were then hand-picked and placed on the adhesive surface of a piece of scotch tape fixed to a bench surface with its adhesive side up. Once numerous biotite flakes had been mounted on the adhesive side of this piece of scotch tape, a fresh piece of scotch tape was placed over them and firmly pressed along its length so as to ensure the two pieces of scotch tape were stuck together with the biotite flakes firmly wedged between them. The upper piece of scotch tape was then peeled back in order to pull apart the sheets composing the biotite flakes, and this piece of scotch tape with thin biotite sheets adhering to it was then placed over a standard glass microscope slide so that the adhesive side and the thin mica flakes adhered to it. This procedure was repeated with another piece of scotch tape placed over the original scotch tape and biotite flakes affixed to the bench, the adhering biotite flakes being progressively pulled apart and transferred to microscope slides. As necessary, further hand-picked biotite flakes were added to replace those fully pulled apart. In this way tens of microscope slides were prepared for each sample, each with many (at least 10–20) thin biotite flakes mounted on them. This is similar to the method pioneered by Gentry. A minimum of 30 microscope slides was prepared for each sample to ensure good representative sampling statistics.Each thin section for each sample was then carefully examined under a petrological microscope in plane polarized light and all radiohalos present were identified, noting any relationships between the different radiohalo types and any unusual features. The numbers of each type of radiohalo in each slide were counted by progressively moving the slide backwards and forwards across the field of view, and the numbers recorded for each slide were then tallied and tabulated for each sample. Results

All results are listed in Table 1. In the Stone Mountain monzogranite 210Po radiohalos outnumbered all other radiohalo types. For the six samples 291 thin sections were scanned and yielded 1139 210Po radiohalos, 93 214Po halos, and 88238U radiohalos, the average proportions being approximately 13 210Po radiohalos to every 214Po and 238U radiohalo, which occurred in approximately equal numbers. For the individual samples these proportions varied from a low of about six 210Po radiohalos for every 214Po radiohalo, to a high of 69 210Po halos for every 214Po radiohalo.238U radiohalos were always found in similar numbers to the 214Po radiohalos. Additionally, in sample SMG-5 two218Po radiohalos were found, while in sample SMG-2 where no 214Po radiohalos were found, four of the 210Po radiohalos were found in muscovite, an unusual but not unknown occurrence.239A smaller number of radiohalos (437) were counted in 563 slides from twelve samples of the La Posta pluton. Indeed, radiohalos were relatively rare in the biotite flakes from the hornblende-biotite facies, large biotite facies, and small biotite facies zones of the pluton. Only the muscovite-biotite facies core of the pluton

contained appreciable numbers of radiohalos, the proportions being 86 210Po radiohalos, three 214Po radiohalos and one 238U radiohalo in 180 slides from four samples. Of potential significance is the substantially voluminous occurrence of radiohalos in the genetically and spatially related Indian Hill and other monzogranite plutons, three samples yielding 279 210Po radiohalos, 11214Po radiohalos and 45 238U radiohalos in 130 slides. This is a distribution of approximately 25 210Po radiohalos for every 214Po and every four 238U radiohalos. Thus >210Po radiohalos are approximately as prolific in the Stone Mountain monzogranite as they are in the Indian Hill and other monzogranites, while the muscovite-biotite granodiorite core of the La Posta pluton has less than approximately one quarter of the number of radiohalos found in the genetically and spatially related Indian Hill and other monzogranites. Table 1. Compilation of the Po, U, and th radiohalos counted in samples from the three granitic plutons.

Pluton Sample Number of Slides

Radiohalos Additional Notes (approximate proportional radiohalo numbers) 210Po 214Po 218Po 238U 232th

Stone Mountain

SMG-1 30 192 5 0 11 0 (38:5:0:2:0)

SMG-2 30 90* 0 0 1 0 *4 in muscovite

SMG-3 30 222 9 0 4 0 (49:2:0:1:0)

SMG-4 30 138 2 0 1 0

SMG-5 30 179 36 2 26 0 (6:1:~0:1:0)

SMG-6 141 288 41 0 45 0 (6:1:0:1:0)

La Posta

PRB-6 50 8 0 0 0 0 Hornblende-biotite facies

PRB-7 50 2 0 0 0 0 Large biotite facies

PRB-5 53 0 1 0 1 0

Small biotite facies PRB-22 50 0 0 0 0 0

PRB-4 50 36 0 0 6 0

Muscovite-biotite facies

PRB-20 30 15 3 0 1 0

PRB-24 50 18 0 0 0 0

PRB-25 50 17 0 0 0 0

PRB-21 30 56 11 0 15 0 Indian Hill monzogranite

PRB-23 50 159 0 0 0 0

Other monzogranite PRB-26 50 64 0 0 30 0

PRB-27 50 0 0 0 0 0 Pegmatite

Cooma RLG-2 41 373 44 0 418 37 (9:1:0:10:1)

The single sample of the Cooma granodiorite yielded the largest numbers of radiohalos, as anticipated from the reported occurrence of radiohalos around zircon and monazite inclusions in the biotite of this granodiorite.240However, unlike the Stone Mountain monzogranite, the La Posta granodiorite, the Indian Hill and other monzogranites,238U radiohalos are a little more prolific than 210Po radiohalos, and 232Th radiohalos are found around monazite radiocenters. In the 41 slides examined there were approximately nine 210Po radiohalos to every one 214Po radiohalo, every ten 238U radiohalos and every one 232Th radiohalo. So Po radiohalos are far more prolific in the Cooma granodiorite. The ratio 210Po:214Po of 9:1 in the Cooma granodiorite is similar to that in the Stone Mountain monzogranite, although there is an average of approximately four 210Po radiohalos per slide in the six Stone Mountain monzogranite samples compared to nine 210Po radiohalos per slide in the single sample of Cooma granodiorite. Similarly, for comparison, whereas there are only approximately three 238U radiohalos in every ten slides of the Stone Mountain monzogranite, there are at least 100 238U radiohalos in every ten slides of the Cooma granodiorite. Discussion Flood Origin of these Granitic Plutons

It is arguably beyond dispute that these three granitic plutons were intruded as hot magmas during the Flood, and that therefore these radiohalos found in them formed subsequently, during the Flood and thereafter. Froede241 “believes that the Stone Mountain granitic magma formed as a result of the mixing of some remelted original primordial granite which melted surrounding rocks and sediments” and suggests “that possibly the source magma of Stone Mountain was derived from deep within the crust during the tectonic event identified as the Alleghenian Orogeny (a Flood generated orogenic event).” However, the only evidence presented for these claims is that “the Stone Mountain granite is compositionally different from all of the other granites in the area.” Nevertheless, Froede is convinced by the field evidence that the Stone Mountain monzogranite was intruded as a hot magma during the Flood and then cooled rapidly, as evidenced by the pluton’s mineralogical and compositional homogeneity and its uniform grain size. Indeed, experimental work has shown that plutonic rocks with crystal sizes similar to those found in the Stone Mountain pluton can be grown in a matter of days or weeks.242 Furthermore, there is field evidence of contact metamorphism and metasomatism,243, 244 so there is agreement that the Stone Mountain pluton formed by the intrusion of a hot granitic magma. However, based on geochemical, mineralogical and structural evidence the source of this granitic magma is undoubtedly the nearby Lithonia Gneiss,245, 246 which itself appears to be a product of the regional metamorphism of the host rocks to the pluton. Indeed, isotopic evidence suggests that the same regional metamorphic event responsible for the Lithonia Gneiss and the metasediments that host the pluton was also responsible for the partial melting of the Lithonia Gneiss itself, conventional K-Ar ages obtained from its micas being within the range of radioisotopic “ages” obtained for the Stone Mountain monzogranite.247, 248, 249, 250, 251 This still leaves unanswered the question of when the precursor sediments were deposited, but U-Pb “ages” of about 480 Ma for zircon grains in the Lithonia Gneiss252 probably indicate these are detrital

zircon grains inherited from the original sediments, which were thus probably deposited early in the Flood. This is consistent with the time of deposition of the fossiliferous sediments now making up strata in the Appalachians, including these metasediments in the Piedmont of Georgia.253The rocks into which the plutons of the Peninsular Ranges Batholith, including the La Posta pluton, have intruded are metasedimentary units that include the pelitic and psammitic schists and gneisses of the roof pendant in the La Posta pluton into which the Indian Hill monzogranite pluton has intruded (fig. 2).254, 255 These metasedimentary rocks are part of the sandstone-shale belt of Gastil,256 a flysch-type sequence which extends southward through Baja California and which in southern California was named the Julian Schist by Hudson.257 While the relative age of the Julian Schist is poorly constrained, an ammonite imprint found on a piece of quartzite within the Julian Schist has been identified as triassic (Hudson), and Upper triassic mollusks are reported from part of the sandstone-shale belt in the northern part of the Peninsular Ranges Batholith.258 These fossils therefore attest to the sediment precursors of the pre-batholithic metasedimentary rocks having been deposited during the Flood. Evidence that the La Posta pluton was intruded as a hot granitic magma includes the narrow discontinuous border facies where the pluton cooled against the older granitic rocks it intruded, and the contact metamorphic effects on marbles in the metasedimentary roof pendant immediately adjacent to the pluton at Dos Cabezas.259 Thus the La Posta pluton was probably intruded into the metamorphosed Flood-deposited sediments towards the end of the Flood. Though much of this granitic magma was undoubtedly sourced from oceanic crust that was partially melted after being metamorphosed during subduction near the margin of the overlying North American continental crust, there is evidence of contamination of the ascending diapir with this older metasedimentary continental crust (inheritance of detrital zircon grains) to produce the S-type muscovite-biotite granodiorite core of the pluton.260, 261 This subduction would have been a part of the global tectonic movements late in the Flood, and the oceanic crust being subducted would likely have been new oceanic crust generated during the Flood,262 so both sources for the granitic magma that produced the La Posta pluton were formed and deposited during the Flood. Heat from the intrusion of the La Posta pluton appears to have been responsible for partial melting of the metasediments (Julian Schist) into which it was intruding, and this melt was first injected as pegmatites before the main body of granitic magma that had been generated intruded as the Indian Hill and the other garnetiferous muscovite-biotite monzogranite plutons (fig. 2).263, 264 There is a strong general concensus based on overwhelming evidence that the source of the hot granitic magma that cooled to form the Cooma pluton was partial melting of the high-grade metamorphic gneisses and migmatites that are adjacent to the pluton.265, 266, 267 Indeed, the boundary of the granodiorite with the surrounding migmatites is gradational, and the granodiorite pluton is central to the metamorphic zones around it that therefore represent a regional aureole to the pluton. The metasediments can in turn be traced outwards from the pluton through the decreasing grade regional metamorphic zones to the adjacent original Ordivician sedimentary rocks, turbidites that are predominantly clay/quartz mixtures of shales and greywackes which elsewhere in the Lachlan Fold Belt contain an abundance of graptolite fossils.268 Detrital zircon grains with inherited U-Pb ages, found in both the Cooma granodiorite and the surrounding metasediments from which it is derived,269 are similarly found in these fossiliferous Ordovician sediments elsewhere in the Lachlan Fold Belt.270 Thus it is beyond dispute that these sediments, which were the source via partial melting of the Cooma granodiorite, were first deposited early during the Flood, and the granitic magma was intruded as a hot diapir at the heart of this regional metamorphic complex also during the Flood. Implications

Having established that the granitic rocks of these three plutons were not only intruded as hot magmas and cooled during the Flood, but that the sources of these were Flood-deposited sediments and oceanic crust formed during the Flood (for much of the La Posta magma), the radiohalos found in the biotite grains within these granitic rocks need to be understood within the framework of the year-long Flood about 4,500 years ago. There are a number of immediate implications. First, the presence of so many dark, fully-formed (mature) 238U radiohalos in these granitic rocks (and232Th radiohalos also in the Cooma granodiorite) indicates that at least 100 million years worth of radioactive decay at today’s rates271, 272, 273, 274 has occurred in these granitic rocks since the biotites in them cooled sufficiently to record the α-decays from the parent 238U (and 232Th) in the tiny zircon (and monazite) inclusions in the biotites. Because these granitic rocks mostly formed from sediments deposited early in the Flood year, this implies that this would be a minimum estimate of the amount of radioactive decay that occurred during the Flood. Indeed, the La Posta pluton probably formed near the end of the Flood year, and yet the biotites in its granodiorite core and in its genetically and spatially related Indian Hill monzogranite pluton still record at least 100 million years worth of radioactive decay at today’s rates. Thus these U and Th radiohalos are a physical, integral, historical record of at least 100 million years worth (at today’s rates) of accelerated radioactive decay during the Flood and its accumulated rock record.275, 276, 277This, in turn, implies that all conventional radioisotopic dating of these rocks, which relies on the assumption of constant decay rates, is grossly in error. Furthermore, the large pulse of heat flow generated by the accelerated decay would have helped to initiate and drive global tectonic processes during the Flood year and to accomplish catastrophically much geologic work, including regional metamorphism and anatexis of crustal and mantle rocks to produce granitic and other magmas.Second, because the granitic rocks in these plutons are not primordial, that is, formed by fiat creation, the Po that parented the Po radiohalos found in the biotites in them cannot have been primordial either. Thus the hypothesis that the three different types of Po radiohalos found in biotites always represent the decay of primordial Po (original Po not derived by U-decay)278, 279, 280, 281, 282, 283, 284, 285 has been falsified, as has the related hypothesis that any granitic rocks in which Po radiohalos are found must be primordial rocks produced by fiat creation. This is, to say the least, extremely disappointing, because so many young-earth creationists (the present authors included) have in the past often used the Po radiohalos as evidence of fiat creation of the rocks containing them. Nevertheless, the falsifying of this hypothesis does not in any way falsify the general creation hypothesis But it does illustrate that the science built on that belief is subject to the normal rules of the scientific method, in particular, the making of predictions and the proposing of hypotheses that can be either verified or falsified. However, the presence of the Po radiohalos in these granitic rocks, which formed during the Flood by the cooling of hot magmas produced by the melting of Flood-deposited sediments, remains an enigma that still requires an explanation. The Source of the U-Decay Products

The fact that the radiohalos are not homogeneously distributed in the La Posta pluton potentially provides another clue, for even though biotite is present throughout the pluton it is in the muscovite-biotite granodiorite core where most of the radiohalos are found. Indeed, the Stone Mountain monzogranite, the Indian Hill monzogranite and the Cooma granodiorite are all muscovite-biotite granitic rocks similar to the muscoviteboitite granodiorite in the core of the La Posta pluton, so this suggests that the mineral and chemical composition of the granitic rocks determines their radiohalo content. Obviously, U and Th must be present, concentrated in accessory minerals such as zircon and monazite within biotite flakes. The apparent correlation between the presence of muscovite and the radiohalos suggests that the source of the granitic magma, which then largely controls the composition of the granitic rock, is crucial. The common factor between all

these muscovite-biotite granodiorites and monzogranites in these plutons is that their magmas were sourced in sedimentary rocks containing detrital zircon grains, sedimentary rocks that were first metamorphosed before anatexis extracted granitic magmas from them. These are then known as S-type granitic rocks, and the presence of muscovite in them is indicative of that classification. Furthermore, U-Pb isotopic data on zircons in these monzogranites and granodiorites confirms inheritance of zircons that were detrital grains in the original sediments. It is also significant that muscovite-biotite, or two-mica, granitic rocks often contain above average concentrations of U, and may even contain accessory uraninite.286, 287 Indeed, two-mica granites are spatially and genetically associated with hydrothermal vein uranium deposits in western Europe and North America, the granitic rocks being favorable sources of leachable U by hydrothermal fluids in the late stages of the cooling of the plutons. However, none of these granitic plutons (the Stone Mountain, La Posta, Indian Hill, and Cooma plutons) is known either for its accessory uraninite grains or for being associated with, or even hosting, hydrothermal vein uranium deposits. The only exception is a reference to the occurrence of a secondary uranium mineral, uranophane, associated with the Stone Mountain pluton.288 This indicates that there must have been leachable U in this pluton, which in this instance must have been dissolved and concentrated by, and precipitated from, supergene ground waters. So if U has been leached from the Stone Mountain pluton simply by oxidizing ground waters near the earth’s surface, it is almost certain that more highly reactive hydrothermal fluids, produced both from the crystallizing and cooling magma and by the influx of water contained within the country rocks being intruded,289 would have been even more capable of leaching and transporting U and its decay products through the monzogranite and its constituent minerals.Now if these monzogranite and granodiorite plutons do not contain accessory U minerals, then what may have been the source of leachable U in them? Clearly, the answer is obvious, given that the 238U radiohalos in the biotites of these granitic rocks all surround tiny inclusions of zircon. For example, in the Cooma granodiorite Williams290 found that the U content of the zircon grains ranged from 20 to 831 ppm, while the monazite grains ranged from 1281 to 7222 ppm U. However, of even greater significance to the present discussion is that Williams found that in the Cooma metamorphic complex the detrital monazite in the metasediments began to dissolve at lower amphibolite facies and virtually disappeared by upper amphibolite facies. At conditions above the upper amphibolite facies it began to regrow. Thus, whereas the detrital monazite U-Pb ages survived through to the mid-amphibolite facies, at higher grades the monazite grains only record the metamorphism and granite genesis. Similarly, while the detrital zircon was unaffected by metamorphism until the inception of partial melting when new zircon precipitated as overgrowths on the surfaces of the detrital grains, the U-Pb ages of these overgrowths record the metamorphism and granite genesis, in contrast to the preserved and modified detrital zircon U-Pb ages. Thus as a result of the dissolving of both monazite and zircon grains as the metamorphic grade increased towards partial melting and genesis of the granitic magma, U and its decay products would have been released into solution and were not all incorporated into the new growth of monazite and zircon, as evidenced by the resetting of the U-Pb ages. In particular, this implies that the U-decay products that had accumulated in the detrital zircons and monazites prior to the metamorphism and anatexis were not incorporated in the new growth of zircon and monazite, being therefore free to migrate dissolved in the hydrothermal fluids of the magma as it crystallized and cooled.Similarly, the Stone Mountain monzogranite, the La Posta granodiorite core and the Indian Hill monzogranite all have evidence of inherited detrital zircon grains in which the U-Pb isotopic system was reset by metamorphism and anatexis of the source sediments. The U-decay products released from these zircons during magma genesis were thus separated from their parent U and free to migrate within the melt. Upon cooling and crystallization of the melt, the U-decay products would then migrate into the hydrothermal fluids also released by the cooling magma. Thus the available zircon U-Pb isotopic data for these granitic rocks291, 292, 293, 294 unambiguous evidence of the isotopic separation of U-decay products, including Po isotopes, from their parent 238U. These decay products were then available in large quantities within the zircon grains that had been incorporated into the S-type granitic rocks from their sediment precursors. This process thus eliminates one of the claimed formidable obstacles to any secondary transport of Po isotopes into radiocenters within biotite flakes to subsequently form the Po radiohalos.295 This isotopic separation process has been demonstrated to occur naturally. Hydrothermal Fluid transport

Quite obviously none of the radiohalos could form until the biotite crystals had formed and cooled sufficiently to preserve the α-particle tracks (with no erasure by thermal annealing). The fact that Po (and also U and Th, of course) radiohalos are found in the biotites of these granitic rocks indicates that these radiohalos formed below the temperature at which radiohalos are thermally erased from biotite. The only available data suggests that thermal erasure of radiohalos in biotite occurs at and above 150°C.296, 297 This temperature corresponds to that of hydrothermal fluids. Depending on the depth of emplacement during magma intrusion, 150°C is well below the temperature of second boiling and magma degassing, when the water and volatiles held in solution in the magma are released.298, 299 Of course, hydrothermal transport of U-decay products such as Ra, Rn, and Po would have all started as soon as hydrothermal fluids formed at temperatures above 150°C at which thermal erasure of α-tracks occurs. There would be no record of decay product passage at those elevated temperatures between or within mineral grains in the granitic rocks, because the α-tracks (and fission tracks, if U were also being transported) would be erased. Some time would thus elapse during pluton cooling for the dissolved isotopes to diffuse some distance in the flowing hydrothermal fluids and to become concentrated in new radiocenters without leaving any trace of their passage. The only stipulation demanded by the observable evidence is that by the time the temperature dropped below the radiohalo thermal erasure level (around 150°C in biotite) the species held in the new radiocenters must be only one of the three Po isotopes. There is no evidence of any other α-emitters in the Po radiohalos.300, 301It would thus seem plausible to postulate initial formation of the new radiocenters by transport of 226Ra and/or 222Rn, as their half-lives (1,622 years and 3.8 days respectively) allow more time for the transport process than the 3.1 minute half-life of 218Po. This 3.1 minute half-life was initially regarded as an obstacle to any secondary transport process. Both Ra and Rn are readily soluble in water, with Rn primarily as a gas and Ra probably bonding with halides.302However, Po is also readily transported in hydrothermal fluids as halide and sulfate complexes.303 Halide and sulfate species are common in hydrothermal fluids.304 Not only is Rn a gas, but its diffusion coefficient of 0.985 cm2 day-

1(1.14 × 10-5 cm2 sec-1) at a water temperature of only 18 °C305 is comparable with the diffusion coefficient for 218Po of 7.9 × 10-2 cm2 sec-1 in nitrogen gas at ambient temperatures with an 80% relative humidity.306 By comparison, Pb has a diffusion coefficient within seven different minerals of 10-18 cm2 sec-1.307 Furthermore, biotite has a sheet structure with a perfect cleavage which preferentially and readily facilitates the passage of fluids through the mineral structure, in contrast to minerals that rarely contain radiohalos. Gentry et al.308 maintained that in minerals the diffusion coefficients are so low that there is a negligible probability for atoms of the Po isotopes to migrate even 1 µm through the mineral structures before decaying; but this argument would be irrelevant if the diffusion were occurring in hydrothermal fluids flowing along the cleavage planes in the biotite flakes.However, Gentry309, 310 has maintained that Po radiohalos do not occur along cracks or conduits in biotite, pointing to the photographic evidence.311, 312, 313, 314, 315, 316, 317 This assertion is emphatically incorrect. Biotite flakes are peeled apart along their cleavage planes when mounting them for observation

and photography, which is why cracks or defects are not usually seen. Thus radiohalos in biotites are always on cleavage planes, which are “ready made” cracks in the biotite’s crystal structure that provide conduits for the flow of fluids.In any case, how far do the hydrothermal fluids have to carry the 222Rn and/or 218Po? Because the source of these isotopes is the zircon crystals within the biotite flakes, and the resultant Po radiohalos are also in the same or adjacent biotite flakes (which is readily apparent from the microscope examination of normal rock thin sections where the total rock fabric is in view), the transport distances can be measured in the micron (µm) to millimeters (mm) range. These distances would easily be accomplished within the 3.8 day half-life of 222Rn with its diffusion coefficient of 1.14 × 10-5cm2 sec-1 (0.985 cm2 day-1) in water at 18 °C. The diffusion rate would be much faster in water at 150–200 °C. By contrast, even though 218Po has a similarly fast diffusion rate, because of the much shorter half-life of 218Po (only 3.1 minutes) hydrothermal transport of 222Rn would seem the most likely means of transporting the descendant Po isotopes to the new radiocenters. Brown318 favored 226Ra to allow even more time for the required transport, yet he calculated that given a constant supply of 226Ra in a hydrothermal fluid the equilibrium concentrations in the fluid of all three Po isotopes would be reached in about 100 years after a zero-level starting point. However, we would consider that the timeframe for 226Ra transport is longer than the timeframe allowable for the cooling of the granitic rocks from the temperatures at which the biotites crystallize (and include the zircon grains) and at which the hydrothermal fluids are exsolved, to the temperature at which α-tracks are thermally erased. All this cooling had to have occurred within much less than the year of the Flood, given that most, if not all, of the erosion that has exposed these plutons to the earth’s surface occurred at the close of the Flood, only months after the intrusion and cooling of the granitic magmas earlier in the Flood year (probably only weeks earlier in the case of the La Posta and Indian Hill plutons). In our opinion, this restrictive timeframe would rule out 226Ra (half-life 1,622 years) as the species transported in the hydrothermal fluids. Instead, the fast diffusion rate of gaseous 222Rn (half-life 3.8 days) would appear to be adequate for a timeframe of only days for its transport by hydrothermal fluids while the granitic rocks were cooling through the temperatures of thermal erasure of α-tracks. Supply of Sufficient Polonium

The next question to resolve is whether this proposed transport mechanism would supply enough 218Po to the new radiocenters to subsequently produce the Po radiohalos? Gentry319 has calculated that the radiocenters of very dark218Po radiohalos, for example, may have needed to contain as much as 5 × 109 atoms (a concentration of more than 50%) of 218Po, which he maintained needed to be in the radiocenters at the time of their formation to subsequently be successful in producing the 218Po radiohalos. However, this calculation is based on fiat creation of the 218Po as primordial within the radiocenters, a hypothesis that we have argued here from the observable data is falsified. On the other hand, the 222Rn hydrothermal fluid transport model does not require 5 × 109 atoms of 218Po to be delivered to each radiocenter all at the same time. Fluid flow could have progressively supplied this quantity over a period of days, the 218Po atoms decaying at any given time in the radiocenter being replaced by more 218Po atoms from the flowing hydrothermal fluids. All that is required is a steady hydrothermal fluid flow with a constant supply of Rn and Po, together with favorable conditions at deposition sites that became the radiocenters.Given that some of the apparent U-Pb ages of the detrital zircons in these granitic plutons are extremely high, being equivalent to hundreds of millions of years worth of decay at today’s rates, the implication is that the zircons also held within them relatively large concentrations of all the U-decay products in equilibrium at the time of metamorphism, anatexis, magma generation, and subsequent cooling. It has been calculated that in one gram of 238>U there are 2.53 × 1021 atoms. In radioactive equilibrium with its decay products, there would be associated 9.11 × 1014 atoms of 226Ra, 5.8 × 109 atoms of 222Rn, 3.22 × 106 atoms of 218Po, less than 3 atoms of 214Po, and 2.13 × 1011 atoms of 210Po.320Thus, even when the zircon grains only have U concentrations of hundreds of ppm, the relative numbers of 222Rn atoms would still be high and sufficient to deliver the needed concentrations of Po to the new radiocenters. This of course assumes that hundreds of millions of years worth of radioactive decay at today’s rates had occurred in these zircon grains prior to the Flood, an assumption which is verified by the presence of mature U radiohalos in pre-Flood (Precambrian) granitic rocks (for example, Gentry,321, 322, 323, 324 Henderson,325 Henderson and Turnbull,326Holmes,327 Kerr-Lawson,328, 329 Stark,330 Wiman,331 Wise332). Thus a sufficient number of 222Rn atoms would have been available to supply the new radiocenters with the needed concentrations of 218Po atoms, perhaps even supplemented by hydrothermal fluid transport of some 218Po atoms before they decayed. It would also seem possible that because of the even larger number of 210Po atoms also available (2.13 × 1011 210Po atoms for every 2.53 × 1021238U atoms) that some of these might also have been transported in the hydrothermal fluids, given the longer half-life of 210Po (138 days compared with the 3.8 days of 222Rn) and the probable similar diffusion rate. This concurrent hydrothermal fluid transport of 210Po may be needed to explain the high numbers of observed 210Po radiohalos in the biotites of these granitic rocks compared to the numbers of 214Po radiohalos (ratios varying from about 6:1 to 69:1), which are usually similar to the numbers of 238U radiohalos (except in the Cooma granodiorite). Such hydrothermal fluid transport of 210Po has in fact been documented, with hydrothermal fluid transport of 210Po having been measured over distances of up to several kilometers and transit times of 20–30 days.333, 334transport Timescale

In determining the timescale for the hydrothermal fluid transport of 222Rn and for the establishment of new radiocenters for subsequent radiohalo development, the almost complete absence of 218Po radiohalos in the biotites of these granitic rocks must be significant (only two 218Po radiohalos have been observed in one of the Stone Mountain monzogranite samples). This would seem to indicate that while the other Po radiohalos were produced, there was insufficient time for the transport of sufficient U-decay products to establish significant new centers containing 218Po atoms to produce 218Po radiohalos. On the other hand, transport was slow enough for most 218Po atoms to decay in transit before reaching the sites where 210Po was redeposited.It is also evident that the extremely short half-life of 214Po (164 microseconds) gives it a lower probability of surviving transport than 210Po has, so 214Po radiohalos were not always formed compared with radiohalos from the longer-lived 210Po atoms. Because the same pattern of six or more 210Po radiohalos to every 214Po radiohalo is found in almost every sample from these three granitic plutons (plus the subsidiary associated Indian Hill and other monzogranite plutons) there must be a common factor in operation that needs an explanation, such as the one given here. In other words, the pattern in the ratios of quantities of the different Po radiohalos evidently is directly related to the transport mode, distance and time. This observation supports the secondary transport model for the separation of the Po isotopes from their parent 238U in the formation of the three discrete types of Po radiohalos. Establishment of New Radiocenters

The final question that needs answering is how do the new radiocenters become established? Together with hydrothermal fluid transport, there needs to be a mechanism by which the Po isotopes are concentrated at particular locations that become discrete radiocenters. transport may be as 222Rn, but radon is an inert gas and has no chemical affinity with other species, so there is no chemical propensity for it to concentrate at discrete locations. Thus it would appear that the radiocenters could only have formed after the 222Rn had decayed to 218Po. This is consistent with only Po isotopes having been in the radiocenters, since only rings equivalent to α-emissions from the Po isotopes surround the radiocenters. Po

behaves geochemically similar to Pb, with an affinity for S, Se, and halides, and even forms polonides with other metals.335 Gentry et al.336 have demonstrated that where Pb, S, and Se were available in coalified wood, Po transported through the coalified wood by fluids became attached to these species with which it has a chemical affinity, and became concentrated enough in radiocenters to produce 210Po radiohalos.Some biotites in granitic rocks that host hydrothermally-produced porphyry Cu ore deposits have inclusions of native Cu 0.002–0.01 µm thick and up to 1.0 µm in diameter in favored lattice planes.337 These tiny Cu inclusions were evidently deposited from Cu-bearing hydrothermal fluids that flowed along the cleavage planes within the biotite crystals. It is therefore reasonable to expect that the same hydrothermal fluids responsible for transporting Ra, Rn, and Po would have also transported metal and other ions, just as is observed,338 and would thus have similarly deposited tiny inclusions of metals and other elements along the cleavage planes within biotites. Collins339 has correctly observed that the crystal lattice of biotite contains sites where negatively charged halide or hydroxyl ions can be accommodated. These lattice sites and other imperfections found along cleavage planes, being relatively large, would provide space for metal and other ions such as Po to enter and take up lattice positions or be concentrated at particular discrete places along the cleavage planes where the chemical environment was conducive. Collins also contended that the Po radiohalos formed as a result of the diffusion of 222Rn in “ambient” fluids within the crystallizing granitic rocks. In this way Po was incorporated in discrete radiocenters along the cleavage planes in the biotite flakes where suitable ions had been concentrated in lattice sites and crystal imperfections, and where the chemical environment was conducive to Po being concentrated to form the discrete radiocenters. It needs to be emphasized again that all the Po atoms required to give the desired high concentration of Po in the radiocenters to produce the observed intensity of Po radiohalos do not have to be delivered by the fluid transport process at the same time. As Po atoms decayed further fluid flow delivered more Po atoms to the radiocenters, where the metal or other ions that had scavenged Po from the passing fluids had become free to scavenge more Po. Thus the required ring density is reached by accumulation over a period of time, during which fluid flow continues and supply of Po atoms is available. Model Predictions and Implications

It needs to be stressed that this secondary transport model for the origin of the Po-rich radiocenters and therefore the Po radiohalos is tentative. Further data collection and analysis is needed. It is another hypothesis or model that is open to either verification or falsification. The strength and usefulness of this model can be tested by its ability to make predictions about future discoveries which can be tested. One predication that could be made is that Po radiohalos should be found not only in granitic plutons, but also in regional metamorphic rocks. It has been argued here that some granitic plutons containing Po radiohalos were derived from the regional metamorphic rocks adjacent to them, or associated with them; and that the zircons, which were the source of the 238U-decay products that were transported by hydrothermal fluids to form the Po radiohalos, were originally detrital zircons in the metasediments. Thus it is predicted that Po radiohalos should be found, along with U and Th radiohalos, in the metamorphic rocks that surround, and were the source of, the Cooma granodiorite. To have produced Po radiohalos the other required ingredient would have been the passage of hydrothermal fluids through the biotite crystals containing the tiny zircon and monazite inclusions. Thus the finding of Po radiohalos in these Cooma metamorphic rocks would also confirm the model for regional metamorphism in which hydrothermal fluids circulated and permeated through sediment layers of differing mineralogy and composition to facilitate the transformation of the precursor minerals to new metamorphic minerals now characteristic of each of the regional metamorphic zones we observe in metamorphic complexes today.340, 341The presence of U and Th radiohalos in metamorphic rocks has already been documented,342, 343 and there is also some tentative documentation of Po radiohalos in high-grade metamorphic rocks.344 But concerted systematic observations now need to be made to verify the geological distribution and occurrence of all types of radiohalos in appropriate metamorphic rocks.Verification of this hydrothermal fluid transport model for the secondary formation of Po radiohalos in both granitic and metamorphic rocks would have other far-reaching and powerful implications. Whereas it can be perceived as disappointing that the fiat creation hypothesis for the Po radiohalos and their host granitic rocks has been falsified, the timescale considerations in that hypothesis still remain. Any hydrothermal fluid transport model for the Po radiohalos must envisage extremely rapid flow of hydrothermal fluids, along with extremely rapid cooling of the granitic magmas and metamorphic rocks—cooling from the temperatures of their formation to below the temperature at which α-tracks are thermally erased. It is in that window of falling temperature that the fluid flow must occur to rapidly transport the Po isotopes and their precursors, and the α-tracks they make along their fluid flow paths must also be erased.345 The short 222Rn half-life requires this falling temperature window to be very short time-wise. And this implies very rapid cooling of the granitic magmas and the metamorphic rocks. The clear implication is that granitic plutons and metamorphic complexes that contain Po radiohalos had to have cooled very rapidly. The hydrothermal fluids that transported the Po isotope precursors also rapidly transferred the heat from the crystallizing and cooling granitic magmas, and away from the high grade metamorphic zones to the outer limits of the metamorphic complexes.346, 347Thus it is contended that the presence of Po radiohalos in granitic and metamorphic rocks implies an extremely short timescale for the formation and cooling of these rocks (days, not weeks or years), a timescale consistent with the year of the catastrophic global Flood on a young earth.Finally, because the Po radiohalos imply that rapid convective flows of hydrothermal fluids in granitic and metamorphic rocks rapidly cooled them, they also imply that these flows would have been responsible for the rapid deposition of metallic ore deposits.348 This implication encompasses all major classes of metallic ore deposits, ranging from porphyry Cu ± Au ± Mo deposits hosted by granitic rocks to vein deposits of gold and other metals, and to massive sulfide deposits containing base and other metals. Deposit sizes from small to giant at many distinctive strata levels throughout the global geological record are included. Rather than disappointment and dismay at the failure of the hypothesis regarding the Po radiohalos as evidence for fiat creation, we have powerful far-reaching implications for the rapid formation of granitic and other plutonic rocks, regional metamorphic complexes, and metallic ore deposits on a global scale within the Flood year. Conclusions

The discovery and documentation of the three types of Po radiohalos in the biotites within three granitic plutons that were clearly sourced and formed during the Flood year falsifies the hypothesis for the formation of these Po radiohalos and their host granitic rocks during the beginning . Furthermore, the presence of dark, mature U and Th radiohalos in the same biotites in these same granitic rocks may be considered physical evidence of at least 100 million years worth of radioactive decay at today’s rates within a part of the Flood year. We consider this to be evidence of accelerated nuclear decay during the catastrophic Flood. Accordingly, conventional radioisotopic dating of rocks based on the assumption of constancy of decay rates is grossly in error. Furthermore, the heat generated by this accelerated nuclear decay would have contributed to catastrophic tectonic and geologic processes during the Flood.Many related lines of evidence can be brought together in development of a viable hydrothermal fluid transport model for the precursors to the Po isotopes (principally 222Rn), and probably also some Po atoms themselves. Sourced from zircon and monazite grains already included within biotite flakes, the hydrothermal fluids would have carried these isotopes only short distances along the cleavage planes of the same and adjacent biotite flakes to deposition sites where the chemical environment was suitable

for concentration of the Po isotopes into radiocenters that then formed the Po radiohalos. The short half-lives of these isotopes require the hydrothermal fluid transport and chemical concentration timeframes to have been extremely short—less than in the order of ten Po half-lives. Furthermore, after Po atoms are deposited at radiohalo sites, the temperature must drop below the α-track annealing temperature before radiohalos can form. This implies that the timescale for cooling of the granitic plutons was also extremely short, measured in half-lives of these isotopes (days, not years).The possibility of Po radiohalos, and thus also rapid hydrothermal fluid flows, in metamorphic rocks has powerful implications for the rapid formation and cooling of regional metamorphic complexes. This needs further investigation. Additionally, the Po radiohalo evidence for rapid hydrothermal fluid flow has far-reaching implications for the rapid deposition and formation of many classes of metallic ore deposits hosted by, and associated with, granitic, other plutonic, and metamorphic rocks. Thus the Po radiohalos are potentially powerful evidence for rapid geological processes within the year of the Flood on a young earth. Acknowledgments

Full acknowledgment is given to the ground-breaking, pioneer work on polonium radiohalos by Dr. Robert Gentry. We are both personally indebted to Bob for the training and counsel he gave us on radiohalos that has enabled us to accomplish this research project. We have both spent time in the field with Bob and received from him personal instruction on the technique of mounting biotite flakes onto microscope slides. We would both have wished that the outcome of our research could have corroborated Bob’s conclusions. However, in disagreeing with him we still wish to recognize and emphasize his essential pioneering research that was foundational to our research reported here. We are also grateful to Carl Froede for assistance to obtain the Stone Mountain pluton samples, and grateful for the helpful comments of an anonymous reviewer that greatly improved the readability of our paper. Finally, we acknowledge the gifts of the donors to the RATE (Radioisotopes and the Age of The Earth) project that made this radiohalo research possible.

Implications of Polonium Radiohalos in Nested Plutons of the Tuolumne Intrusive Suite, Yosemite, California

by Dr. Andrew A. Snelling and Dallel Gates on April 8, 2009 Abstract The formation of granite plutons has conventionally been thought to be a slow process requiring millions of years from generation to cooling. Even though new mechanisms for rapid emplacement of plutons have now been proposed, radioisotope dating still dominates and dictates long timescales for pluton formation. However, a new challenge to those long timescales has arisen from radiohalos. Polonium radiohalos found in biotite flakes of granites in Yosemite National Park place severe time constraints on the formation and cooling of the granite plutons due to the short half-lives of the polonium isotopes. The biotite flakes must have formed and cooled below 150ºC before the polonium supply was exhausted and the radiohalos could be preserved, so the U decay had to be grossly accelerated and the formation of the plutons had to be within 6–10 days. Furthermore, rapid cooling of the plutons was facilitated by the hydrothermal fluid convection that rapidly generated the Po radiohalos, challenging conventional thinking that cooling is a slow process by conduction. It is evident that there were greater volumes of hydrothermal fluids in the later central intrusions of the nested plutons of the Tuolumne Intrusive Suite. So as expected, more Po radiohalos were generated in these plutons as they were sequentially intruded, confirming the hydrothermal fluid transport model for Po radiohalo formation. Thus granite pluton formation is consistent with the timescale of a young earth, and accelerated radioisotope decay renders the absolute ages for these granite plutons grossly in error.

Shop Now Keywords: Granite plutons, Yosemite National Park, Magma

emplacement, Magma cooling, Polonium radiohalos, Hydrothermal fluids, Accelerated U decay, Nested plutons, Tuolumne Intrusive Suite, Sequential emplacement, Explosive volcanism. Introduction

Granites constitute a major portion of the continental crust. They outcrop over many areas of the earth’s surface as discrete bodies called plutons, ranging in size from 10 km2 to thousands of km2. The granite magmas are believed to be sourced from great depths in the lower to mid levels of the continental crust, but the plutons crystallize in the upper crust, typically at depths of 1–5 km. Furthermore, granite plutons are often part of batholiths, which are regional areas comprised of hundreds of plutons.As far as can be ascertained, granite magmatism primarily occurs in the continental crust and involves four separate but potentially quantifiable stages—generation, segregation, ascent, and

emplacement—that operate over length scales ranging from 10-5 to 106 meters (Petford et al. 2000). Once in place, the final stage is cooling. Explanations for the formation of even a single granite pluton have become somewhat controversial, even in the conventional geologic community, as once held conventions are being challenged. No longer is research focusing on just the mineralogy, geochemistry, and isotopes of granites as clues to their formation (which has hithertofore supposedly required long timescales of millions of years), but on the physical processes as well. The results of such research have drastically shortened the intrusion timescales of many plutons to just centuries and even months (Petford et al. 2000).Various evidences are now being cited that change the long-held, extended time frames for granite formation (Coleman, Gray, and Glazner 2004). Conventional thinking has been that plutons form from the slow rising of diapirs, large molten masses that intrude into the host rocks and then cool. However, the problem of how the host rocks provide the space for these intruding diapirs has been increasingly recognised. In contrast, there are field data that indicate persuasively that plutons have formed from small batches of magma that accumulated in succession by dike intrusions. This new thinking drastically reduces the timescales for magma intrusion to form granite plutons, but most geologists are still convinced, based on their unerring commitment to radioisotope dating, that plutons require long uniformitarian time frames to form and then to cool primarily by conduction. Thus, the formation and the cooling of granite plutons are still regarded as prima facie evidences against the year-long, catastrophic global Flood on a young earth (Young and Stearley 2008).Granites are composed of several major minerals (quartz, K-feldspar, plagioclase, biotite, & hornblende), with minor constituents such as zircon (zirconium silicate). Tiny zircon grains (1–5 microns in diameter) are often found encased within large flakes (1–5 mm in diameter) of ubiquitous biotite. The zircon grains usually carry trace amounts of 238U, whose radioactive decay has provided a means by which it is claimed the ages of granites can be measured. Nevertheless, as the 238U in the zircon grains decays to 206Pb, it leaves physical evidence of that decay in the form of radiohalos, spherical zones of discoloration around these zircon grains (the radiocenters). Radiohalos are, in fact, the damage left by the emission of alpha (a) during the 238U decay process. The crystal structure of the surrounding biotite is

damaged by the a-particles being “fired” in all directions like “bullets,” producing various concentric shells of darkening or discoloration (which are dark rings when viewed in cross-section). The radii of these concentric rings are related to the energies of the a-decay daughters in the 238U decay series (fig. 1b).Of the different radiohalo types distinct from 238U (and 232Th), presently the only ones to be identified with known a-radioactivity are the Po (polonium) radiohalos (fig. 1a, c, d). There are three Po isotopes in the 238U-decay chain. In sequence they are 218Po (half-life of 3.1 minutes), 214Po (half-life of 164 microseconds), and 210Po (half-life of 138 days). Found also in fluorite and cordierite, these radiohalos could only have been produced by either the respective Po radioisotopes that then parented the subsequent a-decays, or by non- a-emitting parents (Gentry 1973, 1974). Because of the radiohalos being located along cleavages and cracks in fluorite grains and biotite flakes, secondary fluid transport processes are thought to have been responsible for supplying the required Po radioisotopes to the radiocentres. The reason for the attempts to account for the Po radiohalos by some secondary process is simple—the half-lifes of the respective Po isotopes are so short that the only alternative is the Po was primary, that is, the Po was independent of 238U originally in the granitic magmas which are supposed to have slowly cooled to form the granite plutons. However, there are obstacles to any secondary process. First, there is the problem of isotopic separation of the Po radioisotopes from their parent 238U having occurred naturally. Second, the concentration of Po necessary to produce a radiohalo is as high as 5 x 109 atoms (approximately 50% Po), and yet the host minerals contain only ppm abundances of U, which apparently means only a negligible supply of Po daughter atoms is available for capture in a radiocenter at any given time.

Fig. 1. Composite schematic drawing of (a) a 218Po halo, (b)

a 238U halo, (c) a 214Po halo, and (d) a 210Po halo, with radii proportional to the ranges of the a-particles in air. The nuclides responsible for the a-particles are listed for the different halo rings (after Gentry 1973). Therefore, there are strict time limits for the formation of the Po radiohalos by primary or secondary processes in granites. It was for this reason that Gentry (1974, 1986, 1988) proposed that the three different types of Po radiohalos in biotites resulted from the decay of primordial Po (original Po not derived by 238U decay), and thus claimed that the host granites also had to be primordial, that is produced by fiat creation. He thus perceived all granites to be Precambrian, and part of the earth’s crust created during the beginning . However, Wise (1989) documented that six of the 22 locations reported in the literature where Po radiohalos had been

found were hosted by Phanerozoic granites which had been formed during the Flood. Additionally, many of the occurrences of Po radiohalos were in proximity to higher than normal U concentrations in nearby rocks and/or minerals, suggesting ideal sources for fluid separation and transport of the Po. Indeed, Snelling (2000) documented reports of 210Po as a detectable species in volcanic gases, in volcanic/hydrothermal fluids associated with subaerial volcanoes and fumaroles, and associated with mid-ocean ridge hydrothermal vent fluids and chimney deposits, as well as in groundwaters. The distances travelled by the Po in these fluids were up to several kilometres. Such evidence supports a viable secondary transport model for Po in hydrothermal fluids in granite plutons after their emplacement and during the waning stages of the crystallization and cooling of granite magmas (Snelling 2005a; Snelling and Armitage 2003; Snelling, Baumgardner, and Vardiman 2003).Po radiohalos thus appear to indicate that very rapid geological processes were responsible for their production, due to their very short half-lifes. This places severe time constraints on the processes by which granites can form, that is, granites had to form rapidly in much shorter time periods than is conventionally interpreted from the longer half-life of238U decay (4.46 x 109 years). The potential problems thus arise with the conventional interpretation of isotopic systems and/or plutonic processes. Glazner, et al. (2004) have stated:The prevailing view that plutons cool in less than a million years requires such conflicting ages to reflect the problems in isotopic systematics. However, it may be that many such age differences are real and that the problem lies instead with assumptions about plutonic processes.However, the existence of Po radiohalos in granite plutons supports the convention that plutonic processes occurred in very short time frames, so the problem has to be with the interpretation of the isotopic systematics, a concern echoed by Paterson and Tobisch (1992). Snelling (2005a), Snelling and Armitage (2003), and Snelling, Baumgardner, and Vardiman (2003) have proposed a model for the secondary transport of Po in hydrothermal fluids to form Po radiohalos during pluton cooling, so it needs to be recognized just how rapidly plutonic processes must have occurred. A classic location for the widespread outcropping of granites is in the Sierra Nevada of eastern Central California (fig. 2). Known as the Sierra Nevada Batholith, hundreds of granite plutons outcrop over an area of 40,000–45,000 km2. The batholith is conventionally of Mesozoic age, and lies along the western edge of the Paleozoic North American craton (Bateman 1992). It was emplaced in strongly deformed but weakly metamorphosed strata ranging in conventional age from Proterozoic to Cretaceous. To the east of the batholith in the White and Inyo Mountains, sedimentary rocks of Proterozoic and Paleozoic age crop out, and metamorphosed sedimentary volcanic rocks of Paleozoic and Mesozoic age crop out west of the batholith in the western metamorphic belt. The plutonic rocks of the batholith range in composition from gabbro to leucogranite, but tonalite, granodiorite, and granite are the most common rock types. Most of the plutons have been assigned to intrusive suites that appear to be spatially related to one another by being intruded sequentially and thus show regular age patterns.In the central Sierra Nevada are the spectacular granite outcrops of the Yosemite National Park (fig. studies on granites and the formation (Bateman 3), so these have been the focus of many previous 1992). This present study investigates the occurrence and distribution of U and Po radiohalos in the biotites of selected granite plutons in various, easily accessed outcrops in Yosemite National Park and shows how they provide evidence and support of the rapid formation of these granites. A particular focus was the set of nested plutons of the Tuolumne Intrusive Suite, which in contrast to the other granite plutons appear to have been intruded in a progressive sequence to form a very large zoned pluton. Generation, Emplacement and Cooling of Granites

The generation of granite magmas and emplacement of granite plutons are still topics of debate among geologists today (Pitcher 1993). In recent years, a consensus has emerged that granite magmatism is a rapid, dynamic process operating at timescales of ≤100,000 years (Paterson and Tobisch 1992; Petford et al. 2000). Petford et al. (2000) state that research into the origin of granite has shifted away from geochemistry and isotopic studies towards understanding the physical processes involved. Heat advected into the lower crust from underlying hot mantle-derived basaltic magmas would rapidly and efficiently cause partial melting of crustal rocks, producing enough melt in 200 years or less to form a granite magma that can then be transported to the area of emplacement in the upper crust (Bergantz 1989; Huppert and Sparks 1988;

Jackson, Cheadle, and Atherton 2003).Transport of the melt and magma (melt plus suspended solids) operates over two length scales (Miller, Watson, and Harrison 1988). First, segregation is small-scale movement of melt (centimeters to decimeters) within the source region. Second, once the melt is segregated, long-range (kilometer-scale) ascent of the magma through the continental crust to the site of final emplacement occurs. Crucial physical properties of a granite melt that facilitate its segregation are viscosity and density. Traditionally, granite melt has been thought to have a viscosity close to that of solid rock, but experimental studies have now demonstrated that the viscosity is a function of the composition, temperature and water content of the melt (Clemens and Petford 1999; Pitcher 1993).

Fig. 2. Generalized geology of the Sierra Nevada and adjacent areas

of eastern California, showing the location of the Yosemite National Park (after Bateman 1992). Deformation has been shown from field evidence to be the dominant mechanism that segregates and focuses granite melt flow in the lower crust, and this has been confirmed by rock deformation experiments (Brown and Rushmer 1997; Rutter and Neumann 1995). However, the proven efficiency of melt segregation by deformation makes it unlikely that large, granite magma chambers will form in the region of partial melting (Petford 1995; Petford and Koenders 1998). Instead, the most viable driving force for subsequent large-scale vertical transport of the melt through the continental crust is gravity. However, the traditional idea of buoyant granite magma ascending through the continental crust as slow-rising, hot diapirs or by stoping has been largely replaced. New models involving the ascent of granite magmas in narrow conduits, either as self-propagating dikes (Clemens and Mawer 1992; Clemens, Petford, and Mawer 1997; Petford 1995) along pre-existing faults (Petford, Kerr, and Lister 1993; Yoshinobu, Okaya, and Paterson 1998) or as an interconnected network of active shear zones and dilational structures (Collins and Sawyer 1996; D’Lemos, Brown, and Strachan 1993), are overcoming the severe thermal and mechanical problems associated with transporting very large volumes of magma through the upper brittle continental crust (Marsh 1982). A striking aspect of the ascent of granite melt in dikes compared to diapiric rise is the extreme difference in magma ascent rate between

both processes, with the former up to a factor of 106 faster depending upon the viscosity of the material and conduit width (Clemens, Petford, and Mawer 1997; Petford, Kerr, and Lister 1993). In fact, field and experimental studies support the narrow dike widths (~1–50 m) and rapid ascent velocities predicted by fluid dynamical models (Brandon, Chacko, and Creaser 1996; Scalliet et al. 1994). Thus these dike ascent models have brought the timescale for granite magmatism more in line with that for large scale and volume catastrophic volcanism.

Fig. 3. Scenic views in the Yosemite National Park. The total landscape is composed of many outcropping granite plutons

that have intruded one another. The final stage, emplacement, in the granite forming process has challenged geologists for most of the twentieth century with the so-called space problem (Glazner et al. 2003; Pitcher 1993), the way in which the host rocks make room for the newly incoming magma. This problem becomes all the more acute where batholithic volumes (>1 x 105 km3) of granite magma are considered to have been emplaced in a single episode. However, the recognition of the important role played by tectonic activity in making space in the crust for incoming magmas during their ascent has helped to potentially solve this problem (Hutton 1988). Also contributing to the solution have been the more realistic determinations of the geometry of granite plutons at depth, and the recognition that emplacement is an episodic process involving discrete pulses of magma. The majority of plutons so far investigated appear as flat-lying to open funnel-shaped structures with central or marginal feeder zones, consistent with field studies that have demonstrated plutons to be sheeted on a decimeter to kilometer scale (Ameglio and Vigneresse 1999; Bouchez, Hutton, and Stephens 1997; Hutton 1992; Petford 1992). Thus the best comprehensive model of pluton emplacement, combining all empirical studies, envisages pluton growth

commencing with a birth stage, characterized by lateral spreading, followed by an inflation stage, marked by vertical thickening. This would result in plutons, at the fastest magma delivery rates, being emplaced in less than 1,000 years (Harris and Ayres 2000). Petford et al. (2000) concluded with the comment:The rate-limiting step in granite magmatism is the timescale of partial melting (Harris Vance, and Ayers 2000; Petford, Clemens, and Vigneresse 1997); the follow-on stages of segregation, ascent and emplacement can be geologically extremely rapid—perhaps even catastrophic.Once emplaced the magma must crystallize completely and cool to form the final granite pluton. Traditionally this process has been considered to have been primarily by conduction, thus taking millions of years. However, more recently, cooling models have increasingly incorporated convective cooling as the major component (Norton and Knight 1977; Parmentier 1981; Spera 1982; Torrance and Sheu 1978), and empirical studies (Brown 1987; Hardee 1982) have proved that thick igneous bodies do in fact cool primarily by circulating water (Snelling and Woodmorappe 1998). Thus, computer programs have been used to generate the most recent models for cooling plutons (Hayba and Ingebritsen 1997; Ingebritsen and Hayba 1994).The initial source of the water required for this convective cooling is within the magma itself, the same water dissolved in the magma that lowered its viscosity and thus aided its emplacement. As the granite crystallizes the dissolved water becomes concentrated in the residual magma, which increases its cooling rate. When the residual magma eventually becomes saturated with water as the temperature continues to fall, the water is released as steam under pressure that is thus forced through the cooling granite pluton fracturing its outer contact zone, and out into the host rocks through those fractures carrying heat with it (Burnham 1997; Candela 1991; Zhao and Brown 1992). This in turn allows any cooler water present in the host rocks to flow through those same fractures back into the granite pluton, thus setting up a convective cell circulation between the host rocks and the pluton (Cathles 1977). This facilitates the rapid increase of the cooling process, as more and more heat is carried by these hydrothermal fluids from the magma out into the host rocks where it dissipates. Spera (1982) concluded: Hydrothermal fluid circulation within a permeable or fractured country rock accounts for most heat loss when magma is emplaced into water-bearing country rock . . . Large hydrothermal systems tend to occur in the upper parts of the crust where meteoric water is more plentiful.Thus Snelling and Woodmorappe (1998) concluded that millions of years are not necessary for the cooling of large igneous bodies such as granite plutons. The Significance of U and Po Radiohalos

When radiohalos where first reported between 1880 and 1890, they remained a mystery until the discovery of radioactivity (Gentry 1973). Now they are recognized as any type of discolored radiation-damaged region within a mineral, resulting from the a-emissions from a central radioactive inclusion or radiocenter. Usually the radiohalos when viewed in rock thin sections appear as concentric rings that were initiated by the a-decay of 238U or 232Th series (Gentry 1973, 1974). Radiohalos are usually found in igneous rocks, most commonly in granitic rocks in which biotite is a major mineral. In fact, biotite is the major mineral in which the radiohalos occur. While observed mainly in Precambrian rocks (Gentry 1968, 1970, 1971; Henderson and Bateson 1934; Henderson, Mushkat, and Crawford 1934; Iimori and Yoshimura 1926; Joly 1917a, b, 1923, 1924; Kerr-Lawson 1927, 1928; Owen 1988; Wiman 1930), radiohalos have been shown to exist in rocks stretching from the Precambrian to the Tertiary (Holmes 1931; Snelling 2005a; Stark 1936; Wise 1989).Within the 238U decay series, the three Po isotopes have been the only a-emitters observed to form radiohalos other than 238U itself (fig. 1). These isotopes and their respective half-lifes are 218Po (3.1 minutes), 214Po (164 microseconds), and 210Po (138 days). Their very short half-lifes constrain the formation of the granites that they have been found in to a short time frame (Gentry 1986, 1988; Snelling 2000, 2005a), because the Po radiohalos can only form after the granites have crystallized and cooled, yet the Po isotopes are already in the granite magma when it is emplaced. Thus, if granite magma emplacement and pluton cooling are not extremely rapid, then these Po isotopes would not have survived to form the Po radiohalos (Snelling 2008a). This is consistent with, and in support of, a young earth model. As the rings for the Po precursors are usually missing (Snelling, Baumgardner, and Vardiman 2003), the source of the Po for the radiohalos has been an area of contention (Snelling 2000). Was it primary, or did a secondary process transport it? Gentry (1986) proposed that the Po radiohalos had been produced by primordial Po, having an origin independent of any U, so therefore, all granites and granitic rocks were formed by fiat creation during the Creation. In contrast, based on all the available evidence, Snelling (2000) suggested a possible model for transporting the Po via hydrothermal fluids during the latter stages of cooling of granite plutons to sites where the Po isotopes would have been precipitated and concentrated in radiocenters that then formed the respective Po radiohalos in the granites.Subsequently, Snelling and Armitage (2003) investigated the radiohalos in the biotite flakes within three granite plutons, demonstrating first that these granite plutons had been intruded and cooled during the Flood. They found that the biotite grains contained both fully-formed 238U and 232Th radiohalos around zircon and monazite inclusions (radiocenters) respectively, thus providing a physical, integral, historical record of at least 100 million years worth (at today’s rates) of accelerated radioactive decay during the recent year-long Flood. However, Po radiohalos were also often found in the same biotite flakes as the U radiohalos, usually less than 1 mm away. They thus argued that the source of the Po isotopes must have been the U in the zircon grains within the biotite flakes, the same zircon inclusions that are the radiocenters to the U radiohalos.Snelling and Armitage (2003) then went on to progressively reason the evidence that confirms the tentative model suggested by Snelling (2000). Because the precursor to 218Po is the inert gas 222Rn, after it is produced by 238U decay in the zircon grains it is capable of diffusing out of the zircon crystal lattice. Concurrently, as previously described, as the emplaced granite magma crystallizes and cools, the water dissolved in it is released below 400ºC so that hydrothermal fluids begin flowing around the constituent minerals and through the granite pluton, including along the cleavage planes within the biotite flakes. As argued by Snelling and Armitage (2003), and elaborated by Snelling (2005a), these hydrothermal fluids were capable of then transporting 222Rn (and its daughter Po isotopes) from the zircon inclusions to sites where new radiocenters were formed by Po isotopes precipitating in lattice imperfections containing rare ions of S, Se, Pb, halides or other species with a geochemical affinity for Po. Continued hydrothermal fluid transport of Po would have also replaced the Po in the radiocenters as it a-decayed to produce the Po radiohalos, thus progressively supplying the 5 x 109 Po atoms needed to form fully registered Po radiohalos.Significantly, as none of the radiohalos (Po or U) could form or be preserved until the biotite crystals had formed and cooled below the thermal annealing temperature for a-tracks of 150ºC (Laney and Laughlin 1981), yet the hydrothermal fluids probably started transporting Rn and the Po isotopes immediately they were expelled from the magma just below 400ºC, this implies cooling of the Po-radiohalo-containing granite plutons had to be extremely rapid, in only 6–10 days (Snelling 2008a). Snelling, Baumgardner, and Vardiman (2003) and Snelling (2005a) have summarized this model for hydrothermal fluid transport of U-decay products (Rn, Po) in a six-step diagram. The final step concludes with the comment:With further passing of time and more a-decays both the 238U and 210Po radiohalos are fully formed, the granite cools completely and hydrothermal fluid flow ceases. Note that both radiohalos have to form concurrently below 150ºC. The rate at which these processes occur must therefore be governed by the 138 day half-life of 210Po. To get 218Po and214Po radiohalos these processes would have to have occurred even faster.Of course, if the U and Po radiohalos have both formed in a few days during the 6–10 days while the granite plutons cooled during the Flood,

then this implies 100 million years worth of accelerated 238U decay occurred over a time frame of a few days. Thus the U-Pb isotopic systematics within the zircons in these granite plutons are definitely not providing absolute “ages” as conventionally interpreted. The Granites of the Sierra Nevada Batholith in Yosemite National Park

No other large batholith has offered conditions as favorable for geologic study as the Sierra Nevada Batholith, where exposures are good almost everywhere due to the glaciation in the high elevations (fig. 3) and the arid climate in the eastern escarpment (Bateman 1992). Before 1956, the batholith was considered a barrier to relating the stratified rocks in the western metamorphic belt to remnants within the batholith and to the strata east of the batholith in the Basin and Range Province, until plate tectonics provided a “solution,” due to the Sierra Nevada being considered to lie within the zone affected by Mesozoic and Cenozoic convergence of the North American plate with plates of the Pacific Ocean. The batholith is a segment of the Mesozoic batholiths that encircle the Pacific Basin. Systematic mapping of the region (fig. 2) by geologists of the U.S. Geological Survey grew out of independent studies of discrete areas or topics by individuals or small groups of individuals, and was completed at the 1:62,500 scale in 1982. The relevant quadrangle areas have also been combined into two comprehensive maps, one by Huber, Bateman, and Wahrhaftig (1989) covering the Yosemite National Park area and its surroundings (summarized in fig. 4), and the other by Bateman (1992) covering the belt across the batholith between latitudes 37º and 38ºN.

Fig. 4. Geologic map of the southern and central Yosemite

National Park (after Huber, Bateman, and Wahrhaftig 1989). The locations of the samples used in this study are indicated. The legend listing the chronologic sequence of mapped units is below. Those units sampled are indicated in bold.Studies of the individual plutons within the batholith have provided crucial contributions to the development of the model for rapid granite pluton formation discussed above. For example, Reid, Evans, and Fates (1983) studied magma mixing in granite rocks of the central Sierra Nevada and concluded that the intrusion of mafic magmas in the lower crust were important in the generation of the Sierra Nevada Batholith, having caused partial melting that generated granite magmas. These mafic and granite magmas then mixed during their emplacement, the evidence for this relationship being found in the El Capitan Granite and the Half Dome Granodiorite in the Yosemite National Park. Subsequently, Ratajeski, Glazner, and Miller (2001) concluded that the intrusion of the Yosemite Valley Suite involved two probably closely timed pulses of mafic-felsic magmatism. The first stage yielded the El Capitan Granite, mafic enclaves and the Rockslides diorite, while the second stage yielded the Taft

Granite and a mafic dike swarm. A previous study by Kistler et al. (1986) attributed the compositional zoning of the Tuolumne Intrusive Suite to the initial generation of a basalt magma in the lower continental crust. This basaltic magma then interacted with and melted some of the more siliceous and isotopically more radiogenic lower crust rocks to produce mixtures that were emplaced into the upper crust as the equigranular outer units of the suite. These studies thus confirm the role of mafic magmas in the rapid heating of the lower crust to rapidly form granite magmas.Various other studies have been done on the emplacement of the Sierra Nevada granite plutons. Paterson and Vernon (1995) applied the popular model for the emplacement of spherical granite plutons, that is, “ballooning” or in situ inflation of the magma chamber, to their studies of the Papoose Flat Pluton and the plutons of the Tuolumne Intrusive Suite. They concluded that

many such plutons are better viewed as syntectonic nested diapirs, which implies that magma ascent may have occurred by the rise of large magma batches. Furthermore, normally zoned plutons may have thus formed by intrusion of several pulses of magma, rather than by in situ crystal fractionation from a single parent melt. Glazner et al. (2003) addressed the problem of making space for large batholiths such as the Sierra Nevada by suggesting that isostatic sinking of the growing magmatic pile into its substrate would have displaced the sub-batholithic crust toward the backarc region via large-scale intracrustal flow. They thus concluded that this may be the solution for the space problem, the crust beneath batholiths having been involved in lateral, large-scale, two- or three-dimensional intracrustal flow accompanied by thrust faulting. Mahan et al. (2003) studied the McDoogle Pluton near the eastern margin of the Sierra Nevada Batholith, and found field, microstructural, and geochronological evidence that indicated the pluton had been emplaced as a subvertically sheeted complex, not by the diapiric rise of multiple batches of magma. Thus, such sheeted dike emplacement of the pluton would have reduced the time frame for the pluton’s formation, which was confirmed by zircon U-Pb isotope data. McNulty, Tong, and Tobisch (1996) had similarly studied the Jackass Lakes Pluton in the central Sierra Nevada, and concluded that this pluton had also formed via sheet-like assembly of a dike-fed magma chamber. Furthermore, the bulk emplacement was facilitated by multiple processes, including lateral expansion of sheets and ductile wall-rock shortening at the final emplacement site, stoping and caldera formation, and possibly roof uplift or doming. McNulty, Tong, and Tobisch (1996) concluded with the comment:Hybrid viscoelastic models also offer realistic

alternatives to end-member models (that is, dike versus diapir). More accurate models of pluton emplacement will allow better understanding of the construction of magmatic arcs, and ultimately how tectonics are manifested at plate boundaries.Studies of the evidence for how and when the plutons in the Sierra Nevada Batholith were emplaced are thus challenging previous conventional models and their associated timescales. For example, Coleman and Glazner (1997) considered the Sierra Nevada Batholith as a whole and concluded that during what they informally called the Sierra Crest magmatic event extremely voluminous magmatism resulted in rapid crustal growth. From approximately 98 to 86 Ma (a veritable instant in conventional geologic time) greater than 4000 km2 of exposed granodioritic to granitic crust was emplaced in eastern California to form about 50% of the Sierra Nevada Batholith, including the largest composite intrusive suites (such as the Tuolumne). Furthermore, although they comprise an insignificant volume of exposed rocks (less than 100 km2), mafic magmas were intruded contemporaneously with each episode of magmatism during this event, often mingling with the granite magmas during emplacement. Thus, the heat from these mantle-derived mafic magmas appears to have triggered this large-scale granite magmatic event. The Tuolumne Intrusive Suite (consisting of the Kuna Crest Granodiorite, Glen Aulin Tonalite, Half Dome Granodiorite, Cathedral Peak Granodiorite, and the Johnson Granite Porphyry) in the Yosemite National Park area has recently been used prominently as a prime example of the evidence that large and broadly homogenous plutons have accumulated incrementally supposedly over millions of years (Glazner et al., 2004). As previously discussed, a growing body of data suggests that many granite plutons were rapidly assembled as a series of sheet-like intrusions, while others preserve evidence that they were rapidly injected as a series of steep dikes. The Tuolumne Intrusive Suite of Yosemite National Park has long been thought to have crystallized from several large batches of magma that were emplaced in rapid succession (Bateman and Chappell 1979). Thus, Glazner et al. (2004) cited the abundant, unequivocal field evidence for the incremental dike emplacement of the plutons of the Tuolumne Intrusive Suite. For example, in many places the outer margin of the Tuolumne is clearly composed of granodiorite dikes that invaded its wall-rocks. Furthermore, near its contact with the Glen Aulin Tonalite, the Half Dome Granodiorite contains sheets of varying composition and tabular swarms of mafic enclaves, but then grades inward to a more homogeneous rock. There in the Half Dome Granodiorite the occurrence of dikes or sheets is less certain, but they concluded that the textural homogeneity of large plutons like the Half Dome Granodiorite could also reflect the post-emplacement annealing of amalgamated dikes or sheets, and such a pluton thus might contain any number of cryptic contacts.This field evidence thus supports the model of Petford et al. (2000) for the incremental emplacement of very large zoned plutons such as the Tuolumne Intrusive Suite in less than 100,000 years. However, Glazner et al. (2004) state that the geochronologic data contradicts that timescale. In particular, U-Pb zircon data from the Tuolumne Intrusive Suite indicate that the plutons were assembled over a period of 10 m.y. between 95 and 85 Ma, with the oldest intrusions at the margins and the youngest at the center (Coleman and Glazner 1997; Coleman et al. 2004). The Half Dome Granodiorite evidently was intruded over a period of about 4 m.y., with older ages near the outer contact and younger ages near the inner contact, even though it has been mapped as a single continuous pluton. Nevertheless, Coleman, Gray, and Glazner (2004) admit that the apparent lateral age variations in the Tuolumne Intrusive Suite are not consistent with the field evidence for its emplacement as a series of small intrusions assembled incrementally as sheets or dikes through the entire suite, and not just its outer units where such evidence is so obvious. Furthermore, they state that when large plutons are dated multiple times by the zircon U-Pb method, it is fairly common for the resulting dates to disagree by more than the analytical errors.Bateman and Chappell (1979) reported on their comprehensive study of the concentric texturally and compositionally zoned plutonic sequence of the Tuolumne Intrusive Suite, in which they sought to develop and test a model for the origin of comagmatic plutonic sequences in the Sierra Nevada Batholith. Their study involved detailed petrologic and geochemical investigations of a large suite of samples in two traverses across the Tuolumne plutons. Modal, major oxide and trace element analyses, as well as some mineral analyses, were undertaken in order to characterize each of the plutons and quantify the mineralogical and compositional variations within and between them. Structural and textural variations were also described. They concluded that the compositional zoning within the suite indicated that with decreasing temperature the sequence solidified from the margins inward, with solidification being interrupted repeatedly by surges of fluid core magma.Bateman (1992) provided a comprehensive compilation of all the data from the studies of the Sierra Nevada Batholith up until that date, and this includes descriptions of all the plutons investigated in this current study. The Granodiorite of Kuna Crest (Kkc) (fig. 4) is dark gray and equigranular, with the average composition changing from quartz diorite to granodiorite. Its modal composition is quartz (15–22%), K-feldspar (9–15%), plagioclase (44–50%), biotite (10–12%), hornblende (7–13%), and sphene (0.5–1.0%) (Bateman and Chappell 1979). The Half Dome Granodiorite (Khd) is coarser grained than the Granodiorite of Kuna Crest (Kkc), and includes an outer equigranular facies and an inner megacrystic facies. Hornblende (5 mm x 1.5 cm) and biotite (1 cm wide) crystals decrease in abundance inward, while plagioclase abundance remains constant, but both quartz and alkali (K)-feldspar abundances increase inward. Its modal composition is quartz (20–27%), K-feldspar (16–26%), plagioclase (39–51%), biotite (4–11%), hornblende (1–8%), and sphene (0.2–1.2%) (Bateman and Chappell 1979). The Cathedral Peak Granodiorite (Kcp) contains blocky alkali-feldspar megacrysts (commonly 3 cm x 5 cm), with the size and abundance of the megacrysts decreasing inward. Except for the inward decrease in abundance of these megacrysts and an absence of hornblende in the innermost parts, the modal composition of the Cathedral Peak Granodiorite is fairly constant, with quartz (24–30%), K-feldspar (20–28%), plagioclase (40–52%), biotite (1.3–4.5%), hornblende (0–2%), and sphene (0.1–0.7%) (Bateman and Chappell 1979). The Sentinel Granodiorite (Kse) (fig. 4) is equigranular and contains well-formed crystals of hornblende and biotite, and abundant wedgeshaped crystals of sphene. The Yosemite Creek Granodiorite (Kyc) is a dark-gray medium- to coarse-grained granitic rock of highly variable composition containing plagioclase phenocrysts. Both these plutons have sometimes been regarded as members of the Tuolumne Intrusive Suite, but are usually placed in the Intrusive Suite of Jack Main Canyon, or the Intrusive Suite of Sonora Pass by some workers.The Intrusive Suite of Yosemite Valley includes the El Capitan Granite and the Taft Granite, which have yielded U-Pb isotopic ages of about 102–103 Ma (Stern et al. 1981). The El Capitan Granite (Kec) (fig. 4) is a weakly to moderately megacrystic, leucocratic biotite granite. It is light gray, medium to coarse grained, and contains K-feldspar megacrysts (1–2 cm long) and small “books” of biotite. The Taft Granite (Kt) is medium-grained, very light gray, and on the Q-A-P diagram plots in the granite field.The Intrusive Suite of Washburn Lake, or of Buena Vista Crest according to some workers, includes the Granodiorite of Illilouette Creek (Kic) (fig. 4), which has yielded a discordant U-Pb age of 100 Ma (Stern et al. 1981). The Granodiorite of Illilouette Creek is the oldest, most mafic, and largest intrusion in this suite of plutons. It is dark, medium-grained, equigranular hornblende-biotite granodiorite and hornblende tonalite, with the combined hornblende and biotite content varying from 15% to 50%. Sparse euhedral crystals of hornblende are as long as 10 cm.The intrusive relationships between these plutons can be seen in Fig. 4. Bateman (1992) also reported that many of the biotite flakes found in the Sierra Nevada granite plutons contain tiny zircon crystals around which are “pleochroic halos,” another name for radiohalos. This observation had been previously made by Snetsinger (1967), who identified which mineral formed the nuclei (radiocenters) of the pleochroic

halos in biotites in some of the Sierra Nevada granites. Because it was zircons that formed the radiocenters to those observed halos, they were undoubtedly 238U radiohalos. Field and Laboratory Work

Each of the chosen granite plutons was sampled at the locations shown in Fig. 4. Access to the outcrops was available by road and by walking trails. The samples were collected where the outcrops were freshest with the approval of the Yosemite National Park via the granting of a sampling and research permit. Some of the sampled outcrops are shown in Fig. 5. Fist-sized (1–2 kg) pieces of granite were collected at each location, the details of which were recorded using a Garmin GPS II Plus hand-held unit.

Fig. 5. Outcrops of granites, many in road cuts, in the Yosemite National Park that were sampled for this study (for

location details see fig. 4). A standard petrographic thin section was obtained for each sample. Photo-micrographs representative of some of these samples of the Yosemite granites as seen under the microscope are provided in Fig. 6. In the laboratory, portions of the samples were crushed to liberate the biotite grains. Biotite flakes were then handpicked with tweezers from each crushed sample and placed on the adhesive surface of a piece of Scotch tape™ fixed to the flat surface of a laminated board on a laboratory table with its adhesive side up. Once numerous biotite flakes had been mounted on the adhesive side of this piece of tape, a fresh piece of Scotch tape™ was placed over them and firmly pressed along its length so as to ensure the two pieces were stuck together with the biotite flakes firmly wedged between them. The upper piece of tape was then peeled back in order to pull apart the sheets composing the biotite flakes, and this piece of tape with thin biotite sheets adhering to it was then placed over a standard glass microscope slide so that the adhesive side and the thin mica flakes adhered to it. This procedure was repeated with another piece of Scotch tape™ placed over the original tape and biotite flakes affixed to the board, the adhering biotite flakes being progressively pulled apart and transferred to microscope sides. As necessary, further handpicked biotite flakes were added to replace those fully pulled apart. In this way tens of microscope slides were prepared for each sample, each with many (at least 20) thin biotite flakes mounted on it. This is similar to the method pioneered by Gentry (1988). A minimum of 50 microscope slides was prepared for each sample (at least 1,000 biotite flakes) to ensure good representative sampling statistics.

Fig. 6. Photo-micrographs of some of the Yosemite granites used in this study, the locations of which are plotted on Fig.

4. All photo-micrographs are at the same scale (20× or 1 mm = 40µm) and the granites are as viewed under crossed polars. Each slide for each sample was then carefully examined under a petrological microscope in plane polarized light and all radiohalos present were identified, noting any relationships between the different radiohalo types and any unusual features. The numbers of each type of radiohalo in each slide were counted by progressively moving the slide backwards and forwards across the field of view, and the numbers for each slide were then tallied and tabulated for each sample. Results

All results are listed in Table 1. Of the thirteen rock units sampled, four units had some samples yielding no radiohalos: the Granodiorite of Kuna Crest (two samples), the Sentinel Granodiorite (one sample), the Yosemite Creek Granodiorite (one sample), and the Tonalite of the Gateway (one sample). Nevertheless, all the granitic rock units sampled contained at least some radiohalos. In Table 1, the number of radiohalos per slide was calculated by adding up the total number of all radiohalos found in all samples of that particular rock unit, divided by the number of slides made and viewed for counting of radiohalos. The number of polonium radiohalos per slide was calculated in a similar way, except it was the total number of polonium radiohalos divided by the number of slides examined for that rock unit. And finally, the ratio in the last column was calculated by taking the number of 210Po radiohalos and dividing by the number of 238U halos.Photo-micrographs of some representative radiohalos are shown in Fig. 7. The 238U radiohalos in Fig. 7a and b are “over exposed” meaning there has been so much rapid 238U decay that the resultant heavy discoloration of the biotite has blurred all the inner rings (compare with fig. 1). Often only holes remain in the centers of the 238U radiohalos where the tiny zirocn radiocenters have been lost during the peeling apart of the biotite flakes to tape them to the microscope slides in Fig. 7a (especially) other incomplete radiohalos stains can be been (lower right). These are due to this biotite sheet not cutting through the radiocenters of these (spherical) radiohalos. These stains likely represent four 210Po radiohalos and another 238U radiohalo, but only the visible complete radiohalos were recorded in Table 1. The outer ring of the 214Po radiohalo is very faint and see in these photo-micrographs. In Fig. 7d the single 210Po radiohalo is easily identified by its single outer ring about 39 µm (microns) in diameter. Note that its radiocenter is a hollow “bubble” where hydrothermal fluids deposited the 210Po atoms which then a-decayed to discolor the biotite and form the radiohalo. This feature is not so clearly seen in Fig. 7c, where the 210Po radiocenter is only about 100 µm from the nearly 238U radiocenter in the same biotite flake. The hydrothermal fluids thus did not have far to transport 222Rn and Po from the 238U radiocenter to form and supply the 210Po radiocenter within weeks so that the 238U and 210Po radiohalos formed concurrently. In Fig. 7e are three

“over-exposed” 210Po radiohalos. This is indicative of there having been a lot of 210Po atoms in the radiocenters that then decayed. The diffuseness of the radiation damage is due to the large sizes of the radiocenters, which appear to now be empty “holes” that may originally have been fluid-filled “bubbles.” There are also remnants of much larger fluid inclusions in the same biotite flake. And finally, in Fig. 7f are three more diffuse 210Po radiohalos, as well as 210Po radiation staining around an elongated radiocenter that appears to have been a fluid inclusion. The other radiation stains in the same biotite flake represent radiohalos whose radiocenters are not in this plane of observation on this cleavage plane in this biotite flake.The data in Table 1 indicate that all these granitic rock units contain more 210Po radiohalos than 238U radiohalos (except the Sentinel Granodiorite which has equal numbers). There is also a wide range in the radiohalo abundances, from the Tonalite of the Gateway with only one 210Po radiohalo in two samples, and the Granodiorite of Kuna Crest with only five 210Po radiohalos and three 238U radiohalos (0.05 radiohalos per slide), to the Cathedral Peak Granodiorite with 325 210Po radiohalos and six 238U radiohalos (3.31 radiohalos per slide). Thus the ratio of the number of 210Po radiohalos to the number of 238U radiohalos varies from 1:1 in the Sentinel Granodiorite and 1.7:1 in the Granodiorite of Kuna Crest to 54:1 in the Cathedral Peak Granodiorite. The only rock units that contain other halos apart from 210Po and 238U halos are the Granite of Lee Vining Canyon and the Granodiorite of Arch Rock which both contain some 218Po halos, and the Half Dome Granodiorite with a single 214 halo.

Intrusive Suite

Rock unit (Pluton)

Samples (slides)

Radiohalos Number of radiohalos per slide

Number of Po radiohalos per slide

Ratio210Po:238

U 210Po

214Po

218Po

238

U

232Th

Tuolumne

Granodiorite of Kuna Crest

3 (150) 5 0 0 3 0 0.05 0.03 1.7:1

Half Dome Granodiorite

2 (100) 55 1 0 30 0 0.82 0.53 1.8:1

Cathedral Peak Granodiorite

2 (100) 325 0 0 6 0 3.31 3.25 54:1

Johnson Granite Porphyry 1 (50) 157 0 0 6 0 3.26 3.14 26:1

Jack Main Canyon (Sonora Pass) (?)

Yosemite Creek Granodiorite

2 (100) 8 0 0 0 0 0.08 0.08 —

Sentinel Granodiorite

3 (150) 29 0 0 29 0 0.39 0.19 1:1

Washburn Lake (Buena Vista Crest) (?)

Granodiorite of Illilouette Creek

2 (100) 24 0 0 8 0 0.32 0.24 3:1

Yosemite Valley

El Capitan Granite

3 (150) 111 0 0 17 0 0.85 0.74 6.5:1

El Capitan Granite enclave 1 (50) 68 0 0 0 0 1.36 1.36 —

Taft Granite 1 (50) 58 0 0 6 0 1.28 1.16 9.7:1

Fine Gold

Tonalite of the Gateway

2 (100) 1 0 0 0 0 0.01 0.01 —

Granodiorite of Arch Rock

2 (100) 106 0 7 10 0 1.23 1.13 10.6:1

Scheelite Granite of Lee Vining Canyon 1 (50) 108 0 2 13 0 2.46 2.2 8.3:1

Discussion The results obtained for these Yosemite granites confirm the model for the formation of polonium radiohalos proposed by Snelling (2005a). Both 238U and 210Po radiohalos were found present together in the same biotite flakes in fourteen of the 25 samples studied. Because the thermal annealing temperature of radiohalos in biotite is 150ºC (Armitage and Back 1994; Laney and Laughlin 1981), the 238U and 210Po radiohalos in these biotite flakes had to have formed concurrently below that temperature. However, the short half-life of 210Po places a time constraint on the necessary conditions for the

formation of the biotite flakes within the crystallizing and cooling granites and then the radiohalos of only 6–10 days or several weeks at most. The almost complete absence of 214Po and 218Po radiohalos implies both an insufficient supply of hydrothermal fluids and a slow rate of hydrothermal fluid transport, which restricted the formation of those radiohalos due to their very short half-lifes. It also implies that 222Rn was likely absent in the hydrothermal fluids. Therefore, Po was most likely transported as 210Po in the fluids to the nucleation sites where the 210Po radiohalos formed. Fig. 8 is a schematic conceptual temperature versus time cooling curve diagram which visualizes the timescale constraints on granite magma crystallization and cooling, hydrothermal fluid transport, and the formation of polonium radiohalos (Snelling 2008a). Granite magmas when intruded are at temperatures of 650–750ºC, and the hydrothermal fluids are released at temperatures of 370–410ºC after most of the granite and its constituent minerals have crystallized. However, the accessory zircon grains with their contained 238U crystallize very early at higher temperatures, and may have even been already formed in the magma when it was intruded. Thus the 238U decay producing Po isotopes had already begun well before the granite had fully crystallized, before the hydrothermal fluids had begun flowing, and before the crystallized granite had cooled to 150ºC. Furthermore, by the time the temperature of the granite and the hydrothermal fluids had cooled to 150ºC, the heat energy driving the hydrothermal fluid convection would have begun to wane and the vigor of the hydrothermal flow would also have begun to diminish (fig. 8). The obvious conclusion has to be that if the processes of magma intrusion, crystallization, and cooling required 100,000–1 million years, then so much Po would have already decayed and thus been lost from the hydrothermal fluids by the time the granite and fluids had cooled to 150ºC that there simply would not have been enough Po isotopes left to generate the Po radiohalos (Snelling, 2008a).

Fig. 7. Photo-micrographs of representative radiohalos in Tuolumne Intrusive Suite granites. All the biotite grains are as

viewed in plane polarized light, and the scale bars are all 50 µm (microns) long.Both catastrophic granite formation (Snelling 2008a) and accelerated radioisotope decay (Vardiman, Snelling and Chaffin 2005) are relevant to the hydrothermal fluid transport model for Po radiohalo formation. However, halo formation itself provides constraints on the rates of both those processes (Snelling 2005a). If 238U in the zircon radiocenters supplied the concentrations of Po isotopes required to generate the Po radiohalos, the 238U and Po radiohalos must form over the same timescale of hours to days, as required by the Po isotopes’ short half-lifes. This requires 238U production of Po to be grossly accelerated. The 500 million–1 billion a-decays to generate each 238U radiohalo, equivalent to at least 100 million years’ worth of 238U decay at today’s decay rates, had to have taken place in hours to days to supply the required concentration of Po for producing an adjacent Po radiohalo. However, because accelerated 238U decay in the zircons would have been occurring as soon as the zircons crystallized in the magma at 650–750ºC, unless the granite magma fully crystallized and cooled to below 150ºC very rapidly, all the 238U in the zircons would have rapidly decayed away, as would have also the daughter Po isotopes, before the biotite flakes were cool enough for the 238U and Po radiohalos to form and survive without annealing. Furthermore, the hydrothermal fluid flows needed to transport the Po isotopes along the biotite cleavage planes from the zircons to the Po radiocenters are not long sustained, even in the conventional framework, but decrease rapidly due to cooling of the granite (Snelling 2008a). Thus Snelling (2005a) concluded from all these considerations that the granite intrusion, crystallization, and cooling processes occurred together over a timescale of only about 6–10 days.However, someone might inquire what requires the hydrothermal fluid flow interval to be so brief? Surely, because the zircon radiocenters and their 238U radiohalos are near to (typically within only 1 mm or so) the Po radiocenters in the same biotite flakes, could not the hydrothermal flow have indeed carried each Po atom from the 238U radiocenters to the Po radiocenters within minutes, but the interval of hydrothermal flow persist over many thousands of years during which the billion Po atoms needed for each Po radiohalo are transported that short distance? In this case the 238U decay and the generation of Po atoms could be stretched over that longer interval. However, as already noted above, by the time a granite body and its hydrothermal fluids cool to below 150ºC, most of the energy to drive the hydrothermal convection system and fluid flow has already dissipated (Snelling 2008a). The hydrothermal fluids are expelled from the crystallizing granite and start flowing at between 410 and 370ºC (fig. 8). So unless the granite cooled rapid from 400ºC to below 150ºC, most of the Po transported by the hydrothermal fluids would have been flushed out of the granite by the vigorous hydrothermal convective flows as they diminished. Simultaneously, much of the energy to drive these flows dissipates rapidly as the granite temperature drops. Thus, below 150ºC (when the Po radiohalos start forming) the hydrothermal fluids have slowed down to such an extent that they cannot sustain protracted flow. Moreover,

the capacity of the hydrothermal fluids to carry dissolved Po decreases dramatically as the temperature becomes low. Fig. 8. Schematic, conceptual, temperature versus time cooling curve

diagram to show the timescale for granite crystallization and cooling, hydrothermal fluid transport, and the formation of polonium radiohalos (after Snelling 2008a). Thus sufficient Po had to be transported quickly to the Po radiocenters to form the Po radiohalos while there was still enough energy at and below 150ºC to drive the hydrothermal fluid flow rapidly enough to get the Po isotopes to the deposition sites before they decayed. This is the time and temperature “window” depicted schematically in Fig. 8. It would, thus, simply be impossible for the Po radiohalos to form slowly over many thousands of years at today’s groundwater temperatures in cold granites. Hot hydrothermal fluids are needed to dissolve and carry the polonium atoms, and heat is needed to drive rapid hydrothermal convection to move Po transporting fluids fast enough to supply the Po radiocenters to generate the Po radiohalos. Furthermore, the required heat cannot be sustained for the 100 million years or more while sufficient 238U

decays at today’s rates to produce the 500 million–1 billion Po atoms needed for each Po radiohalo. In summary, for there to be sufficient Po to produce a radiohalo after the granite has cooled to 150ºC, the timescales of the decay process as well as the cooling both must be on same order as the lifetimes of the Po isotopes. Thus, the hydrothermal fluid flow had to be rapid, as the convection system was shortlived while the granite crystallized and cooled rapidly within 6–10 days,

and as it transported sufficient Po atoms to generate the Po radiohalos within hours to a few days.Formation of these granites, from emplacement to cooling, therefore had to have been on a timescale that previously has been considered impossible. Various studies have shown that emplacement of a melt is rapid via dikes and fractures assisted by the tectonics (Clemens and Mawer 1992; Coleman and Glazner 2004). Other studies have shown that cooling of the melt has been aided by hydrothermal fluids and groundwater flow (Brown 1987; Burnham 1997; Cathles 1977; Hardee 1982; Hayba and Ingebritsen 1997). Conventional thinking, that the formation of granite intrusions is a slow process over hundreds to thousands of years, is in need of drastic revision. The granites of Yosemite show that their formation had to be rapid in order for the radiohalos present in them to exist.The four rock units of the Tuolumne Intrusive Suite of the Sierra Nevada Batholith display a pattern of Po radiohalos in which their numbers increase inwards within the suite according to the time sequence in which these units were progressively intruded. The first granite pluton intruded, the Granodiorite of Kuna Crest, only contains a few 210Po radiohalos, while there are progressively more 210Po radiohalos in the Half Dome Granodiorite, intruded next, and the Cathedral Peak Granodiorite and the Johnson Granite Porphyry, intruded last (table 1). This matches the pattern of Po radiohalos Snelling and Armitage (2003) observed in the zoned La Posta Pluton in the Peninsular Ranges Batholith east of San Diego, where there was also sequential intrusion of the granitic phases now making up that zoned pluton. Fig. 9 shows the sequence of intrusion within the Tuolumne Intrusive Suite. The last phase of these multiple intrusions, the Johnson Granite Porphyry, was also probably related and connected to volcanism at the surface (Huber 1989; Titus, Clark, and Rikoff 2005) (fig. 10). The implication of the Po radiohalos numbers is that the greater the volume of hydrothermal fluids the more polonium would have been transported and the more Po radiohalos would have formed, as has been confirmed by Snelling (2005a, b, 2006, 2008b, c, d). First, in granites where hydrothermal ore deposits have formed in veins due to large, sustained hydrothermal fluid flows, there are huge numbers of Po radiohalos, for example, in the Land’s End Granite, Cornwall, England (Snelling 2005a), and in the Mole Granite, New South Wales, Australia (Snelling 2009). Second, where hydrothermal fluids were produced by mineral reactions, at a specific pressure-temperature boundary during regional metamorphism of sandstone, four to five times more Po radiohalos were generated, precisely at that specific metamorphic boundary (Snelling 2005b, 2008b). Third, where hydrothermal fluids flowingin narrow shear zones had rapidly metamorphosed the wall rocks, Po radiohalos were present in the resultant metamorphic rock, a type of metamorphic rock that otherwise does not host Po radiohalos (Snelling 2006). Fourth, where the hydrothermal fluids generated in the central granite at the highest grade within a regional metamorphic complex flowed and decreased outwards into that complex, the Po radiohalos numbers also progressively decreased outwards in the complex (Snelling 2008c). Fifth, in a granite pluton which has an atypically wide contact metamorphic and metasomatic aureole around it due to the high volume of hydrothermal fluids it released during its crystallization and cooling, Po radiohalos numbers are higher than in other granite plutons (Snelling 2008d).Thus, the significance of the increasing Po radiohalos numbers progressively inwards within this nested suite of plutons in the Tuolumne Intrusive Suite (table 1) according to the order in which they were intruded is the implication that there were progressively more hydrothermal fluids within each successive pluton. It is particularly evident from the much higher Po radiohalos numbers in the last two intrusive phases, the Cathedral Peak Granodiorite and the Johnson Granite Porphyry, that they sustained greater hydrothermal fluid volumes and flows. This increase in the hydrothermal fluids in the later stages of any intrusive sequence is due to the water released as the earlier intrusive phases crystallized and cooled building up in the later residual intrusive phases; particularly if the hydrothermal fluids are not readily escaping out into the surrounding host rocks. Whereas many other granite plutons intruded into sedimentary rocks containing connate and ground waters that assisted rapid granite cooling by convection cells being established outwards from the plutons (Snelling and Woodmorappe 1998), these Tuolumne plutons intruded into existing granite plutons, and then successively one another (fig. 9). Consequently, since granites have poor connective porosities and therefore poor permeabilities, the successively generated hydrothermal fluids would have been essentially “bottled up” in the later intrusive phases. Another “tell-tale” sign of the high volume of hydrothermal fluids that was in the Cathedral Peak Granodiorite is the large K-feldspar megacrysts which dominate its porphyritic texture. Magmatic hydrothermal fluids are known to have played a major role in their formation (Cox et al. 1996; Lee and Parsons 1997; Lee, Waldron and Parsons 1995). It was this continued build-up in the confined volume of hydrothermal fluids that also consequently explains why the last phase in this intrusive suite, the Johnson Granite Porphyry, was likely connected to explosive volcanism to the land surface above these cooling plutons (fig. 10). That large volumes of hydrothermal fluids were increasingly being confined to the inwards migrating hotter crystallizing core of the Cathedral Peak Granodiorite into which the Johnson Granite Porphyry intruded is evident from the observed inward decrease in the size and abundance of the K-feldspar megacrysts in the Cathedral Peak Granodiorite (Bateman and Chappell 1979). Indeed, the explosive volcanism would have released the confining pressure on the increasing volume of bottled-up hydrothermal fluids, the Johnson Granite Porphyry cooling from the residual pulse of magma that supplied the explosive volcanism (Huber 1989; Titus et al.

2005). .Fig. 9. A map view of the sequential emplacement of the

Tuolomne Intrusive Suite to form a set of nested plutons: nodiorite of Kune Crest, (b) (c) Half Dome Granodiorite, and (d) Cathedral Peak Granodiorite and Johnson Granite Porphyry (after Huber 1989). Since the Tuolumne Intrusive Suite is a nested set of plutons, there were severe constraints, due to the 150ºC thermal annealing temperature of the radiohalos, on the lapse of time between the intrusion of each phase of the suite. Each phase had to have been rapidly emplaced, crystallized and cooled sufficiently before the next phases were sequentially intruded, so that the entire suite of nested plutons was in place before the radiohalos began forming below 150ºC. Otherwise, the heat given off by each successively emplaced phase, which intruded its predecessors, would have annealed all radiohalos in them. That each phase had crystallized and cooled before the next phase was intruded has been confirmed by a recent study of the internal contacts within the suite (Zak and Paterson 2005). These are highly variable from relatively sharp, with no contact metamorphic effects from any major temperature differences between the earlier crystallized pluton and the subsequent intruding pluton, to gradational, the latter indicative of large scale mixing where the earlier (host) and subsequent

(intruding) magmas must have both been crystallizing together. Coleman, Gray, and Glazner (2004) concluded that the successive development of the suite was a relatively rapidly emplaced series of small intrusions as possible sheets or dikes to incrementally assemble each pluton (or phase). However, so that annealing of the radiohalos would not occur above 150ºC, all the phases of the entire suite had to have intruded so rapidly that the entire suite cooled below 150ºC more or less at the same time. Furthermore, because of the short half-life of 210Po and the need for the hydrothermal fluids within the cooling granite masses to rapidly transport sufficient 210Po to supply the radiocenters to form the 210Po radiohalos before the 210Po decayed, the successive emplacement and cooling of the entire suite of nested plutons thus must have only taken several weeks.This survival of the Po radiohalos as a result of the rapid sequential emplacement of these nested plutons also implies that there could not have been a “heat problem” (Snelling 2005a). Whatever mechanisms dissipated the heat from these crystallizing and cooling magmas (Snelling 2008a; Snelling and Woodmorappe 1998) did so rapidly and efficiently without annealing the Po radiohalos in the surrounding earlier intruded phases of this nested suite of plutons. Thus this entire intrusive event, consisting of successive pulses of granite magma emplacement and cooling, must only have taken several weeks, culminating with a violent volcanic eruption. That would have finally dissipated the remaining heat by rapidly moving it to the earth’s atmosphere in steam and to the earth’s surface in the rhyolitic tuffs and lavas released by the eruption.

Fig. 10. Final stages in the development of the nested plutons of

the Tuolumne Intrusive Suite (after Huber 1989). The Johnson Granite Porphyry represents the final phase of the suite that intruded the Cathedral Peak Granodiorite and erupted through a volcanic caldera at the earth’s surface above, spewing volcanic ash and debris across it. The volcanic deposit and much of the underlying rock were subsequently removed by erosion to create today’s land surface.Finally, the formation of the hundreds of granitic plutons of the Sierra Nevada batholith, some of which outcrop on a grand and massive scale in the Yosemite area, can thus be adequately explained within the framework for earth history. The regional geologic context suggests that late in the Flood year, after deposition of thick sequences of fossiliferous sedimentary strata, a subduction zone developed just to the west at the western edge of the North American plate (Huber 1989). Because plate movements were then catastrophic during the

Flood year (Austin et al. 1994), as the cool Pacific plate was catastrophically subducted under the overriding North American plate the western edge region of the latter was deformed, resulting in buckling of its sedimentary strata and metamorphism at depth (fig. 11). The Pacific plate was also progressively heated as it was subducted, so that its upper side began to partially melt and thus produce large volumes of basalt magma. Rising into the lower continental crust of the deformed western edge of the North American plate, the heat from these basalt magmas in turn caused voluminous partial melting of this lower continental crust, generating buoyant granite magmas. These rapidly ascended via dikes into the upper crust, where they were emplaced rapidly and progressively as the hundreds of coalescing granite plutons that now form the Sierra Nevada batholith. The presence of polonium radiohalos in many of the Yosemite area granite plutons is confirmation of their rapid crystallization and cooling late in the closing phases of the Flood year. Conventional radioisotope dating, which assigns ages of 80–120 million years to these granites (Bateman 1992), is grossly in error because of not taking into account the acceleration of the nuclear decay (Vardiman et al 2005). Subsequent rapid erosion at the close of the Flood, as the waters drained rapidly off the continents, followed by further erosion early in the post-Flood era and during the post-Flood Ice Age, have exposed and shaped the outcropping of these granite plutons in the Yosemite area as seen today. Conclusion

Conventional thinking has been that granites in the continental crust have formed slowly over 105 to 106 years. In the last two decades though, evidence has accumulated to convince many geologists that granite pluton emplacement was a relatively rapid process over timescales of only years to tens of years. Dilation pressures in the deep crustal sources forced magma through fractures as dikes to feed rapidly shallow crustal magma chambers. Rapid cooling was aided by

hydrothermal convection. Fig. 11. Subduction of an oceanic plate (Pacific plate) during convergence with a

continental plate (North American plate). Magma, formed by partial melting of the overriding continental plate, rises into the upper continental plate to form granite plutons and volcanoes along a mountain chain (after Huber 1989).The evidence left by radiohalos found in Yosemite granites, however, further challenges the timescale of even this recent school of thought. The short half-lifes of polonium isotopes place severe time constraints on the formation and cooling of the biotite flakes containing the radiohalos produced by these polonium isotopes. The

hydrothermal fluids which were critical to the rapid cooling process also transported the 222Rn and polonium isotopes from U decay in zircon inclusions to generate the nearby polonium radiohalos within hours to days, once the granite’s temperature has fallen below 150ºC, the radiohalo annealing temperature. For the supply of 222Rn and Po isotopes to be maintained during the whole pluton formation process, so as to still generate the Po radiohalos, the U decay rate had to have been grossly accelerated, and the Yosemite granite plutons must have formed and cooled below 150ºC within six to ten days. This timescale, of course, is consistent with granite pluton formation within the young earth model. Furthermore, the acceleration of radioisotope decay means that absolute dates for rocks calculated on the assumption of decay having been constant are grossly in error.The nested plutons of the Tuolumne Intrusive Suite provide a test of the hydrothermal fluid transport model for the generation of Po radiohalos. The volume of hydrothermal fluids increased in each pluton as it was successively emplaced, so that the final magma at the center of the suite contained enough volatiles to feed a violent volcanic eruption at the earth’s surface. The model predicted the progressively greater volume of hydrothermal fluids would have generated more Po radiohalos in each successive pluton, and more Po radiohalos were indeed found. Acknowledgments

We would like to thank Dr. Larry Vardiman for his original suggestion to do this radiohalo study in Yosemite National Park, for help in collecting the rock samples, and for support of this research generally. Thanks to Mark Armitage for his help with some of the photomicrographs, and for processing some of the samples to obtain the radiohalos counts. Thanks to the Institute for Creation Research (ICR) for funding much of this project and for providing the equipment and facilities to do some of the research. Thanks to the National Parks Service for permission to collect the samples. And thanks also to

Dallel’s parents and friends for their support and encouragement in her part of this study, which resulted in an M.S. dissertation in the ICR Graduate School.

Testing the Hydrothermal Fluid Transport Model for Polonium Radiohalo Formation: The Thunderhead Sandstone, Great Smoky Mountains, Tennessee–North Carolina

by Dr. Andrew A. Snelling on March 26, 2008 Abstract

The meta-arkoses of the Thunderhead Sandstone in the Great Smoky Mountains of Tennessee and North Carolina contain both detrital zircon grains and metamorphic biotite flakes in all zones of regional metamorphism. The original sandstones after deposition would have contained water. Furthermore, the reaction responsible for the mineralogical changes at the staurolite isograd would have produced large volumes of water. Thus it was predicted that during the regional metamorphism these waters as hydrothermal fluids should have transported Po from the zircon grains to the biotite flakes to generate Po radiohalos in the latter. Also, the greater volume of hydrothermal fluids at the staurolite isograd should have generated more Po radiohalos there. Both predictions were verified, with four–five times more Po radiohalos in the meta-arkoses straddling the staurolite isograd. These results also verify the hydrothermal fluid transport model for Po radiohalo formation. It was concluded that the regional metamorphism, the hydrothermal fluid flows, the cooling of the regional metamorphic complex, and the formation of the Po radiohalos all had to have occurred within a few weeks. This is feasible in the context of catastrophic plate tectonics and grossly accelerated 238U decay during the Flood. Shop Now

Keywords: Po radiohalos, 238U decay, hydrothermal fluid transport

model, sandstones, regional metamorphism, meta-arkoses, detrital zircon grains, metamorphic biotite flakes, staurotile isograd, mineral reaction Introduction

Radiohalos research was a major focus of the RATE (Radioisotopes and the Age of The Earth) project (Snelling 2000). As a result of this research it was concluded that the 238U and Po radiohalos frequently found together in biotite flakes in granitic rocks had to have formed simultaneously (Snelling 2005). Because of the very short half-lives of the parent Po isotopes, this implies that hundreds of million of years worth of 238U decay (at today’s rates) had to have instead occurred in only a matter of a few days. There needs to have been that much decay of 238U to produce both the visible physical damage (the 238U radiohalos) and the 500 million–1 billion polonium atoms required to generate the

polonium radiohalos. However, that much polonium would then have decayed within a few days. A hydrothermal fluid transport model was thus proposed which explains how the polonium was separated from its parent 238U, transported very short distances, and then concentrated in radiocenters close by to form the polonium radiohalos (Snelling and Armitage 2003; Snelling, Baumgardner, and Vardiman 2003; Snelling 2005).Another outcome of this research was the discovery of plentiful polonium radiohalos in metamorphic rocks (Snelling 2005), an occurrence not previously documented. However, such a finding was predicted, because hydrothermal fluids are generated in water-saturated sedimentary rocks as they become deeply buried, helping to transform them into regional metamorphic complexes (Stanton 1982, 1989; Snelling 1994). Thus it was argued that the same hydrothermal fluid transport model could likewise explain the formation of polonium radiohalos in those regional metamorphic rocks where an adequate supply of 238U decay products was available (Snelling 2005).In continued research, a test of this polonium radiohalo formation model in metamorphic rocks was proposed, and reasoned as follows. Sandstones often contain some zircon grains, derived from erosion of, for example, granitic rocks and deposited in water-transported sandy sediments. Chemical weathering of such source rocks, plus abrasion of grains during water transport, destroys biotite grains, so they tend to be absent in sandstones. However, after metamorphism of sandstones, the resultant schists and gneisses usually contain biotite grains. Thus it would seem that the biotite grains formed via mineral reactions during the metamorphism. Such mineral reactions have been studied in laboratory experiments, and in them water is often a by-product (Spear 1993). At the temperatures of these metamorphic processes, such water would become hydrothermal fluids, capable of transporting any 238U decay products from nearby zircon grains and depositing polonium in biotite flakes to form polonium radiohalos. If this is correct, metasandstones should contain polonium radiohalos, and metasandstones could be studied to test the claim. The Thunderhead Sandstone, Tennessee–North Carolina

The thick Thunderhead Sandstone forms a significant part of the 4,500–7,500 meter (15,000–25,000 feet) thick Great Smoky Group of the Ocoee Series in the Great Smoky Mountains along the Tennessee–North Carolina border in the southern part of the Blue Ridge province of the Appalachian Highlands (King 1964; Hadley and Goldsmith 1963; King et al. 1958). Its Upper Precambrian designation suggests it may have been deposited early in the Flood. The most common rock in the formation is relatively homogeneous medium- to coarse-grained feldspathic sandstone (arkose), with interbeds of argillaceous sandstone, and dark-gray argillite. The Ocoee Series was subsequently thrust northwest along the

Greenbrier Fault early in the Paleozoic (fig. 1). The

Thunderhead Sandstone comprises about half of the thrust sheet. Fig. 1. A geologic cross-section of the Great Smoky

Mountains from Pigeon Forge, Tennesse, across Mt. Le

Conte to the Oconaluftee Ranger Station near Cherokee, North Carolina (after Moore 1988). After thrusting, the lithologic units of the entire Ocoee Series and the underlying Precambrian crystalline basement complex were regionally metamorphosed coincident with the orogenic (mountain-building) deformations during formation of the Appalachian Highlands, beginning in the Devonian (early-middle Flood). In the northwest the rocks were metamorphosed to the greenschist facies, but increasing temperatures and pressures to the southeast produced almandine amphibolite facies rocks. This regional metamorphism thus produced in the Thunderhead Sandstone a series of chemically and mineralogically distinct zones of schists and gneisses (fig. 2) (Allen and Ragland 1972). These zones are named according to the presence of the highest pressure/temperature metamorphic minerals in the rock. Shaly interbeds in the Thunderhead Formation are completely recrystallized throughout the sequence, so the demarcation of the isograds is based on the minerals in the shales. As the intensity of the metamorphism increases laterally from northwest to southeast—the shaly interbeds successively contain biotite, garnet, staurolite, and kyanite in the biotite, garnet, staurolite and kyanite zones, respectively. The boundaries between adjacent zones are called isograds. Fig. 2. Geologic and metamorphic map of the central Great Smoky Mountains, showing the Thunderhead Sandstone,the

isograds between regional metamorphic zones, and the location of the meta-arkose samples collected in this study (after Allen and Ragland 1972). The arkosic sandstone in the Thunderhead Formation is slightly different. Figure 3 depicts the mineralogic variations within the metamorphosed arkoses of the Thunderhead Sandstone along a traverse from northwest (biotite zone) to southeast (kyanite zone). With the exception of garnet in the garnet and staurolite zones, the same mineral assemblage of quartz, K-feldspar (microcline), plagioclase, biotite, and muscovite is found throughout the sequence of meta-arkoses. Relict quartz and K-feldspar in the metamorphosed arkoses of the Thunderhead Sandstone exhibit little recrystallization through the biotite and garnet zones until the staurolite zone (Allen and Ragland 1972). In the garnet zone the presence of metamorphic garnet in the meta-arkose, which should not be stable according to the whole rock chemistry, indicates that equilibrium was obtained only in the interstitial portions of the rock and mineral system. Regional Metamorphism—Hydrothermal Fluids and Po Radiohalos

Currently, in every regional metamorphic zone the meta-arkoses of the Thunderhead Formation contain both zircons and biotite flakes. In the original sedimentation process biotite flakes were probably destroyed, leaving the original Thunderhead sandstone without any biotite. However, Allen and Ragland (1972) specifically noted that the accessory zircon grains they observed in the Thunderhead were of detrital origin. Thus the original Thunderhead sandstones probably contained zircons but no biotite. Because the zircon grains would likely have still contained minor amounts of uranium, they could thus have been a source of 238U decay products, including polonium. During regional metamorphism biotite and hydrothermal fluids were generated—some from pre-metamorphism pore waters and some from metamorphic reactions. Therefore, according to the hydrothermal fluid transport model for polonium radiohalo formation, those hydrothermal fluids should have transported the polonium diffusing out of zircon grains into adjacent biotite flakes, where

it should have concentrated in radiocenters and generated polonium radiohalos. Fig. 3. Mineralogic variations within the Thunderhead Sandstone

(after Allen and Ragland 1972). The sample site numbers are those of Allen and Ragland (1972), as are the mineral percentages they determined. Allen and Ragland (1972) found from analyses of the bulk rock geochemistry that metal/Al ratios in the Thunderhead meta-arkoses remain constant throughout the biotite and garnet zones. The preservation of relict grains in the biotite and garnet zones was attributed to lack of complete recrystallization during the regional metamorphism due to a lack of a significant aqueous phase. The high porosities and permeabilities inherent in the original sandstones would have resulted in most of their pore waters being driven off by the heat and load pressure during the initial stages of metamorphism. Structural water and some absorbed pore water in the clays of the sandstone matrix probably provided the water necessary for crystallization of the micas in the biotite and garnet zones. Thus most of the water was held in crystal structures within the meta-arkoses and was not readily available to act as a transporting medium. According to the hydrothermal fluid transport model for polonium radiohalo formation, relatively little radiohalo generation would be expected—at least in the meta-arkoses of the Thunderhead Formation.

Near the staurolite isograd, the boundary between the garnet and staurolite zones, however, numerous chemical changes are apparent in the bulk rocks and in the micas (Allen and Ragland 1972). These changes and the disappearance of relict minerals suggest a significant aqueous phase was generated at the staurolite isograd. Mineral phases such as staurolite were formed that contain notably less structural water, while chlorite disappears entirely in the pelitic beds within the meta-arkoses, muscovite decreases sharply, and biotite becomes more abundant. This suggests the following reaction predominated at the staurolite isograd: 54 muscovite + 31 chlorite →54 biotite + 24 staurolite + 152 quartz + 224 water This reaction has been confirmed experimentally (Hoschek 1967, 1969). In the pelitic beds it would have released some 63 percent of the structural water from the reacting minerals. The generation of large quantities of water by this reaction within the pelitic interbeds at the prevailing high temperatures determined experimentally would have resulted in relatively large volumes of hydrothermal fluids migrating down the PH20 free-energy gradient into the adjacent meta-arkoses. Within the meta-arkoses these hydrothermal fluids would have provided an aqueous transporting medium that resulted in a rapid catalyzing action. This would have caused the recrystallization of all relict grains and a rapid approach to equilibrium. At the entry of this aqueous phase, chemical equilibrium was set up over the macrosystem of large volumes of meta-arkose, rather than just in the interstitial microsystems encountered in the lower metamorphic grade zones.These conditions in the Thunderhead meta-arkoses at the staurolite isograd should have been ideal for the generation of Po radiohalos in them, assuming that Po radiohalo formation does indeed occur as described by the hydrothermal fluid transport model (Snelling and Armitage 2003; Snelling, Baumgardner, and Vardiman 2003; Snelling 2005). Detrital zircon grains to provide 238U decay products, and metamorphic biotite flakes to host Po concentrations in radiocenters, were present in the meta-

arkoses, and around the staurolite isograd the copious quantities of hydrothermal fluids flowed through the meta-arkoses as a result of the mineral reaction in the pelitic interbeds. Therefore, it was predicted that many more Po radiohalos should be found in the Thunderhead Sandstone in the meta-arkoses surrounding the staurolite isograd than elsewhere in the meta-arkoses throughout these regional metamorphic zones. Field and Laboratory Work

A field test of this prediction was thus proposed. Nine samples of the meta-arkoses of the Thunderhead Sandstone were collected from road-cut outcrops along U.S. Highway 441 between Cherokee, North Carolina, and Gatlinburg, Tennessee (figs. 2 and 4). This effectively formed a traverse through the kyanite, staurolite, garnet, and biotite zones of the regional metamorphism as already described (Allen and Ragland 1972). A basement gneiss sample was also collected.

Fig. 4. Outcrops of the meta-arkoses of the Thunderhead Sandstone, where the samples for this study were collected,

mainly along U.S. Highway 441 between Cherokee NC and Gatlinburg TN. Their locations are plotted on Fig. 2. (a) Sample site RSM-2, kyanite zone (b) Sample site RSM-3, staurolite zone (c) Sample site RSM-4 & 5, staurolite zone (note the shaly interbeds to the bottom right) (d) Sample site RSM-6 & 7, garnet zone (e) Sample site RSM-8, garnet zone (f) Sample site RSM-10, biotite zone A standard petrographic thin section was obtained for each meta-arkose sample. In the laboratory, portions of each sample were crushed to liberate the constituent mineral grains. For each sample, biotite flakes were then hand-picked using tweezers and placed on the adhesive surface of a piece of clear Scotch tape. Once numerous biotite flakes had been mounted on the adhesive surface of this tape, a fresh piece of clear Scotch tape was placed over them and firmly pressed along its length so as to ensure the two pieces of tape were stuck together with the biotite flakes firmly wedged between them. The upper piece of clear Scotch tape was then peeled back in order to pull apart the biotite flakes. This upper piece of clear Scotch tape with thin biotite sheets adhering to it was then placed over a standard glass microscope slide. This procedure was repeated with another piece of clear Scotch tape placed over the original Scotch tape with the biotite flakes adhering to it. These adhering biotite flakes were progressively pulled apart and transferred to microscope slides. As necessary, further hand-picked biotite flakes were added to replace those fully pulled apart. In this way 50 microscope slides were prepared for each meta-arkose sample, each slide with many (at least 20–30) thin biotite flakes mounted on it. This is similar to the method pioneered by Gentry (Gentry, pers. comm.). The basement gneiss sample was treated in the same way. Fifty microscope slides for each sample were prepared to ensure good representative sampling statistics. Thus there was a minimum of 1,000 biotite flakes mounted on microscope slides for each sample.

Fig. 5. Representative photo-micrographs of the meta-arkose samples of the

Thunderhead Sandstone used in this study collected from outcrops of each regional metamorphic zone (fig. 4), as plotted on Fig. 2. All photomicrographs are at the same scale (20× or 1 mm = 40 μ) and the meta-arkoses are as viewed under crossed polars. (a) Sample RSM-2 (kyanite zone): quartz, biotite, muscovite, zircon

(b) Sample RSM-3 (staurolite zone): quartz, plagioclase, biotite, muscovite, garnet (c) Sample RSM-4 (staurolite zone): quartz, biotite, garnet, muscovite, staurolite (d) Sample RSM-5 (staurolite zone): quartz, muscovite, biotite (e) Sample RSM-6 (garnet zone): quartz, plagioclase, muscovite, biotite, zircon (f) Sample RSM-7 (garnet zone): quartz, biotite, garnet, muscovite (g) Sample RSM-8 (garnet zone): quartz, muscovite, biotite (h) Sample RSM-10 (biotite zone): quartz, plagioclase, muscovite, biotite Each slide for each sample was then carefully examined under a petrological microscope in plane polarized light, and all radiohalos present were identified, noting any relationships or unusual features. The numbers of each type of radiohalo in each slide were counted by progressively moving the slide backward and forward across the field of view, and the numbers recorded for each slide were then tallied and tabulated for each sample. Because of the progressive peeling apart of many of the same biotite flakes during the preparation of the microscope slides, it was possible that some of the radiohalos appeared on more than one microscope slide. Only radiohalos whose radiocenters were clearly visible were thus counted to ensure each radiohalo was only counted once. Results

Representative photo-micrographs of meta-arkose samples from each regional metamorphic zone are shown in Fig. 5. All results are listed in Table 1. Nine of the samples (eight meta-arkoses and one basement gneiss) contained only 210Po radiohalos, while one meta-arkose sample also contained 214Po radiohalos. Some representative examples of the radiohalos in the samples can be seen in Fig. 6. Table 1 lists both the total number of 210Po and 214Po radiohalos found in each sample, and the average numbers of Po radiohalos per slide in each sample. The total number of Po radiohalos found in each sample was then plotted against each sample’s relative position along the traverse in Fig. 2 through the metamorphic zones, which is displayed in Fig. 7.

As can be readily seen in Table 1 and Fig. 7, whereas seven of the meta-arkose samples averaged a total of around 30 Po radiohalos each, the two samples straddling the staurolite isograd contained 177 and 147 Po radiohalos, respectively. Discussion

The results of this test of the hydrothermal fluid transport model for Po radiohalo formation were astounding, being exactly as predicted. The Po radiohalos were four–five times more abundant in the two meta-arkose samples straddling the staurolite isograd than in the immediately adjoining meta-arkose samples in the garnet and staurolite zones (table 1 and fig. 7). The Po radiohalo numbers were even less in the other meta-arkose samples, including the one sample from the high-grade kyanite zone.

Table 1. Data table of radiohalos numbers counted in samples of the meta-arkoses of the Thunderhead Sandstone and

the basement gneiss.

Radiohalos

Sample Number of Slides

210Po 214Po 218Po 238U 232Th Number of Po Radiohalos per Slide

Metamorphic Zone

RSM-1 50 4 0 0 0 0 0.08 Basement Gneiss

RSM-2 50 34 0 0 0 0 0.68 Kyanite

RSM-3 50 24 0 0 0 0 0.48 Staurolite

RSM-4 50 26 19 0 0 0 0.90 Staurolite

RSM-5 50 147 0 0 0 0 2.94 Staurolite

RSM-6 50 177 0 0 0 0 3.54 Garnet

RSM-7 50 41 0 0 0 0 0.82 Garnet

RSM-8 50 35 0 0 0 0 0.70 Garnet

RSM-9 50 6 0 0 0 0 0.12 Garnet

RSM-10 50 28 0 0 0 0 0.56 Biotite

The numbers of Po radiohalos do not correlate with metamorphic grade. There were only 34 Po radiohalos in the kyanite zone (high grade) meta-arkose sample compared with only 28 Po radiohalos in the biotite zone (low grade) meta-arkose sample. Yet there were U-bearing zircon grains and biotite flakes present in all samples of the Thunderhead Sandstone along the traverse from low grade through to high grade regional metamorphism.Neither the Po which generated the Po radiohalos nor the biotite flakes which host the Po radiohalos were primordial. Unlike the zircon grains, the biotite flakes were not present in the arkoses when they were deposited but were produced by mineral transformations and reactions during the subsequent regional metamorphism. This means that the Po which generated the Po radiohalos in the biotite flakes had to be transported from in situ nearby sources into the biotite flakes after they had formed. As has been argued by Snelling and Armitage (2003) and Snelling (2005), the only in situ nearby sources of Po are the decaying 238U atoms in the zircon grains in the originally deposited arkoses. Thus it is argued that the required Po had to be transported from the zircon grains into the biotite flakes after they had formed, and hydrothermal fluids (hot waters) seem to be the logical

candidate (Snelling and Armitage 2003; Snelling 2005).

Fig. 6. Some representative examples of the210Po radiohalos found in biotite grains separated from the meta-arkoses of

the staurolite and garnet zones in the Thunderhead Sandstone in this study. All photo-micrographs are at the same scale (40× or 1 mm = 20 μm) and the biotite grains are as viewed in plane polarized light. (a) & (b) RSM-4 (c), (d) & (e) RSM-5 (f), (g) & (h) RSM-6 When arkoses (and sandstones) are deposited by and from moving water, some of that water is often trapped between the mineral grains making up the sandy sediments. The cement that binds the mineral grains together to transform the sand into sandstone and arkose usually is precipitated from that trapped water, but also from meteoric water that percolates down into the sediments. Once lithified, sandstone and arkoses still often contain much ground water. When such water-saturated sedimentary rocks subsequently become deeply buried and are subjected to tectonic forces, the heat generated thereby turns the contained waters into hydrothermal fluids as the sedimentary rocks undergo regional metamorphism. Stanton (1982, 1989) and Snelling (1994) have argued that such hydrothermal fluids are primary catalysts in helping to transform sedimentary rocks into regional metamorphic complexes.It was these hydrothermal fluids generated during regional metamorphism that were available to transport Po from 238U decay in detrital zircon grains into metamorphic biotite flakes to form Po radiohalos (Snelling and Armitage 2003; Snelling 2005). It was thus predicted, based on the hydrothermal fluid transport model for Po radiohalo formation, that Po radiohalos would be found in regionally metamorphosed sedimentary rocks. Consequently, because a search for Po radiohalos in metamorphic rocks was undertaken, Po radiohalos have been found in metamorphic rocks (Snelling 2005, 2006, 2008b).The results of this study also confirm that the hydrothermal fluid transport model for Po radiohalo formation applies to regional metamorphic rocks. The 6–41 Po radiohalos per sample in each of the meta-arkose examples, except for the two straddling the staurolite isograd (table 1 and fig. 7), would appear to have been generated from Po transported by the hydrothermal

fluids produced from the water originally in the sandstones during their regional metamorphism. However, where during the regional metamorphism the mineral reaction in the pelitic interbeds at the staurolite isograd produced a lot of extra hot water, the extra flow of hydrothermal fluids in the adjacent meta-arkoses generated four–five times more Po radiohalos, 144 and 177 in two relevant meta-arkose samples (table 1 and fig. 7).This successful verification of the hydrothermal fluid transport model for Po radiohalo formation adds to the supporting evidence found by Snelling (2006). Where metamorphism along shear zones had been rapid, even in conventional terms, due to tectonic “pumping” of hydrothermal fluids, Po radiohalos had been generated in biotite flakes in the resultant rocks. In these examples, mainly 210Po radiohalos were generated in the metamorphic biotite flakes. This has timescale implications for these metamorphic processes and the hydrothermal fluid flows. 218Po and214Po have half-lives of 3.1 minutes and 164 microseconds respectively, whereas 210Po’s half-life is 138 days. Thus, even if 218Po from 238U decay diffused out of the detrital zircon grains, by the time the hydrothermal fluids had transported the Po into the biotite flakes, where it was concentrated in radiocenters by Po-bonding atoms such as Cl or S at lattice defects, the 218Po had decayed through 214Po to 210Po, so only 210Po radiohalos would be generated.This implies that the Po transport, from within the zircon grains the >1 mm (approximately 2–10 mm) distances across into the biotite flakes and along the cleavage planes in them to the Po radiocenters, probably took as long as a few days to even weeks. Note that in contrast, many granites contain 218Po and/or 214Po radiohalos, as well as 210Po radiohalos, due to the much shorter transport distances (<1 mm) because the source zircon grains are within the biotite flakes where the Po radiohalos are generated.

Fig. 7. Po radiohalos for the meta-arkose samples along the traverse in

this study (fig. 2) through the regional metamorphic zones across the Great Smoky Mountains, Tennessee–North Carolina.On the other hand, the Po radiohalos in both these metamorphic rocks and granites would only have formed below 150°C, the annealing temperature of radiohalos in biotite. As in crystallizing granites, at higher temperatures during regional metamorphism, Po transport would have commenced as soon as the hydrothermal fluids were produced. Even at temperatures well above 400°C, the temperatures at which the mineral reaction occurred at the staurolite isograd, the hydrothermal fluids would have flowed vigorously (but under pressure) transporting available Po. However, because the Po radiohalos could not be generated and visually registered in the biotite flakes until the temperature in the metamorphosed rocks fell below 150°C, the cooling of the whole regional metamorphic complex needs to have been relatively rapid, within days to a few weeks, to ensure there was still

sufficient 210Po to produce the 210Po radiohalos before all the 210Po decayed.It may be countered that because 238U today decays slowly, there would have been a continuous supply of Po over millions of years. So the hydrothermal fluid transport of Po and the generation of the Po radiohalos could have taken millions of years of incremental additions of Po to the radiocenters. However, the concurrent formation of 238U and Po radiohalos in the same biotite flakes in many granites (Snelling and Armitage 2003; Snelling 2005, 2008a), and other evidence (Vardiman, Snelling, and Chaffin 2005), is consistent with 238U decay having been grossly accelerated during an event, or events, in earth history, particularly the Flood. This is when the deposition of the Thunderhead Sandstone is envisaged, followed by the regional metamorphism. So an abundant supply of Po during this accelerated 238U decay in the detrital zircons was only very short-lived. Thus, unless the Po was transported rapidly from the detrital zircons to the radiocenters in the metamorphic biotite flakes, the Po would have decayed before the Po radiohalos could have formed.Furthermore, both the hydrothermal fluid flows and the regional metamorphism had to also have been rapid and short-lived. Unless the hydrothermal fluid flows below 150°C were rapid, the transported Po would have decayed before reaching the radiocenters. However, the hydrothermal fluid flows are driven by the heat energy associated with the regional metamorphism. As with cooling granite bodies (Snelling 2008a), much of the heat would have been dissipated by the time the temperatures in the regionally metamorphosed rock had fallen below 150°C, so the hydrothermal fluid flows would have begun to diminish. Thus, the regional metamorphism had to be a rapid event to drive the rapid hydrothermal fluid flows.In the context of the year-long Flood event, catastrophic plate tectonics would have driven the rapid, catastrophic earth movements that produced the tectonic settings, where rapid regional metamorphism of thick sedimentary rock sequences would have taken place (Austin et al. 1994). Coupled with catastrophic plate tectonics, concurrent catastrophic accelerated radioisotope decay (Vardiman, Snelling, and Chaffin 2005) would have provided a rapid burst of heat in those developing regional metamorphic complexes to generate the rapid hydrothermal fluid flows and the metamorphic mineral reactions. Thus the presence of the Po radiohalos in the regionally metamorphosed Thunderhead Sandstone are testimony to the catastrophic tectonic and geologic processes that formed the Great Smoky Mountains as part of the Appalachian mountain-building episode early in the Flood, and validate the hydrothermal fluid transport model for their formation. Conclusions

Based on the mineralogical changes produced by regional metamorphism in the arkoses of the Thunderhead Sandstone, Great Smoky Mountains, Tennessee–Carolina, a test of the hydrothermal fluid transport model for Po radiohalo formation was proposed. These meta-arkoses contain both detrital zircon grains (a potential source of Po from 238U decay) and metamorphic biotite flakes (a potential host for Po radiohalos). When originally deposited the arkoses would have retained pore and meteoric waters, which during regional metamorphism would have become hydrothermal fluids. Furthermore, the reaction responsible for the mineralogical changes at the staurolite isograd (the boundary between the garnet and staurolite metamorphic zones) would have produced large volumes of water as hydrothermal fluids. It was thus predicted that if the hydrothermal fluid transport model for Po radiohalo formation is valid, then there should be Po radiohalos in the biotite flakes of these meta-arkoses, and there should be greater numbers of Po radiohalos at the staurolite isograd.Both predictions were verified. All nine samples of the meta-arkoses collected along a traverse through the regional metamorphic zones contained Po (mainly 210Po) radiohalos. Furthermore, the two samples straddling the staurolite isograd contained four–five times more Po radiohalos than the other seven samples. These results also verify the hydrothermal fluid transport model for Po radiohalo formation. The presence of mainly 210Po radiohalos was also consistent with the longer transport distance (> 1mm) from the zircon grains to the biotite flakes. It was concluded that, because these Po radiohalos could only have formed below 150°C (the annealing temperature of radiohalos in biotite), both the regional metamorphism and the hydrothermal fluid flows to transport the required Po had to be rapid. These processes, plus the cooling of the regional metamorphic complex and the formation of the Po radiohalos, had to have all occurred within a few weeks. This is all feasible in the context of catastrophic plate tectonics and grossly accelerated238U decay during the Flood. Acknowledgments

This research was encouraged by Kurt Wise, who also provided the logistical support for the field work. Mark Armitage is acknowledged for his work in processing the samples and counting the radiohalos. Funding was provided by the Institute for Creation Research from donations received toward the RATE project.

EVIDENCES FROM THE MAGNETIC FIELD

More Evidence of Rapid Geomagnetic Reversals Confirms a Young Earth

by Dr. Andrew A. Snelling on January 8, 2015 Abstract

For almost three decades the paleomagnetic record of extraordinarily rapid polarity reversals of the earth’s magnetic field in basalt lava flows at Steens Mountain in southern Oregon has stood as a challenge to the conventional millions-of-years geodynamo model. It has also been a severe embarrassment, because it is consistent with predictions of rapid polarity reversals of the earth’s magnetic field during the Flood according to the young-earth freely-decaying electric currents model for the generation of the geomagnetic field. Thus there has been a recent attempt to re-measure the paleomagnetic record in the Steens Mountain basalts using a new untried method, but the results and their re-interpretation are far from convincing. Instead, published at the same time, a new independent study of the paleomagnetic record in mud layers in a former post-Flood Ice Age lake in Italy has used Ar-Ar dating of interbedded volcanic ash layers to constrain the timeframe of a well-documented geomagnetic polarity reversal to less than 100 years. When accelerated radioactive decay is factored in, the timeframe for this reversal is reduced to just months, further stunning evidence consistent with the young-earth model for the earth’s magnetic field and rapid reversals during the Flood and its aftermath on a young earth. Keywords: earth’s magnetic field, paleomagnetic field directions, basalt lava flows, Steens Mountain, Oregon, rapid

geomagnetic polarity reversals, geodynamo, young-earth freely decaying electric currents model, Sulmona Basin, Italy, calcareous muds, tephra layers, post-Flood Ice Age, Ar-Ar dating, sanidine, accelerated radioactive decay. IntroductionBack in 1985 Coe, Prévot, and their scientific colleagues reported in three papers the evidence they had found of extremely rapid polarity changes of the earth’s magnetic field recorded in basalt lava flows at Steens Mountain in southern Oregon.1,2,3 These scientists carefully documented that Steens Mountain provided an excellent record of a geomagnetic reversal, because the volcano had spewed out 56 separate lava flows during that episode, so that each rock layer provided a time-lapse snapshot of the reversal.Their studies resulted in a benchmark directional record with 49 distinguishable paleomagnetic field directions from two well-exposed rock sequence sections more than a mile apart. Within this detailed record were three gaps of approximately 90° between one directional group and the next. These gaps were thought possibly to represent interludes in volcanic activity, but the absence of evidence of any hiatus between successive flows either side of the gaps suggested instead that the geomagnetic field may have changed very rapidly at these times. These tantalizing results spurred detailed sampling from bottom to top of flows that straddled these directional gaps. Results for the samples from the flow straddling the first directional gap were intriguing.4 They discovered that toward the top of that flow the basalt had recorded a different paleomagnetic orientation than the basalt lower down in the same flow (see Figure 1). Coe and Prévot interpreted this to mean that the geomagnetic field had shifted by about 3° per day during the few days it took this basalt lava flow to cool. Such a rate of change is about 500 times faster than that seen in direct measurements of the field today.

Figure 1. The geomagnetic polarity reversal record in basalt lavas on Steens Mountain, Oregon. (a and b) Variations in

the paleomagnetic field direction during the reversal in the sequence of numbered lava flows on Steens Mountain.1 Three large gaps are denoted by thick black arrows. Each point represents the average paleomagnetic field direction of a group of superposed lava flows, solid and open circles indicating downward and upward inclination respectively.3 (c) Variation in the paleomagnetic field direction of flow B51 samples as a function of position.4 Shown as well are the mean directions of the underlying flow B52 and the overlying flow B50.Continuing their painstaking work, a follow-on study reported results of detailed sampling of the basalt flows which straddle the second of the three gaps in the record of changes in the direction of the geomagnetic field.5 They reported that their results indicated the rate at which the orientation of the ancient geomagnetic field had rotated could have reached an astounding 6° per day over an eight-day period during cooling of one of these basalt flows.6 Furthermore, they argued that these field changes recorded in these basalt lava flows at Steens Mountain did reflect genuine changes in the earth’s main magnetic field. Reactions

Reactions to these claims of evidence for extraordinarily rapid changes in the geomagnetic field direction were swift and vocal, because such evidence was an affront to the uniformitarian mindset regarding their slow-and-gradual view of the earth’s geologic history. “Principle of Least Astonishment’” was the title of an opinion piece in the journal Nature, in which

geophysicist Ronald Merrill of the University of Washington (Seattle) tried to grapple (unsuccessfully) with this newly published evidence confirming that extraordinarily rapid reversals of the earth’s magnetic field have indeed occurred.7 He wrote on the origin and history of the field:

“ . . . most geomagnetists dismissed the claim by applying the principle of least astonishment—it was easier to believe that these lava flows did not accurately record the changes in the earth’s magnetic field than to believe that there was something fundamentally wrong with the conventional wisdom of the day . . . .” Indeed, these findings at Steens Mountain veer far from the standard college geology textbook image of how the earth is supposed to work. Said Roberts of the University of California, Los Angeles: “To a theoretician like myself, these results are almost inconceivable.”8 Yet earth scientists by their own admissions lack a firm understanding of the earth’s magnetic field. According to the current theory in uniformitarian thinking, slowly swirling currents of molten iron within the earth’s outer core create a dynamo that powers the magnetic field. It is believed that once every few thousand years the field flips orientation, swapping the north pole for the south pole. These magnetic reversals, as they are called, supposedly take about 10,000 years from start to finish, because it would take that long for the geodynamo to crank down so as to switch direction before cranking up again to generate the field again, but with the reversed polarity.Most geophysicists questioned the original finding. “I can’t really understand the mechanism,” said Hoffman of California Polytechnic State University.9 In the face of this conundrum, some geophysicists tried (unsuccessfully) to explain the rapid field changes in terms of something else other than fluid movements in the outer core itself. Critics have pointed out that the magnetization recorded in the basalt lava flows might not be primary, because it is not uncommon to find basalt lava flows that have been remagnetized long after they cooled, for example, due to chemical alteration. Thus they claimed that the “alleged” rapid geomagnetic field changes in reality reflect imperfections in the paleomagnetic recording process, resulting in an “artefact” according to Bloxham of Harvard University.However, Coe and Prévot (with Camps) tackled such criticisms head-on in their reports, making a convincing case against the “magnetic artefact” argument. The two lava flows they had studied have quite different magnetic properties and yet show similar signals, making it harder to blame some glitch in the recording of the paleo-geomagnetic field in these basalts. Hoffman agreed: “We haven’t found anything really questionable about the rock magnetics.” Similarly, they convincingly countered other hypotheses, such as that the changes in the magnetization reflected changes in the external geomagnetic field associated with, for example, a magnetic storm.Bloxham acknowledged that he and his fellow geophysicists had a hard time explaining away the findings. “People are taking them seriously,” he said. Indeed, Merrill agreed: “They are some of the best experimentalists in the world. They’ve made it much more difficult to be a skeptic. In short, if Coe et al. are correct, then the consequences could be much more profound than they say. All this leaves us with a dilemma: we would like to apply the principle of least astonishment, but to which data and interpretations? Some scientists will accept the view as given by the authors [Coe et al.]. Others, I suspect, will choose to believe the rock record is still inaccurate . . . .” However, Merrill and all his uniformitarian colleagues failed to consider his own stated alternative—that there is “something fundamentally wrong with the conventional wisdom of the day” on the origin and history of the earth’s magnetic field. Why do they fail to consider that alternative? Because they would have to abandon their dynamo theory and its millions of years timescale! Enter a Young-Earth Explanation

Even before Coe, Prévot, and their colleagues announced their discoveries, a viable alternative model for both the origin of the geomagnetic field and the rapid field polarity reversals that fits all the data had been proposed and published. Back as early as 1973 young-earth creationist Thomas Barnes had proposed a model for the generation of the earth’s magnetic field by freely-decaying electric currents in the earth’s core.10 Subsequently, Russ Humphreys built on that model,11 and then used it to explain the paleomagnetic evidence recorded in the basalt lava flows in the sea floor of geomagnetic field

polarity reversals having happened rapidly during the Flood and its aftermath (see Figure 2).12 Figure 2. How the earth’s magnetic field has changed since the

earth’s creation, its intensity decaying due to the energy loss of the freely decaying electric currents in the liquid outer core, but interrupted by rapid polarity reversals during the Flood and its aftermath due to the Flood’s catastrophic plate tectonics changing the flow directions in the convection cells in the liquid outer core.11,12Humphreys was able to demonstrate that during the upheaval of the Flood the flow of the molten iron in convection cells in the outer core carrying the freely-decaying electric currents meant that the resultant geomagnetic field generated would have rapidly changed direction and reversed its polarity because of that fluid movement.13 On the sea floor at the earth’s surface new basalt lava

flows were erupting rapidly due to the rifting apart of the old pre-Flood ocean floor and mantle plumes in mantle convection cells rising as a result of the catastrophic plate tectonics during the Flood.14 Each new basalt lava flow recorded the polarity direction of the geomagnetic field at the time it cooled. So due to the geomagnetic field reversing rapidly, and the basalt lava flows being erupted rapidly, the result was that these geomagnetic field polarity reversals were recorded in these sea floor basalts, both laterally and vertically. This paleomagnetic “striping” within the sea floor basalts was one of the key pieces of evidence that convinced geologists that the sea floor plates had spread, pushing the continental plates with them, albeit at a drift pace within their uniformitarian paradigm.However, Humphreys was able to demonstrate that because the paleomagnetic recordings of the polarity reversals were often in patches within the basalt sea floor and even within individual basalt flows, the reversals having occurred rapidly within days was a better explanation. The catastrophic plate tectonics model for the geology of the Flood thus provided a better context to explain the geomagnetic field polarity reversals. Thus Humphreys had even predicted that evidence of rapid reversals would be found before Coe, Prévot and their colleagues announced their discoveries, which of course then provided confirmation of both the Humphreys geomagnetic field model and the catastrophic plate tectonics model of the Flood. Coe Recants?

How much more data then did Coe, Prévot and their colleagues need to generate before the geophysical community was prepared to abandon its failed geodynamo theory? More work continued at Steens Mountain, with other investigators finding additional evidence to support the original findings that the earth magnetic field had reversed its polarity rapidly in the past within days to a week or two.15 Coe also had other investigators work with him at other nearby sites to correlate the sequence of basalt flows and paleomagnetic findings at those sites with the sequence of lava flows that outcrop on Steens Mountain with their reported paleomagnetic record.16 They thus claimed in their 2011 paper to have provided “the most detailed account of a magnetic field reversal yet observed in volcanic rocks (with) forty-five new distinguishable transitional (T) directions together with 30 earlier ones reveal(ing) a much more complex and detailed record…”. They

also stated that the additional data “confirms most parts of the earlier record but also reveals a more complex reversal history.” However, it would seem that Coe has been under enormous pressure to somehow recant his previous findings with some new way to explain away the previous impeccable evidence he had championed. That this has been the case is evident from a paper he had published in 2014 in which he states it “is important to set the record straight”, citing “the Steens rapid-field-hypothesis . . . was misinterpreted by creationists in their attempts to reconcile the geological and young age time scales (e.g. Humphreys, 1990).”17 In this 2014 paper, Coe used a new batch of samples from the basalt flow at Steens Mountain which straddled the first geomagnetic field directional gap and which in his 1989 paper he had announced their laboratory measurements had shown that within that single basalt lava flow the geomagnetic field had shifted by about 3° per day during the few days it took that basalt lava flow to cool. In processing these new samples in his laboratory, Coe abandoned using the step-heating technique which he had used previously to measure the paleomagnetism in the basalt lava low samples, instead using a relatively new technique which is not as well-known and as thoroughly tested. He also abandoned the alternating-field demagnetization procedure, which is not quite as reliable but still widely used.The step-heating technique is very well-tested and has been relied on in paleomagnetic studies since the 1940s. In this technique a sample’s loss of magnetization is measured as it is heated up slowly through a series of small temperature steps. Instead, he used a relatively new technique in which the basalt samples were continuously and rapidly heated at 40 degrees Celsius (72 degrees Fahrenheit) per minute, measuring the demagnetization continuously. Coe also invented a new scenario called “thermal alteration”, in which the slow reheating of a basalt flow, as in the step-heating technique, supposedly altered its paleomagnetic record. However, this scenario is questionable, as heating basalt to temperatures below its Curie temperature of about 500°C, which is well below its melting point, should not affect the paleomagnetism it has recorded. Instead, this new rapid-heating technique is supposed to give less time for thermal alteration to occur.Thus the results using this new rapid-heating technique, Coe and his new collaborators now claim in this 2014 paper, call into question the earlier results from his 1989 paper, which showed a steady change of the geomagnetic field direction, by about 60 degrees, for samples going deeper and deeper into the interior of this basalt lava flow which straddled the first geomagnetic field directional gap in the sequence of basalt lava flows at Steens Mountain. However, if the new technique is right, then it would call into question nearly 75 years’ worth of paleomagnetic conclusions in hundreds of other studies all based on the well-tested step-heating technique.In the normal step-heating technique, the experimenter waits for several minutes at each temperature for the basalt sample to get demagnetized before further heating the sample up through the next temperature increment. This puts the experimental emphasis on the larger magnetic grains in the basalt sample (grains of the iron oxide mineral called magnetite) because they are slower to change their magnetization at high temperatures, and because they are unlikely to change their magnetization after the basalt lava cooled after it erupted and flowed. However, in the rapid continuous-heating technique the magnetite grains have only a few seconds to change their magnetization at each temperature. That tends to put the experimental emphasis on smaller magnetite grains that can change magnetization more easily. Therefore those smaller grains are more likely to have been re-magnetized by the recent thousands of years in which the earth’s magnetic field has had normal polarity after these basalt lava flows cooled.Thus the old step-heating technique primarily tested the magnetization of the more robust, magnetically “stable” set of larger magnetite grains in the basalt, but this new continuous rapid-heating technique primarily tested the magnetically “unstable” smaller magnetite grains. The results produced by the old well-tested technique are thus not influenced much by the smaller, magnetically “unstable” grains, so that technique should be a much more reliable way o f determining the earth’s past magnetic field while the basalt was cooling down below its Curie temperature, about 500°C. If secular paleomagnetic experts were not so eager to join Coe in discarding his earlier results from this basalt lava flow

because of the time implications, then they would not be so eager to trust this new experimental technique. Yet Coe and his collaborators still admitted at the end of their 2014 paper that “the question (of) whether or not brief episodes of field change much faster than current secular variation have occurred is very much alive and debated.” A New Independent Study

This “story” doesn’t end there. The results of a new independent study, in which different samples from a totally different geologic and geographic situation were used, have since been published.18 And what is especially helpful, this new study did not use basalt lava flows samples, so the possibility of thermal

alteration of them is not an issue.In this study, the researchers investigated the sediment layers that were deposited on the floor of what was once a small lake in the Apennines of Italy. This small lake existed during the Ice Age of the so-called Pleistocene, which within the young age chronology we would all agree was post-Flood. The lake filled with layers of whitish, faintly laminated to massive calcareous muds, interspersed with numerous tephra (volcanic ash) layers resulting from nearby volcanic eruptions. Today what remains is a small sedimentary basin called the Sulmona Basin, and the continuous sequence of mud and tephra layers in three main unconformity-bounded alluvial-fluvial-lacustrine units are now well exposed in outcrop (see Figure 3). Figure 3. Location maps and geological sketch of the northernmost sector of the Sulmona Basin, Italy, and a composite

section of the Sulmona Pleistocene (post-Flood Ice Age) sedimentary sequence, with the Ar-Ar dates for tephra layers and the paleomagnetic record indicated.18 In a previous paleomagnetic investigation this research team had drilled to a depth of 65 meters (213 feet) through the former lake’s strata sequence and had constrained the location of the so-called Matuyama-Brunhes geomagnetic polarity reversal to being within the oldest and lowermost unit. Within the recovered core they identified at least ten tephra layers that could be correlated by being continuously traced laterally to those recognized in the surrounding outcrops of the Sulmona sequence. So in this study they located the same stratigraphic interval cropping out about 500 meters (1640 feet) to the southeast of their previous drill-hole site and carefully sampled the correlated 3 meter (10 feet) section of interest with 46 contiguous hand samples each spanning 6–16 cm (15–41 inches) of stratigraphic thickness.In the laboratory at least one sample per layer had its magnetic susceptibility and natural remnant magnetization (NRM) measured. For 36 samples, distributed throughout the section, they also carried out a stepwise thermal demagnetization, in 10–11 steps up to 450°C. They also did careful measurements of the variation of magnetic susceptibility in heating-cooling cycles in order to identify the Curie temperatures of the main magnetic minerals in the samples, and to check the possible occurrence of significant alteration during heating.Pristine sanidine (K-feldspar) crystals were handpicked under a binocular microscope from the three tephra layers within and spanning the 3 meter (10 feet) stratigraphic section being investigated. A total of 124 crystals were submitted for argon-argon (Ar-Ar) dating at two laboratories. Both laboratories used the sanidine standard from the Alder Creek Rhyolite as the neutron fluence monitor. Rather than absolute ages, the reported ages were calculated relative to the age of the Alder Creek sanidine standard because the objective was to provide a determination of the time intervals spanning the stratigraphic section and the measured paleomagnetic properties of the samples within it.This research team found that these Sulmona lake calcareous mud sediments in the 3 meter (10 feet) stratigraphic section they so carefully investigated are characterized by excellent paleomagnetic properties, which allowed the reconstruction of the Matuyama-Brunhes geomagnetic polarity transition in very fine detail. The strong correlation and consistency between the rock magnetic and paleomagnetic stratigraphic trends between this stratigraphic section and the original drill-hole core demonstrated the lateral continuity of the experimental results and the reliability of the paleomagnetic signal for their high-resolution geomagnetic reconstruction. They also found that their data were consistent with magnetite (Fe3O4) being the main carrier of the magnetic remanence and indicated that the concentration of magnetic minerals is generally uniform throughout the investigated sequence.They found that the 180° polarity flip (reversal) associated with the Matuyama-Brunhes geomagnetic polarity transition occurred sharply in a 2 cm (0.8 inch) sub-layer cut from the same hand sample block between two adjoining levels, at 152 cm (59.8 inches) and 154 cm (60.6 inches) of stratigraphic depth respectively. And it was recorded consistently between seven independent sub-samples via both series of paleomagnetic measurements. Next, the high precision Ar-Ar dates obtained on the three tephra layers spanning this stratigraphic interval in which this geomagnetic polarity reversal was recorded and preserved were used to provide tight chronological constraints on this Sulmona sequence of calcareous mud and tephra layers. Assuming the Ar-Ar ages are correct, they calculated an average sedimentation rate for the calcareous mud layers of about 21 cm (8.3 inches) per thousand years, or about 2 mm (0.08 inch) per year. Thus at that rate of deposition, this implies the 2 cm (0.8 inch) sub-layer that recorded the

Matuyama-Brunhes geomagnetic polarity reversal accumulated in about 100 years, and therefore the geomagnetic field reversal transition occurred in less than 100 years, which is still extremely fast compared to the usually assumed transition times of hundreds of thousands of years to millions of years (see Figure 4). Figure 4. (a) Virtual geomagnetic pole (VGP) path

reconstructed for the paleomagnetic data from the discrete samples around the Matuyama-Brunhes transition in the Sulmona strata sequence. (b) Stratigraphic trends for the VGP latitude (blue curve) and the relative paleo-intensity (RPI) scaled to unit maximum (red curve) for the Sulmona strata sequence compared with the schematic reversal path, illustrating the succession of the reversal precursor, polarity switch and rebound. The colored areas indicate the stratigraphic intervals of minimum RPI that have been correlated with the precursor and transit phases, the latter being the 2 cm (0.8 inch) thick mud layer recording the rapid reversal.18However, this conclusion assumes the rate of radioactive decay of 40K, the basis of the Ar-Ar dating method, has remained constant in the past at the slow decay rate measured today. Yet there are several lines of good evidence that radioactive decay rates were accelerated during past catastrophic events, especially during the Flood year when geological processes were also operating at catastrophic rates.19 Then at the close of the Flood it is logical to envisage that the tempo of geological processes did not slow abruptly, but tapered off, and this is borne out by the abundant evidence of localized superstorms and catastrophic flooding resulting in localized sedimentary deposits in the decades before the post-Flood Ice Age gripped the planet.20 Thus it would

be expected that deceleration of the radioactive decay rates also occurred during the same period and on into the post-Flood Ice Age, and the evidence of “inflated” radioactive ages for post-Flood rocks is consistent with that logical expectation.Therefore, if accelerated radioactive decay was still decelerating, and the rates were still significantly faster than today’s measured slow rates, in the period after the Flood and continuing on into the post-Flood Ice Age, then the sediment deposition rate in the Sulmona Basin, Italy, as determined by the Ar-Ar dating of the interspersed tephra layers (albeit with 40K radioactive decay still more rapid than today’s measured slow rate), could easily have been more like 4 cm (1.6 inches) per year, a quite reasonable rate during the several centuries long, stormy Ice Age. That would reduce the geomagnetic field polarity transition time to just a few months. Such a rapid polarity reversal rate compares quite well with the evidence for fast reversals that were still occurring in the last stages of the Flood. It also supports the general picture we have of many fast reversals during the Flood itself. This all collapses the so-called paleomagnetic time scale down from millions of years to just months. Conclusions

For many years studies of the paleomagnetism recorded in basalt lava flows on Steens Mountain in southern Oregon had provided impeccable evidence that reversals of the geomagnetic field polarity had in the past occurred extraordinarily rapidly, in a matter of only days to weeks. This has been a severe embarrassment to the conventional geoscience community because such a rapid rate for geomagnetic field polarity reversals is totally inconsistent with their preferred millions-of-years geodynamo model for the generation of the earth’s magnetic field. Their embarrassment was intensely heightened by young-earth creation scientists being able to use this evidence at Steens Mountain to support their young-earth freely-decaying electric currents model for the generation of the earth’s magnetic field and rapid polarity reversals during the Flood and its aftermath. This explains Coe’s recent efforts to use the results of a new untried rapid-heating technique to re-measure the paleomagnetism stored in those Steens Mountain basalt lava flows in order to “reinterpret” and overturn his earlier evidence of the extraordinarily rapid geomagnetic field polarity reversals. However, the original results using the long-established step-heating measurement technique are not so easily overturned and disregarded.Instead, a totally independent study by a different research team in a different location and geologic setting has found unmistakably clear further evidence supporting past rapid polarity reversals of the earth’s magnetic field. In the muddy sediment layers of a former post-Flood Ice Age lake they have found the indisputable record that the so-called Matuyama-Brunhes geomagnetic polarity transition occurred rapidly. They used high precision Ar-Ar dating of sanidine crystals from volcanic ash (tephra) layers between the mud layers to constrain the timeframe of sedimentation and therefore the polarity reversal recorded in one thin mud layer to just 100 years or less. However, when the evidence for grossly accelerated radioactive decay rates during the Flood and their deceleration through the post-Flood Ice Age are factored into the Ar-Ar dating, the rates of both the sedimentation of the thin mud layer and the geomagnetic field polarity reversal recorded in it reduce to just a few months. This is thus consistent with the Steens Mountain evidence of extraordinarily rapid geomagnetic field polarity reversals, which are only consistent with the young-earth model for the generation and rapid reversals of the earth’s magnetic field during the Flood and its aftermath.The majority of geoscientists believe the earth is billions of years old, and so they have been striving for nearly a century to develop a successful “dynamo” model to explain how the earth’s magnetic field might maintain itself over that long time. After reviewing analytical theories, computer simulations, and laboratory experiments, young-earth creation scientist Humphreys has concluded that all those efforts have fallen short of proving the geomagnetic field could be maintained by a dynamo.21 In contrast with this apparent failure, Humphreys has demonstrated with the remarkable success how his young age model for the origin and operation of the geomagnetic field explains the magnetic fields of other bodies in our solar system, especially for the planet Mercury, a model consistent with the young age of the earth and the universe of only about 6,000 years.

The “Principle of Least Astonishment”!

by Dr. Andrew A. Snelling on August 1, 1995

Originally published in Journal of Creation 9, no 2: 138-139.

Abstract A decade ago, Prévot and Coe (and colleagues) reported in three papers the evidence they had found of extremely rapid changes of the Earth’s magnetic field recorded in lava flows at Steens Mountain. Shop Now So ran the heading in the journal Nature, as

geophysicist Ronald Merrill of the University of Washington (Seattle) tried to grapple (unsuccessfully) with the newly published evidence confirming that ‘extraordinarily rapid’ reversals of the Earth’s magnetic field have indeed occurred.1 , 2 A decade ago, Prévot and Coe (and colleagues) reported in three papers the evidence they had found of extremely rapid changes of the Earth’s magnetic field recorded in lava flows at Steens Mountain in southern Oregon (USA).3,4,5 Scientists regard Steens Mountain as the best record of a magnetic reversal because the volcano spewed out 56 separate flows during that episode, each of these rock layers providing time-lapse snapshots of the reversal. Within one particular flow, Prévot and Coe discovered that rock toward the top showed a different magnetic orientation than did rock lower down. They interpreted this to mean that the field shifted about 3° a day during the few days it took the single layer to cool.6 Such a rate of change is about 500 times faster than that seen in direct measurements of the field today, so,most geomagnetists dismissed the claim by applying the principle of least astonishment—‘it was easier to believe that these lava flows did not accurately record the changes in the earth’s magnetic field than to believe that there was something fundamentally wrong with the conventional wisdom of the day’on the origin and history of the field.7There the story would have ended, except that Coe and Prévot have continued their painstaking work. Now they have reported that the rate at which the orientation of the ancient magnetic field rotated reached an astounding 6° per day over an 8-day period, and have argued that these field changes recorded in these lava flows at Steens Mountain do reflect changes in the Earth’s main magnetic field.8These findings veer far from the textbook image of how the Earth is supposed to work. Says Roberts of the University of California, Los Angeles, ‘to a theoretician like myself, these results are almost inconceivable’.9 Yet earth scientists lack a firm understanding of the Earth’s magnetic field. According to current theory, swirling currents of molten iron within the Earth’s outer core create a dynamo that powers the magnetic field. It is believed that once every few hundred thousand years, the field flips orientation, swapping north pole for south pole. These so-called magnetic reversals supposedly take about 10,000 years from start to finish.Most geophysicists questioned the original finding. ‘I can’t really

understand the mechanism’, says Hoffman of California Polytechnic State University.10 In the face of this conundrum, some geophysicists are trying—so far unsuccessfully—to pin the rapid shifts on something other than the core itself. Critics have thus pointed out that the magnetisation might not be primary; it is not uncommon to find lava flows that have been remagnetised long after they cool, for example, because of chemical alteration. Thus they concluded that the alleged rapid changes in the Earth’s field really reflect an imperfection in the magnetic recording process, an ‘artefact’ according to Bloxham of Harvard University. However, Coe and Prévot (with Camps) have now tackled such criticism head-on, making a convincing case against the ‘magnetic artefact’ argument. The two lava flows they have studied have quite different magnetic properties and yet show similar signals, making it harder to blame some glitch in the record. Hoffman agrees: ‘We haven’t found anything really questionable about the rock magnetics.’ Similarly, they have convincingly countered other hypotheses, such as that the changes in the magnetisation reflected changes in the external magnetic field associated with, say, a magnetic storm. Bloxham acknowledges that he and his geophysicist colleagues are having a hard time explaining away the findings. ‘People are taking them seriously’, he says.11 Indeed, Merrill agrees. ‘They are some of the best experimentalists in the world. They’ve made it much more difficult to be a skeptic’, he says.12 ‘In short, if Coe et al. are correct, then the consequences could be much more profound than they say’ concludes Merrill.13 ‘All this leaves us with a dilemma; we would like to apply the principle of least astonishment, but to which data and interpretations? Some scientists will accept the view as given by the authors [Coe et al.]. Others, I suspect, will choose to

believe the rock magnetic record is still inaccurate …’ However, Merrill and all his uniformitarian colleagues have failed to consider his own stated—alternative that there is ‘something fundamentally wrong with the conventional wisdom of the day’ on the origin and history of the Earth’s magnetic field! Why? Because they would have to abandon their dynamo theory and its millions of years time-scale? In fact, there is a viable alternative explanation for both the origin of the geomagnetic field and for the rapid field reversals (in days and weeks, not thousands of years) that fits all the data—freely decaying electric currents in the Earth’s core, as proposed by young-earth creationists Barnes and Humphreys,14,15 with the rapid field reversals associated with the Flood event. Indeed, Humphreys predicted that evidence of rapid reversals would be found before Coe et al. announced their ‘discovery’. How much more data then do Coe et al. need to generate before the geophysical community is prepared to abandon its failed dynamo theory? Perhaps Merrill could be right on one point – ‘Eventually, the consequences should be profound’ We may yet all be astonished!

The Earth’s Magnetic Field and the Age of the Earth

by Dr. Andrew A. Snelling on September 1, 1991

Originally published in Creation 13, no 4 (September 1991): 44-48. Dr. Thomas G. Barnes drew attention to the fact that the strength of the earth’s magnetic field was decreasing. On this basis he concluded that the magnetic field was less than 10,000 years old. As early as 1971, creation scientist Dr. Thomas G. Barnes, then Professor of Physics at The University of

Texas at El Paso, drew fresh attention to the fact that the strength of the earth’s magnetic field was decreasing.1He noted that between 1835 and 1965 geophysicists had made some 26 measurements of the magnetic dipole moment of the earth’s magnetic field. When plotted against time (that is, the year of measurement) these data points fitted a decay curve which Barnes calculated had a ‘halflife’ (halving period) of only 1,400 years. On this basis he concluded that the earth’s magnetic field was less than 10,000 years old, and so the earth must likewise be that young (see Figure 1). Which hypothesis? Evolved or created?

Needless to say, because of the powerful implications of this evidence Barnes received much opposition from the evolutionary community. Evolutionist geophysicists simply poured scorn on Barnes’ conclusions because they argued that any ‘decay’ of the earth’s magnetic field merely represented the latest phase in the ongoing history of waxing and waning field strengths as the field repeatedly reverses during multiplied millions of years.2 But Barnes stoutly repulsed this objection by denying the validity of the ‘fossil’ magnetism (palaeomagnetism) measurements of reversed magnetic polarity (direction) in rock strata.3Evolutionary geophysicists were already ‘locked into’ their multi-million-year timescale not only because of the radioactive dating of the rocks in which the palaeomagnetic reversals were measured, but because of their presumed ‘dynamo’ mechanism for operation of the earth’s magnetic field. It is generally believed that the earth’s magnetic field is generated by electric currents in the earth's innermost region, the core, which is presumed to consist of a metallic iron-nickel mixture. However, according to the ‘dynamo’ hypothesis, these electric currents are believed to be produced by the slow circulation of molten material that carries unequal amounts of positive and negative electric charge. The energy for this is thought to come from the earth’s rotation and/or its internal heat.4,5

Humphrey’s models for the history of the earth’s magnetic field (adapted from Humphreys—see reference 10). [Ed. note: Full-scale images available inCreation.] So the generating mechanism is presumed to

operate like a dynamo, (similar to an electricity generator) causing the field and maintaining it over large periods of time. Consequently, a

reversal of the earth’s magnetic field (which is difficult for them to explain anyway) could be expected to be a slow process. Thus the evolutionary view has been that a transition from one magnetic polarity (direction) to the other generally took millions of years, or several thousand

years at the very least.6However, this so-called dynamo hypothesis, the operational mechanism preferred by most geophysicists, has many problems associated with it which have been well documented. 7,8,9,10 Reversals have occurred

More recently, creation scientist Dr. D. Russell Humphreys (Physicist at the Sandia National Laboratories, Albuquerque, and Adjunct Professor of Physics at the Institute for Creation Research, San Diego) has reviewed the evidence for the validity of these ‘fossil’ magnetism11studies and has found that fully half of all the 200,000 plus geological samples tested

have a measurable magnetization whose direction (‘polarity’) is reversed with respect to the earth’s present magnetic field. He was forced to conclude that the variety, extent, continuity and consistency of the reversal data all strongly suggest that most of the data are valid, so that there is no option but to accept that reversals of the earth’s magnetic field must have occurred. So how can these reversals of the earth’s magnetic field be reconciled with Barnes’ evidence that the earth and its magnetic field are less than 10,000 years old? Barnes and Humphreys have both argued convincingly for a viable alternative hypothesis to the evolutionists’ dynamo idea. They propose that the earth’s magnetic field comes from freely circulating electric currents created initially with a high built-in energy. As these currents subsequently lose their energy due to friction, the magnetic field will decay as the current strength decays.12,13,14,15,16However, a collapsing magnetic field cutting across a conductor (the earth’s iron-nickel core) will generate more current, which helps to retard the rate of decay, otherwise the field would vanish more quickly. In fact, if we were to calculate how much current is being generated from the measured rate of collapse of today’s magnetic field, this current is sufficient to account for the actual known strength of the field as it is today! Besides being a good confirmation of the model, this means that the evolutionist’s ‘dynamo’, if it ever existed, must now be switched off.Now we have already seen that this decay is real, having been measured for over 160 years, as pointed out by Barnes and documented by McDonald and Gunst.17 So this Barnes-Humphreys mechanism can account for this realtime decay of the earth’s magnetic field over the past 160 years, the current generated from such field decay correlating well with calculations of the amount of current actually present within the core. Furthermore, Humphreys maintains that it can also account for the magnetic reversals recorded in the rocks having taken place in only days to weeks!18,19 The flood and rapid reversals Now measurements of this ‘fossil’ magnetism in rock strata (being the local field direction and strength) are different to the global measurements of the strength of the earth’s total magnetic field as reported by Barnes, yet the ‘fossil’

magnetism (palaeomagnetism) does record the behaviour of the field during the earth’s history. Geophysicists have now recognized a continuous sequence of roughly 50 magnetic polarity (field direction) reversals in the magnetism ‘fossilized’ in rock strata that span the last 600 million years of the evolutionists’ timescale, from the so-called Cambrian period when the first metazoan (multi-celled) fossils ‘appear’ in the rock record to the present. However, since some fossiliferous strata also have reversed polarities preserved in them, the magnetic field must have been reversely polarized when those sediments were being laid down.Many creationists argue that the Flood produced most of these fossiliferous rock layers in a single year. Thus, these reversals of the earth’s magnetic field have to be envisaged as occurring on average every week or two during the Flood year. If this were the case, we should then be able to find field evidence of the reversal process having occurred this rapidly, otherwise the Barnes-Humphreys freely decaying electric currents mechanism for the generation of the earth’s magnetic field in less than 10,000 years is also in trouble.But the field evidence has now been found. As already reported,20 palaeomagnetic measurements of a lava flow at Steens Mountain in Oregon have shown that one of these magnetic polarity transitions (part of a complete reversal) took place in about two weeks, the time period over which the lava would have cooled. As would be expected, the investigators, both evolutionists, were astonished by these results and had difficulty accepting them, but finally had to admit: ‘…even this conservative figure of 15 days corresponds to an astonishingly rapid rate of variation of the geomagnetic field direction of 3∞ per day. …The rapidity and large amplitude of geomagnetic variation that we infer from the remanence directions in flow B51, even when regarded as an impulse during a polarity transition, truly strains the imagination.…We think that the most probable explanation of the anomalous remanence directions of flow B51 is the occurrence of a large and extremely rapid change in the geomagnetic field during cooling of the flow, and that this change likely originated in the (earth’s) core.’21 The sun’s magnetic field

In order to further bolster his case for rapid magnetic polarity reversals, Humphreys22 has also pointed to a natural object, namely the sun, which demonstrates that a large body can rapidly reverse its magnetic field.23 Observations show that the sun reverses the polarity of its general magnetic field every 11 years, in synchronism with its sunspot cycle. When the number of sunspots is at a minimum, the observed field on a large scale has its lines of force going mainly north and south. As the number of sunspots begins to increase, the strength of the north-south part of the field diminishes. In about 5.5 years the north-south component has diminished to zero and the number of sunspots is at a maximum. Then things begin to happen in reverse. A south-north part of the field appears in the opposite direction from its predecessor and the number of sunspots starts to diminish. After another 5.5 years, the number of sunspots is at a minimum again, and the field is back to its original shape, but with the north and south poles of the field having switched places, that is, the sun’s magnetic field has reversed its polarity.Physicists and astronomers do not yet have a theory that completely explains this complex reversal phenomenon. One probable reason why they have had difficulty explaining the sun’s reversals is that, because they believe the sun’s magnetic field is also generated by a dynamo, they have been looking for a mechanism which would not only reverse the sun’s field, but also regenerate and maintain it for billions of years. But if the sun is relatively young (only thousands of years), there is no need for the regeneration requirement. The sun would merely be winding up and unwinding whatever magnetic field it had at creation, losing magnetic energy each solar cycle. Its long-term behaviour would thus be a steady decay modulated by the solar cycle of reversals. Earth’s physical mechanism

Dr. Humphreys has now proposed a physical mechanism for reversals of the earth’s magnetic field during the Flood.24We have already seen there is agreement that the earth’s magnetic field is generated in the earth’s metallic iron-nickel core, most evolutionary scientists preferring a dynamo, as opposed to the free-decay model of Barnes and Humphreys. The latter involves an initial endowment of energy in the core at the time of creation and that energy has dissipated and decayed freely as electrical currents in the core since then, the currents generating a magnetic field at the earth’s surface and beyond, which has decayed in step with the decay of electrical currents.However, because the metallic iron-nickel in the earth’s outer core is in a fluid state, internal motions occur in this region due to convection flow, for which there is evidence even at present. Humphreys suggests that a powerful event in the earth’s core at the beginning of the Flood produced this convection, perhaps by the heating of the core due to a sudden increase of radioactive decay or cooling of the mantle above the core, but these are as yet tentative suggestions that need further analysis. However, once convection flows were initiated in the earth’s core, such flows moving upwards in the core towards the mantle would produce a magnetic flux up into the mantle, which would then be conducted to the earth's surface as a magnetic excursion.These convective ‘updraughts’ in the earth’s core would have carried more magnetic flux to the surface than ‘downdraughts’ would have carried away from the surface, so the convective updraughts would have rapidly cancelled out any previous flux above it. The work done by these convection flows in pushing a magnetic flux upward would generate new electric currents, which in turn would generate new flux in the opposite direction. Thus a cycle of magnetic reversals are set up due to these recurring convection currents, which are maintained as long as there is a strong heat source

within the core. In support of his model, Humphreys draws comparisons with convection currents within the sun, which we have already seen are responsible for a rapid magnetic reversal cycle there. Earth’s magnetic field history

Humphreys’ model for the history of the earth’s magnetic field is more complex than Barnes’ original picture of a steady state decay from creation to now, but it does not differ on the essential hypothesis that the earth’s magnetic field has freely decayed since creation. Figure 2 shows Humphreys’ model for the history of the earth’s magnetic field, which he divides into five episodes: Creation of the magnetic field along with the earth. Steady decay for nearly 2,000 years until the Flood. Rapid reversals during the year of the Flood. Large fluctuations continuing for up to two thousand years after the Flood. Resumption of steady decay from about the time of Christ until now.

The last period includes the historical measurements which show decay, as reported originally by Barnes.25 The model for the reversal process as proposed by Humphreys is simple compared to the evolutionary ‘dynamo’ theories. It differs fundamentally from the dynamo theories in that it is not intended to maintain the earth’s magnetic field for billions of years. Rather, it inverts a previously existing field over and over again. Far from maintaining a field indefinitely, this process accelerates the decay of a planetary magnetic field. The field strength at the peak of each cycle is less than the peak of the previous cycle, because the inverting process does not completely reproduce the flux. This means that the energy contained in the post-Flood magnetic field would be considerably less than that of the pre- Flood field.According to Humphreys, even though creationist explanations of planetary magnetic fields are still in their infancy, they appear to be more complete and successful than the 40-year-old dynamo theories. Indeed, recent magnetic measurements by the Voyager spacecraft as it flew past Uranus and Neptune have confirmed Humphreys’ predictions on the origin of the planetary magnetic fields.26,27 Furthermore, recent measurements have cast doubt on whether a dynamo really does operate in the earth’s core at present. 28 In addition, there is no dynamo theory which accounts for the extremely rapid variations reported at Steens Mountain by Coe and Prevot,29 but Humphreys’ model accounts for this data particularly well. Dynamo theorists even acknowledge that their theories are incomplete, very complex, and not very successful at making predictions. 30 As one such theorist has said: ‘…you would have thought we would have given up guessing about planetary magnetic fields after being wrong at nearly every planet in the solar system…’31 Age of the earth

If the creation scientist Humphreys is correct, and seeing that his predictions about planetary magnetic fields in the solar system have been verified, and his model for magnetic reversals here on earth does fit well to the geophysical and rock palaeomagnetic data compared to the woeful state of the dynamo model, then such a decrease in the energy of the earth’s magnetic field implies that it is not eternal but relatively recent. Consequently, Humphreys has extrapolated today’s energy decay rate back to a theoretical maximum energy,32 and so has derived an upper limit for the age of the earth’s magnetic field at 8,700 years.However, he concludes that the rate of energy loss would have been greater during and just after the Flood, due to the postulated powerful heating event in the core at the time of the Flood which set in motion the convection flow, that in turn produced the magnetic reversals and rapid dissipation of the field energy. Figure 3 shows one scenario suggested by Humphreys in which about 90% of the earth’s magnetic field energy was lost during the Flood or shortly thereafter. He suggests, thereby, that this would make the age of the field about 6,000 years, thus again providing powerful evidence that the earth is as young.

Fossil Magnetism Reveals Rapid Reversals of the Earth's Magnetic Field

by Dr. Andrew A. Snelling on June 1, 1991 Originally published in Creation 13, no 3 (June 1991): 46-50. Fossils with magnetic properties demonstrate the rapid reversals of the Earth's magnetic field in the past. Shop Now Almost everyone is familiar with a compass needle. The magnetic properties of the metallic iron in the needle ‘force’ the needle to swing on its pivot until it lines up with the north-south direction of the earth’s magnetic field. Indeed, every molecule of the metallic iron in the needle has these magnetic properties. ‘Fossil’ magnetism

Iron also occurs in many types of rocks, not usually in its metallic form, but as an oxide mineral called magnetite, which as the name suggests is magnetic. Just as all the molecules in the compass needle align themselves along the earth’s magnetic field, so do the molecules in the magnetite grains in rocks.This will happen at the time a magnetite particle in a sediment or volcanic ash comes to rest, or in a lava (hot volcanic rock) as it cools to 500°C. Once the sediment layer is deposited and buried, or the lava flow has cooled below 500°C, the direction of the earth’s magnetic field as recorded by magnetite grains in these rocks cannot usually be changed by subsequent geological events (except for metamorphism—the process of changes to rock under the influence of elevated pressures and temperatures), even if the direction of the earth’s magnetic field has subsequently changed. This magnetism in the rocks is thus in essence ‘fossilised’, and so is usually called palaeomagnetism. Magnetic Reversals

The existence of this palaeomagnetism in the rocks has claimed a lot of attention since the 1960s. At that time it was discovered that there were what appeared to be magnetic ‘stripes’ in the rocks on the ocean floor. The stripes represented sections in the rock of normal (the same as today) and reversed directions of the earth’s magnetic field, and this has been used as evidence for so-called sea-floor spreading and continental drift.1Since their discovery, a lot of questions have been raised regarding the validity of these magnetic polarity (direction) reversals. Doell and Cox2 state that, ‘The reversed magnetisation of some rocks is now known to be due to a self-reversal mechanism’. Thus Jacobs3 claimed that, ‘Such results show that one must be cautious about interpreting all reversals as due to field reversal and the problem of deciding which reversed rocks indicate a reversal of the field may in some cases be extremely difficult.’However, since this initial skepticism, a number of careful field, laboratory, and theoretical studies, as reported by McElhinney4 and Jacobs5, have shown that self-reversal cannot explain more than a small percentage of the reversely magnetized samples. Indeed, Humphreys6 has recently reviewed the evidence for the validity of these ‘fossil’ magnetism studies and has found that fully half of all the 200,000-plus geological samples tested have a measurable magnetization whose direction (‘polarity’) is reversed with respect to the earth’s present magnetic field. He concluded that the variety, extent, continuity and consistency of the reversal data all strongly suggest that most of the data are valid, so that there is no option but to accept that reversals of the earth’s magnetic field must have occurred.Geophysicists have now recognized a sequence of 26 such magnetic field reversals in rock extending from the ’Upper Miocene’ to the present, presumed to represent the past

5.5 million years of the evolutionist’s timescale. In the fossiliferous rock layers of the evolutionist’s past 600 million years, from the lowest metazoan (multi-celled) fossils of the so-called ‘Cambrian explosion’ to the present, there appear to have been recorded in a continuous sequence roughly 50 of these magnetic polarity reversals. The Mechanism?

The problem with the interpretation of these magnetic data is the presumed mechanism for operation of the earth’s magnetic field, and thus the presumed multi-million year timescale for these reversals.The earth’s magnetic field is generally considered by most geophysicists to be associated with electric currents in the earth’s innermost region, the core, which is believed to consist of a metallic iron-nickel mixture, and is presumed to operate like a dynamo. These electric currents are believed to be produced by the slow circulation of molten material that carries unequal amounts of positive and negative electric charge.7,8 Consequently, reversal of the earth’s magnetic field could be expected to be a slow process, and thus the evolutionary view has been that a transition from one magnetic polarity (direction) to the other generally took millions of years. Certainly, at least several thousand years have now been estimated as necessary for the completion of one such reversal.9In any case, this operational mechanism preferred by most geophysicists, the so-called dynamo hypothesis, has many problems associated with it which have been well documented.10-13Since the field reversals are recorded in the fossil strata, the reversals must have happened when the strata were being laid down. Many creationists argue that the Flood produced most of the fossil layers in a single year. Thus, these reversals of the earth’s magnetic field have to be envisaged as occurring on average every week or two during the Flood year.Such changes are obviously very rapid compared to the evolutionist’s multi-thousand-year or million-year-plus time-scales predicted by their dynamo hypothesis. However, creationists Dr. Thomas G. Barnes (Professor Emeritus of Physics, The University of Texas at El Paso) and Dr. D. Russell Humphreys (physicist at the Sandia National Laboratories, Albuquerque, and Adjunct Professor of Physics at the Institute for Creation Research, San Diego) have argued convincingly for a viable alternative hypothesis to the dynamo. They propose freely decaying electric currents in the earth’s core.14-18 This mechanism accounts for the real-time decay of the earth’s field over approximately the past 150 years, the current generated from such field decay correlating well with calculations of the amount of current actually present within the core. In addition, it can account for the magnetic reversals recorded in the rocks having taken place in a matter of only days to weeks!19,20 Found! A field test

A convincing test of Humphreys’ proposal, that reversals of the earth’s magnetic field must have taken only a matter of days or weeks within the time-frame of the year-long Flood only 4,500 or so years ago, would be to look for evidence of such rapid reversals within rock layers that would have formed, or are known to have formed, that rapidly. Indeed, Humphreys has suggested this himself.21 He suggested that the best candidates for strata which clearly formed within a few weeks and yet contained a full reversal, would be distinct lava flows thin enough that they would have cooled below 500°C within a few weeks.There are several sites where reversal transitions are recorded in the rock layers in some detail, continuously tracking both direction and strength in small steps.22,23 However, a large portion of these magnetic reversal transitions are not recorded in a single, rapidly formed, rock layer, and so don’t meet the criteria for a test case . Now two geoscientists have reported their examination of such a lava flow and found just such a polarity transition recorded in it.24,25Coe and Prevot are respected palaeomagnetists, who for some years have been involved with a large group of geoscientists undertaking detailed investigations of magnetic polarity changes in the immense pile of lava flows at Steens Mountain in Oregon, near the California-Oregon border. These lava flows have been studied along two traverses up the mountain and are regarded as Miocene, with the reversal record ‘dating’ from 15.5 +/- 10.3 million years ago.Coe and Prevot carefully sampled a relatively thin (1.9 metres) lava flow, designated as flow number B51, at a point where their team’s previous investigations had suggested a rapid transition (magnetic polarity change) was likely to have been recorded. A group of nine lava flows with similar magnetic polarity directions (essentially ‘reversed’ polarity), the last one being B52, precedes a 90° jump to the ‘normal’ direction of flow B50 above, which is followed up the sequence by a group of six flows with directions that are indistinguishable from one another but very similar to the ‘normal’ direction of flow B50. Palaeomagnetic measurements by Coe and Prevot on the numerous samples they collected through the entire thickness of flow B51 show a bumpy but continuous transition from the ‘reversed’ polarity in the lava flows below to the ‘normal’ polarity in the lava flows above, just as expected.Next comes the question as to how long it took for this magnetic reversal recorded in the lava flow to occur? This can be reasonably ascertained if it is possible to calculate how long it took for the lava flow to cool to 500°C, since at that temperature the magnetization of the magnetic grains in the basalt would be ‘frozen’.For this purpose, Coe and Prevot used a very simple model of heat conduction that has been long established,26 and which suffices to calculate a reasonable value of the cooling time of a basalt flow, as verified by the use of actual temperature measurements from similar lava flows on the island of Hawaii.27From their calculations, they concluded that the entire lava flow would cool to 500°C or below in about 15 days. This means that the magnetic polarity transition recorded in the lava flow had to be made in less than two weeks! An ‘astonishingly’ rapid reversal rate! Coe and Prevot commented: ‘This period [of 15 days] is undoubtedly an overestimate…Nonetheless, even this conservative figure of 15 days corresponds to an astonishingly rapid rate of variation of the geomagnetic field direction of 3° per day.’28They also estimated that the minimum change in magnetic field intensity was at an average rate of at least 300 gammas per day. This compares with typically measured rates of geomagnetic variation globally today of only a few degrees per century and about 150 gammas per year.29,30 No wonder Coe and Prevot found the calculated rate in lava flow B51 at Steens Mountain hard to believe: ‘The rapidity and large amplitude of geomagnetic variation that we infer from the remanence directions in flow B51, even when regarded as an impulse during a polarity transition, truly strains the imagination…’31 With due caution, Coe and Prevot thus felt prompted to search for alternative explanations. However, since other hypotheses required ‘special pleading’, they decided that the most straightforward interpretation explains the data best, that is, ‘the balance of evidence now in hand weighs in favor of rapid geomagnetic field variation.’32 They concluded: ‘We think that the most probable explanation of the anomalous remanence directions of flow B51 is the occurrence of a large and extremely rapid change in the geomagnetic field during cooling of the flow, and that this change most likely originated in the [earth’s] core. This interpretation must remain tentative until our investigation is completely finished, but, if true, it has important implications for the reversal process and the state of the earth’s interior.’33 How significant?

With just this one study completed on this flow, being the one and only example to date of a rapid magnetic polarity reversal found recorded in a rapidly formed single rock layer, we cannot be dogmatic that Coe and Prevot are correct, although as far as we can tell their work is very meticulous and quite thorough. They have been suitably tentative, although they have explored every other possibility as far as they can ascertain. Of course, part of their reticence to

accept the implications of their own results is due to their strict adherence to the evolutionary time framework in which the postulated dynamo generating the earth’s magnetic field has supposedly operated.However, so significant is this discovery, Coe and Prevot’s paper was highlighted and commented upon in the international weekly journal Nature. 34 In

that report, the author was cautiously favourable to Coe and Prevot’s interpretation of the palaeomagnetic data, being unable to challenge the data presented by Coe and Prevot, or the analysis by which they arrived at their conclusions.However, quite predictably, the same author seemed reluctant to abandon his ingrained evolutionary view that thousands of years are necessary for a geomagnetic reversal. Instead, he appeared to be hoping that some alternative explanation will eventually emerge which would relieve him from the implications of the field data for reversals. But, he also admitted: ‘Palaeomagnetism has a history of giving shocks to the geological and geophysical community. Usually these are initially unpalatable, although they are later accepted.’35 Conclusions

So, as Humphreys says, if Coe and Prevot are correct, we can infer important facts about the earth at the time when this ‘Miocene’ lava was flowing at Steens Mountain, a time which many creationists would place during the latter part of the Flood year, or soon thereafter.36 Some physical process must have then been at work in the earth’s core which could produce very rapid reversals of the earth’s magnetic field.The magnetic field change found recorded in flow B51 at Steens Mountain was about 50,000 times faster than the 2,000 plus years previously thought to be the theoretical minimum time for geomagnetic reversals, and millions of times faster than the shortest reversals previously found recorded in geological strata, that is, according to the evolutionary time-scale. But these actual field data were found exactly as the creation scientist Humphreys, working within a young earth framework, predicted they would be. So if the magnetic reversals have occurred in days and weeks rather than thousands and millions of years, then the earth’s rock layers, in which there is a continuous sequence of these magnetic reversals, are by implication probably only thousands of years old. Thus these data are important new evidence for a young earth.

Rocks Around the Clock: Do Zircons Contain Reliable Time Stamps and Early Earth’s Secrets?

by Dr. Andrew A. Snelling and Dr. Elizabeth Mitchell on February 26, 2014 Abstract

Zircon grains are found in rocks all over the earth. Despite debate about the accuracy of the uranium “clocks” they contain, scientists led by University of Wisconsin’s John Valley say they’ve found one grain with a confirmed age of 4.4 billion years. From it they suggest information the secular world finds surprising about hospitable conditions on the early earth. When we examine the assumptions underlying their claims, however, we find their conclusions are built on a wobbly house of cards. Do zircons—crystals of zirconium silicate—contain clocks you can trust? Crystals of zirconium silicate can be found inside many sorts of rocks in the earth’s crust. Most are small, and they often contain even smaller particles of enormous interest. Trace elements trapped in the crystals may offer clues to the conditions under which the crystals were formed. Oxygen isotopes and atoms of radioactive uranium trapped in the crystals are, many believe, frozen in time.Confined as they are in these crystals, many scientists believe that the ratio of parent radioactive uranium to daughter lead atoms in zircons can be used to calculate the ages of the crystals. These tiny zirconium silicate crystals can survive seemingly intact despite erosion, changes in environment, and metamorphic conditions that radically alter most rocks. Therefore, the oldest zircons are considered to be the best indicators of what the early earth was like.Though apparently impervious to their environmental conditions, zircons can be ravaged from within. Radiation emitted from trapped uranium and thorium atoms can disrupt their crystalline structure. It is possible for the lead atoms—all believed to be the products of radioactive decay—to move. Therefore, many debate the accuracy of these clocks in the rocks.A team led by University of Wisconsin geosciences professor John Valley, writing in the February 23, 2014 issue ofNature Geosciences, reports they have pinpointed the location and identity of the individual lead atoms in sub-microscopic sections within one zircon grain from the Jack Hills sandstone north of Perth, Australia. This zircon grain is the width of four human hairs. The research team claims to have confirmed that the lead atoms in that particular crystal’s clock have not moved significantly since the crystal was formed 4.4 billion years ago.Confident they have a clock they can trust, Valley’s team also made a surprising discovery about the conditions under which the crystal was formed. Because secular scientists like Valley believe the earth is 4.56 billion years old, they believe this little crystal has a lot to say about the earth shortly after it coalesced into molten rock from matter thrown from a solar nebula. Oxygen isotope ratios in the crystal are consistent with formation in an environment that contained liquid water.The little crystal Valley’s group analyzed supposedly dates to a time some

scientists call the Hadean age. The name is drawn from Hades, the mythological Greek god of the underworld. Even the student unfamiliar with Greek mythology recognizes the hellish implications of the name Hades, reflecting the secular belief that the early earth remained a hot and uninhabitable place for a long time.Their findings, Valley’s team says, suggest instead that the earth cooled and formed a crust quite quickly, within 100 million years of its fiery beginnings. The oldest known fossils—stromatolites—carry a conventionally assigned age of almost 3.5 billion years, far younger than this zircon. But those surprisingly cool conditions documented in the crystal, presumably only 160 million years after the solar system formed, allowed water to condense on earth and form oceans in which life may well have evolved as early as 4.3 billion years ago. This is an image of the latest history-making Jack Hills zircon. Though lead (Pb) atoms in the zircon presumably migrated into clusters 3.4 billion years ago under the influence of the grain’s hot environment at that time, researchers assume the atoms haven’t budged since then. Image: John

Valley et al./University of Wisconsin-Madison in Nature Geoscience through Yahoo.com

This is a timeline purporting to display the unwitnessed version of earth’s history created byevolutionists. It is not possible to accept this version of history, which is built on a host of unverifiable assumptions piled one upon another. Chain of Evidence, or Chain of Assumptions?

In their paper “Hadean age for a post-magma-ocean zircon confirmed by atom-probe tomography” Valley and colleagues interpret their research results through the lens of multiple levels of assumptions. Each interpretation is built on the assumptions at that level and the interpretation from the previous level. Let’s analyze their chain of arguments very carefully. As we unravel their claims, the discerning reader will see that the whole tapestry Valley has woven falls apart. Just the Facts, Please What are the observational facts? What did Valley’s team actually see? They examined tiny zircon grains, each measuring about the width of four human hairs. These zircons were extracted from a metamorphosed sandstone layer in a low range of hills called the Jack Hills on a sheep ranch in a remote arid region about 500 miles (800 km) north of Perth, Western Australia. That’s all! From here on Valley’s team makes assumptions to build each level of their interpretation. What they believe about the history of these crystals determines the story they believe the crystals are telling. History of the Zircons

First, it is assumed that the particles making up the Jack Hills sandstone in which the zircons were found were eroded from pre-existing rocks and transported by water to be deposited in this layer. And what kind of rock could have produced these zircons in the first place? Since zircon grains initially crystallize at high temperatures (1800°C), the team assumed the zircon grains in this sandstone must have come from a rock crystallized from hot magma. Sometime after the rock cooled, they believe it was eroded and the zircons birthed in it were transported by water to Jack Hills. This history all sounds reasonable, but none of it was observed. This entire scenario is based on inferences about what happened in the distant past, including an assumed naturalistic origin for the earth. History of the Earth

Secular scientists like those on Valley’s team assume that the earth was formed out of a solar nebula as hot matter was thrown out from the sun and coalesced to form a ball. Subsequent meteoric bombardment blasted our moon from the earth, so the story goes, and the energy from that hit “that formed our moon . . . melted and homogenized the earth,”1 as Valley explains in a news release, leaving its surface an ocean of magma. Thus they assume that the earth formed from the sun after the sun formed, and then only subsequently after the magma ocean cooled enough for water to condense from steam was the earth covered in water. That water, they believe, then eroded the rocks which had crystallized and cooled from the magma ocean, and then transported and deposited the resulting sand and zircon grains in this sandstone layer. Tiny Tales of Grand Scope

The next level of interpretation begins with the U-Th-Pb (uranium-thorium-lead) dating of the tiny zircon grains extracted from the Jack Hills sandstone. Of the hundreds of zircons that were analyzed and dated, only four yielded dates greater than 4.3 billion years old. Yet as the writers admit, those four grains have been used to provide “a basis for theories of crustal growth, tectonics, surface conditions and possible habitats for life on early Earth”!2 In other words, from four microscopic mineral grains a whole story has been told about the early history of the earth. That story is based on the assumption that only random natural processes have operated over eons of time with no hint that any Creator was necessary or involved.Now, of those four tiny grains deemed to be old enough, only one grain was selected for this present study. The authors do admit that there has been a lot of “uncertainty about the cumulative effect of un-annealed radiation damage and mobility of radiogenic isotopes [which] has led to questions about the reliability of ages and other geochemical characteristics of these zircons.”3 In fact, it was for these reasons the study of that solitary zircon grain was undertaken. The Dates Are Good Except When They Aren’t

Like other scientists who have previously dated this and the other zircon grains, the authors of this study never question that the U-Th-Pb dating method is anything but reliable in providing absolute ages. While recognizing potential problems owing to the mobility of lead atoms within the zircon grain, they are completely blind to the many other unverifiable, worldview-based assumptions that govern their interpretation of their entire radiometric dating methodology.They never recognize the underlying unprovable assumptions on which the U-Th-Pb system is based. The starting conditions (e.g., the amount of lead present when the crystal formed) can never be known—how do we know that noneof the daughter lead atoms we measure today were not there in the zircon grain at the beginning? Actually, they doassume there were at least some daughter lead atoms at the beginning, but only because of what is believed to be primordial lead in one iron meteorite, which has no parent uranium atoms but some daughter lead atoms in it! They are therefore constrained by what they believe about that meteorite to concede that some lead atoms could have been present when this zircon grain originally formed, even though lead atoms are thought to not fit into the zircon crystal lattice. But how much “daughter” lead was not derived by uranium decay? Even admitting that some “daughter” lead atoms might have been in the grain to start with does not tell them how much lead not derived from uranium decay there might have been.Next, can we be sure the U and Th have always decayed at the same rates we measure today? No! We have measured U and Th decay for only 100 years, but is it reasonable to assume the decay rates have been constant at today’s rates for 4.5 billion years? This is not to suggest that natural laws have changed, only that conditions have not always been the same, and those conditions may have affected the rate at which processes like radioactive decay took place. In fact, this is not idle speculation and conjecture! We have solid evidence that radioactive decay rates cannot have been constant. For example, discordant dates have been obtained on the same rocks by the different radioisotope methods. Discordant dates have been derived from helium diffusion and U-Pb dates on the same zircon crystals. Coexistent U and Po radiohalos argue against perpetual uniformity of decay rates. So do grossly discordant radiocarbon and radioisotope dates.4 Given ample evidence observable in the present that decay rates have not been constant throughout the supposed “deep time,” it is not reasonable to assume they have been uniform through unobservable eons.Finally, how can we be sure there has been no contamination of the relevant trace elements inside these zircons? Such removal or introduction of the “parent” or “daughter” atoms would completely invalidate the clocks in the crystals. Along that same line, migration of the lead atoms within the crystals would also “reset” the dates, rendering the “ages” of the crystals completely inaccurate. How can we be sure there has been no resetting of the dates during the billions of years? To answer this last question was the exact reason for this present study. And while the researchers decided the lead atoms in this little zircon have not moved enough to matter, they have not even begun to address the other unverifiable assumptions on which their methods are based. Tunnel Vision

So how good for this purpose was this one tiny zircon grain? Did their analyses demonstrate that the lead atoms did not move? And if so, what does that do for the trustworthiness of Valley et al.’s conclusions? Actually, even their own published photos—including those in the news releases (see the photo above)—demonstrate conclusively that this grain, like all the others, has a complex internal pattern of concentric crystal zones. They freely admit that these zones are compositionally different. Yet the authors only partially acknowledge this heterogeneity when they mention that there is a core that they date at ~4.4 billion years. They analyzed many tiny spots, and they describe an outer overgrowth (clearly visible as gray in the above photo) which they date at ~3.4 billion years, based primarily on the Pb-Pb dates. But in so doing they ignore a Th-Pb date, which they relegated to the supplemental information attached to their paper, that yields a date of only 492 million years! In fact, even within the “~4.4 billion year-old” core, their published images clearly show

compositional variations (the core is only the innermost zoned section inside the blue colored area in the photo above). Between this innermost core and the gray overgrowth crust there are clearly additional compositional zones within the blue colored area, including some they label as “disturbed.” Plus, there are tiny quartz inclusions. Such quartz inclusions are problematical for them because quartz crystallizes at a much lower temperature than zirconium silicate, raising the questions of how quartz inclusions could be there if the zircon crystallized first at high temperatures, and how could they have survived intact if the zircon has been reheated and also weathered through all the time and conditions to which it supposedly has been subjected. Zooming in on Lead Atoms

Finally, we come to the crux of the present study, the atom-probe tomography analyses of nano-domains. This new technique purports to count atoms within even tinier regions than those addressed above, much less than a tiny fraction of a hair’s width. Valley’s group shows, and therefore claims, that within the tiny area they scanned there are distinct clusters of atoms with uniform Pb isotope composition correlated with clusters of atoms of the rare element yttrium (Y). They consider the apparently uniform isotopic composition in these clusters combined with the presence of yttrium to be like a fingerprint identifying the migration of those lead atoms into these clusters. They confirmed that the Pb isotope composition in the full volume of these very tiny (sub-microscopic) clusters was the same as that obtained by the standard SIMS (secondary ion mass spectrometry) technique used to date the tiny spots elsewhere within this zircon grain. However, they then admit that the cores of these very tiny clusters yield a Pb isotope composition that equates to a Pb-Pb age for them of ~5.5 billion years, which they quickly add “is significantly older than the age of the Earth and clearly not correct.”5 That of course begs the question as to how do we really know whether any of the other ages are correct? How Much Is Too Much?

Given the great heterogeneity of even the most relevant parts of this zircon grain and the dating aberrancies so casually disregarded, how does Valley’s team conclude that the ~4.4 billion year age is accurate? After all, determining the accuracy of this date was the objective of the study! They admit these very tiny clusters formed as a result of migration of Pb atoms within the crystal after it formed. (Remember, it is this migration that scientists suspect of resetting the clocks in the zircon and making their times suspect.)On their published U-Pb dating diagram, however, the authors project a line representing the Pb isotope composition of the cores of the very tiny clusters from the ~4.4 billion years age (when the zircon grain supposedly crystallized) to where the line “happens” to intersect the U-Pb isotopes growth curve at the ~3.4 billion years age—the presumed age of the zircon’s outer overgrowth (the gray-colored outer zone in the photo above). Because they assume that overgrowth resulted from heating of the rock containing the zircon grains, they assume the Pb atoms migrated to form these very tiny clusters in the nano-domains within the core during that heating event. Yet if that process—a heating event that metamorphosed the host sandstone—caused the clustering in the first place, why have subsequent events and geologic processes presumably not perturbed those lead atoms further during the subsequent ~3.4 billion years! The ages measured in the relatively larger spots in the crystal core must therefore be reliable, they

conclude, because only very tiny clusters of migrated lead atoms were created within the much larger spots by the disturbance of outside forces, and so there cannot have been any additional disturbance since then. The clusters of migrated lead atoms musthave been frozen in time! Why? Because those who claim to have the key to confirming the age of the world’s oldest rocks need for them to be so! And all this just goes to confirm, they believe, that the earth must have

been covered by a magma ocean prior to the crystallization of this tiny zircon grain ~4.4 billion years ago, a magma ocean caused by the impact that formed the moon!

Journey to the Center of the Earth So much about earth history depends on a correct understanding about the inner workings of our planet. But how can we

know anything about the earth’s interior since we can’t actually go there and see it firsthand? Jules Verne captured imaginations in 1864 with his epic science fiction novel A Journey to the Center of the Earth. Despite huge technological advances, such a journey would be

impossible, not because we lack interest but because the earth isn’t hollow.How do we know this? In fact, how do we know anything about the earth’s interior? This question isn’t trivial. Our modern economy depends on a correct understanding of the earth, as we incessantly search for oil and essential minerals, and predict deadly earthquakes or volcanic eruptions. Moreover, the modern debate about the origin of the solar system and the universe revolves, in part, around what makes up the earth’s interior and the dynamic forces that shaped and moved the continents.Drilling alone can’t tell us much. Until recently the deepest drill-hole, the Kola Superdeep Borehole in Russia, reached a depth of 7.6 miles (40,230 feet, or 12,262 m). This impressive feat took nearly twenty years (1970–1989). Oil wells drilled in Qatar in 2008 and 2011 reached only a few hundred feet (tens of meters) deeper, but these are all still pin pricks compared to the 3,960 miles (6,371 km) to the earth’s center. The Size and Density of the Earth

The earth’s vast size is hard to imagine. Yet humans have known about it since early times. Pythagoras (about 530 BC) was probably the first to recognize that the earth is a sphere.1 By sitting at the harbor and observing the approach of ships from beyond the horizon—first the masts and sails, and then the hull peeped over the horizon—he realized that the earth’s surface must be curved.Eratosthenes (276–196 BC), chief librarian at Alexandria in Egypt, devised a simple and elegant method for estimating the size of the earth and the distance to its center, without the need to travel around the world (see sidebar for details). He calculated the earth’s circumference to be approximately 25,000 miles (40,234 km), only 2% above the actual value.Isaac Newton furthered our knowledge of the forces holding the earth together when he formulated the law of gravity. All the particles of the earth are pulled toward the center of gravity, and the spherical shape is the natural result.These principles are necessary to help us investigate the composition of the earth. What kinds of materials—light or heavy, liquid or solid—fill this sphere? To begin, we must establish three basic facts: volume, mass, and density. Volume

Volume is easy to calculate. We know the “space” inside a ball simply by knowing its circumference. The earth’s circumference has been confirmed by surveying measurements, both on the earth and from space. The earth is not quite a perfect sphere, but we can still easily calculate its circumference and volume. Mass

The mass of the earth—the amount of matter it contains—is a little tougher to find. It can be estimated from the orbital period of the moon (the time it takes the moon to complete one orbit around the earth). Density

We can calculate the earth’s density by dividing the mass by the volume. This gives us a hint about what kind of materials are inside the earth. We simply need to compare this density to the densities of typical rocks we find on the surface. Typical rocks have densities of about 156–187 pounds per cubic foot (2.5– 3.0 grams per cubic cm). Yet the earth’s density is much higher—an average of 343 pounds per cubic foot (5.5 grams per cubic cm). How then can we reconcile these different values? Not Just Compressed Rock

With increasing depth, the pressure within the earth becomes immense. The temperatures also increase. The weight of the overlying rock compresses the interior, which increases the density.We can measure this effect in the laboratory. Yet if we compress surface rocks to pressures equivalent to the earth’s interior, we still do not obtain the same high density.So we have to conclude that the earth is not made entirely of rock. The material deep within the earth must have a much higher density than simply that of compressed rock. Evidence from Seismic Waves

We can learn something about a body of material by the way certain waves pass through it. Such waves pass through air, water, or molasses in different ways.An earthquake generates seismic waves that can travel all the way through the interior of the earth. It is somewhat similar to a pebble dropped into a pond. The waves emanate in circles out from the point of impact and are clearly visible. The sound waves that we generate in the air when we speak are similar but invisible. Seismic waves in rocks are similar to the invisible sound waves in the air.As seismic waves travel through the earth away from an earthquake, they eventually reach the earth’s surface again where they can be detected (Figure 1).

We can then use them to probe the earth’s interior in a way similar to how x-rays reveal our internal anatomy.By analyzing these seismic waves, researchers have constructed a model of the earth’s interior (Figure 2). At a depth of about 1,796 miles (2,890 km)—about 2,163 miles (3,481 km) from the center of the earth—an abrupt change in the behavior of seismic waves indicates that there must be a sudden increase in the earth’s density. This corresponds to the core-mantle boundary. Evidence of the Core from Seismic Waves

Earthquakes generate various seismic waves (such as P-waves) that travel through the earth’s interior. By analyzing how these waves change behavior when they reach different regions, we can learn where the density changes significantly. At a depth of about 1,796 miles (2,890 km), an abrupt change indicates a sudden increase in density. This corresponds to the core-mantle boundary.If we look at a chart of different metal densities, iron best fits the density at the core, and olivine (a magnesium-iron silicate mineral) best fits the mantle. Even though the core is made of the same basic iron material, certain seismic waves travel differently through the outer core, indicating that it must be liquid, while the inner core is solid.

Giant’s Causeway Northern Ireland

by Dr. Andrew A. Snelling on July 1, 2014 The Giant’s Causeway, Northern Ireland’s most iconic landmark, has attracted millions of curious travelers over the centuries. Some 40,000 strange, interlocking columns form a “road” of stepping stones that lead from the coastal cliffs down into the sea. The edges of each column line up so perfectly they look like the work of a skilled Inca mason.

AlbertoLoyo | Thinkstockphotos.com

Rising up along northern Ireland’s coast is a series of tall, geometric stepping stones. These basalt columns formed during the flood, as lava oozed over the region, cracking into regular patterns as it cooled. Legend has it that Irish giant Finn MacCool built the causeway so he could travel across the sea to fight a challenger in Scotland without getting his feet wet. (Similar columns rise from the sea in the Scottish Isles.) Evolutionary geologists say the causeway was formed by massive volcanic eruptions 50–60 million years ago. How Did It Really Happen?

The first clue is that these columns are made out of basalt, a rock formed from cooling lava. When we observe lava cooling today, it shrinks and cracks. Under the right conditions—uniform mineral content and slowly falling temperatures—the cracks follow geometric patterns.As the lava contracts, fractures first appear on the surface. Then the cracks extend deeper into the mass as it cools, forming the pillar-like columns.The columns contracted at the bottom and top simultaneously. This would mean that the bottom shrank upward, while the top shrank downward. In

many cases the bottom is convex, as expected, while the upper segment is concave, producing what are called “ball-and-socket” joints.In theory, based on how cooling lavas should behave, the basalt columns should all be six-sided (hexagonal). However, nearly one-third are five-sided (pentagonal), and a few others are four-, seven-, and eight-sided. This goes to show that real-world geology doesn’t always follow our initial, simple theories.Most columns are about 15 to 20 inches (38–51 cm) in diameter, around the size of a common patio stone. The size of the columns was primarily determined by the speed at which the lavas cooled. And not all the columns are vertical. Some are tilted where the cooling surface was sloped. Several lines of evidence indicate that Giant’s Causeway formed during several volcanic eruptions that occurred in rapid succession. After each eruption, the thick basalt started to congeal, cool, and harden, aided by being briefly covered with water, before the next lava flow covered it. The middle flows in the sequence are slightly different in content than the others, and these are the ones that consist of regular, well-developed columns, particularly in their lower parts. The “causeway” is part of a massive basalt deposit, known as the Thulean Plateau, estimated to cover 700,000 square miles (1,800,000 km2) and be nearly half a mile thick. Where did all this material come from? We simply don’t see anything on that scale today. The Flood produced just the right conditions. As the earth’s plates moved rapidly apart (opening up the Atlantic Ocean), huge fissures opened in the crust. Massive amounts of thick lava flowed through these openings into the North Atlantic,

covering Greenland, Iceland, western Scotland, and northeast Ireland. These land areas were closer together then but shifted apart as the plates continued to move at the Flood’s end and rapidly decelerated in the early post-Flood era. The basalt lavas here did not erupt violently, but instead poured out of the ground like a thin oil (similar to the volcanoes in Hawaii today, but on a much larger scale). Eruptions were intermittent in pulses, as seven successive flows, most of them measuring nearly 100 feet (30 m) thick, stacked on top of one another. Later erosion exposed some of the columns that formed within these layers.Iron fits this estimated density and behavior. Iron would also explain the earth’s

magnetic field. If a small amount of nickel is added to the iron, the earth’s overall density almost perfectly matches the earth’s average density.Even though the core is made of the same basic material, it appears that it is divided into two parts: an outer and an inner core. Certain seismic waves travel differently through the outer core, indicating that it must be liquid, while the inner core is solid. Volcanoes—Windows to the Earth’s Interior

We learn other clues about the interiors of continents by the materials that volcanoes belch out. As molten rock passes through the earth’s deep continental crust, chunks of rocks are broken off. When the lavas erupt and cool, many of these chunks remain intact.The basalt lavas that picked up these chunks of continental rocks on their way to the earth’s surface are a different kind of material. So they must have a different source below the crust, from the uppermost mantle. This is consistent with the seismic evidence. Sometimes these basalt lavas also bring up chunks of uppermost mantle rock.Another confirmation that we are looking at upper-mantle rocks is the rare occurrence of diamonds in them. Inside the earth, diamonds are stable at depths greater than 100 miles (160 km). The conditions at shallower depths can actually turn diamonds into graphite! That means the likely source of these diamond-bearing rocks is at least 100 miles down in the upper mantle. Their composition confirms what we expected the upper mantle to be like. Evidence from the Earth’s Wobble

Another clue about the earth’s makeup is its wobble. The earth spins like a top, with its spin axis tilted at 23.5°. This spin causes it to bulge slightly (by 13 miles [21 km]) at the equator and to contract a little at the poles. So the earth wobbles as it spins.This wobble occurs in a predictable pattern. If the “top” were made out of the same material throughout, it would theoretically take about 31,500 years for the earth’s wobbling axis to complete one full circle. But instead, we can calculate that it would take only 26,000 years .By measuring the earth’s wobble and bulge, and estimating the forces of gravity exerted by the sun and moon, it has been shown that material in the earth’s interior must be much denser than that on its surface. Iron in the earth’s core helps explain these observations. Evidence from Meteorites

Another hint of the material within solid planets comes from out in space. Between Mars and Jupiter is the asteroid belt, which contains rocky objects ranging in size from less than an inch (mere millimeters) to several hundreds of miles (or kilometers) across. Collisions in the asteroid belt cause fragments of asteroids to be ejected from their orbit into a collision course with the earth. Entering earth’s atmosphere, most asteroids burn up, forming meteors or shooting stars. Those fragments that reach the earth’s surface are called meteorites. Most meteorites (but not all) are believed to have come from the asteroid belt.Stony meteorites constitute almost 95% of catalogued meteorites. The major mineral in them is olivine. This is the same major component in the chunks of mantle rock brought up to the earth’s surface. Just over 4.5% of meteorites are irons. They consist of iron-nickel alloys, which match the composition of the earth’s core deduced from other evidence.Secular astronomers generally claim the asteroid belt is leftover materials from when the solar system formed. If this is the case—and we do not know for sure—the asteroid belt may be “leftovers” from that process, and asteroid fragments that fall to earth as meteorites may provide us with samples of the possible internal composition of rocky planets. Conclusion

While we cannot directly sample deep inside the earth, researchers can use several lines of evidence together to provide a confident answer to our question—what is inside the earth? Our best scientific estimates are that beneath the outer skin, called the crust, is a rocky mantle composed primarily of olivine, and at the center of the earth is the core, composed primarily of iron with some nickel as an alloy. Under the unique stress and heat inside the earth during the Flood event, these interior rocks would have weakened by a factor of over a billion, allowing the fragments from the breaking up of the original supercontinent to slide catastrophically into their current configuration. The earth’s interior has yielded many other secrets about the forces at work at the edges of those continental fragments, helping us piece back together the original appearance of the earth’s continental plates and how they behaved when they moved apart and crashed into each other. (More to come in future issues of the magazine!) Eratosthenes’ Method—Around the World in Only a Day

One of the most amazing calculations in all of earth history was possible because a mathematician in Egypt used his head rather than his feet. You need to know only two points on a sphere to calculate the distance around the rest of the sphere. Eratosthenes realized he could determine a second point without even traveling anywhere. He had heard that at the city of Syene, located on the Nile River (where Aswan is today), the sun shines vertically at noon on the summer solstice. (The solstice is the longest day of the year, in the Northern Hemisphere, usually June 21.) So a

vertical stick there casts no shadow. At his own hometown of Alexandria, roughly 500 miles (805 km) to the north of Syene, he noticed a very perceptible shadow.Next, all he had to do was the math (basic algebra). He could easily determine the angle from the center of the earth (θ) to Syene and Alexandria. It was just over 7°, or almost exactly one 50th of 360°. That means that the approximate length of the whole circumference was 50 times the distance between Syene and Alexandria—that is, 50 x 500 = 25,000 miles. Calculations from the same measurements can also tell us the distance to the center of the earth—approximately 3,960 miles.

The Devils Marbles

Northern Territory, Australia by Dr. Andrew A. Snelling on July 1, 2014

An early Australian explorer trekking into central Australia found large, round boulders scattered across the surface, sometimes in huge stacks, and sometimes precariously balanced on a tiny base. He reported in amazement, “This is the Devil’s country; he’s even emptied his bag of marbles around the place!” And the name stuck.

LSphotos | Thinkstockphotos.com Strewn around the ground in Australia’s interior are rounded, free-standing boulders. The original granite blocks were formed during Creation and later sculpted in the harsh environmental conditions after the Flood.The Devils Marbles are an iconic landmark in Australia’s Outback. The local indigenous Australians call the region Karlu Karlu (“round boulders”) and consider it a sacred site. A dreaming story says the Devil Man created these features when he left twirled clusters of hair on the ground that became round boulders. Evolutionary geologists say the rocks formed deep in the earth 1.7 billion years ago, and then erosion over long ages produced these features at the surface. How Did It Really Happen?

The erosion of the granite in the conventional geologic story does explain the boulders but not the timing of their formation. Two catastrophic episodes in earth history could explain when granite formed rapidly.The actual science

behind these boulders is pretty straightforward. Deep in the earth’s crust (its thin outer skin) the temperatures and pressures were so high that the rocks sometimes melted to form granite magma (molten rock). This magma then squeezed upwards along fractures and collected wherever spaces were forced to open up close to the earth’s surface. There the granite magma cooled and crystallized to form the rock called granite.These granite masses shrunk a little as they cooled and crystallized, but no cracks opened up because the immense weight of the overlying rock layers pushed the rock mass tightly together. However, once the overlying rock layers eroded away during the Flood, the release of weight allowed cracks to open up.Because of the regular pattern of mineral crystals in granite, the cracks followed an even and geometric pattern (see figure). The granite mass broke up into many large blocks, roughly cubic in shape.Many of these blocks wore away quickly under the heavy rains and harsh conditions that immediately followed the Flood. Water carried chemicals down into the cracks, causing the granite to weather and decay rapidly.Two processes sped up the breakdown. The surfaces constantly expanded and contracted as a result of chemical weathering and daily temperature fluctuations. In today’s desert environment, the heat of the sun causes the thin outer “skins” of the blocks, along with the minerals in them, to expand slightly; after nightfall they contract slightly. The outer skins eventually cracked and fell off, rounding the boulders so they look like peeling onions. These processes together are thus called spheroidal or “onionskin” weathering. The net result is the piles of perched and rounded granite boulders, or tors. How Were Devils Marbles Formed?

The boulders are remnants of a granite mass that formed deep in the earth during creation. As the magma cooled, it shrunk and cracked. But the weight of the overlying rock layers kept the cracks from appearing.When the Flood washed away the overlying rock layers, it released the weight on the granite, and cracks opened up. The receding floodwaters scraped the continent down to the bedrock, exposing the granite.Because of the regular pattern of crystals in granite, the cracks produced a regular pattern of large blocks. These blocks wore away quickly under the heavy rains and harsh chemical conditions following the Flood.The breakdown was accelerated by daily temperature fluctuations that caused the thin outer “skins” to expand and contract. Eventually the skins fell off, rounding the boulders like peeling onions.

Arches of Utah

Arches National Park, Utah by Dr. Andrew A. Snelling on July 1, 2014

Located just outside Moab, Utah, is a wonderland of more than 2,000 natural arches. Towering 85 feet (26 m) overhead, and spanning 65 feet (20 m) is the best-known rock arch in the world, Delicate Arch. Nearby is one of the world’s longest natural arches, Landscape Arch (a whopping 291 feet, or 89 m, long). Everywhere you turn are spectacular arches of various shapes and sizes, such as Double Arch, Skyline Arch, and Tower Arch. Why are there so many natural arches in this one area? How Did It Really Happen?

gcgebel | Thinkstockphotos.com Standing alone on a hillside is the world’s best-known arch, Delicate Arch, towering 85 feet (26 m) overhead. The flood set in motion a sequence of events that produced such wonders very rapidly.Evolutionary geologists recognize that massive earth movements were required, but they mistakenly assume long spans of time. The problem is that they have chosen to ignore the unique impact the Flood had upon the earth’s surface.Creating such delicate features requires more than gouging big holes into sandstone. A long series of events had to happen beforehand. First, some process had to create tall, thin rock walls, out of which the arches were carved. These rock walls are called fins (see figure). They appear in parallel rows, like the furrows of a plowed field, and we can still see some today.Only later did water, chemicals, and—to a lesser extent—wind, eat away at these walls. In most cases the whole wall would crumble, but in some cases only the lower portions collapsed. Today we’re looking at the remains of these rows of walls (fins).Creating rows of rock walls requires special conditions. Sandstone must be deposited on top

of less stable material, which then shifts upward and causes the sandstone to break up into parallel strips. Arches National Park sits atop thick underground salt beds, which are very unstable. During the Flood, hot salty waters deposited these beds in a wide basin in this area, now part of the Colorado Plateau region.After the Flood deposited the salt beds, the waters tore debris from the nearby Uncompahgre Plateau (an Indian word meaning “dirty water” or “rocks that make water red”) and deposited the sands on top of the salt beds. These sediment layers included the Navajo Sandstone and the Entrada Sandstone. The weight of these accumulating rock layers caused the salt beds to liquefy and push up into salt domes. The arching and bending of the sand layers over the salt domes produced parallel fractures in the sandstone. Later the Flood deposited another mile of younger sediments (about 5,000 feet, 1,524 m) on top of the Entrada Sandstone.Next this whole region was uplifted at the end of the Flood, and the waters that rushed violently off the continent washed away most of the layers above the sandstone. The uplift further released pressure on the sandstone and caused gentle warping in the Entrada Sandstone, opening up additional closely spaced, parallel joints, 10–20 feet (3–6 m) apart.Most arches are carved out of the Entrada Sandstone, especially at the edges of the gentle hills that rose above the valleys. Slightly acidic rainwater slowly broke down the sandstone’s cement (made of lime), progressive ly releasing the sand grains. Such weathering and erosion by water and wind enlarged the fractures to produce narrow parallel sandstone walls or fins. Frost and cycles of freezing and thawing caused expansion and contraction of the rock surfaces, which progressively peeled off (exfoliated).Eventually holes appeared along the fractures that ran up and down the walls. The seeping water collected at the bases of the walls and evaporated slowly. All this extra water caused the bases to weather more rapidly than the tops. Fragments began to loosen and fall, enlarging the openings into holes and then arches.Alternately, some of the holes may have appeared at the bottoms of the fins in places where the fins had filled in with sand and soil. Acidic water in the sand and soil wore away these holes while the fins were still underground. Later, the sand soil was removed, exposing the arches.Eventually arches will wear through and collapse. Forty-three arches have collapsed due to erosion since 1970. Their loss is a sober reminder how delicate—and recent—these formations are. Rapid processes created them and are now destroying them. How Were Arches Formed?

Arches are the remnants of a vast sandstone layer deposited on top of salt beds. When the sandstone was deposited on the salt beds, the weight caused the salt to liquefy and push up, fracturing the sandstone into parallel strips.

Rainwater broke down the sandstone and enlarged the fractures, producing tall, thin walls known as fins. The arches were carved out of these fins (left).Water, chemicals, and—to a lesser extent—wind, ate away at these walls. In most cases the whole wall crumbled, but in some cases only the lower portions fell (center).The seeping water collected at the bases of the walls. This caused the bases to weather more rapidly than the top. Openings were enlarged into holes and then arches (right).

Hawaii’s Volcanic Origins—Instant Paradise by Dr. Andrew A. Snelling on January 1, 2014

The young age worldview changes how you see everything, even a “paradise” like Hawaii. If the Flood destroyed the earth, where’d these islands come from? Only catastrophic earth movements—a result of the Flood—can explain this string of jewels.

Mention Hawaii, and it conjures up thoughts of a tropical paradise. Pristine waterfalls, luxuriant creeping vegetation, and squawking, duck-like coots remind millions of annual visitors about the Creator’s handiwork.But red hot lavas slowly moving across fields and engulfing roads are never far away. Indeed, the Hawaiian Islands are a string of active and extinct volcanoes that hint at a catastrophic past. If the volcanoes that formed Hawaii’s eight major islands had been formed before or during the Flood, the Flood would have deposited sediments on their flanks. But they have none. So we know the volcanoes must have erupted following the Flood.So how did eight islands pop up in a neat row in the middle of the Pacific Ocean after the Flood, 3½ miles (19,297 feet, or 5882 m) above the surrounding seafloor? The origin of these gems gives us a fascinating window into the incredible tectonic forces that tore apart the planet during the Flood. Indeed, we now have enough geologic clues to begin reconstructing what took place in the Pacific .Paradise RevisitedThe Hawaiian Islands are an archipelago of eight major islands, numerous small islets, and undersea mountain peaks called seamounts (Figure 1). They extend in an arc some 1,500 miles (2,400 km) from the island of Hawaii (the “Big Island”) in the southeast to the Kure Atoll in the northwest. The total land area of the Hawaiian Islands is a mere 6,423.4 square miles (16,636.5 sq. km), small compared to the world’s largest archipelago—the Malay Archipelago—which includes 24,000 islands and covers a million square miles. Figure 1—Rising Lava and a String of Pearls The Hawaiian Islands are the last in a string of volcanic islands that arose as the Pacific Plate moved over a “hot spot” in the crust. At the end of the Flood, eruptions began to produce dozens of islands stretching over 3,600 miles (5,800 km). The hot spot currently sits under Hawaii’s Big Island. The first islands, called the Emperor Seamounts, were small and most never grew large enough to reach the ocean surface. Radiometric potassium-argon dating shows that these seamounts are oldest, and the Hawaiian Islands are youngest. These islands formed quickly, over a few years, not “millions of years.”

Illustration by Tasa Graphic Arts, Inc. Yet the comparison is not fair. The Malay islands are made out of crust material from the nearby continents of Asia and Australia, while the Hawaiian Islands are made out of volcanic rock from the earth’s mantle. These volcanic islands are part of an even longer chain that extends all the way to Alaska. It is estimated that volcanic material in this chain would be enough to cover the entire state of California one mile thick. That was a lot of lava belching out of the earth in the past!1The Big Island at 4,028 square miles (10,432.5 sq. km) is made up of five broad, rounded, still-active shield volcanoes, the tallest being Mauna Kea, which towers to 13,803 feet (4,207 m) above sea level. If measured from its base on the ocean floor, its height is 33,100 feet (10,100 m), making it taller than Mt. Everest! Its still-active neighbor Mauna Loa, just 120 feet (37 m) lower, is the largest volcano in the world, covering a land area of 2,035 square miles (5,271 sq. km). Where Do the Lavas Come From?

The earth has an outer skin or crust, beneath which lies the mantle.2 Scientists believe the molten basalt that erupts from these huge volcanoes rises from the upper mantle. There is even evidence that a plume of hot rock is still welling up from the mantle and feeding the active volcanoes on the Big Island (Hawaii).

This mantle plume has pushed up the ocean floor beneath Hawaii, forming a huge, shallow “blister” or swell over 620 miles (1,000 km) wide. Currently the most active volcano is Kilauea on the Big Island, but the newest volcano is the Loihi Seamount, just to the southeast of Hawaii.Maui is the next largest island in size and the next in the chain. The islands quickly become smaller and smaller. Maui’s area is only 727.2 square miles (1,883.4 sq. km). Furthermore, its largest volcano, Haleakala, is only 10,023 feet (3,055 m) tall and is no longer active. Indeed, the volcanoes and the volume of lavas get progressively smaller as you progress along the chain toward the northwest.3 Intriguing Chains

This intriguing pattern does not end with the eighth island. Farther northward is yet another line of seamounts (undersea mountain peaks). Known as the Emperor Seamounts, this chain stretches another 2,100 miles (3,400 km) northward to Alaska’s Aleutian Trench (Figure 1). These seamounts are the remnants of former volcanoes but do not rise above the ocean surface. (Curiously, a few of these seamounts are flat-topped, implying they once were exposed above sea level and were eroded off.)A very interesting pattern appears. The largest and active volcanoes are at one end. As you move northward along the chain, the past lava output and volumes become progressively less and the volcanoes smaller, until the volcanoes don’t even rise above the surface and are long dead. What caused this progression?One clue is the relative ages of the rocks on the Hawaiian Islands and Emperor Seamount chains. Using the standard radiometric dating technique that measures the radioactive decay of potassium to argon (the potassium-argon method), we learn that the youngest volcanic rocks are on the island of Hawaii. (That’s what we would expect since its volcanoes are still active.) The volcanic rocks become progressively older northward along the chain. The central islands of Midway Island and Kure Atoll are said to be 28 million years old, and then the seamounts along the Emperor Chain date from 47 million years northward to 81 million years (Figure 1).While creationists strongly dispute the actual ages, they agree with the relative nature of the measurements (more later). The Moving Pacific Plate

The discovery that the earth’s crust is broken into moving plates has provided us with an elegant explanation for the islands’ pattern. The Pacific plate (making up much of the floor of the Pacific Ocean) has been moving northwestward. As the plate moved over the essentially stationary Hawaiian mantle plume, the rising molten rock built a series of seamounts and islands in quick succession (Figure 2). Figure 2—Hawaii Is a Hot Spot Most of the world’s volcanoes form where crustal plates crash into each other, but Hawaii is different. It lies over a “hot spot,” or mantle plume, where hot material breaks through the thin ocean crust.

Illustration by Tasa Graphic Arts, Inc. Radiometric dates show progressive “aging” from Hawaii (the youngest) to the seamounts (the oldest). These measure radiometric decay over months and years, not “millions of years (Ma).”Thus the seamount at the northern end of the Emperor chain was formed first, when that point was over this “hot spot,” incorrectly dated by the faulty radiometric method at some 81 million years ago. As the plate moved, it eventually reached the position where it is today, with the island of Hawaii and the Loihi Seamount sitting on top of the mantle plume (Figure 2).Old-earth, secular geologists say this plate movement has always been slow and gradual. To bolster their supposed case, they point to an interesting correlation. If you plot the radiometric ages of the different islands and seamounts against the distances from Kilauea, the rate of 2.6–3.6 inches (6.6–9.1 cm) per year just “happens to be” about the same as the plate movement today. However, if the plate motion had been uniformly slow at today’s rate, all the volcanic islands should have been of similar sizes.As for the “bend” where the Emperor and Hawaiian chains meet, it is thought the direction of the Pacific plate’s motion changed, starting some “47 million years ago” according to evolutionary scientists. No one knows yet why this direction changed. Perhaps the answer will provide some new interesting insights. It has also been suggested, though, that before this “bend” occurred the “hot spot” may also have been moving slightly.4 Making Sense of the Evidence

So what are we to make of all this within the young framework for the earth’s history?Creation geologists do not dispute that plate tectonics has occurred. However, they believe substantial evidence confirms that it occurred catastrophically during the Flood.5 Furthermore, as the Flood was waning, the plate motions decelerated from tens of feet (meters) per second to their current snail’s pace of only an inch or two (mere centimeters) per year. Any movement of the hot spot also would have ceased, while catastrophic outpourings of lavas from the hot spot rapidly decreased.And this view makes even better sense of the observed evidence, such as the sizes of the recent islands, which grew bigger due to larger volumes of lavas. As the plates slowed, there would have been more time for the upwelling mantle “hot spot” to send up lavas, even if the eruptions decreased. Thus the island of Hawaii is much larger than the other islands.In contrast, the plate was moving so rapidly when the Emperor chain was being formed that few of the volcanoes had time to grow big enough to breach the ocean surface.Perhaps the plate began slowing down as it changed direction to produce the bend between the two chains. Only when the plate motion slowed was there enough time to build the Hawaiian Islands, even if the lava outpourings slowed to a comparative trickle. Those Radiometric Dates?

But what about those potassium-argon millions-of-years dates? There are good reasons they must be regarded as greatly exaggerated.Excess argon rises with the lavas from beneath the earth’s crust, contaminating them so that they yield excessively old dates.6 This volcanic argon gas does not arise from radioactive decay of the potassium in the rocks, but instead it is trapped in the basalts, making them “read” older. Furthermore, potassium-argon dates of volcanic rocks on seamounts can increase with depth underwater, regardless of actual age.7This type of faulty assumption behind radioactive dating leads to exaggerated dates.8 Another crucial, unverifiable assumption made by evolutionary scientists is that the decay rate has been constant throughout time—that is, the radioactive “clocks” have always ticked at the same

rate. But creation research has demonstrated that all the decay rates were grossly accelerated in the recent past, during the global Flood cataclysm.9This finding indicates that, just as plates accelerated during the Flood and then decelerated, so radioactive decay rates accelerated, apparently in lockstep, and then decelerated. Thus the volcanic rocks that formed earlier as the Pacific plate moved over the “hot spot” yield exaggerated radioactive dates due to quickly ticking radioactive clocks. As the Flood ended, both plate motions and radioactive decay rates slowed. These are not true absolute dates because the “clock” was ticking faster than it does today.So while the Hawaiian Islands today appear to be a tropical paradise, they were built during the aftermath of the Flood cataclysm. Not only were the tectonic plate motions and volcanic eruptions catastrophic, but even radioactive decay was occurring at catastrophic rates.

The Florida Sinkhole Tragedy

Why Did It Happen, and Could It Happen Again? by Dr. Andrew A. Snelling on March 5, 2013

On Thursday, February 28, at about 11:00 PM (Eastern Time) a Florida man was in bed sleeping when a huge hole opened under his house, swallowing part of the inside of his house and him with it.Because it was deemed too dangerous to keep searching, on Saturday rescue workers called off their search for 36-year-old Jeffrey Bush, who had not been heard from since the hole appeared under his house in Seffner, just east of Tampa, in Hillsborough County. The remains of his house were perched over a huge sinkhole 20 feet wide and at least 30 feet deep, which was seriously unstable. So, on Sunday crews began demolishing the house from outside the perimeter of the sinkhole, which may extend down as much as 50 to 60 feet.While some in the neighborhood did not know of the risks, sinkholes are common in Florida. In addition to Florida, other U.S. hotspots for sinkholes include Texas, Alabama, Missouri, Kentucky, Tennessee, and Pennsylvania, according to the U.S. Geological Survey.Under most of Florida’s relatively thin veneer of soils, surface sands, and clays are numerous stacked limestone beds, the total thickness of which is up to 3,000 feet. Conventionally dated as Pliocene to Eocene (supposedly 3–40 million

years old), in the young age framework of earth history these fossil-bearing limestone layers were only deposited after the Flood waters had finished draining off the rest of North America. Their accumulation continued for a few decades into the post-Flood era, prior to the onset of the Ice Age.On the one hand, these thick limestone beds are a blessing, as they comprise the Floridan aquifer system, a huge reservoir of groundwater stored in interconnected cracks and pores within the rock (see map 1). This Floridan aquifer system is among the most productive in the world, supplying millions of gallons of water to homes and businesses throughout Florida, especially in the Tampa-Orlando area (see map 2). On the other hand, however, these groundwaters are also responsible for creating sinkholes! Unfortunately, these groundwaters within the limestones are slightly acidic. Rainfall percolates down through soils, sands, and clays that contain organic matter, producing humic acid. The slightly acidic groundwater then dissolves the limestone that lies beneath the soil, creating large voids or cavities in the limestone. If such cavities grow upwards, weakening the limestone, then when the overlying sands and clays can no longer support the weight of the soil and whatever is on top of it, the earth collapses into the cavity (see diagram).

(Source http://www.swfwmd.state.fl.us/hydrology/sinkholes/) Thus, Florida’s geological makeup increases the likelihood of sinkholes. Development of groundwater resources for municipal, industrial, and agricultural water supplies places additional stresses on this groundwater system and can alter the balance of the natural water cycle. Excessive pumping of groundwater and surface water, as well as periods of drought, can lead to falling regional groundwater levels and cause the soil to settle, thus triggering sinkholes to form. Others form under the weight of runoff-storage ponds, which cause the underground support material to collapse.Of course, this process does not require millions of years. With all the groundwater being pumped from the limestone, plus high rainfall and other factors, the large cavities that become sinkholes can form in tens to hundreds of years.Sinkholes of the sort that swallowed this unfortunate Florida man form suddenly. They are called cover-collapse sinkholes. When they occur, a hole typically forms and grows over a period of minutes to hours. Sediments may continue to slump down the sides of the sinkhole for several days, and erosion of the edges can last even longer. Fortunately, these cover-collapse

sinkholes are quite rare. A recent assessment of 1,400 sinkholes found only one or two.As frightening as it sounds, sinkholes happen all the time. Usually, though, they are slow-motion processes that can take years. More common is the slow, gradual subsidence of land, forming bowl-shaped depressions at the surface in a process than can last years, giving those affected plenty of warning.More than 500 have been reported in Hillsborough County since 1954 (see map 3). A monster 400-foot sinkhole that sucked in a house, five sports cars, two businesses, and part of a swimming pool appeared near Orlando in 1981. Sinkholes can reach more than 100 feet deep and several hundred feet wide. Others are tiny—a few feet across and maybe a foot deep. Some hold water and form ponds. It is fortunate that one sinkhole opening, does not necessarily mean another nearby is imminent. They are usually isolated events, according to the Florida Geological Survey. However, certain events such as a hurricane following a period of drought can trigger a series of sinkholes to occur within minutes to hours of each other. Sadly, dangerous sinkholes forming suddenly are yet another sign that we live in a sin-cursed world.

Volcanoes—Windows Into Earth’s Past

by Dr. Andrew A. Snelling on July 1, 2010 Audio Version

Few natural catastrophes today compare to the awesome spectacle of a volcanic eruption. The Mount St. Helens eruption of May 18, 1980, the most destructive in recorded U.S. history, unleashed the same energy as 400 million tons of TNT, or approximately 20,000 Hiroshima-size atomic bombs.1 Yet its explosive power is miniscule compared to past eruptions. The Mount St. Helens eruption produced an impressive 0.25 cubic miles (1 km3) of volcanic ash. But that is nothing compared to the eruption of Taupo (New Zealand) about 1,800 years ago, which produced 8 cubic miles (35 km3) of ash. Even this is dwarfed by an earlier Yellowstone eruption, soon after the Flood, which produced at least 480 cubic miles (2000 km3) of ash.2Such was the magnitude of these explosions that they blasted away huge holes in the earth, called calderas. The Taupo caldera is now filled by a huge lake, and the Yellowstone “hole” is so big you can only discern its boundaries with the help of satellites.Yet these eruptions are tiny compared to a different type of volcano that deposited gargantuan stacks of thick layers known as “continental flood basalts.”3 For example, the Deccan Traps of India are over a mile (2000 m) thick and spread over nearly 200,000 square miles of the Indian subcontinent (500,000 km2)—about the same area as modern France! The Siberian Traps in Russia are even thicker (more than 480,000 cubic miles [2 million km3] in volume), though they cover a slightly smaller area (130,000 square miles [340,000 km2]).It’s hard to imagine the scale of an event that would produce these flood basalts. Many large cracks, or fissures, had to open in the earth all at once, for so much lava to pour out over such a wide area. No eruptions today are that large, though a small fissure did open in Iceland back in 1783–84, belching out around 3.4 cubic miles (14 km3) of basalt lava (the same Laki area that created so much international concern this year).Before we can understand the unique forces necessary to fuel such immense eruptions in the past, we must first look at clues about volcanoes in the present.

Types of Volcanoes Volcanoes occur in various sizes and forms. Many of the best-known volcanoes, especially the picturesque ones, are large, steep-sided cones. These include Mount St. Helens, Mount Fujiyama (Japan), Mount Pinatubo (Philippines), Mount Ngauruhoe (New Zealand), and many others. They form as successive layers of lava and ash pile up. Technically they are called explosive composite volcanoes, or stratovolcanoes.4,5 It is likely that Yellowstone was originally a stratovolcano, but much bigger than any volcano we see today.Another type of volcano is found in Hawaii, such as Kilauea. These have gently sloping sides and are called shield volcanoes. Though spectacular, their eruptions are not explosive. Actually, these Hawaiian volcanoes are taller than Mount Everest, if their heights are measured from their bases on the deep ocean floor.

They produce oozing lava similar to the material we find in the Deccan Traps, but not on the same scale. The lava is usually only a few feet deep over a square mile or less. Types of Lavas and Eruptions

The different types of volcanoes vary depending on the content of the molten rock (magma) that formed them. Volcanoes are fed from deep inside the earth. Various geologic events, such as friction of moving plates, cause the melting of rock deep beneath the earth’s surface. This molten rock then rises to the surface as magma. If the melting rock includes lots of a chemical component called silica, it will be very thick (viscous) and resist moving. But if the magma is low in silica, it will flow very easily.Silica is very common in the rocks of the earth’s “outer skin,” or crust. The region below the crust, called the mantle, does not have so much silica. If the magma comes from melting at the top of the mantle, then it will be low in silica and flow easily. This rock is called basalt, and it’s what we find in the traps and in Hawaii’s shield volcanoes.If, however, the magma gets contaminated as it rises through fractures in the crust, then the proportion of silica increases and the magma gets thicker. (Rocks of this kind are called andesite and dacite.) On the other hand, if just crustal rocks melt, they form another, thicker kind of magma—granite—which has the highest silica content. When these granite magmas reach the surface, they are called rhyolite.Since basalt lavas flow easily, they erupt non-explosively. Consequently, they tend to spread out to build gently sloping shield volcanoes. However, dacite magma is thicker, so it squeezes out like tar, forming steep-sided volcanoes. Also, any gas and steam that is trapped in the rising dacite magma can’t easily escape. So the pressure increases, like that in a corked bottle which has been shaken. Eventually the volcano erupts violently, breaking up the magma into frothy blocks (pumice) or fine-grained particles of ash (pyroclastics).6 Windows into Earth’s Interior

The lavas that flow out of today’s volcanoes are very small in volume compared to lavas from the monster volcanoes of the past. How can we explain the physical forces that could produce so much magma?Conventional geologists face a quandary. Today’s lava flows are small because the magma chambers below the volcanoes contain only small amounts of magma, and the continental plates are moving so slowly that they can’t facilitate the melting of much new magma.In contrast, the basalts of the Deccan and Siberian Traps are massive. The eruptions must have been enormous, with huge volumes of lava constantly pouring out rapidly from many large fissure volcanoes. Only some unique catastrophe could have formed all this magma.

Where Do Volcanoes Occur and Why?

Volcanoes give us another clue about the forces at work inside the earth. Most active volcanoes are located near the margins of the earth’s crustal tectonic plates7 (Figure 1). This is especially true where one plate appears to be sinking or is being pushed under the adjoining plate, such as where the Pacific plate is sinking under the North American plate in the U.S. Northwest (see d in Figure 2), or where the Philippine plate is sinking under the Eurasian plate near Japan (see ain Figure 2). The sinking, or “subducting,” slab causes mantle and crustal rock to melt, which produces magmas that rise to erupt through volcanoes.Other active volcanoes occur where the plates are splitting apart, such as in the East African Rift Valley and along ridges in the middle of the ocean basins (see c in Figure 2).8In a few exceptional places, active volcanoes are located over “hot spots” under the plates, where plumes of hot mantle rocks are rising towards the earth’s surface (see b in Figure 2).9 The best

known examples of these are the Hawaiian volcanoes. The continental flood basalts are

found where such hot spots occurred in the past. Earth’s Catastrophic Past

Contrary to conventional (slow-and-gradual) thinking in geology, present volcanoes are not the key to understanding the earth’s past. The volume of lava and deposits was much too large and catastrophic to be explained by today’s volcanic activity.10,11For old-earth scientists, the location of continental flood basalts above former mantle plumes is explained by slow-and-gradual plate tectonics theory, but Flood geologists point out that the volume is not explained. The conventional idea of a slow rate of mantle flow and plate movements cannot explain such huge volumes of basalt lavas. Indeed, they had to be generated and erupt catastrophically. Even using conventional long-ages dating, these flood basalts were produced in a veritable geologic “instant.” The Flood

This is another powerful example of evidence that can be explained by catastrophic plate tectonics during the Flood.12 The breakup of the fountains of the great deep at its onset and continuing for 150 days would have involved not only the bursting out of water from inside the earth, but also steam and prodigious volumes of lavas. Then after the fountains were closed and plate movements slowed, volcanic activity decreased at the end of the Flood. This is also reflected in the documented declining power of post-Flood volcanoes to their relative quiescence today.13

Does Sand Prove Long Ages?

by Dr. Andrew A. Snelling on July 9, 2010

Dr. Andrew Snelling, AiG–U.S., gives a young earth creation explanation of the formation of beaches and other sands. I am a strong "young earth" creation scientist who has been unable to answer questions from old earth people or find technical help to respond to the following: "beach sand demonstrates that the earth is at least millions of years because its origin is lava, coral, and other metamorphic rock, and sedimentary rock is formed from the erosion and reconsolidation of sands that had already been formed."Please help. I would greatly appreciate a young earth explanation of the formation of beaches and other sands. I can only say that they werecreated that way; however, why there are different kinds of sand, such as the black Hawaiian beach sands and other special sands that appear to have had local sources.

Whenever anyone, makes a claim that some aspect or process of the earth “demonstrates” that the earth is at least millions of years old, we should immediately challenge them as to what assumptions they are using to make such a judgment. After all, no one was there in the past to see that aspect or process in operation, so how could anyone possibly know that the rate of that aspect or process occurred in the past at the same rate it is occurring today? We simply cannot know!It is instead an assumption that is implicit in such a statement, for example, that beach sand demonstrates that the earth is at least millions of years old. That statement assumes that erosion to produce the sand on beaches has always occurred at the rate that it is observed to occur today—and most of the time erosion does occur slowly and gradually today. So most people have been indoctrinated with the idea that because geological processes are slow and gradual today, then they have always been that way in the past—and so that to erode all the sand that is now on the beaches “must have” taken millions of years! Geological processes have not always been slow and gradual, as the rates we observe today are. The global watery catastrophe cataclysmically convulsed the earth and totally reshaped it. Since we don’t see things like global floods operating today—with the earth catastrophically convulsing everywhere due to the earth’s crust being ripped apart, steam and red hot volcanic materials being blasted everywhere, and torrential rainfall—the present is not the key to the past.In other words, it was because of what happened during the Flood that the earth is the way it is today. All modern geology is built on this assumption of geological processes always occurring at the same slow and gradual rates we observe today, and is known as uniformitarianism. It is a belief about the past that cannot be observed, because we can’t go back to the past. All we have is the evidence in the present of sand on beaches, and any explanation as to how that sand got there and the rate at which it accumulated is based on assumptions about how to interpret the evidence of slow and gradual erosion we see today. In other words, the conclusion you come to depends on the mental glasses you are wearing, such mental glasses being the lens of interpretation through which one interprets the world one sees. This is what we mean by one's worldview. In any case, there is observational evidence in the present that erosion rates aren’t always slow and gradual, and that sand can be eroded rapidly and accumulate rapidly to form beaches. In the late spring and early summer of 1983, there was snowfall in the high country of the upper Colorado River basin causing excessive runoff to pour into Lake Powell behind Glen Canyon Dam in northern Arizona. In order to avoid the dam wall overflowing, engineers decided to allow greater than normal outflows through the spillway tunnel in an effort to drain away the excess water. On June 28, 1983, they increased the flow to 32,000 cubic feet per second out through the 40-foot-diameter spillway tunnel. However, within a matter of seconds the flow of water in the spillway tunnel changed abruptly from smooth to turbulent, as large pieces of concrete and bedrock were hurled from the discharge end of the tunnel. Furthermore, the water exiting the tunnel became red (the color of the surrounding sandstone), and noticeable ground vibrations (earthquakes) were felt. The spillway tunnel was immediately closed, so that damage could be evaluated.A survey team discovered extensive damage in the spillway tunnel due to the process called cavitation. The water was moving so swiftly and in such a large volume that vacuum bubbles were produced in the water that imploded in an explosive-like process that delivered hammer blows to the concrete lining of the tunnel at pressures estimated to be as much as 440,000 lbs per square inch! No wonder the three-foot-thick, steel-reinforced concrete lining of the tunnel had been gouged out in several huge pits. At an elbow where the tunnel levels out, a hole 32 feet deep, 150 feet long, and 40 feet wide had been cut through the lining into the red sandstone bedrock beneath. That enormous hole required 63,000 cubic feet of concrete to fill! The speed of this erosion had been very rapid, most of the erosion occurring during the few seconds when the red color of water appeared and ground vibrations were generated. It was estimated that the cavitation was pulverizing the concrete, steel and sandstone at a rate in excess of 1,000 cubic feet per second during the peak period of this erosion.This event demonstrates what Derek Ager, the former professor of geology at the University College in Swansea, Wales, maintained in his ground-breaking book The New Catastrophism, published by the Cambridge University Press in 1993. The subtitle of that book was “The importance of the rare event in geological history.” Ager maintained, and with much good evidence, that most geologic work was done during very brief catastrophic episodes. In

other words, the sand in any sandstone layer would have been produced by a catastrophic episode of erosion such as was observed in the spillway tunnel of the Glen Canyon Dam in 1983. To substantiate this claim and make it relevant to the issue of the formation of beaches and beach sands, we focus on something that happened off the coast of Iceland. In 1963 volcanic eruptions on the seafloor adjacent to Iceland produced a new island, which was called Surtsey. Amazingly, within a few months of the volcanic activity ceasing in 1964, erosion by the ocean produced a coastline with beaches covered in sand. In fact, within a year or two the island had become vegetated and populated with insects and animals. It didn’t take thousands of years for either the beaches to form or the island to be populated. Yet anyone who hadn’t observed what actually happened, but who instead arrived to see the island, may well have concluded, using the assumption of slow and gradual processes over millions of years, that the beaches on the island looked as though the island and the beaches were millions of years old! Instead, it was all observed to happen within months.It is relevant, in closing, to refer back to the cataclysmic Flood event the earth experienced as. The Flood waters had to drain away to have the present exposed land surface with its topography. My point is that as the Flood waters drained off the earth’s surface, massive erosion would have occurred at a catastrophic scale and rate. There is abundant evidence (on which most everyone agrees) that many of the earth’s high mountains and plateaus today were uplifted only relatively recently. That would have been at the end of the Flood, when the new ocean basins would have also been deepened so as to collect the Flood waters draining off the uplifting continental surfaces. That’s why there are such great thicknesses of sediments on the continental shelves surrounding the continents, because as the Flood waters drained off they eroded and dumped those sediments offshore. Then and since the Flood, nearshore ocean currents would have swept sand onto the coastlines to form beaches.The water flows would have been similar to what was witnessed at the Glen Canyon Dam, so the rapid erosion of rocks would have produced huge volumes of sand, which dumped offshore and on the coastline to form the sandy beaches and the immediate sandy offshore areas. Since this would have happened during the closing months and weeks of the Flood year and in the years thereafter, the sand on the beaches and the formation of the beaches didn’t take millions of years. And of course, the waters eroded the local rocks and materials that then accumulated as beach sands locally, which explains the black Hawaiian beach sands, for example.So in conclusion, the interpretation of the evidence we see of sandy beaches today and how they formed depends on your starting assumptions. If it is assumed that only slow and gradual erosion processes seen today were all that were capable of eroding the sand and forming the beaches, then it would have taken millions of years. However, observational evidence in the present and tell us that geological processes have not always been occurring at the same rate, but that there have been catastrophes in the past, particularly a global catastrophe

Thirtieth Anniversary of a Geologic Catastrophe

by Dr. Andrew A. Snelling on May 18, 2010

The May 18, 1980, eruption of Mount St. Helens in the state of Washington is regarded by many as the most significant geologic event of the twentieth century.

May 18 marks the thirtieth anniversary of one of the most violent natural disasters of our time, the colossal 1980 eruption of Mount St. Helens. This catastrophic geologic event not only shocked the world because of its explosive power and made headline news, but challenged the foundations of evolutionary theory.The May 18, 1980 eruption of Mount St. Helens in the state of Washington is regarded by many as the most significant geologic event of the twentieth

century, excelling all others in its extraordinary documentation and scientific study. Although not the most powerful explosion of the last century, that eruption provided a significant learning experience within a natural laboratory for the understanding of catastrophic geologic processes. And thirty years later we learn that Mount St. Helens still confronts the underlying slow-and-gradual assumptions of modern geologic thinking.

The beautiful mountain before it erupted thirty years ago today. (Photo by R. Fleshman from www.creationism.org) Today’s Mount St. Helens (Photo by R. Fleshman from www.creationism.org) On May 18, 1980, a steam blast equivalent to 20 megatons of TNT destroyed the northern side of the once-pristine shape of the volcano. Geologists, who are accustomed to thinking about slow evolutionary processes forming geologic features, were astounded to witness many of these same features form rapidly as a result of that and subsequent eruptions. We are indebted to Dr. Steven Austin of the Institute for Creation Research for his work in documenting carefully the geologic results of this astounding catastrophe. The following undeniable lessons still confront us, thirty years on. 1. Rapid Formation of Sediment Layers

Up to 600-feet thicknesses of sediment layers formed as a result of the primary air blast, landslides, resultant water wave on nearby Spirit Lake, volcanic ash flows, mudflows, air falls of volcanic ash, and steam water. The most surprising accumulations resulted from the volcanic ash flows that moved at high velocities from the volcano. These deposits included fine volcanic ash beds from a tiny fraction of an inch thick to greater than 3 feet thick, each representing just a few seconds to several minutes of accumulation. Furthermore, one such layered deposit, 25 feet thick, accumulated within three hours during the evening of June 12, 1980. It was deposited from volcanic ash flows moving at hurricane velocity. Geologists were staggered that such coarse and fine sediment layers could be separated into distinct strata by such a catastrophic flow process from a slurry moving at freeway speed.Sadly, most geologists still conventionally think that such sedimentary layering has to represent long seasonal variations, or annual changes, as layers accumulate very slowly. They normally think that catastrophic sedimentary processes homogenize materials, depositing coarse and fine grains together. However, what researchers observed at Mount St. Helens emphatically teaches us that sedimentary layering does form very rapidly by catastrophic flow processes, such as those that would have occurred during the Flood. 2. Rapid Erosion

From everyday experience it is observed that rivers and creeks erode very slowly. Thus it is usually assumed that great time periods are needed to form deep canyons. However, at Mount St. Helens very rapidly erosion occurred, producing erosion features that challenge conventional thinking about how landscapes form.Two-third of a cubic mile of landslide and eruption debris from the May 18, 1980, eruption covered 23 square miles of the North Fork of the Toutle River, blocking the drainage from Spirit Lake westward into the Pacific Ocean. It was the largest debris avalanche observed in human history! The deposits averaged 150 feet thick. Then on May 19, 1982, another explosive eruption of Mount St. Helens melted a thick snow pack in the crater, creating a destructive, sheet-like flood of water, which became a mudflow. Reaching the landslide and eruption debris deposits of the North Fork of the Toutle River, the flow formed channels which cut through the blockage of the drainage westward. Bedrock was eroded up to 600 feet deep to form two canyons on the north flank of the volcano. Individual canyons up to 140 feet deep were cut through the landslide debris and volcanic ash deposits. The erosion left elevated plateaus to the north and south resembling the North and South Rims of the Grand

Canyon. Toutle River Canyon (Photo courtesy USGS) Also, gully-headed side canyons and amphitheater-headed side canyons resemble the side canyons to the Grand Canyon. The breach did not occur straight through the obstruction, but took a meandering path, which reminds us of the meandering path of the Grand Canyon through the high plateaus of northern Arizona. This “Little Grand Canyon of the Toutle River” is a one-fortieth scale model of the real Grand Canyon.The small creeks which flow through the headwaters of the Toutle River today might seem, by present appearances, to have carved out these canyons very slowly over a very long time period, except for the fact that the erosion was observed to have occurred extremely rapidly! Geologists should thus have

learned that the long timescales they have been trained to assign to the erosion of deep canyons are not accurate, and that deep canyons found elsewhere could likewise have formed very rapidly, including the Grand Canyon of Arizona. 3. Rapid Formation of Fossil Deposits

The volcanic blast of May 18, 1980, destroyed the surrounding forests. By late that afternoon one million logs were floating on nearby Spirit Lake. Many of these logs were actually floating upright. Even though the roots had been broken off, the logs were thicker at the root end and the wood obviously denser so that the root ends sank before the tops of the logs. Indeed, thousands of upright, fully submerged logs were subsequently observed sitting on the floor of the lake, looking as though they were a forest of trees. Investigations showed many had become buried by more than 3 feet of sediment, while others were still resting on the floor of the lake.Geologists could easily have misinterpreted these upright buried logs as representing multiple forests that had grown on different levels over periods of many thousands of years. This is in fact how the petrified upright logs at Specimen Ridge in Yellowstone National Park had been interpreted, as successive forests growing over many thousands of years. However, the lesson from Mount St. Helens is that fossilized upright logs had to be buried rapidly. 4. Rapid Formation of a Peat Layer

The enormous log mat floating on Spirit Lake lost its bark and branches, rubbed off by the abrasive action of wind and waves. Scuba investigations of the lake bottom subsequently revealed that sheets of bark intermingled with volcanic sediments had formed a layer of peat many inches thick. Together with broken branches and root materials, the sheets of bark gave the peat a coarse texture and a layered appearance. This “Spirit Lake peat” resembles, both compositional ly and texturally, certain coal beds of the eastern United States.Geologists suppose that coal beds formed by the accumulation of organic material in vast swamps where the plants grew in place. By slow growth and accumulation, they estimate about 1,000 years was required to form each inch of coal. However, typical swamp peat deposits are very fine, with a texture looking like coffee grounds or mashed potatoes. They are homogeneous because of the intense penetration of the roots which dominate swamps. Thus root material is the dominant coarse component of modern swamp peats, while sheets of bark are extremely rare. This is the exact opposite of what was found in the “Spirit Lake peat.” Yet the

Spirit Lake peat is texturally and compositionally similar to coal. Thus the lesson from Spirit Lake at Mount St. Helens is that this first formation stage of coal beds is rapid, and due to catastrophic destruction of forests, not the slow and gradual growth of plants in swamps. Conclusion

Mount St. Helens provided a rare opportunity to study geologic processes that within a few months produced changes that geologists assumed required many thousands of years. Mount St. Helens served as a miniature laboratory for catastrophism! The eruption and its aftermath challenged the timescales most geologists attach to geologic processes and changes that are used to construct the long geologic ages underpinning Darwinian evolution. Thus the Mount St. Helens catastrophe challenged, and still challenges, the slow and gradual interpretation of the accumulation of the geologic record and provides the stepping stone to help us imagine catastrophism on a global scale during the cataclysmic Flood.

The Cooling of Thick Igneous Bodies on a Young Earth

by Dr. Andrew A. Snelling and John Woodmorappe on August 5, 2009 Abstract One of the scientific objections to a young earth is the apparent evidence that large plutons of granitic and other igneous intrusive rocks necessarily required millions of years to cool from magmas. This paper was originally published in the Proceedings of the Fourth International Conference on Creationism, pp. 527–545 (1998) and is reproduced here with the permission of the Creation Science Fellowship of Pittsburgh. Abstract

Not only is the presence of water deep in the earth’s crust crucial in producing granitic magmas, but water is also included within such melts. Once a pluton is emplaced (probably rapidly by dikes) and crystallization begun, the magma’s water content significantly aids cooling. Meteoric water also penetrates into the pluton via joints and fractures that develop in the cooled outer rind of the pluton, setting up hydrothermal circulation. The permeability of the cooling pluton is maintained as the cooling/cracking front penetrates inwards, while vapor pressures ensure the fracturing of the surrounding country rocks. Thus, convective cooling rapidly dissipates heat over a timescale compatible with a young earth. Introduction

One of the persistent scientific objections to the earth being young (6,000–7,000 years old rather than 4.55 billion years), and the Flood being a year-long, global event, has been the apparent evidence that large plutons of granitic and other igneous intrusive rocks found today at the earth’s surface necessarily required millions of years to cool from magmas. The purpose of this work is to examine critically this oft-quoted assumption.Deep in the earth’s lower crust the temperatures are sometimes high enough to melt the rocks locally, particularly if there are applied high pressures due to tectonic forces and/or elevated temperatures. The latter can result from the proximal presence of basaltic magmas ascended from the upper mantle. Most geologists now agree that large “blobs” of granitic magmas are thus generated at 700–900°C, and owing to the fact that these blobs are “lighter” than the surrounding rocks, they are supposed to have risen like balloon-shaped diapirs into the cooler upper crust. There they crystallize into the familiar granitic rocks. When exposed at the earth’s surface due to erosion, these plutons cover large areas, sometimes hundreds of square kilometers. Indeed, it is estimated that up to 86% of the intrusive rocks within the upper continental crust are of granitic composition.1Young2 has insisted that an immense granitic batholith like that of southern California required a period of about one million years in order to crystallize completely, an estimate repeated by Hayward3 and Strahler4 , the latter in a widely-quoted anti-creationist book. Others quote on the order of 10 million years for the complete process of magma generation, injection, and cooling. Pitcher says:My guess is that a granitic magma pulse generated in a collisional orogen may, in a complicated way involving changing rheologies of both melt and crust, take 5–10 Ma to generate, arrive, crystallize and cool to the ambient crustal temperature.5 Of course, to this must be added the time to unroof the batholith. However, most recent estimates of these timespans are inflated, as they are based not solely on presumed cooling rates, but primarily on radiometric dating determinations and other uniformitarian assumptions. Water in Granitic Melts

Recent research in experimental igneous petrology has shown that the temperatures required for melting of rocks to form granitic magmas are significantly lowered by increasing water activity up to saturation, and the amount of temperature lowering increases with increasing pressure.6 A corollary to this is that water solubility in granitic magmas increases with pressure, and therefore depth, so that whereas at 1 kbar pressure (3–4 km depth) the water solubility is 3.7 wt%;7 at 30 kbar pressure (100 km depth) the water solubility is approximately 24 wt%.8 Indeed, the amount of water available is one of three crucial factors in the control of granitic magma formation, the others being parent rock composition and temperature.9 Three sources are believed to provide the needed water—adjacent country rocks, subducted hydrated oceanic crust, and hydrous minerals present in the melting rock itself. These three processes may act either simultaneously or independently of each other. While the adjacent country rocks are of local importance, the other two sources are regarded as supplying large quantities of water.Water is generally recognized as the most important magmatic volatile component, both for its abundance and for its effects on physical and chemical properties of melts. Indeed, the dramatic effects of the changes of water contents of melts on phase relations is due to the variation of physical properties of melts with changing water content (for example, viscosity, density, diffusivity, solubility of other elements). Therefore, the role of water in melting processes (collecting and segregation of melts), migration of melts, and crystallization of magmas is fundamental.Experimental investigations have demonstrated that pressure is the most important parameter controlling water solubility in granite petrogenesis, although the influence of temperature and melt composition is also of importance.10However, water-saturated conditions commonly do not prevail in ascending granitic magmas. Usually they are water-undersaturated, and their viscosity and density thus ensures that they ascend to higher crustal levels where crystallization and cooling of granitic plutons takes place. Thus, if there has been a relatively fast pressure release due to rapid ascent and emplacement of the granitic magma, even if initially water-undersaturated at depth, fast crystallization will occur, and, once water saturation is reached, excess water may be released. Ascent of Granitic Magmas

There has always been a problem with the accepted “wisdom” of slow magma ascent in balloon-shaped diapirs—the so-called space problem. How does a balloon-shaped diapir with a diameter of several kilometers or more find room to rise through the earth’s crust from 20–40 km (or more) depths and then the space to crystallize there (even at 2–5 km depth) in spite of the continual confining pressures? As Petford, Kerr, and Lister point out,The established idea that granitoid magmas ascend through the continental crust as diapirs is being increasingly questioned by igneous and structural geologists.11

Clemens and Mawer12 maintain that the idea of long distance diapir transport of granitic magmas is not viable on thermal and mechanical grounds, so they favor the growth of plutons by dike injection propagating along fractures. Pitcher comments:. . . what is particularly radical is their calculation that a sizeable pluton may be filled in about 900 years. This is really speedy!13 However, Petford, Kerr, and Lister’s calculations show that a crystal-free granitoid melt at 900 °C, with a water content of 1.5 wt%, a viscosity of 8 × 105 Pa s, a density of about 2600 kg/m3 and a density contrast between magma and crust of 200 kg/m3, can be transported vertically through the crust a distance of 30 km along a 6 m wide dike in just 41 days.14 This equates to a mean ascent rate of about 1 cm/sec. At this rate they calculated that the Cordillera Blanca batholith of northwest Peru, with an estimated volume of 6,000 km3, could have been filled from a 10 km long dike in only 350 years. Magma transport has to be at least this fast through such a dike or else the granitic magma would “freeze” due to cooling within the conduit as it ascended. Yet because of the radiometric dating constraints on the fault movements believed responsible for the dike intrusion of the granitic magma, Petford, Kerr, and Lister couldn’t accept this 350 year rapid filling of this batholith, but concluded that the intrusion of the batholith must have been very intermittent, the magma being supplied in brief, catastrophic pulses, while the conduit supposedly remained in place for 3 million yearsEpidote is found in some granitic rocks and therefore can have a magmatic origin, its stability in granitic magmas being restricted to pressures of =6 kbar (21 km depth). Brandon, Creaser, and Chacko15 experimental work has shown that epidote dissolves rapidly in granitic melts at pressures of <6 kbar, such that at 700–800°C (temperatures appropriate for granitic magmas) epidote crystals (0.2–0.7 mm) would dissolve within 3–200 years. Therefore, if magma transport from sources in the lower crust were slow (>1,000 years), epidote would not be preserved in upper-crustal batholiths. However, granitic rocks of the Front Range (Colorado) and the White Creek batholith (British Columbia) contain epidote crystals, and Brandon, Creaser, and Chacko found that the 0.5 mm wide epidote crystals in the Front Range granitic rocks would dissolve at 800°C in less than 50 years. They concluded:Preservation of 0.5 mm crystals therefore requires a transport rate from a pressure of 600 to 200 MPa [6 to 2 kbar] of greater than 700 m year-1.16This equates to a maximum ascent rate of 14 km per year, which is similar to magma transport rates for dikes based on numerical modeling,17, 18, 19, 20 and close to measured ascent rates for upper crustal magmas.21, 22, 23 By contrast, the modeling of magma transport by ascending diapirs has yielded slow ascent rates of 0.3–50 m per year, meaning ascent times of 10,000–100,000 years.24, 25 In fact, in his widely-quoted anti-creationist book, which is replete with outdated uniformitarian claims, Strahler26 has alleged 150,000 years. In reality, however, the preservation of epidote crystals in some granitic rocks which crystallized at shallow crustal levels not only implies magma transport had to be rapid (very much less than 1,000 years), but that the transport had to be via dikes rather than diapirs.The mechanical behavior of partially molten granite has been investigated experimentally at temperatures of 800°–1100°C, 250 MPa and confining pressure, different strain rates and under fluid-absent conditions.27 Over that temperature range, strength decreased progressively from 500 MPa to less than 1 MPa. The comparative viscosity of the melt alone was estimated at 950° and 1000 °C from the distance it could be made to penetrate into a porous sand under a known pressure gradient. Rutter and Neumann concluded:Shear-enhanced compaction is inferred to drive melt into a network of melt-filled veins, whereupon porous flow through the high-permeability vein network allows rapid drainage of melt to higher crustal levels.Furthermore, it was suggested that the overall kinetics are faster than just gravity-driven porous flow because transport distances to the veins are small and melt pressure gradients, although small, are hundreds to thousands of times higher than those arising in large-scale porous flow. And once the melt accumulates in veins, the effective permeability due to channel flow in the fractures is several orders of magnitude higher than for intergranular flow.Even more recent experiments have determined the viscosity of Himalayan leucogranite between 800° and 1100°C, 300 and 800 MPa, for meltwater contents of 3.98 and 6.66 wt%.28 The melt viscosity was found to be independent of pressure, and so the experimentally determined phase equilibria constrain the viscosity of this granite to around 104.5 Pa s during its emplacement. It was concluded thatThese viscosities and the widths of dikes belonging to the feeder system (20–50 m) are consistent with the theoretical relationship relating these two parameters and show that the precursor magma of the leucogranite was at near liquidus conditions when emplaced within host rocks with preintrusion temperatures around 350°C. Calculated terminal ascent rates for the magma in the dikes are around 1 m/s. Magma chamber assembly time is, on this basis, estimated to be less than 100 years (for a volume of 150 km3). In addition, the dynamical regime of the magma flow in the dikes was essentially laminar, thus allowing preservation of any chemical heterogeneity acquired in the source.The investigators also noted that repeated injections of magmas over protracted periods will increase the temperatures of the host rocks, and whereas the first injected magmas will traverse cold crust through dikes, later ones will encounter a hotter medium so that the lower viscosity contrast may then be more favorable to diapiric ascent. Conductive Versus Convective Cooling

Until relatively recently, both intrusives and extrusives were believed to cool primarily by conduction (fig. 1). In the last 20 years or so, however, the role of convective cooling (fig. 1) has become increasingly appreciated.29, 30 In addition, a variety of empirical studies31, 32, 33 have proved that thick igneous bodies do, in fact, cool primarily by circulating water. Cooling models which assume exclusive conductive cooling have been superseded by those which recognize convective cooling in the host rock,34 followed by those which allow for the convective cooling of the outer parts of the plutons also,35 and finally those which allow for constant permeabilities of both host rock and plutons.36, 37, 38

Fig. 1. Cooling of a pluton by (a)

conduction or (b) convection. Vectors are proportional to the rate of heat flow to the surface. The most recent generation of models39 for cooling plutons has been based on the computer program HYDROTHERM.40 Unlike earlier models, this program takes into account the multiphase flow of water, and the heat it carries, at temperatures in the range 0–1200°C and pressures in the range of 0.05–1,000 MPa. Based on a small pluton (2 × 1 km, at 2 km depth), the model indicates that the cooling time is 5,000 years (at a system permeability of 10 md). Increasing the permeability to

33 md shortens the time to only 3,500 years. Unfortunately, however, the program HYDROTHERM has not been applied to plutons of batholitic dimensions. For this reason, our study, described below, must rely on simpler models. Such an approach is justified by the fact that reanalysis of the data used in simpler models, by HYDROTHERM, does not lead to substantially different conclusions regarding inferred cooling time, as predicted by simpler models.41To begin our study, we must point out that it is at least theoretically possible that some intrusive igneous lithologies had supernatural origins during creation—some initial rocks had to be supernaturally created with an appearance of a formational history and therefore age. And, of those magmas intruded during the Flood, a large fraction of their latent heat of crystallization may date back to creation and the pre-Flood era. This follows from the fact that 20%–60% of the crystals in a granitic magma may already be crystallized at the time of intrusion.42Since the latent heat of a crystallizing magma is 65 cal/g and the specific heat is only 0.3 cal/g/°C,43 it follows that an intrusion with 50% pre-crystallization has already, in effect, experienced a built-in cooling of over 100°C.Furthermore, there is evidence accumulating that many granitic bodies, including the large batholiths, may be essentially “rootless” and not as thick (deep) as the areal extents they cover have seemingly suggested. The subsurface shapes of intrusive igneous masses have been until recently only indirectly known. Mafic bodies appear to have simple dike-like forms extending to great depths, whereas the granitic types are elongate to equant in plan view and extend only to a fraction of their diameters in depth. From a combination of seismic, gravity, and heat flow data, Hamilton and Myers44 suggested that batholithic masses in particular may be only a few kilometers thick. More recently, a seismic reflection study of the internal structure of the English Lake District batholith showed the presence at depth of interpreted granitic sills 500–1,000 m thick separated by country rock, which suggested to Evans et al.45 that the batholith is made up of a series of horizontal sheets with flat tops and floors, or an overall laccolithic structure. Similar sill-like geometries occur in sections of the Sierra Nevada batholith46 and the High Himalaya,47 while the Harney Peak Granite pluton of the Black Hills (South Dakota) has now been mapped as a multiple intrusion that consists of perhaps a few dozen large sills (which are probably no more than 100 m thick, extend laterally for only a few kilometers, and have gentle dips in accord with a domal pattern) and thousands of smaller sills, dikes, and irregularly-shaped intrusions.48 Hutton49 has reviewed granite emplacement mechanisms in three principal tectonic settings and concluded that the plutons have been constructed by multiple granite sheeting parallel to shear zone walls and deformation fabrics. A detailed fractal analysis of the geometries of small to medium laccoliths and plutons50 indicates that they exhibit scale-invariant tabular-sheet geometries, which also implies that larger intrusions (and notably batholiths) are composed of composite sheets of smaller intrusions. This conclusion has been corroborated by a theoretical analysis51 which suggests an upper limit of 2.5 km for the thickness of any single sheet of magma. Finally a variety of geophysical evidences, recently summarized,52 constrain batholiths to total thicknesses of less than 12 km. The implications of all these findings is that many granitic plutons and batholiths consist of relatively thin sills and laccoliths, and hence the time-scale of the apparent crystallization and cooling “problem” is significantly diminished.The convective overturn caused by settling crystals, in the magma chamber, is a significant factor in the dissipation of its heat. This allows a 10-meter diameter sill to cool in one year53 and, at the other extreme, for a 10 km thick lava “ocean” to theoretically cool in 10,000 years54 by this process alone. In the case of a 2.15 km cuboid pluton which cools by conduction through the country rock (but whose magma can experience convective overturn), its temperature will drop from 850°C to 650°C in 3,000 years55 by this factor alone. If, however, the cooling is exclusively conductive both outside and inside the magma chamber, the time increases to 20,000 years.Plutons with considerable amounts of magmatic water cool much faster than do those which don’t. Spera has developed a parameterized model for cooling plutons which accounts for heat transfer by conduction and convection within the magma chamber and into the surrounding country rocks.56 According to his model’s central equation linking the crucial parameters, the thermal history of a pluton is most sensitively dependent upon the depth of pluton emplacement, the heat-transfer characteristics of the local environment (for example, emplacement into

hydrous or anhydrous country rock), the size of the pluton, and the bulk composition of the melt. Fig. 2. Influence of magma water content on the cooling

history of granodiorite (GD) plutons (radius = 5 km, magma chamber/country rock contact temperature = 600°C, emplacement pressure = 2 kbar). Increasing the water content by a factor of 2 (from 2 to 4 wt%) decreases solidification times by a factor of about 7 (after Spera58).From the essential results of his study, Spera concluded that emplacement depths and the scale of hydrothermal circulatory systems are first-order parameters in determining the cooling times of large plutons. Fig. 2 shows the “remarkable role” water plays in determining the cooling time. For a granodioritic pluton 10 km wide emplaced at 7 km depth, the cooling time from liquidus to solidus temperatures decreases almost ten-fold as the water content increases from 0.5 wt% to 4 wt%, other factors remaining constant. However, Spera also found that if the temperature of the

magma chamber—country rock contact decreases from 700°C to 500°C, which depends on the geothermal gradient, the emplacement depth, and the hydrothermal fluid/magma volume ratio, the cooling time decreases by eighteen-fold (with only 2 wt% water content). Additionally, conduction cooling times were estimated to vary with the square of the radius R, whereas in convective cooling the solidification time varies approximately according to R1.3. Spera concluded:

Hydrothermal fluid circulation within a permeable or fractured country rock accounts for most heat loss when magma is emplaced into water-bearing country rock . . . . Large hydrothermal systems tend to occur in the upper parts of the crust where meteoric water is more plentiful.57 Rock Permeability: The Rate-Determining Factor of Cooling

All of the factors endogenous to the magma itself pale into insignificance, in terms of cooling rate of igneous, once either meteoric or connate water can enter near or into a hot igneous body at an appreciable rate. This is so whether the convection is a “heat engine” driven by the cooling body itself,59 or is a result of extraneous forced convection (discussed below).60 The rate of convective cooling itself scales closely with the rate of water circulated through a temperature anomaly,61 and the volume of water involved in cooling a pluton is less than the volume of the igneous body itself.62 Equation 1 gives the rate of water flux and is a summary of equation (A1) in Cathles.63 The flux rate (Q in Equation 1) is closely proportional to the rate of heat removal from the pluton, since it is the water that carries away virtually all of the heat in a pluton whenever convective cooling dominates over conductive cooling.

Q=[KA (ΔT)/[V] (1) Q scales with size of intrusion because large intrusions generate proportionately more powerful convective “heat engines.”64 The K refers to permeability of both host rock and igneous body (in millidarcies). The other term, A,

encompasses the respective products of other variables (the gravitational constant, the coefficient of thermal expansion of water, and water density changes with depth), whereas V refers to the viscosity of the hydrothermal water. ΔT refers to the elimination of three-quarters of the temperature anomaly between the original temperature of the intrusion and that of the country rock. For instance, if the magma had been intruded at 800°C and the country rock’s temperature had been originally 200°C, there would be 600°C of temperature to eliminate. Thus, in the formula ΔT would equal 450°C. Based on differing geologic conditions, all of the variables in Equation 1, with the exception of permeability K, can change by only about a factor of 2 or so. The situation is entirely different for permeability K. The permeability K of earth materials varies by several orders of magnitude in crystalline rocks.65 It is thus obvious that the value of Q, and hence the time needed to cool the pluton, is, for all practical purposes, governed by K. This is borne out by Fig. 3 (which is modified after fig. 6 of Cathles).66 It indicates the time to cool off a pluton of specified transverse dimension as a function of the permeability of the pluton and host rock. (Actually, the cooling in Fig. 3 starts with solidus temperatures and ends at 25% of the difference between ambient temperatures and solidus temperature. The remainder of the cooling to ambient crustal temperatures is not covered by Fig. 3, but is accounted for later.) The effects of changing permeability K, on cooling time, is striking (fig. 3). An infinitely-long batholith that is 11 km wide, 16.5 km thick, and is buried 20 km below the surface of the ground, when at zero rock permeability (that is, conductive cooling only) needs a few million years to cool. But with the intensity of convective cooling that is allowed by a permeability K of 10 millidarcies (easily exceeded—see below), the time to cool this batholith falls to a mere 3,000 years. To put this cooling batholith in geothermal perspective, let us consider this: it implies an average geothermal output of 25 W/m2 sustained for the 3,000 years. This pessimistically assumes that the geothermal circulation extends no further than the batholith itself, but thus allows for the presence of parallel batholiths nearby (as is usually the case in orogenic belts), which must undergo their own convective cooling. The quoted heat output is half that of the present-day Grimsvotn geothermal region of Iceland (50 W/m2, sustained over 100 km2 and for 400 years.67 We now perform a sensitivity analysis for the batholithic-emplacement parameters assumed for Fig. 3. Varying the geometry of the pluton (that is, its width-thickness ratio), and its depth of burial relative to its size, from the values arbitrarily chosen for Fig. 3, is relatively unimportant.68 For instance, if the burial depth was doubled, the time to cool would be much less than doubled. Conversely, if it were halved, time to cool would decline by much less than a factor of two. This owes to the fact that the convective cell becomes somewhat more efficient when at greater depth (and vice-versa for shallower depth), and this partly cancels out the increasing (or decreasing) distance which the hot hydrothermal fluid has to travel before reaching the surface and dissipating its heat. This discussion does not imply that all of the large batholiths had cooled by the time they were uplifted after the Flood. Since most (virtually all?) large batholiths show satellite intrusions and/or pegmatites, this indicates that their centers could have been still liquid at the time they had been uplifted and/or unroofed. And in many areas of the world, geothermal activity from still-hot igneous bodies continues to the present, itself challenging an old earth (see below). The Extent of Permeability and Hydrothermal Activity Since the plutons’ cooling rates are essentially limited by rock and crustal permeability, as well as the depth of hydrothermal action, we must go beyond theory and examine how these agents are, in turn, limited under realistic

geologic conditions. We also need to understand how these factors came into play during and after the Flood. Fig. 3. Diagram showing scaling relationships for identical

intrusive geometries cooling by conduction or convection (modified after Cathles74). The particular geometry of the intrusions is indicated in the insert diagram. The solid lines show convective cooling times for different permeabilities (0.1, 1.0 and 10 millidarcies). By way of introduction, Darcy’s Law allows for the same level of permeability in a rock to be governed by apertures of widely-divergent sizes, and this has been confirmed by actual observations.69 For instance,70 it is clear that a permeability K of 10 md, needed to cool the batholith within 3,000 years (fig. 3), can result from 10-micron microcracks spaced every 0.7 cm, 0.2 mm hairline cracks separated from each other at outcrop scale (100 m), or even 1 mm joints spaced 10 km apart. Strictly speaking, Darcy’s Law applies to permeable rather than fractured media. However, both theoretical and experimental evidences indicate that fractured domains closely approximate the behavior of equivalent-porous domains when large distances and travel times are involved, when the network of fractures is continuous, and when the heat source which drives the movement of water is large in comparison to the geometry of the fractures and the intervals which separate them.71 These conditions are largely fulfilled by cooling plutons. Moreover, reasonably similar values are obtained for cooling models which allow for a mass flux going through widely-separated fractures of

high permeability (and separated by large intervals of low rock-permeability) when contrasted with models which simply compute an equivalent average permeability for the same domain.72, 73 Nevertheless, a residual-cooling model, described below, considers the consequences of the convective cooling, which results from hydrothermal water flowing through widelyseparated (but interconnected) fractures which cut through large thicknesses of otherwise-impermeable rock.Darcy’s Law is based on the assumption that apertures are perfectly planar and of constant size. Concerns that deviations from these assumptions would cause a severe reduction in actual permeability in the rock have proved unfounded. To begin with, many if not most joints and cracks are reasonably close to planar.75 Moreover, studies on sinuous apertures demonstrate that their permeability is reduced by only about 10–30% over that of perfectly planar

ones.76 And while on the subject of theory versus actual geology, it should be noted that convective circulation of the type of interest to us is very difficult to destabilize.77But how permeable are rocks in actuality? Studies which infer the permeabilities of rocks on a microscopic or hand-sample scale greatly underestimate the permeability of the crust from which they came.78, 79 This indicates that apertures in rocks tend to occur frequently, but at irregular intervals. Thus, the limiting factor now becomes the largest permeability existing over a significant fraction of a given crustal region. This should seldom if ever pose a problem, for joints are virtually universal in granitic terrains,80 as are microfractures.81 In fact, the considerable difficulty of locating granites with low permeability, suitable for long-term storage of radioactive wastes,82 attests to this fact. And, even when located, such bodies often turn out to be dissected by previously-unrecognized joints.83Among existing granites, the largest K in an area is 1–100 md (not including joints),84 and these values underestimate the permeability it had when hydrothermal solutions circulated through it.85 The latter results from the clogging of apertures during cooling, as is manifested by secondary mineralizations in fractures in the rock.86, 87 There is evidence that presently-impermeable granites were once very permeable, even with microsized apertures. When examined under cathodoluminiscence, seemingly-intact granitic fabrics betray evidence of a former extensive network of microcracks.88Thus far, we have discussed long-inert granites. By contrast, the permeability of a granite in the actual process of cooling remains unknown. The most recent models assume that an initially-impermeable granite does not become appreciably permeable until it cools below about 360°C, at which time its ductile behavior gives way to brittle behavior, and thus jointing becomes possible.89 Even if this is correct, it need not imply that plutons are virtually impermeable, in a creationist-diluvialist context, when their fabrics are still ductile. Owing to the ubiquity of repeated tectonic stresses as a result of the Flood and its aftermath, combined with the high viscosity of even hot granitic rock, joints will still open up and probably remain open for significant intervals of time before they are “healed” by the flowing of the still-ductile granitic fabric.These rates of repeated creation of joints (under catastrophic tectonism) and the opposing rates of “healing” in still-ductile rock need to be quantified. An analysis of some of these factors,90 albeit in an actualistic context, suggests the following conclusions: for a sialic pluton at a geothermal gradient of 125°C, and subject to a strain rate of 10-12, the brittle-ductile transition occurs at about 390°C. Under identical conditions, but in the case of a more mafic granitic rock (for example, diorite), the same transition occurs at about 490°C.Crustal strain rates of 10 -13 have been measured after moderate earthquakes, and long-term strain rates on the order of 10-14 are considered plausible.91 It is unclear how much greater the strain rates were during Flood-related tectonism. Assuming that the conditions discussed above, for a sialic pluton, can be validly extrapolated to considerably higher strain rates, the ductile-brittle transition then occurs at approximately 500°C at a strain rate of 10-10, and even, at least theoretically, at approximately 600°C under a strain rate of 10-8.92 However, at such high strain rates, the heating and remelting of crustal material increasingly becomes a factor. More research is needed to understand and quantify these effects.Both theoretical and experimental evidence indicate that, not only can ostensibly-ductile hot granite behave as a brittle material under sufficient impulsive tectonic stresses, but so can granitic magma itself.93 Moreover, even without the presence of repeated tectonic stresses, and as discussed in the ensuing paragraphs, there are a variety of evidences against a simple ductile/brittle boundary at or about 360°C.How deep can meteoric water operate? Uniformitarian beliefs had such water limited to only the upper few to several kilometers of the crust, and to crustal temperatures of only a few hundred degrees. Deep boreholes, spaced many thousands of kilometers apart,94, 95 have surprised everyone by revealing that free water exists to at least 12 km depth. They also have contradicted the notion that crustal permeability greatly decreases, if not disappears, at such depths because the overpressure was supposed to crush pores and cracks shut.96 To those who make much of the “testable predictions” claimed for uniformitarian geology, here is yet another example of a set of predictions proved false. Furthermore, seismic data suggest that fractures can exist, at least transiently, down to 15 or 20 km.97As for temperatures, we now have isotopic evidence that meteoric waters interacted with gabbros, implying temperatures of 500–900°C.98 This also means that such waters can reach the melting zone itself for mafic magmas,99to say nothing of the cooler sialic magmas which give rise to granites. Forced Convection and the Removal of Residual Plutonic Heat

We now consider what takes place when the convective cell that cools the pluton has eliminated 75% of the temperature anomaly (fig. 3), and starts to die down. All this time, tectonically and hydrostatically-driven groundwater movement (occurring during and after the Flood) has been taking place, but, until now, has been shunted away by the powerful convection around the pluton. Now, with the “heat engine” petering out,100 the pluton becomes subject to forced convection from the extraneous groundwater migrations.The limiting factor in the remaining cooling rate now becomes the thinnest distance between parallel watercooling surfaces within the pluton itself. Thus, in order for the remaining heat of the pluton to be dissipated in 2,000 years, the joints allowing free access of water to the pluton need not be spaced any closer than 180 m in a slab-shaped block.101Under comparable conditions, a 160 m diameter granitic spheroid cools in 2,000 years.102 These computations, however, do not take actual temperature into account. Allowing a joint-dissected pluton to have previously cooled from 850°C (assumed temperature of intrusion) to 650°C, only 2,000 more years are needed to cool conductively the pluton to an ambient crustal temperature of 300°C if each dimension of the cuboid pluton is on the order of 400–500 m.103 This latter computation does not take into account the constant hydrothermal bathing of the cube’s walls. What if the Apertures Clog Up?

These rough calculations account for the complete closing of microcracks, and thus pessimistically assume zero permeability (and thus exclusive conductive cooling) of the jointed slabs, spheroids, and cubes themselves. Under such restrictions, the convective water cooling is restricted to the jointed surfaces.However, several factors counteract the sealing of microcracks. One is size. As microcracks approach macroscopic size (1 mm in aperture), they become exponentially more resistant to clogging.104 The common occurrence of partially-filled veins in rock indicates that the sealing of cracks often does not go to completion.105 Also, if the water table fluctuates drastically in an area (as from tectonics), this acts to help keep crustal fractures open.106 Tectonic action counteracts clogging by increasing fluid pressure and causing the flushing out of streamlines, as is manifested by the increase of geothermal activity after even small earthquakes.107 It is also recognized that, where there are high tectonic strain rates, permeabilities at least ten times greater than we have adopted for our model (fig. 3) may be sustained at depth in spite of competing processes such as silica deposition.108 Obviously, such strain rates must have been the norm during and after the Flood, as a consequence of rapid mountain-building, crustal readjustments, etc.Finally, when cracks do get filled up, they are easily

replaced by new ones, especially under catastrophic conditions. Indeed, the rocks which occur in tectonic environments show evidence of repeated generations of mineral-filled fissures and extension cracks, and so permeability of the host rock becomes quickly restored.109 For instance, a new 0.5 cm-wide fracture spaced every 1 km apart will create, or re-create, a crustal permeability K of approximately 10 darcies.110 This is three orders of magnitude greater than that needed for a batholith to cool in 3000 years (see fig. 3). Furthermore, as new joints develop, they allow access of water to hot surfaces. The ensuing cooling generates a new generation of microcracks from the thermoelastic gradients produced

by the percolating water.111 Thus, in a sense, both macro- and micro-cracks are self-regenerating, much like the hairs of the fabled Medusa. Boundary Conditions: Magma and Infiltrating Waters (Extrusives)

Thick lava flows, being surficial, generally cannot develop convection cells as can plutons (see fig. 3). They remain, however, quite vulnerable to cracking and water infiltration. Lister has demonstrated an intense positive feedback process which exists between meteoric water and lava flows (fig. 4).112 Upon contact with water, the lava surface cools rapidly, creating a thin, solid crust. In doing so, a very steep temperature gradient between the recently water-cooled surface (100°C) and the magma just below the surface (1000°C) has been formed, causing severe thermoelastic tension. This soon leads to cracking of the hardened lava crust, allowing water access to the hot interior. So, at once, the lava is cooled

to a greater depth, and a new zone of thermoelastic stress is created. Fig. 4. Feedback between water and a thick lava flow or

pluton. Water cooling creates an extreme temperature gradient (shown hatched) in a thin layer of the igneous body. Tensile stresses caused by the gradient lead to further cracking. The cooling front progresses downwards as water enters new cracks and the process repeats itself.The cycle repeats itself, and the extreme temperature gradient is displaced downwards. All the while, the water-cooled crust is growing thicker, the cracks with their concomitant entry of water keep propagating, and the cooling front is advancing

downward. Eventually, the fractures in the lava solidify completely, allowing access to deeply-penetrating water.113 This completes the cooling of the thick lava flow.Based on calculations, the feedback-generated cooling front can move 5–170 m in a year.114 At the slowest rate, this suffices for cooling the thickest layers of lavas on earth in a few thousand years. Empirical observations on the cooling of a lava lake,115, 116 have demonstrated the movement of a cooling front of over 2 m a year, and further evidence for the importance of this process comes from the heat-production rates of an Icelandic geothermal system.117 It is also recognized that this feedback process explains the occurrence of columnar jointing in basalts,118 and the fact that entablatures in ancient lavas follow downward-growing joints.119Boundary Conditions: Magma and Circulating Water (Intrusives)We now focus on processes which make plutons themselves accessible to hydrothermal waters. Consider crustal permeability first. The magma injected into host rock itself exerts pressure upon the host rock, facilitating its fracture,120 and all the more so whenever the intrusion is emplaced rapidly.121 Also, the heat from the pluton122 itself induces fracturing in the country rock as the fluid pressure in the pores of the host rock increase from the heat.123Upon entry of the pluton’s heat into these new cracks, the process repeats itself.124Plutons are commonly surrounded by rim monoclines or anticlines. In the past, this has been mistaken as evidence for regional tectonic action. Now it is realized that these regional structures are caused by the fact that, as the plutons cooled, they first weakened the wall rock by giving off heat and fluids.125 Subsequently, the plutons foundered as they cooled, causing the adjacent and superjacent wall rock to buckle downward. Obviously, such a process could only help open up the country rock, and then the pluton itself, to circulating ground water.Although plutons also rapidly become permeable, let us pessimistically suppose that, unlike the situation discussed in describing Fig. 3, we have permeable crust and a perpetually-impermeable pluton. As before, we have a convective cell, but water cannot enter the pluton itself. So, the heat must leave the pluton itself solely by conduction, and a cooling time of 3000 years (to within 25% of ambient crustal temperatures) suffices for an infinitely-long impermeable pluton which is 0.6 km wide, 0.9 km thick, and 11 km deep.126 For thicker plutons, the limiting factor becomes the spacing of joints. These would have to split the cooling pluton into slabs no larger than 0.6 × 0.9 km, which, as discussed above, is easily met.Many mineral/metal deposits appear to have been formed by fluids of magmatic-hydrothermal origin associated with granitic and other plutons. Indeed, a granitic magma has enough energy to drive roughly its mass in meteoric fluid circulation.127, 128 Meteoric fluids would thus seem to dominate the magmatic fluid component of even up to 10 wt% or so for some granitic magmas, but several factors can act to focus the magmatic fluids in parts of the hydrothermal system.129 Magmatic fluids are released only while the intrusion is crystallizing, and fractionation of the magmatic fluids to the upper part of the magma chamber can focus their release in a small region of the crust compared with the full extent of the hydrothermal system, so magmatic

fluids can locally dominate over meteoric fluids and should not be ignored for the part they can play in cooling plutons.130 Fig. 5. Cross-section of the margin of a magma

chamber traversing (from left to right): country rock, cracked pluton, uncracked pluton, solidus, crystallization interval, and bulk melt (after Candela132).Following the emplacement of a granitic magma in the upper crust, crystallization occurs due to the irreversible loss of heat to the surrounding country rocks.131 Heat passes out of the magma chamber at the margins of the body, and the solidus moves towards the interior of the chamber, defining an inwardly progressing boundary (fig. 5). As crystallization proceeds, water increases in concentration in the residual melt. When the saturation water concentration is lowered to the actual water concentration in the melt, first boiling occurs and water (as steam) is expelled from solution in the melt, which is driven towards higher crystallinities. Bubbles of water vapor then nucleate and grow, causing second (or resurgent) boiling within the zone of crystallization just underneath the solidus boundary and the already crystallized magma

(fi g. 5). As the concentration and size of these vapor bubbles increase, vapor saturation is quickly reached, but initially the vapor bubbles are trapped by the immobile crystallized magma crust.133 The vapor pressure thus increases and the

aqueous fluid can then only be removed from the sites of bubble nucleation through the establishment of a three-dimensional critical percolation network, with advection of aqueous fluids through it or by means of fluid flow through a cracking front in the crystallized magma and out into the country rocks. Once such fracturing of the pluton has occurred (and the cracking front will go deeper and deeper into the pluton as the solidus boundary moves progressively inwards towards the core of the magma chamber), not only is magmatic water released from the pluton carrying heat out into the country rocks, but cooler meteoric water in the country rocks is able to penetrate into the pluton and to establish hydrothermal circulation.There is now petrographic evidence, in the form of complex quartz growth histories,134 which is consistent with the above-discussed sequence of events. Abrupt zone boundaries in quartz crystals indicate fluctuations in melt composition and/or temperature during the crystallization interval.135 In fact, the acceptance of erratic temperature fluctuations in the melt is not favored,136 precisely because of the belief that large plutons “should” cool at slow, continuous rates!In conclusion, therefore, a long-impermeable pluton is, for our purposes, as unrealistic as it is pessimistic. Pressure build-up within the magma137 will cause the solidified rind of the pluton to crack in short order, resulting in a permeable pluton (fig. 3). The more water dissolved in the magma, the greater will be the pressure exerted at the magma/rock interface.138 If the magma moves in surges, there will be a cyclic cooling and heating of the pluton’s solidified rind, and the resulting thermal stress will exacerbate its cracking.139 As the pluton cools, the cracking front moves progressively deeper into the pluton as the magma/rock boundary recedes inward.However, this release of magmatic water from a pluton will tend to be focused towards the top or apical region of the magma chamber. The vapor bubbles which nucleate on the magma chamber side-walls will tend to rise as they grow, combining with adjacent vapor bubbles and migrating upwards as a plume towards the top of the magma chamber.140Because the density of water vapor is reduced as it rises, the buoyancy of the plume is further enhanced, so that this process of bubble-laden plume flow may be a driving force for convection within some magma chambers. Furthermore, the rate of plume flow can be calculated,141 and in the case of a typical granitic magma chamber with 6 wt% water at saturation emplaced at 7–8 km depth, a bubble-laden plume would rise to the top of the pluton in less than a year.142

Fig. 6. Schematic cross-section through a

hypothetical granodiorite stock at the stage of waning magmatic activity in the development of a porphyry copper (±molybdenum ±gold) system (after Burnham144). A breccia pipe and dikes have formed as a result of wallrock failure, while the chaotic line pattern represents the extensive fracture system developed in the apex above the H2O saturated magma. Note that the granodiorite has intruded into already extruded comagmatic volcanics. A relevant example that graphically illustrates the rapid release of magmatic fluids through fractures concentrated at the apex of a granitic magma chamber is the typical development of a porphyry copper (±molybdenum ±gold) ore deposit system (fi g. 6), which is now well understood.143 A stock-like body of granodioritic magma is emplaced at shallow depth in a subvolcanic environment, and when water saturation is reached and second boiling occurs the vapor pressure becomes concentrated at the apex or carapace, while the concurrent crystallization process also expands the crystallizing rock mass. The net result is large-scale, brittle fracture of the already

crystallized pluton above, so that an intense stockwork of fractures develops into which hydrothermal fluids can flow to deposit their metallic loads (fig. 6). The myriad of fractures is extended upward and outward by continued hydraulic action (hydrofracturing), even into the wallrocks and sometimes the overlying volcanics that were earlier extruded from the same magma chamber—a chimneylike fracture system that channels ore-bearing fluids and heat away from the underlying cooling magma chamber.Breccia pipes also demonstrate that initiallyimpermeable rinds often fail catastrophically, particularly as a result of the rapid build-up of vapor pressure at the tops of magma chambers.145 We can only underestimate the significance of these intense fracture systems and breccia pipes in the tops of plutons and overlying rocks, as subsequent erosion and the unroofing process must tend to remove them (except in the case of surviving porphyry copper deposits). There is every reason to suppose that this fracturing of the tops of plutons and overlying roof-rocks is ubiquitous, but such fracturing will invariably assist subsequent deep weathering and their rapid erosion and removal to expose the plutons beneath. The same holds for many extrusive equivalents of plutons. The vents responsible for extrusion of comagmatic lavas/volcanics and release of steam and heat from the cooling plutons below have been subsequently eroded away. At other times, however, extrusive equivalents of plutons have only belatedly been recognized to be in genetic association with each other. Such has been the case, for example, for many tuff-batholith associations in the western USA.146Petrographic evidence147 contradicts the view that plutons remain impermeable for significant periods of time. To the contrary: cracking begins as soon as the quartz is brittle enough, and before the granitic magma has even fully crystallized,148 and continues during its subsequent cooling.149Finally, the observed rates of geothermal output in modern hydrothermal systems are explicable only if meteoric water has free access to both hot rock and intrusives.150 Note also that the previously-discussed water-induced feedback cooling mechanism of thick lava

flows151 must apply to plutons, if only because lithostatic pressure has relatively little effect on the process.152 Rapid Cooling of Igneous Bodies: Geologic Non-Problems

We must now account for the implications of rapid cooling. Consider igneous mineralogy and the belief that relatively large crystals in extrusives mean long cooling times. To begin with, this premise is, on its own terms, inconsistent with the ubiquitous distribution of very tiny crystals in many very thick lava flows,153 which are precisely the ones supposed to take the longest to cool.

Ironic to Young’s argument154 about the slowly-cooling Palisades Sill, it also consists of relatively small crystals and shows evidence of emplacement in 3–4 pulses,155 each of which could have cooled relatively rapidly.156 Of course, the Palisades Sill need not have cooled (or even congealed) within one year (except at its surface) before becoming overlain by fossiliferous rock. In fact, a still-flowing lava soon develops a crust strong enough157 to support a walking person (approximately 770N),158 and so could also support a modest overburden of sediment almost immediately. And, based on analogy with the Kilauea lava,159 a crust of hardened lava a few meters thick can form in a few months, thus being capable of supporting a significant overburden of fossiliferous sediment within that time frame. Consistent with all of these suggestions, the Palisades Sill shows evidence of cooling in both top-down and bottom-up directions,160 as well as evidence for it (and its probable extrusive equivalent) having been deposited subaqueously,161 which, of course, would have greatly accelerated the development of a crust thick enough to support an appreciably-thick superjacent layer of fossiliferous sediments.It is now recognized that relatively large crystals found in extrusives are not evidence for protracted periods of cooling, if only because these phenocrysts could have formed long before the emplacement of the magma.162 But even in situ crystals can grow rapidly.163 lronically, we now realize that it is the rate of nucleation in the magma, rather than the rate of its cooling, which determines the eventual size of its crystals.164Contrary to old uniformitarian beliefs, phaneritic textures in granites are not evidence for millions of years of slow cooling. Macroscopic igneous minerals can crystallize and grow to requisite size, in a sialic melt, well within a few thousand years.165, 166 So, for that matter, can phaneritic crystals in a mafic melt.167, 168 It is extraneous geologic factors, not potential rate of mineral growth, which constrain the actual size of crystals attained in igneous bodies.169Perhaps the most vivid and relevant example is that of granitic pegmatites, regarded as dike-like offshoots of granite plutons because of their spatial associations and identical major mineralogies and bulk compositions.170 At the point of aqueous vapor saturation of a granitic melt, crystal fractionation can sometimes occur, so that volatiles are concentrated in a mobile vapor (hydrothermal)-residual melt phase which readily migrates (usually upwards) into open fractures within the wallrocks immediately adjacent to the granitic pluton, but sometimes within the granite itself.171 It is widely assumed and stated in most textbooks that the giant crystal sizes (sometimes meters long) in pegmatites require very long periods of undisturbed crystal growth, that is, that pegmatite magmas cool slowly. However, London172 noted that constant crystal growth rates of approximately 10-6cm/s could produce quartz and feldspar crystals of pegmatitic dimensions in a few years. Furthermore, in a model of the cooling history of the large Harding pegmatite dike, New Mexico,173 applied conservative boundary conditions (for example, heat loss by conduction only, which is unrealistic) with a magma-wallrock temperature difference of 300°C at emplacement and calculated that the center of the pegmatite dike would have cooled below its equilibrium solidus in about 1–2 years.What about entablatures and colonnades? It is now recognized that these basaltic textures do not give unambiguous estimates for cooling rates.174 Entablatures form when lavas cool at 1–10°C per hour,175 and colonnades do so at tenfold slower cooling rates. But both estimates are compatible with much higher cooling rates,176 so long as therelative cooling rates of these features differ by at least an order of magnitude. Convective Cooling of Plutons: Petrographic Signatures

We now examine some of the pitfalls of attempting to minimize the significance of hydrothermal cooling. There is considerable evidence for hydrothermal action (for example, hydrothermal ore deposits, widespread hydrothermal alteration), but absence of evidence for such a process associated with most plutons is not evidence that hydrothermal convective cooling has not occurred. As noted earlier, a major result of hydrothermal action will be intense fracturing in the rocks overlying plutons and the upper zones of plutons themselves, but this has also facilitated erosion and thus removal of the evidence.Consider secondary hydrous minerals (epidote, chlorite, serpentine, and various clay minerals). Gabbros betray isotopic evidences for hydrothermal alteration, but are “astonishingly free” of such hydrothermal minerals.177 This is because groundwater alteration has occurred at excessive temperatures for these low PT assemblages. Likewise, if certain granites were cooled by hydrothermal fluids at temperatures higher than commonly supposed, there would be no secondary minerals to show this.However, even this reasoning generously allows for waters cooling the pluton to have experienced free access to its fabric. In actuality, if the fluids flowed mostly through larger cracks or joints, then only the walls of large granitic blocks would show alteration. In fact, such is typical of granites.178 Cathles179 warns against geologists consciously or unconsciously attempting to infer the volume of hydrothermal fluids having circulated through a pluton based on the degree of its alteration. One pluton whose petrographic fabric shows little alteration may have passed a thousand-foldgreater volume of hydrothermal fluids than did a second pluton whose fabric shows more alteration than

the first!180Now consider contact metamorphic aureoles. Their size doesn’t give unequivocal evidence for the importance or unimportance of hydrothermal cooling, in spite of models which predict that large aureoles are associated with primarily conductive cooling and small ones result from extensive hydrothermal cooling at high crustal permeabilities.181 The size of the aureole actually shows the maximum distance reached by a certain high temperature emanating from the cooling pluton.182 If, as predicted, microcracks tend to clog as convective cooling proceeds, there may come a time when there is a temporary impermeable cap above the pluton.183 The contact metamorphic aureole would enlarge as the hydrothermal fluids pool and temporarily flow greater distances from the pluton. Furthermore, tectonic effects can perturb, and temporarily expand, circulation streamlines. Rapid Convective Cooling of Plutons: Isotopic Signatures

An exciting line of evidences for extensive former hydrothermal activity around plutons is provided by the isotopic fractionating of 18O/16O and 2H/1H, and high permeabilities also favor the formation of such signatures.184Compared with ocean water, meteoric water tends to be isotopically lighter, by several parts per million, and magmatic water tends to be heavier. Therefore, whenever groundwater interacts with plutons, these rocks should be slightly depleted in 18O relative to 16O and, to a less reliable extent, be likewise slightly depleted in deuterium (2H) relative to protium (1H). Large assemblages of plutons, exposed over vast areas (such as the Canadian Cordilleras185) show this.It is the contrast between isotopic signatures of pluton and host rock that is the most informative. However, the absence of

such isotopic signatures need not mean that hydrothermal cooling was unimportant in the history of the pluton, for the following reasons (any of which would have blurred or eliminated the isotopic contrast between pluton and host rock). The magma itself may have been anomalously light isotopically, ground water may have mixed with the magma itself (especially under catastrophic conditions),186 the isotopic signature may have been obscured or erased by subsequent geologic effects,187 etc.Let us now consider a different hydrological cycle prior to the Flood. Paucity of rainfall facilitates the evaporation of water in landlocked bodies of water, making their isotopes heavier.188 Whenever these waters (and/or their connate water equivalents) had interacted with the cooling plutons, there would be little or no isotopic contrast between them and the magmatic water. Of course, we cannot know the isotopic composition of the connate waters which existed when the earth was created and which were the first to cool the plutons.Under such conditions, the first isotopically-light water came into existence only after extensive Flood rainfall had taken place. Upon percolating to great depths and displacing the older, isotopically-heavy connate water, hydrothermal-cooling isotopic signatures were created. Earlier-cooled plutons carry no such signatures despite alsohaving experienced extensive hydrothermal cooling.

Conclusions

With this work, yet another objection to the young-earth creationist position has hopefully been answered. Millions of years are not necessary for the cooling of large igneous bodies. Moreover, the geologic role of hydrothermal cooling has already been extended to account for the rapid origin of thick metamorphic lithologies.189, 190 We now have evidence that regional metamorphism is, thus not unexpectedly, associated with hydrothermal circulation systems which extend 10–100 km from the metamorphic belt itself.191 Moreover, the metamorphic fabric itself can give access to circulating fluids as a result of the microcracking that is now recognized to be a consequence of metamorphic reactions.192Gabbros themselves can be metamorphosed to the point of acquiring metamorphic hornblende (for example, the so-called amphibolite facies of metamorphism) in a time period as short as a few thousand years down to a few centuries.193A number of uniformitarian authors194, 195, 196 have pointed out the discrepancy which exists between the large measured permeabilities routinely measured within the earth’s crustal rocks (implying hydrothermal systems having lifetimes of only thousands of years), and the (supposed) need for various geothermal processes to have persisted for millions of years. For this reason, claims have been made about hydrothermal action being episodic and recurring.197,198, 199 The progressive elimination and rejuvenation of rock permeability, over countless cycles, has also been invoked.200 While, as discussed above, there indeed is much evidence for the previous searing of cracks, the pointed fact is the continued existence of high crustal permeability (primarily cracks and fractures at all scales) in spite of such evidences. Ironically,

therefore, hydrothermal cooling not only negates the cooling of plutons as a valid argument for an old earth, but, in and of itself, is more compatible with a young earth. Future Research

It has been noticed that rapid drops in groundwater levels are sometimes correlated with magmatic activity.201 This needs to be explored in the light of the Flood and its aftermath. The computer model HYDROTHERM,202 thus far applied only to small plutons,203 needs to be employed in order to perform a more sophisticated study of cooling batholiths. Moreover, the composite nature of these large igneous bodies must be better understood and then taken into account in modeling their cooling. The multiphase flow of water simulated by HYDROTHERM also indicates that, as water approaches its critical point (at which time the distinction between liquid water and steam disappears), “superconvection” or “runaway convection” potentially occurs.204 In other words, convective heat transfer becomes suddenly enhanced by a factor of 100 or more. For this to have a chance to take place, a permeability of about 100 md (which is an order of magnitude larger than we have adopted for the cooling batholith: fig. 3) is required,205 along with a narrow window of temperatures. Present evidence suggests that “superconvection” may occur during cooling of small plutons, but probably not of batholiths. Nevertheless, this question must be thoroughly addressed.More research is needed on the catastrophic extrusion of ancient voluminous lava flows, particularly that which follows up on the following tantalizing lines of evidence: the presence of large vesicles206 in basalts (suggestive of suddenly-trapped volatiles), and textural evidence of very small changes in temperature over considerable distances traveled by extruded lava.207 The latter is true of the Columbia River Basalts (northwest USA), and is consistent with their “extraordinarily rapid emplacement” over an area with a transverse distance of 500 km.208A major follow-up to this work needs to be a study of economic mineral deposits in the light of the rapid cooling of large igneous bodies. An analogy from the eastern Pacific Ocean provides a fascinating example: massive sulfide deposits of a few tons each have formed, from hydrothermal activity, in less than one year.209 AcknowledgmentsHelpful comments and three recent technical references were brought to our attention by Steven A. Austin of theInstitute for Creation Research. Other information was provided by several uniformitarian specialists. Additionally, we need to stress that all the work on this paper was our own, including the sourcing of all relevant research papers. However, even though we did not use it, we recognize the “Catastrophe Reference Database” (CATASTROREF) produced by Steven Austin (version 1.2, January 1997) as a very useful source of information on this and many other topics.

Catastrophic Granite Formation

Rapid Melting of Source Rocks, and Rapid Magma Intrusion and Cooling by Dr. Andrew A. Snelling on February 6, 2008

Abstract

The timescale for the generation of granitic magmas and their subsequent intrusion, crystallization, and cooling as plutons is no longer incompatible with the young time frames of the global, year-long Flood cataclysm and of 6,000–7,000 years for earth history. Though partial melting in the lower crust is the main rate-limiting step, it is now conjectured to only take years to decades, so partial melting to produce a large reservoir of granitic magmas could have occurred in the pre-Flood era as a consequence of accelerated nuclear decay early in the Creation. Rapid segregation, ascent, and emplacement now understood to only take days via dikes would have been aided by the tectonic “squeezing” and “pumping” during the catastrophic plate tectonics driving the global Flood cataclysm. Now that it has also been established that granitic plutons are mostly tabular sheets, crystallization and cooling would be even more easily facilitated by hydrothermal convective circulation with meteoric waters in the host rocks. The growth of large crystals from magmas within hours has now been experimentally determined, while the co-formation in the same biotite flakes of adjacent uranium and polonium radiohalos, the latter from short-lived parent polonium isotopes, requires that crystallization and cooling of the granitic plutons only took about 6–10 days. Thus the sum total of time, from partial melting in the lower crust to crystallization and cooling of granitic plutons emplaced in the upper crust, no longer conflicts with the young age time frame for earth history, nor is it an impediment to accounting for most of the fossil-bearing geologic record during the global year-long Flood catastrophe.

Keywords: granites, magma, partial melting, melt segregation, magma ascent, dikes, magma emplacement,

emplacement rates, crystallization and cooling rates, convective cooling, hydrothermal fluids, polonium radiohalos Introduction The major, almost exclusive, rock type in some areas on the earth’s surface, such as in the Yosemite National Park, is granite. Huge masses of many adjoining granite bodies outcrop on a grand scale throughout that area (fig. 1), as they also do along the length of the Sierra Nevada and the Peninsular Ranges of central and southern California respectively. The Sierra Nevada batholith is the collective name given to all the granite bodies that outcrop in, and form much of, the magnificent Sierra Nevada range. Each recognizably distinctive granite mass, the boundary of which can be traced on the ground, is marked as a separate geologic unit called a pluton on a geologic map. Hundreds of such granite plutons, ranging in size from 1 km2 to more than 1,000 km2, and each with its own name, make up the Sierra Nevada batholith. The batholith stretches in a belt approximately 600 km (373 miles) long northwest–southeast and more than 165 km (102 miles) wide. It is uncertain how deep the granite plutons are, that is, how thick they are. Evidence suggests that many may only be several kilometers (or less) thick.

Fig. 1. Panoramic view of the

Yosemite valley with the Half Dome rising above the cliffs to the right, as seen from Glacier Point. The entire landscape in this panoramic view is composed of granites.The Sierra Nevada batholith, and the Peninsular Ranges batholith just south of it, are part of a discontinuous belt of batholiths that circle the Pacific Ocean basin. For example, granite batholiths are found all through the coastal ranges along the west coast of South America and extend northward from the Sierra Nevada through Idaho and Montana, western Canada, and into Alaska. The granite plutons making up the Sierra Nevada batholith have intruded into and displaced earlier sedimentary and

volcanic strata sequences, some of which had been transformed by heat, pressure, and earth movements into metamorphic rocks. These strata sequences have been variously designated as Upper Proterozoic (uppermost Precambrian) to Paleozoic and Paleozoic to Mesozoic. (In the young age framework for earth history, that makes them Flood strata.) After the granite plutons intruded underground into these strata sequences, erosion (at the end of the Flood and since) removed all the rocks above the granites to expose them at today’s ground surface. Again, it is uncertain as to just what thickness of overlying rocks have been eroded away, but it is likely only 1–3 km.Because we don’t observe granites forming today, debate has raged for centuries as to how granites form. While there is now much consensus, some details of the processes involved are still being elucidated. Nevertheless, the conventional wisdom has been adamant until recently that granites take millions of years to form, which is thus an oft-repeated scientific objection to the recent year-long global Flood on a 6,000–7,000 year-old earth (Strahler 1987; Young 1977).Several steps are required to form granites. The process starts with partial melting of continental sedimentary and metamorphic rocks 20–40 km (12–25 miles) down in the earth’s crust (a process called generation) (Brown 1994). This must be followed by the collection of the melt (called segregation), then transportation of the now less dense, buoyant magma upwards (ascent), and finally the intrusion of the magma to form a body in the upper crust (emplacement). There, as little as 2–5 km (1–3 miles) below the earth’s surface, the granite mass fully crystallizes and cools. Subsequent erosion exposes it at the earth’s surface. When reviewing this list of sequential processes, it is not difficult to understand why it has been hitherto envisaged that granite formation, especially the huge masses of granites outcropping in the Yosemite area, must surely have taken millions of years (Pitcher 1993). Of course, such estimates are claimed to be supported by radioisotope dating.However, this long-accepted timescale for these processes is now being challenged, even by conventional geologists (Clemens 2005; Petford et al. 2000). The essential role of rock deformation is now recognized. Previously accepted granite formation models required unrealistic deformation and flow behaviors of rocks and magmas, or they did not satisfactorily explain available structural or geophysical data. Thus it is now claimed that mechanical considerations suggest granite formation is a “rapid, dynamic process” operating at timescales of less than 100,000 years, or even only thousands of years. Magma Principles

First, however, it will be helpful to explain what magma is and why it is thought to exist underground. The molten material which flows from volcanoes is known as lava and cools to form volcanic rocks. So lavas must be molten rocks; that is, they were originally rocks that melted deep inside the earth underneath volcanoes. When deep inside the earth, these molten rock materials are called magmas because they are slightly different in composition and physical properties due to the steam and gases they have dissolved in them that erupt separately from the lavas through volcanoes.Before volcanic eruptions there are warning “rumbles” inside volcanoes. These are earthquakes generated by the magmas moving up into the volcanoes. Such earthquakes have allowed geologists to reconstruct how magmas first “pond” below volcanoes in reservoirs known as magma chambers before their final passage upward through volcanoes to erupt as lavas. If the magma cools when it “ponds” in the magma chamber, rather than rising further to erupt at the earth’s surface, then it crystallizes as an intrusion. Subsequent erosion of all the overlying rock layers eventually exposes such intrusions at the earth’s surface.This scenario has been confirmed by copper mining operations that have excavated into granite intrusions that must have formed under volcanoes. The remnants of such volcanoes overlie the granite intrusions, and their volcanic rocks are the same compositions as the granite intrusions (the former magma chambers) (fig. 2). Similarly, seismic surveys across the mountains somewhat central to many ocean basins have detected the magma chambers under the rift zones where lavas have erupted onto the ocean floor. Because the magma is less dense than the surrounding rocks, the passage of the seismic (sound) waves when recorded and compiled actually produces images (or three-dimensional pictures) of the magma chambers.

Fig. 2. Schematic cross-section through a

small granite pluton at the stage of waning magmatic activity in the development of a porphyry copper ore deposit. The chaotic line pattern represents the extensive fracture system in the apex above the cooling water-saturated granite magma. Note that the granite has intruded into the volcanic rocks that earlier erupted from the volcano its magma supplied. Laboratory experiments have produced very small quantities of magmas by the melting of appropriate rocks. Such experiments are not easy to perform because of the difficulties of simulating the high temperatures and pressures inside the earth. The required laboratory apparatus thus only contains a very small vessel in which magmas can be produced. Yet many such experiments have enabled geologists to study and understand the compositions and behavior of magmas. Magma ProcessesMeasurements on extruded magma (lava), together with evaluations of the temperatures at which constituent minerals form and coexist, and experimental determinations of rock melting relationships, indicate that magmas near the earth’s surface are generally at

temperatures from 700°C to 1,200°C (1,300–2,200°F). We know from direct measurements in many deep drillholes that rock temperatures inside the earth’s crust increase progressively with depth. This is known as the geothermal gradient. From these measured geothermal gradients it is thus estimated that the temperatures needed to melt rocks and form magmas must occur at depths of greater than 30 km, at and near the bottom of the crust of continents, and in the upper mantle below.Being molten rock materials, magmas are very dense liquids which have varying abilities to flow. Viscosity describes the ability of the magma to flow. This depends on the degree of immobility of the atoms inside the magma, the resistance of their arrangement or bonding to the stress that would cause flow. Viscosity is the internal friction or “stickiness” of a magma. A more viscous magma is very sticky and flows very slowly. A magma (or lava) that flows easily and thus quickly has a low viscosity.Rheology is the study of the flow of magmas and of the ways in which magmas (and rocks) respond to applied pressures or stress. If a body of material returns instantaneously to its initial undeformed state once the stress applied to it wanes, it is said to be elastic. Magmas are not elastic, just viscous and plastic, because once deformed by applied stress they do not recover their original shapes, but instead flow.The viscosity of a magma is dependent on its temperature and composition. It should be fairly obvious that the hotter a magma, the more quickly it will flow, because the heat gives its atoms more energy so their bonding is less resistant to applied stress. A hotter magma is thus less viscous. However, there are two compositional factors that affect magma viscosity the most—silica content and water content.When igneous rocks are analyzed, their content of silicon atoms is expressed as a compositional percentage of silica, which is silicon dioxide (SiO2) or the glassy mineral called quartz (similar to window glass). Granites have a silica composition of around 70%, whereas basalts contain around 50% silica. Thus granitic magmas are far more viscous than basaltic magmas. The latter are also hotter. This is why basalt lavas tend to flow freely, compared with rhyolite (granitic) lavas that are very viscous.The water content of magmas varies, but in general granitic magmas have far more water dissolved in them than basaltic magmas. Indeed, the amount of water dissolved in granitic magmas increases with pressure and therefore depth, from 3.7 wt % water content at 3–4 km depth (Holtz, Behrens, Dingwell, and Johannes 1995) to 24 wt % water at 100 km depth (Huang and Wyllie 1975). The effect of more water in a granitic magma is to reduce its viscosity. It is this greater water content and viscosity of granitic (rhyolitic) magma that make its volcanic eruption so explosive. The viscous granitic magma forms a better/stronger “cork” (as it were) on the volcano, and with so much water as steam, the volcano’s top explodes. By comparison a basalt eruption is usually less explosive because the magma contains much less steam and the lava is much less viscous. Magma Generation by Partial Melting

Typical geothermal gradients of 20°C/km do not generate the greater than 800°C temperatures at 35 km depth in the crust needed to melt common crustal rocks (Thompson 1999). However, there are at least three other factors, besides temperature, that are important in melt generation: (1) water content of magma, (2) pressure, and (3) the influence of mantle-derived basaltic magmas. The temperatures required for melting are significantly lowered by increasing water activity up to saturation, and the amount of temperature lowering increases with increasing pressure (Ebadi and Johannes 1991). Indeed, water solubility in granitic melts increases with pressure, the most important controlling factor (Johannes and Holtz 1996), so that whereas at 1 kbar (generally equivalent to 3–4 km depth) the water solubility is 3.7 wt % (Holtz et al. 1995), at 30 kbar (up to 100 km depth, though very much less in tectonic zones) it is approximately 24 wt % (Huang and Wyllie 1975). This water is supplied by the adjacent rocks, subducted oceanic crust, and hydrous minerals present in the melting rock itself.Nevertheless, local melting of deep crustal rocks is even more efficient where the lower crust is being heated by basaltic magmas generated just below in the upper (hotter) mantle (Bergantz 1989). Partial melting of crustal rocks preheated in this way is likely to be rapid, with models predicting a melt layer two-thirds the thickness of the basaltic intrusions forming in 200 years at a temperature of 950°C (Huppert and Sparks 1988; Thompson 1999). Experiments on natural rock systems have also shown the added importance of mineral reactions involving the breakdown of micas and amphiboles to rapidly produce granitic melts (Brown and Rushmer 1997; Thompson 1999). One such experiment found that a quartzo-feldspathic source rock undergoing water-saturated melting at 800°C could produce 20–30 vol. % of homogeneous melt in less than 1–10 years (Acosta-Vigil et al. 2006).A crucial consequence of fluid-absent melting is reaction-induced expansion of the rock that results in local fracturing and a reduction in rock strength due to the increased pore fluid (melt) pressures (Brown and Rushmer 1997; Clemens and Mawer 1992). Stress gradients can also develop in the vicinity of an intruding basaltic heat source and promote local fractures. These processes, in

conjunction with regional tectonic strain, are important in providing enhanced fracture permeabilities in the region of partial melting, which aid subsequent melt segregation (Petford et al. 2000). Melt Segregation

The small-scale movement of magma (melt plus suspended crystals) within the source region is called segregation. The granitic melt’s ability to segregate mechanically from its matrix is strongly dependent on its physical properties, of which viscosity and density are the most important. Indeed, the viscosity is the crucial rate-determining variable (Woodmorappe 2001) and is a function of melt composition, water content, and the temperature (Dingwell, Bagdassarov, Bussod, and Webb 1993). It has been demonstrated that the temperature and melt’s water content are interdependent (Scalliet, Holtz, and Pichavant 1998), yet the viscosities and densities of granitic melts actually vary over quite limited ranges for melt compositions varying between tonalite (65 wt % SiO2, 950°C) and leucogranite (75 wt % SiO2, 750°C) (fig. 3) (Clemens and Petford 1999). An important implication is that the segregation and subsequent ascent processes, which are moderated by the physical properties of the melts, thus occur at broadly similar rates, regardless of the tectonic setting and the pressures and temperatures to which the source rock has been subjected over time. Furthermore, granitic magmas are only 10–1,000 times more viscous than basaltic magmas (Baker 1996; Clements and Petford 1999; Scalliet, Holtz, Pichavant, and Schmidt 1996), which readily flow.

Fig. 3. Melt viscosity as a function of melt

water (wt %) content for typical tonalite and leucogranite liquid compositions (after Clemens and Petford 1999) at a fixed pressure of 800 MPa. The horizontal line shows the range of water contents typical for natural melts. The estimated log10values of the median viscosities (in Pa s) of the liquids at their “ideal” water contents of 4 wt % (tonalite) and 6 wt % (leucogranite) are 3.8 and 4.9 respectively. Most field evidence points to deformation (essentially “squeezing”) as the dominant mechanism that segregates melt flow in the lower crust (Brown and Rushmer 1997; Vigneresse, Barbey, and Cuney 1996). Rock deformation experiments indicate that when 10–40% of a rock is a granitic melt, the pore pressures in a rock are equivalent to the confining pressure, so the residual grains move relative to one another resulting in

macroscopic deformation due to melt-enhanced mechanical flow (Brown and Rushmer 1997; Rutter and Neumann 1995). These experiments also imply that deformation-enhanced segregation can in principle occur at any stage during partial melting. Furthermore, the deformation-assisted melt segregation is so efficient in moving melt from its source to local sites of dilation (“squeezing”) over timescales of only a month up to 1,000 years. Thus the melts may not attain chemical or isotopic equilibrium with their surrounding source rocks before final extraction and ascent (Davies and Tommasini 2000; Sawyer 1991).According to the best theoretical models, melted rock in the lower crust segregates via porous flow into fractures within the source rock (usually metamorphic) above a mafic intrusion (the heat source), the fractures inflating to form veins (Petford 1995). Local compaction of the surrounding matrix then allows the veins to enlarge as they fill further with melt, and the fluid-filled veins coalesce to form a dike (fig. 4). At a certain critical melt-fraction percent of the source rock, a threshold is reached where the critical dike width is achieved. Once that critical dike width is exceeded, “rapid (catastrophic) removal of the melt from the source” occurs. The veins collapse abruptly, only to be then refilled by continuously applied heat to the source rock. Thus the process is repeated, the granitic melt being extracted and then ascending through dikes to the upper crust in rapid and catastrophic pulses.

Fig. 4. Schematic representation of a possible sequence of events (1–4) resulting from fluid-absent melting reactions in a

protolith above a mafic (intrusive) heat source in the lower crust. Veins fill by porous flow, with some local compaction (inset).

These rapid timescales for melt extraction are well-supported by geochemical evidence in some granites. For example, some Himalayan leucogranites are strongly undersaturated with respect to the element zirconium (Harris, Vance, and Ayres 2000) because the granitic melt was extracted so rapidly from the residual matrix (in less than 150 years) that there was insufficient time for zirconium to be reequilibrated between the two phases. Similarly, based on comparable evidence in a Quebec granite, Canada, the inferred time for the extraction of the melt from its residuum was only 23 years (Sawyer 1991). Magma Ascent

Gravity is the essential driving force for large-scale vertical transport of melts (ascent) in the continental crust (Petford et al. 2000). However, the traditional idea of buoyant granitic magma ascending through the continental crust as slow-rising, hot diapirs or by stoping (that is, large-scale veining) (Weinberg and Podladchikov 1994) has been largely replaced by more viable models. These models involve the very rapid ascent of granitic magmas in narrow conduits, either as self-propagating dikes (Clemens and Mawer 1992; Clemens, Petford, and Mawer 1997), along preexisting faults (Petford, Kerr, and Lister 1993), or as an interconnected network of active shear zones and dilational structures (Collins and Sawyer 1996; D’Lemos, Brown, and Strachan 1993). The advantage of dike/conduit ascent models is that they overcome the severe thermal and mechanical problems associated with transporting very large volumes of granite magmas through the upper brittle continental crust (Marsh 1982), as well as explain the persistence of near-surface granite intrusions and associated silicic volcanism. Yet to be resolved is whether granite plutons are fed predominantly by a few large conduits or by dike swarms (Brown and Solar 1999; Weinberg 1999).The most striking aspect of the ascent of granitic melts in dikes is the extreme difference in the magma ascent rate compared to diapiric rise, the dike ascent rate being up to a million times faster depending on the magma’s viscosity and the conduit width (Clemens, Petford, and Mawer 1997; Petford, Kerr, and Lister 1993). The narrow dike widths (1–50 m) and rapid ascent velocities predicted by fluid dynamical models are supported by field and experimental studies (Brandon, Chacko, and Creaser 1996; Scalliet, Pecher, Rochette, and Champenois 1994). For example, for epidote crystals to have been preserved as found in the granites of the Front Range (Colorado) and of the White Creek batholith (British Columbia) required an ascent rate of between 0.7 and 14 km per year. Therefore the processes of melt segregation at more than 21 km depth in the crust and then magma ascent and emplacement in the upper crust all had to occur within just a few years (Brandon, Chacko, and Creaser 1996). Such a rapid ascent rate is similar to magma transport rates in dikes calculated from numerical modeling (Clemens and Mawer 1992; Petford, Kerr, and Lister 1993; Petford 1995, 1996), and close to measured ascent rates for upper crustal magmas (Chadwick, Archuleta, and Swanson 1988; Rutherford and Hill 1993; Scandone and Malone 1985). Indeed, Petford, Kerr, and Lister (1993) calculated that a granite melt could be transported 30 km up through the crust along a 6 m wide dike in just 41 days at a mean ascent rate of about 1 cm/s. At that rate the Cordillera Blanca batholith in northwest Peru, with an estimated volume of 6,000 km3, could have been filled from a 10 km long dike in only 350 years.It is obvious that magma transport needed to have occurred at such fast rates through such narrow dikes or else the granite magmas would “freeze” due to cooling within the conduits as they ascended. Instead, there is little geological, geophysical, or geochemical evidence to mark the passage of such large volumes of granite magma up through the crust (Clemens and Mawer, 1992; Clemens, Petford, and Mawer 1997). Because of the rapid ascent rates, chemical and thermal interaction between the dike magmas and the surrounding country rocks will be minimal. Clemens (2005) calculates typical ascent rates of 3 mm/s to 1 m/s, which, assuming there is continuous, efficient supply of magma to the base of the fracture system, translates to between five hours and three months for 20 km of ascent. Such rapid rates make granite magma ascent effectively an instantaneous process, bringing plutonic granite magmatism more in line with timescales characteristic of silicic volcanism and flood basalt magmatism (Petford et al. 2000). Magma Emplacement

The final stage of magma movements is horizontal flow to form intrusive plutons in the upper continental crust. This emplacement is controlled by a combination of mechanical interactions, either preexisting or emplacement-generated wall-rock structures, and density effects between the spreading flow and its surroundings (Hogan and Gilbert 1995; Hutton 1988). The mechanisms by which the host rocks make way for this incoming magma have challenged geologists for most of the past century and have been known as the “space problem” (Pitcher 1993). This problem is particularly acute where the volumes of magmas forming batholiths (groups of hundreds of individual granite plutons intruded side-by-side over large areas, such as the Sierra Nevada of California) are 100,000 km3 or greater and are considered to have been emplaced in a single event.New ideas that have alleviated this problem are (1) the recognition of the important role played by tectonic activity in making space in the crust for the incoming magma (Hutton 1988), (2) more realistic interpretations of the geometry of granitic intrusions at depth, and (3) the recognition that emplacement is an episodic process involving discrete pulses of magma. Physical models (Benn, Odonne, and de Saint Blanquat 1998; Cruden 1998; Fernández and Castro 1999; Roman-Berdiel, Gapais, and Brun 1997) indicate that space for incoming magmas can be generated through a combination of lateral fault opening, roof lifting, and lowering of the growing magma intrusion floor. For example,

space is created by uplift of the strata above the intrusion, even at the earth’s surface, and their erosion.The three-dimensional (3D) shapes of crystallized plutons provide important information on how the granitic magmas were emplaced. The majority of plutons so far investigated using detailed geophysical (gravity, magnetic susceptibility, and seismic) surveys appear to be flat-lying sheets to open funnel-shaped structures with central or marginal feeder zones (Améglio and Vigneresse 1999; Améglio, Vigneresse, and Bouchez 1997; Evans et al. 1994; Petford and Clemens 2000), consistent with an increasing number of field studies (collecting fabric and structural data) that find plutons to be internally sheeted on the 0.1 meter to kilometer scale (Améglio, Vigneresse, and Bouchez 1997; Grocott et al. 1999). Fig. 5. Mean (vertical) thickness versus

mean (horizontal) length for granitic plutons

and laccoliths (after Petford et al. 2000). Reduced major-axis regression defines a power-law curve for plutons with an exponent a of 0.6 ± 0.1. Laccoliths (shallow-level intrusions) are described by a power-law exponent of 0.88 ± 0.1 (McCaffrey and Petford 1997). The line a = 1 defines the critical divide between predominantly vertical inflation (a > 1) and predominantly horizontal elongation (a < 1) during intrusion growth. Significantly different power-law exponents rule out a simple genetic relationship between both populations. Differences may be due to mechanical effects, with limits in thickness reflecting floor depression (plutons) and roof lifting (laccoliths).Considerations of field and geophysical data suggest that the growth of a laterally spreading and vertically thickening intrusive flow obeys a simple mathematical scaling or power-law relationship (between thickness and length) typical of systems exhibiting scale-invariant (fractal) behavior and size distributions (McCaffrey and Petford 1997; Petford and Clemens 2000). This inherent preference for scale-invariant tabular sheet geometries in granitic plutons from a variety of tectonic settings (fig. 5) (Petford et al. 2000) is best explained in mechanical terms by the intruding magma flowing horizontally some distance initially before vertical thickening then occurs, either by hydraulic lifting of the overburden (particularly above shallow-level intrusions) or sagging of the floor beneath. Plutons thus go from a birth stage characterized by lateral spreading to an inflation stage marked by vertical thickening.This intrusive tabular sheet model envisages larger plutons growing from smaller ones according to a power-law inflation growth curve, ultimately to form crustal-scale batholithic intrusions (Cruden 1998; McCaffrey and Petford 1997). Evidence of this growth process has been revealed by combined field, petrological, geochemical, and geophysical (gravity) studies of the 1,200 km long Coast batholith of Peru (Atherton 1999). On a crustal scale this exposed batholith was formed by a thin (3–7 km thick) low-density granite layer that coalesced from numerous smaller plutons with aspect ratios of between 17:1 and 20:1. Thus this batholith would only amount to 5–10% of the crustal volume of this coastal sector of the Andes (Petford and Clemens 2000), which greatly reduces the so-called space problem. Detailed studies of the Sierra Nevada batholith of California (which includes the Yosemite area) reveal a similar picture, in which batholith construction occurred by progressive intrusion of coalescing granitic plutons 2–2,000 km2 in area, supposedly over a period of 40 million years (as determined by radioisotope dating) (Bateman 1992). Emplacement Rates

The tabular 3D geometry of granite plutons and their growth by vertical displacements of their roofs and floors enables limits to be placed on their emplacement rates (fig. 6) (Petford et al. 2000). If we assume that a disk-shaped pluton grows according to the empirical power-law relation shown in fig. 5, T = 0.6 (±0.15)L0.6±0.1, then its filling time can be estimated

when the volumetric filling rate is known. Taking conservative values for magma viscosities, wall-rock/magma density differences and feeder dike dimensions results in pluton filling times of between less than 40 days and 1 million years for plutons under 100 km across. If the median value for the volumetric filling rate is used, then at the fastest magma delivery rates most plutons would have been emplaced in much less than 1,000 years (Harris, Vance, and Ayres 2000; Petford et al. 2000). Even a whole batholith of 1,000 km3 could be built in only 1,200 years, at the rate of growth of an intrusion in

today’s noncatastrophic geological regime (Clemens 2005). Fig. 6. Estimated filling times for tabular disk-shaped plutons (after Petford et al. 2000). This thickness (T) to width (L) ratio

is given by the equation in the text for a range of permissible filling rates (Q). Heavy horizontal lines are the thickness ranges estimated using that equation for the Mount Gwens pluton (MGP), the Dinkey Creek pluton (DCP) and the Bald Mountain pluton (BMP) in the Sierra Nevada batholith, California. Vertical lines are the ranges of their possible filling times, bracketed by their filling rates. The colored prism indicates the range of thicknesses estimated independently for the southwest lobe of the DCP using structural data (Bateman 1992).Thus the formation of granite intrusions in the middle to upper crust involves four discrete processes— partial melting, melt segregation, magma ascent, and magma emplacement. According to conventional geologists (Petford et al. 2000), the rate-limiting step in this series of processes in granite magmatism is the timescale of partial melting (Harris, Vance, and Ayres 2000; Petford, Clemens, and Vigneresse 1997), but “the follow-on stages of segregation, ascent, and emplacement

can be geologically extremely rapid—perhaps even catastrophic.” However, as suggested by Woodmorappe (2001), the required timescale for partial melting is not incompatible with the 6,000–7,000 year framework for earth history because a very large reservoir of granitic melts could have been generated in the lower crust in the 1,650 years between Creation and the Flood, particularly due to residual heat from an episode of accelerated nuclear decay during the Creation (Humphreys 2000; Vardiman, Snelling, and Chaffin 2005). This very large reservoir of granitic melts would then have been mobilized and progressively intruded into the upper crust during the global, year-long Flood when the rates of these granite magmatism processes would have been greatly accelerated with so many other geologic processes due to another episode of accelerated nuclear decay (Humphreys, 2000; Vardiman, Snelling, and Chaffin 2005) and catastrophic plate tectonics (Austin et al. 1994), the likely driving mechanism of the Flood event. Crystallization and Cooling Rates

The so-called space problem may have been solved, but what of the heat problem, that is, the time needed to crystallize and cool the granite plutons after their emplacement? As Clemens (2005) states, given that it has now been established that the world’s granitic plutons are mostly tabular in shape and typically only a few kilometers thick, it is a simple matter to model the cooling of granitic plutons by conduction (Carslaw and Jaeger 1980). So using typical values for physical properties of the magma and wall-rock temperatures, thermal conductivities and heat capacities, Clemens (2005) determined that a 3 km thick sheet of granitic magma would take around 30,000 years to completely solidify from the initially liquid magma.However, this calculation completely ignores, as already pointed out by Snelling and Woodmorappe (1998), the field, experimental, and modeling evidence that the crystallization and cooling of granitic plutons occurred much more rapidly as a result of convection due to the circulation of hydrothermal and meteoric fluids, evidence that has been known about for more than 25 years (for example, Cathles 1977; Cheng and Minkowycz 1977; Hardee 1982; Norton, 1978; Norton and Knight 1977; Paramentier 1981; Spera 1982; Torrance and Sheu 1978). The most recent modeling of plutons cooling by hydrothermal convection (Hayba and Ingebritsen 1997) takes into account the multiphase flow of water and the heat it carries in the relevant ranges of temperatures and pressures, so that a small pluton (1 km × 2 km, at 2 km depth) is estimated to have taken 3,500–5,000 years to cool depending on the system permeability. But this

modeling does not take into account the relatively thin, tabular structure of plutons that would significantly reduce their cooling times. Similarly, convective overturn caused by settling crystals in the plutons would be another significant factor in the dissipation of their heat (Snelling and Woodmorappe 1998). Convective Cooling: The Role of Hydrothermal Fluids

Granitic magmas invariably have huge amounts of water dissolved in them that are released as the magma crystallizes and cools. As the magma is injected into the host strata, it exerts pressure on them that facilitates fracturing of them (Knapp and Norton 1981). Also, the heat from the pluton induces fracturing as the fluid pressure in the pores of the host strata increases from the heat (Knapp and Knight 1977), this process repeating itself as the pluton’s heat enters these new cracks.Following the emplacement of a granitic magma, crystallization occurs due to this irreversible heat loss to the surrounding host strata (Candela 1992). As heat passes out of the intrusion at its margins, the solidus (the boundary between the fully crystallized granite and partially crystallized magma) progressively moves inward towards the interior of the intrusion (Candela 1991). As crystallization proceeds, the water dissolved in the magma that isn’t incorporated in the crystallizing minerals stays in the residual melt, so its water concentration increases. When the saturation water concentration is lowered to the actual water concentration in the residual melt, first boiling occurs and water (as superheated steam) is expelled from solution in the melt, which is consequently driven towards higher crystallinities as the temperature continues to fall. Bubbles of water vapor then nucleate and grow, causing second (or resurgent) boiling within the zone of crystallization just underneath the solidus boundary and the already crystallized granite (fig. 7).

Fig. 7. Cross-section through the margin of

a magma chamber traversing (from left to right): country rock, cracked pluton, uncracked pluton, solidus, crystallization interval, and bulk melt (after Candela 1991). As the concentration and size of these vapor bubbles increase, vapor saturation is quickly reached, but initially these vapor bubbles are trapped behind the immobile crystallized granite margin of the pluton (Candela 1991). The vapor pressure thus increases until the aqueous fluid can only be removed from the sites of bubble nucleation through the establishment of a three-dimensional critical percolation network, with advection of aqueous fluids through it or by means of fluid flow through a cracking front in the already crystallized granite and out into the surrounding host strata. Once such fracturing of the pluton has occurred (because the cracking front will go deeper and deeper into the pluton as the solidus boundary moves progressively inward toward the core of the intrusion), not only is magmatic water released from the pluton carrying heat out into the host strata, but the cooler meteoric water in the host

strata is able to penetrate into the pluton and thus establish a convective hydrothermal circulation through the fracture networks in both the granite pluton and the surrounding host strata. The more water is dissolved in the magma, the greater will be the pressure exerted at the magma/granite and granite/host strata interfaces and thus the greater the fracturing in both the granite pluton and the surrounding host strata (Knapp and Norton 1981; Zhao and Brown 1992). Thus by the time the magma has totally crystallized into the constituent minerals of the granite, the solidus boundary and cracking front have both reached the core of the pluton as well. It also means that a fracture network has been established through the total volume of the pluton and out into the surrounding host strata through which a vigorous flow of hydrothermal fluids has been established. These hydrothermal fluids thus carry heat by convection out through this fracture network away from the cooling pluton, ensuring the temperature of the granitic rock mass continues to rapidly fall. The amount of water involved in this hydrothermal fluid convection system is considerable, given that a granitic magma has enough energy due to inertial heat to drive roughly its mass in meteoric fluid circulation (Cathles 1981; Norton and Cathles 1979).The emplacement depth and the scale of the hydrothermal circulatory system are first-order parameters in determining the cooling time of a large granitic pluton (Spera 1982). Water also plays a “remarkable role” in determining the cooling time. For a granitic pluton 10 km wide emplaced at 7 km depth, the cooling time of the magma to the solidus decreases almost tenfold as the water content of the magma increases from 0.5 wt % to 4 wt %. As the temperature of the pluton/host rock boundary drops through 200°C during crystallization, depending on the hydrothermal fluid/magma volume ratio, with only a 2 wt % water content, the pluton cooling time decreases eighteen-fold. As concluded by Spera (1982, p. 299):Hydrothermal fluid circulation within a permeable or fractured country rock accounts for most heat loss when magma is emplaced into water-bearing country rock . . . . Large hydrothermal systems tend to occur in the upper parts of the crust where meteoric water is more plentiful.Of course, granitic magmas rapidly emplaced during the Flood would have been intruded into sedimentary strata that were still wet from just having been deposited only weeks or months earlier.Furthermore, complete cooling of such granitic plutons did not have to all occur during the Flood year.It is also a total misconception that the large crystals found in granites required slow cooling rates (Luth 1976, pp. 405–411; Wampler & Wallace 1998). All the basic minerals found in granites have been experimentally grown over laboratory timescales (Jahns and Burnham 1958; Mustart 1969; Swanson, Whitney, and Luth 1972; Winkler and Von Platen 1958), so macroscopic igneous minerals can crystallize and grow rapidly to requisite size from a granitic melt (Swanson 1977; Swanson and Fenn 1986). So, asks Clemens (2005), how long did it take to form the plagioclase feldspar crystals in a particular granite? Linear crystal growth rates of quartz and feldspar have been experimentally measured and rates of 10 -

6.5 m/sec to 10-11.5 m/sec seem typical. This means that a 5 mm long crystal of plagioclase could have grown in as short a time as one hour, but probably no more than 25 years (Clemens 2005). Actually, it is extraneous geologic factors, not potential rate of mineral growth, which constrain the sizes of crystals attained in igneous bodies (Marsh 1989). Indeed, it has been demonstrated that the rate of nucleation is the most important factor in determining growth rates and eventual

sizes of crystals (Lofgren 1980; Tsuchiyama 1983). Thus the huge crystals (meters long) sometimes found in granitic pegmatites have grown rapidly at rates of more than 10-6 cm/s from fluids saturated with the components of those minerals within a few years (London 1992). Crystallization and Cooling Rates: The Evidence of Polonium Radiohalos

There is a feature in granites that severely restricts the timescale for their emplacement, crystallization, and cooling to just days or weeks at most—polonium radiohalos (Snelling 2005; Snelling and Armitage 2003). Radiohalos are minute spherical (circular in cross-section) zones of darkening due to radioisotope decay in tiny central mineral inclusions within the host minerals (Gentry 1973; Snelling 2000). They are generally prolific in granites, particularly where biotite (black mica) flakes contain tiny zircon inclusions that contain uranium. As the uranium in the zircon grains radioactively decays through numerous daughter elements to stable lead, the α-radiations from eight of the decay steps produce characteristic darkened rings to form uranium radiohalos around the zircon radiocenters. Also present adjacent to these uranium radiohalos in many biotite flakes are distinctive radiohalos formed only from the three polonium radioisotopes in the uranium decay chain. Because they have been parented only by polonium, they are known as polonium radiohalos.The significance of these polonium radiohalos in granites is that they had to form exceedingly rapidly because the half-lives (decay rates) of these three polonium radioisotopes are very short—3.1 minutes (218Po), 164 microseconds (214Po), and 138 days (210Po). Furthermore, each visible radiohalo requires the decay of 500 million to one billion parent radioisotope atoms to form them (Gentry 1973; Snelling 2000). The zircons at the centers of the adjacent uranium radiohalos are the only nearby source of polonium (from decay of the same uranium that produces the uranium radiohalos). The hydrothermal fluids released by the crystallization and cooling of the granites flow between the sheets making up the biotite flakes to transport the polonium from the zircons to adjacent concentrating sites. These then become the radiocenters which produce the polonium radiohalos (Snelling 2005; Snelling and Armitage 2003). Furthermore, the radiohalos can only form after the granites have cooled below 150°C (Laney and Laughlin 1981), which is very late in the granite crystallization and cooling process. Yet uranium decay and hydrothermal transport of daughter polonium isotopes starts much earlier when the granites are still crystallizing. Nevertheless, because of the very short half-lives of these three polonium radioisotopes that necessitate their rapid hydrothermal fluid transport to generate the polonium radiohalos within hours to a few days, it is estimated that the granites also need to have crystallized and cooled within 6–10 days, or else the required large quantities of polonium (from grossly accelerated decay of uranium) would decay before they could form the polonium radiohalos (Snelling 2005; Snelling and Armitage 2003). Such a timescale for crystallization and cooling of granite plutons is certainly compatible with the young timescales for the global Flood event and for earth history. It might be argued that the uranium in the zircon grains could continue to supply polonium and radon isotopes to the polonium deposition sites via hydrothermal fluids for an extremely long time period after the temperature of the granites fell below 150°C, so the polonium radiohalos would not need to form in hours to days. Even though the half-lives of the polonium isotopes are very short, a long steady-state decay of uranium would surely build up slowly the uranium radiohalos, and the hydrothermal fluids would steadily transport the radon and polonium to slowly generate the polonium radiohalos nearby.However, this presupposes that the hydrothermal fluids continued to flow for long periods of time after the granites cooled below 150°C. To the contrary, once the granites and hydrothermal fluids fall below 150°C most of the energy to drive the hydrothermal fluid flow has already dissipated. The hydrothermal fluids are expelled from the crystallizing granite and start flowing just below 400°C (fig. 8). So unless the granite cooled rapidly from 400°C to below 150°C, most of the radon and polonium transported by the hydrothermal fluids would have been flushed out of the granites by the vigorous hydrothermal convective flows as they diminished. Simultaneously, much of the energy to drive these fluid flows dissipates rapidly as the granite temperature drops. Thus, below 150°C the hydrothermal fluids have slowed down to such an extent that they cannot sustain protracted flow, and with the short half-lives of the radon and polonium isotopes, they would decay before those atoms reached the polonium deposition sites. Furthermore, the capacity of the hydrothermal fluids to carry dissolved radon and polonium decreases dramatically as the temperature continues to drop. Thus sufficient radon and polonium had to be transported quickly to the polonium deposition sites to form the polonium radiohalos, while there was still enough energy at and just below 150°C to drive the hydrothermal fluid flow rapidly enough to get the polonium isotopes to the deposition sites before the polonium isotopes decayed. This is the time and temperature “window” depicted schematically in Fig. 8. The time “window” is especially brief in the case of the decay of the 218Po and 214Po isotopes (half-lives of 3.1 minutes and 164 microseconds respectively) and the formation of their radiohalos. It would thus be simply impossible for these polonium radiohalos to form slowly over millions of years at today’s groundwater temperatures in cold granites. Heat is needed to dissolve the radon and polonium atoms, and to drive the hydrothermal convection that moves the fluids which transport the radon and polonium atoms to supply the radiocenters to generate the polonium radiohalos. Furthermore, the required heat cannot be sustained for the 100 million years or more while sufficient 238U decays at today’s rates to produce the required polonium atoms to form the polonium radiohalos. Thus the granites need to have crystallized and cooled rapidly (within 6–10 days) to still drive the hydrothermal fluid flow rapidly enough to generate the polonium radiohalos within hours to a few days.

Fig. 8. Schematic, conceptual,

temperature versus time cooling curve diagram to show the timescale for granite crystallization and cooling, hydrothermal fluid transport, and the formation of polonium radiohalos. Formation of the Yosemite Area Granitic Plutons Finally, the formation of the hundreds of granitic plutons of the Sierra Nevada batholith, some of which outcrop on a grand and massive scale in the Yosemite area, can thus be adequately explained within the young framework for earth history. The regional geologic context suggests that late in the Flood year, after deposition of thick sequences of fossiliferous sedimentary strata, a subduction zone developed just to the west at the western edge of the North American plate (Huber 1991). Because plate movements were then catastrophic during the Flood year (Austin et al. 1994), as the cool Pacific plate was catastrophically subducted

under the overriding North American plate, the western edge region of the latter was deformed, resulting in buckling of its sedimentary strata and metamorphism at depth (fig. 9). The Pacific plate was also progressively heated as it was subducted, so that its upper side began to partially melt and thus produce large volumes of basalt magma. Rising into the lower continental crust of the deformed western edge of the North American plate, the heat from these basalt magmas in turn caused voluminous partial melting of this lower continental crust, generating buoyant granitic magmas. These rapidly ascended via dikes into the upper crust, where they were emplaced rapidly and progressively as the hundreds of coalescing granitic plutons that now form the Sierra Nevada batholith. The presence of polonium radiohalos in many of the Yosemite area granitic plutons (Gates 2007; Snelling 2005) is confirmation of their rapid crystallization and cooling late in the closing phases of the Flood year. Conventional radioisotope dating, which assigns ages of 80–120 million years to these granites (Bateman 1992), appears to be grossly in error because of not taking into account the acceleration of the nuclear decay (Vardiman, Snelling, and Chaffin 2005). Subsequent rapid erosion at the close of the Flood, as the waters drained rapidly off the continents, followed by further erosion early in the post-Flood era and during the post-Flood Ice Age, have exposed and shaped the outcropping of these granitic plutons in the Yosemite area as seen today. Conclusions

Even the conventional long-ages geologic community now regards the formation stages of granite plutons, after partial melting of source rocks to form granitic melts, that is, melt segregation, ascent and emplacement, to be “geologically extremely rapid—perhaps even catastrophic.” At today’s apparently slow rates of partial melting significant granite magmatism is not now occurring. However, a large reservoir of granitic melts could have been generated in the lower crust during the 1,650 years between Creation and the Flood, particularly due to residual heat from an episode of accelerated nuclear decay during the Creation . This very large reservoir of granitic melts would then have been mobilized and progressively intruded into the upper crust during the global Flood cataclysm, when another episode of accelerated nuclear decay would have greatly accelerated many geologic processes, including granite magmatism, driven by catastrophic plate tectonics.Partial melting occurs, due to heating of the lower crust by basalt magmas intruded from the mantle, to the elevated local water content, and to locally increased pressures as a result of tectonic activity. Once it

occurs, continued deformation (“squeezing”) segregates the melt so that it flows. Melt-filled veins then coalesce into dikes as “squeezing” continues episodically, effectively “pumping” the granitic melt into the dikes and up the dike-filled fractures into the upper crust. Thus, with a continuous supply of magma at the base of the fracture system in the lower crust, the magma could typically ascend 20 km into the upper crust in five hours to three months. There

emplacement occurs rapidly as flat-lying sheets due to lateral fault opening, roof lifting, and floor sagging beneath the intrusion as it thickens in as little as 40 days. Fig. 9. Subduction of an oceanic plate (Pacific plate) during convergence with a continental plate (North American plate).

Magma, formed by partial melting of the overriding continental plate, rises into the continental plate to form volcanoes and granite plutons along a mountain chain (after Huber 1991).Because granitic plutons are now recognized as being mostly tabular sheets, their crystallization and cooling occurs much more rapidly as a result of convection due to circulation of huge amounts of outgoing hydrothermal fluids released from the magmas and ingressing meteoric fluids from the country rocks. The pressure of these outgoing hydrothermal fluids fractures the inward crystallizing and cooling pluton margins, facilitating the ingress of cold meteoric fluids, which completes the convection cycle and accelerates the cooling of the pluton. Of course, during the Flood these granitic magmas were often intruded into wet sediment layers. Crystal growth rates of 5 mm in an hour have been experimentally determined. These hydrothermal fluids also transported radon and polonium within biotite flakes to generate polonium radiohalos below 150°C, which due to the very short half-lives of the polonium isotopes must have formed within hours to days. Furthermore, due to uranium decay and hydrothermal fluid transport of daughter polonium starting earlier in the crystallization of the granite plutons, and the need to supply the required large quantities of polonium below 150°C to form the polonium radiohalos before the energy to drive the hydrothermal fluids dissipates, the granite plutons need to have crystallized within 6–10 days.Quite clearly, timescales for the generation of granitic magmas and their intrusion, crystallization, and cooling are no longer incompatible with the young time frame for earth history and its global Flood cataclysm.

Conflicting ‘Ages’ of Tertiary Basalt and Contained Fossilised Wood, Crinum, Central Queensland, Australia

by Dr. Andrew A. Snelling on August 1, 2000 Abstract Originally published in CEN Technical Journal 14, num. 2 (2000): 99–122.

Fossilised wood found entombed in a Tertiary basalt flow at Crinum in central Queensland was identified as probably Melaleuca, and yielded a 14C ‘age’ of about 37,500 years BP and a δ13CPDB value of –25.69 ‰ consistent with terrestrial plant organic carbon, and ruling out contamination. A nearby leaf imprint in the basalt was identified as probably Lauraceae. The olivine basalt yielded an averaged K-Ar ‘model age’ of 47.5 Ma, excessively older than the expected ‘age’ of 30 Ma due to excess 40Ar*.The basalt’s incompatible trace and rare earth element, and Nd-Sr isotope, geochemistry are consistent with its tectonic setting, being an intra-plate continental alkali basalt derived from a homogeneous mantle source and erupted as the Australian plate moved northwards over a stationary hotspot. A Pb-Pb isotopic linear array which gives an apparent ‘age’ of 5.07 ± 0.27 Ga is probably a primary geochemical feature of the basalt’s mantle source. In the context of the Creation/Flood model of Earth history the fossilised wood is from trees which grew in the immediate post-Flood period. The decelerating Australian plate drifted over a mantle hotspot, a structural weakness in the crust allowing magma to erupt as basalt which engulfed the trees. The fossilised wood’s radiocarbon demonstrates the basalt’s youthfulness and the failure of radioisotopic ‘dating’, but is consistent with a Flood/immediate post-Flood stronger magnetic field.hop Now Introduction

The Crinum Colliery, situated near Emerald in the Bowen Basin of central Queensland (Figure 1), was developed to exploit the Lilyvale (German Creek) Seam of the Permian German Creek Coal Measures. During construction of the mine by BHP Australia Coal Pty Ltd in 1993, when Shaft Sinking and Development employees were sinking the upcast ventilation shaft, a rare find was made.1 After digging through the thin surficial sands and clays, followed by Tertiary basalt, 21 m down pieces of fossilised wood were found entombed in the basalt near the base of the flow. The basalt flow unconformably overlies the uppermost siltstone and sandstone units of the German Creek Coal Measures.2The excavators reported at the time that the fossilised wood appeared to belong to two distinct trees, partly standing, still organic in nature and thus not fully petrified.1 The imprint of a leaf was also discovered within the basalt, which was also regarded as remarkable, given the likely temperature (perhaps as high as 1,000°C) of the basalt lava when it entombed the leaf (and the wood). Additionally, what looked like tree roots were found in the siltstone directly below the basalt,

suggesting the trees when alive were rooted into the Permian siltstone and thus growing on a Tertiary land surface over which the basalt lava flowed.3 The investigations reported here focussed on: Identifying the trees represented by the fossilised wood and leaf impression, and testing the wood for a possible14C ‘age’, which might be expected if these were trees growing on a Tertiary (post-Flood?) land surface; and Characterising the geochemistry of the basalt enclosing the fossilised wood, and determining the ‘age’ and source of the basalt by its K-Ar, Rb-Sr, Sm-Nd and Pb-Pb radioisotopic systematics. Local geology Figure 1. Map showing the location of the Bowen Basin in central

Queensland (inset) and the Crinum Colliery north of the town of Emerald (after Devey).5 The other mines exploiting the German Creek Coal Measures are also shown. The exposed Bowen Basin (Figure 1, inset) is the northern section of the 1,800 km long Bowen-Sydney Basin, a meridional accumulation of Permian and Triassic sediments in eastern Queensland and New South Wales.4 Exposures of Bowen Basin sediments extend over an area of 550 km north-south by 250 km across (east-west). Around the western, northern and eastern margins of the basin the Permian sediments onlap the pre-Permian basement, whereas to the south the Bowen Basin sediments themselves disappear beneath the Jurassic-Cretaceous Surat Basin of southern Queensland. The Crinum area is about 50 km by road north-northwest of the town of Emerald at approximately 148°19’E, 23°12’S 5,6 (Figures 1 and 2). The pre-Permian basement to the west of Crinum consists of schist, phyllite, quartzite, slate and recrystallised limestone of the Anakie Metamorphics, overlain further west by the Devonian-Carboniferous

sediments and acid flows and tuffs of the Drummond Basin.6 To the west of Crinum the Permian sediments of the Bowen Basin unconformably overlie the basement metamorphics of the Anakie Inlier, an erosional remnant preserved as a ridge. The complete Permian stratigraphic sequence of the Bowen Basin is not represented in the Emerald-Crinum area. Also, since the original field mapping and during subsequent mining operations, there have been difficulties in correlating strata across such a large basin, and thus variations in the identification and naming of strata have resulted.7,8Nevertheless, the original broad groupings and subdivisions of strata continue to be used and are represented in the Emerald-Crinum area. Thus the first strata to be deposited belong to the Upper Permian Blenheim Sub-Group of the Back Creek Group — about 365 m of quartz and lithic quartz sandstones, conglomerate, and micaceous and carbonaceous mudstone, containing marine fossils (brachiopods and pelecypods), which outcrop to the north and west of Crinum6 (Figure 2). These strata are overlain by 610 m or more of quartz sandstone, sandstone, carbonaceous siltstone and mudstone, coal seams and conglomerate of the German Creek Coal Measures of the Back Creek Group.6 Outcrops occur in a strike-oriented belt immediately to the north-east of Crinum, but this coal measure sequence continues to the south-west underneath Tertiary basalt flows at Crinum and Gordonstone and under soil, gravel and alluvium cover5,6 (Figures 1 and 2). To the south-west of Crinum and west of Emerald beyond the basalt, soil, gravel and alluvium cover are outcrops of undifferentiated Back Creek Group strata (Figure 2) — about 1370 m of quartz and pebbly quartz sandstones, feldspathic and micaceous sandstone and mudstone containing marine fossils (brachiopods, pelecypods and gastropods), and some coal seams.6 On the other hand, directly overlying the outcropping German Creek Coal Measures east of Crinum are more than 610 m of lithic and feldspathic sandstone, conglomerate, tuff, tuffaceous sandstone and mudstone strata of the Fair Hill Formation of the Blackwater Group which contain petrified wood and poorly preserved plant remains.

Figure 2. Geological map of the

Crinum-Emerald area (after Olgers).6 Much of the Permian Bowen Basin sequence is covered by Tertiary basalt flows and sediments, and Quaternary soil, gravel and alluvium. The occurrence of the coal seams interbedded with clastic sediments containing marine fossils poses a challenge to the uniformitarian framework for interpreting the supposed sedimentary environments in which these strata were deposited.9 Thus the depositional basin is interpreted as a shallow marine shelf onto which clastic sediments were deposited by rivers flowing from the presumably exposed land to the west, burying marine animals. On the coastal and alluvial plains it is claimed wetlands developed into coal-forming swamps before slow subsidence allowed the sea to encroach and bury the peat. These coal measures were supposedly deposited by such cyclical repetition until the marine shelf was subsequently totally filled and covered over with fluvial sediments washed in from the north with wood and other plant debris. Alternately, during the global Flood cataclysm the plant debris would have been catastrophically accumulated and buried by the sedimentation within the globe-encircling marine environment. By the end of the Permian it is claimed sedimentation had ceased in the Emerald-Crinum area as the shallow sea retreated eastward.9 Through the entire Mesozoic the area was supposedly a land surface at which presumably the exposed strata were weathered

and eroded. Then in the Tertiary, intense volcanic activity to the west resulted in extensive olivine basalt flows being extruded eastwards across the area, building up a cumulative thickness in places of up to 245 m.6 Interbedded with the basalt flows are layers of claystone, siltstone, sandstone, pebbly sandstone and gravel, up to 105 m thick in total, interpreted as fluvial and lacustrine sediments. Subsequent intense weathering has produced a laterite capping on these Tertiary sediments, which can be seen in outcrop to the south-east and south of Crinum6 (Figure 2). And finally, continued in situ weathering accompanied by fluvial processes have not only shaped the present landscape, but left thin blankets of superficial soil, sand, gravel and alluvium covering all earlier strata, particularly in low-lying areas. Mine geology

The Crinum Colliery has been sited and developed to exploit the Lilyvale Seam of the German Creek Coal Measures5 (Figures 1 and 2). The immediate mine area is in a relatively undeformed and stable region, the coal measure sequence

in the mine lying on the western limb of a gently dipping syncline which gently plunges south-west.2 The regional dip is generally about 3° to the south and south-east. Figure 3 is a simplified longitudinal, west-to-east cross-section through the Crinum Mine drift entries. Flat-lying Tertiary clay and basalt flows unconformably overlie the gently folded and dipping Permian strata, and are generally 20–40 m thick. As many as eight distinct basalt flows have been recognized in the nearby Gordonstone area to the south2 and these are often interbedded or underlain by clay, as is the case at Crinum (Figure 3).

Figure 3. Simplified longitudinal, west-to-east cross-section through the Crinum

Mine drift entries showing the geology and the exploratory drill-holes (adapted from the BHP Australia Coal Pty Ltd’s Crinum Mine Project cross-section). The upcast ventilation shaft was excavated in the approximate position of Drill-hole 05469.The German Creek Seam, and its lateral equivalent at Crinum, the Lilyvale Seam, forms the base of the upper German Creek Coal Measures, which average 160 m in thickness.5 The seam is generally between 3.0 and 4.5 m thick, averaging 3.5 m at Crinum, has only a few thin claystone partings, is vitrinite-rich, low in ash and sulfur, and has excellent coking properties. There are other seams in the upper German Creek Coal Measures above the German Creek (Lilyvale) Seam (in stratigraphic order upwards — the Corvus, Tieri, Aquila and Pleiades Seams), but these are generally thinner or absent in the Crinum area. The upper German Creek Coal Measures are dominated by quartz lithic sandstone, with minor siltstone interbeds (as in Figure 3), which have been interpreted as eight separate lithofacies in what was supposedly a fluvial delta depositional environment prograding onto a shallow marine self. Thus the lower German Creek Coal Measures, which average 110 m thick, do not contain economic coal and are interpreted as a marine sequence. Discovery location

Whereas large-scale open cast strip mining methods have traditionally been utilized to exploit the German Creek (Lilyvale) Seam to the north-east at the Gregory, Oaky Creek and German Creek Mines (Figure 1) where the overburden is shallow,8 at Crinum the seam is deeper and so underground longwall mining methods are being used. Drilling preceded development so that planning could optimize the siting of the transport and conveyor drifts, and the upcast ventilation shaft, with respect to the longwall production panels in the seam.10 Thus the drifts were excavated along the mine section shown in Figure 3, and the upcast ventilation shaft alongside Drill-hole 05469 just 100 m south of that section. Figure 4. Geological log for Drill-hole 05469 showing the strata sequence

intersected by the upcast ventilation shaft (adapted from the BHP Australia Coal Pty Ltd’s Crinum Mine Project drill-hole log). It was during the sinking of the upcast ventilation shaft in 1993 that the excavators found the fossilised wood entombed in the Tertiary basalt flow.1 The strata sequence in the shaft as recorded by Drill-hole 05469 is shown in Figure 4. The excavators reported finding the pieces of fossilised wood at about 21 m down the shaft in the bottom flow of the sequence of Tertiary basalt flows. At approximately 4 m thick, this basalt flow was reported to consist of three distinct sections — lots of vesicles in the ‘frothy’ top of the flow, then below that, coarser basalt with visible phenocrysts and perhaps some columnar jointing, and at the bottom of the flow, fine-grained, dense, hard, massive basalt.1,3 Being relatively thin with such an internal structure, cooling of this flow would have been rapid (perhaps days, but a few weeks at most).11 While Figures 3 and 4 show that there is clay/claystone immediately below the basalt, careful examination of the core recovered from Drill-hole 05469 revealed that the basalt sits at 25.2 m downhole unconformably and directly on the Permian strata of the German Creek Coal Measures. There is no ‘fossil soil’ but a hard, dense silicified claystone/fine-

grained siltstone, grading downwards into siltstone then sandstone. The roof of the Lilyvale Seam is then at 76.5 m downhole, only 51.3 m below the base of the bottom basalt flow which entombed the fossilised wood. What was found

The workmen sinking the shaft reported that they found two distinct trees, still standing, partly organic in nature, and thus not fully petrified.1Because the fossil wood specimens they collected were said to have come from a depth in the shaft of

about 21 m, the basalt flow entombing the trees is about 4 m thick,3 the bottom of the basalt flow in the drill-hole is at 25.2 m and also encases fossilised wood, and what appear to be thick petrified roots were found in the siltstone below,3 then these appear to have been tree stumps over 4 m tall entombed through the full thickness of the basalt flow. (The apparent lack of any preserved ‘fossil soil’ is not altogether unexpected, given that trees are capable of growing on rocky outcrops.) Thus the fossilised wood samples the workmen collected probably came from near the tops of the tree stumps at the top of the basalt flow, which is verified by the vesicular nature of the basalt sample they also collected at the same location, the top of the basalt flow having been described as vesicular.The fossilised wood when found was said to be in three states — ash, charred and intact timber.1 Because the original trees appear to have been rooted into the Permian strata3 and thus growing on a Tertiary land surface, now preserved as the unconformity between the Permian strata and the Tertiary basalt (Figure 3), it is not surprising that when the molten basalt lava at 1000–1200 °C engulfed the trees some of the wood was reduced to ash or was charred. In fact, it is likely that the charring of the outer sections of the tree stumps protected the inner portions. The pieces of fossilised wood collected by the workmen are shown in Figures 5–9, and the effects of charring can readily be seen. The imprint of a leaf (Figure 10) was also discovered in the basalt, indicative of how quickly the molten lava congealed. Close inspection reveals that it is not a ‘gum leaf’, as initially reported.1 Finally, as already mentioned, what clearly appear to be thick petrified/fossilised roots related to the trees were found in the Permian siltstone immediately underneath the Tertiary basalt entombing the fossilised wood,3 and a sample was collected by the workmen (Figure 11).

Figure 5. One of the pieces of fossilised wood recovered from the basalt flow during excavation of the upcast ventilation

shaft (the pen is for scale). The outer areas that were in contact with the hot basalt lava have been burnt to white ash. (Courtesy of BHP Australia Coal Pty Ltd’s Crinum Mine Project.)

Figure 6. Another of the pieces of fossilised wood, showing black charring where it was in contact with the hot basalt lava

(the pen is for scale). (Courtesy of BHP Australia Coal Pty Ltd’s Crinum Mine Project.)

Figure 7. Another piece of the fossilised wood recovered during excavation of the upcast ventilation shaft, showing some

basalt still attached to its charred outer surface (the pen is for scale). (Courtesy of BHP Australia Coal Pty Ltd’s Crinum Mine Project.)

Figure 8. A completely charred piece of the fossilised wood recovered from the basalt (the pen is for scale). (Courtesy of

BHP Australia Coal Pty Ltd’s Crinum Mine Project.)

Figure 9. Another piece of the fossilised wood which shows very little charring. The fossilised wood itself is brown,

probably due to impregnation with iron minerals during fossilisation (the pen is for scale). (Courtesy of BHP Australia Coal Pty Ltd’s Crinum Mine Project.)

Figure 10. The piece of basalt with the imprint of a leaf on its surface. The leaf itself was not preserved and the basalt is

stained with iron minerals, but the leaf imprint is still intact (the pen is for scale). (Courtesy of BHP Australia Coal Pty Ltd’s Crinum Mine Project.)

Figure 11. The apparent fossilised tree roots in a piece of the Permian siltstone recovered during excavation of the upcast

ventilation shaft (the pen is for scale). (Courtesy of BHP Australia Coal Pty Ltd’s Crinum Mine Project.) Collection of samples Contact was made with the mine staff expressing an interest in investigating their discovery. Small fragments of some of their fossilised wood samples were received, and a visit to the mine took place on August 31, 1994. The pieces of fossilised wood recovered by the workmen were examined and photographed, as too was the leaf imprint in the Tertiary basalt sample and the fossilised roots in the Permian siltstone sample (Figures 5–11). However, access to the ventilation shaft was not possible, nor were samples of the basalt directly enclosing the fossilised wood available, having long been dumped with all the other rubble and waste rock. Nevertheless, during the mine visit it was realised that an exploratory hole had been drilled close to where the shaft had been sunk.10 The relevant drill core from Drill-hole 05469 was found, and upon inspection, it contained pieces of fossilised wood, still apparently containing organic carbon, at the bottom of the lowermost basalt flow, encased in the basalt at the boundary of the Tertiary basalt with the Permian siltstone below (Figure 12). This drill core was later provided by the mining company for use in this investigation.

Figure 12. Drill core from Drill-hole 05469 (courtesy of BHP Australia Coal Pty Ltd’s Crinum Mine Project). In the centre of

the photograph is a piece of charred fossilised wood entombed in the very bottom of the Tertiary basalt (to the left and in the next row above) right at the boundary at 25.2 m with the Permian siltstone (to the right). During the mine visit it was noted that the site was devoid of outcrops. However, about 3 km south-east of the mine site large outcrops of the Tertiary basalt were found beside a waterhole in Crinum Creek (Figure 2). Even though these

outcrops probably represent a different (younger) basalt flow to the one that entombed the wood, they were sampled to provide a comparison with the basalt in the drill core, one sample of vesicular basalt from near the top of the main outcrop, and a second sample of massive basalt from vertically halfway down the same large outcrop (Figure 13).

Figure 13. Large outcrop of Tertiary basalt beside the waterhole in

Crinum Creek near the Crinum Colliery. Two samples of basalt were collected from this outcrop. Laboratory work Fragments of the fossilised wood provided by the mine staff, from the large pieces collected by the workmen while sinking the ventilation shaft, were sent to wood specialist Dr Geoff Downes, of the CSIRO Division of Forestry and Forest Products, for identification of the species. Additionally, an enlarged photograph of the leaf imprint in the basalt was circulated to several palaeobotanists for identification. At the CSIRO laboratory a piece of the fossilised wood was taken from

the least heat affected region of the sample and examined by incident light microscopy, as well as by Field Emission SEM. Efforts were made to section the fossilised wood, but permineralization was too advanced. A Leica DRM-RXE light microscope was used to examine fractured and polished surfaces to identify features of taxonomic importance. Transverse and radial longitudinal surfaces (Figure 14) had been polished using a range of abrasive cloths down to 2400 grit. Both incident darkfield and polarised light were then used in an effort to find features that would enable identification of the wood. Additionally, a Phillips Field Emission SEM with an accelerating voltage of less than 10 kV was used to examine fractured surfaces.

Figure 14. Diagram to illustrate the terminology

used to describe the anatomical features of woods, including the types of sections which are cut for microscopy. Other small fragments from the fossilised wood samples found during sinking of the ventilation shaft were sent for radiocarbon (14C) analyses to two reputable laboratories, one set of different fragments to each laboratory. The same radiocarbon laboratories were also sent tiny portions of the same piece of fossilised wood found encased at the base of the same basal basalt flow 25.2 m down Drill-hole 05469. Neither Geochron Laboratories in Cambridge, Boston (USA) nor the Antares Mass Spectrometry Lab-oratory at the Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights near Sydney

(Australia), was told where the samples came from to ensure that there would be no resultant bias. Both laboratories use the more sensitive and reliable accelerator mass spectrometry (AMS) technique for detecting radiocarbon. Geochron is a commercial laboratory and Antares is a major research laboratory.Two pieces each of the basalt samples from the drill core (from the flow which enclosed the fossilised wood) and the outcrop were submitted to the AMDEL Lab-oratories in Adelaide (Australia) for major, minor and trace element analyses. Further sample pieces were sent to the AMDEL Laboratories and Geochron Laboratories for conventional K-Ar dating, and to the PRISE Laboratory in the Research School of Earth Sciences at the Australian National University in Canberra (Australia) for Rb-Sr, Sm-Nd and Pb-Pb isotopic determinations. AMDEL Laboratories is a reputable commercial laboratory employing the latest conventional analytical equipment and techniques such as inductively coupled plasma emission spectroscopy (ICP), while the PRISE Laboratory utilizes all the state-of-the-art and innovative mass spectrometry technology of a university research school with an outstanding international reputation. Results

Wood identification (with G. Downes) Figure 14 provides a diagrammatical explanation of some of the terminology used to describe the anatomical features of woods which can be diagnostic of the family, genus and sometimes species to which they belong. The essential components are the vessels, rays and fibres. Vessels are formed from individual vessel elements which are single cells produced in the vascular cambium. Each cell dies after enlargement and maturation, a part of this process being the removal of the end walls, connecting it with other elements. A long tube or vessel is formed, through which xylem sap passes as part of the transpiration stream. Vessels are orientated axially and form cross-fields where they intersect radially-orientated rays. Within these intersections, or cross-fields, pits or ‘holes’ occur, the arrangement of which varies between taxonomic groups. Similar cross-fields occur where rays cross axially-orientated fibres. The spacing of the vessels and their diameters relative to one another are also diagnostic. For example, vessels can vary from an even spacing of equi-diameter vessels common in eucalypts (diffuse porous), to closely-packed rings of large-diameter vessels (‘early wood’) alternating with small-diameter vessels (‘late wood’) found in oaks (ring porous). Adjacent thick-walled fibres form bordered pits. Certain hardwoods have vestures, which are small occlusions occurring within the pit borders. The thin-walled cells that are relatively undifferentiated or unspecialized infilling between the vessels are called parenchyma, and the pattern of the occurrence of parenchyma tissue can also be taxonomically important. The fossilised wood was identified as most probably belonging to the genus Melaleuca, which is in the Myrtaceae family that includes the eucalypts. However, features which would enable a more definitive identification were not found. The fossilised wood was a diffuse porous hardwood. Ray-to-vessel pitting was found to be simple, with several pits per cross-field. Bordered pit apertures appeared to be occluded, perhaps with silica (SiO2). The important parameters measured and described by light microscope study of the fossilised wood are:

Fibre length 700––800 μm

A lot of parenchyma; elongated; axial. Some possibly vasicentric tracheids.

Vessel diameters 40– –100 μm

Vessel frequency ~10 per mm2

Bordered pits ~5 μm diameter

Vessel-to-ray pitting several small, simple pits per cross-field

Narrow uniseriate rays (therefore, not Casuarina)

Rays 200–300 μm high in tangential longitudinal section commonly 6–10 cells high

Unfortunately, it could not be determined whether the bordered pits had vestures, which would be further diagnostic of Melaleuca. Figures 15 to 25 are Field Emission SEM photo-micrographs illustrating some of the anatomical features found in the Crinum fossilised wood. The resolution possible with the Field Emission SEM system operating at low accelerating voltages enabled resolution of the microfibrillar structure in the cell walls (Figure 18). The tendency of the fossilised wood to fracture along the middle lamella/primary wall interface (Figures 15, 18–20) allowed the microfibril orientation of the primary wall to be seen. In places the fracture extended to the surface of the secondary wall (Figures 18 and 19). The angle of the pit aperture is probably indicative of the microfibril angle of the S2 layer of the secondary wall. The circular orientation of the microfibrils around the bordered pit is evident (Figures 18 and 20), the pits being around 5 µ m diameter. An analysis of the chemical composition of the Crinum fossilised wood by SEM-EDS (Energy Dispersive System) indicated that carbon and oxygen were still present (Figure 25). However, the presence of silicon was also evident, suggesting that the original wood had undergone a considerable degree of permineralization, which would thus be principally silica (SiO2).

Figure 15. Field emission SEM photomicrograph of a radial longitudinal section through the fossilised wood showing

wood fibres (F). Apparent decay of the middle lamella region resulted in fracture through this wall layer, exposing the primary wall. Evidence of bordered pits along fibres is abundant. (Courtesy of G. Downes.)

Figure 16. Field emission SEM photomicrograph of another radial longitudinal section through the fossilised wood.

Exposed on this face are ray (R) and fibre (F) cross-fields. Vessel (V) elements are evident to the left. Bar = 200 μm. (Courtesy of G. Downes.)

Figure 17. Field emission SEM photomicrograph of a fracture surface of the fossilised wood. Bordered pits are well

preserved, with the fracture usually along the middle lamella region, exposing the internal pit face. Bar = 2 μm. (Courtesy of G. Downes.)

Figure 18. Field emission SEM photomicrograph of the fossilized wood showing that cellulose microfibril orientation is

preserved, and the changes in orientation associated with the bordered pits (BP), the primary wall (P) and the S1 layer of the secondary wall. Occlusions (O) in the pit apertures are ubiquitous. Bar = 2 μm. (Courtesy of G. Downes.)

Figure 19. Field emission SEM photomicrograph of the fossilized wood showing the reverse face of a bordered pit (BP)

together with the aperture. The compound middle lamella (CML) is exposed, with the inner face of the secondary wall being evident. Bar = 2 μm. (Courtesy of G. Downes.)

Figure 20. Field emission SEM photomicrograph of the fossilized wood showing that microfibril orientation in and around

a bordered pit (BP) is preserved. The compound middle lamella (ML) region between adjacent fibres is evident. Bar = 2 μm. (Courtesy of G. Downes.)

Figure 21. Field emission SEM photomicrograph of the fossilized wood showing vessel (V) elements and fibres (F) in a

fractured transverse surface. Bar = 50 μm. (Courtesy of G. Downes.)

Figure 22. Field emission SEM photomicrograph of the fossilized wood showing a closer view of a fractured vessel (V)

and fibres (F). The pitting along the vessel wall is apparent. Bar = 20 μm. (Courtesy of G. Downes.)

Figure 23. Field emission SEM photomicrograph of the fossilized wood showing two adjacent fibres slightly separated

along the middle lamella. The left fibre has fractured transversely. Bar = 2 μm. (Courtesy of G. Downes.)

Figure 24. Field emission SEM photomicrograph of the fossilized wood showing a vessel (V) element with the remains of

smooth vesicle-like structures, possibly tyloses. Bar = 20 μm. (Courtesy of G. Downes.) Figure 25. Field emission SEM photomicrograph of the

fossilised wood showing a fractured region of the transverse surface and the preservation of vessel (V) elements. Individual fibres can also be resolved (small arrow). EDS analyses in these regions indicates the presence of silicon, oxygen and carbon. (Courtesy of G. Downes.) Leaf identification Figure 26. A reproduction of a fossilised leaf of Laurophyllum

conspicuum from Nerriga, NSW, Australia (after Hill).12 Scale bar = 1 cm. Identification of the leaf imprint in the basalt (Figure 10) proved straightforward. When seen in the enlarged photograph by

palaeobotanists M. E. White (consultant) and M. Pole (University of Queensland) the fossilised leaf was readily identified as belonging to the family Lauraceae. For comparison, in Figure 26 is a reproduction of a fossilisedLaurophyllum conspicuum leaf from

Nerriga in New South Wales, Australia (140 km east of Canberra).12 The crucial similarities are the venation and the leaf shape. Furthermore, fossilised Lauraceae leaves have been reported from Moranbah in the northern Bowen Basin,13 so this fossilised leaf at Crinum is not ‘out-of-place’. The fact that the original leaf appears to have belonged to a totally different tree to that from which the fossilised wood came does not invalidate the identification, because a vegetated environment normally has a variety of trees. Wood radiocarbon (14C) The radiocarbon (14C) results are listed in Table 1, and reveal that detectable radiocarbon was found in all fossilised wood samples. The results are within the detection limits of the analytical equipment

and therefore provided finite ‘ages’. The one exception was obviously due to the small quantity of carbon extracted from the sample, but the parallel analysis at the other laboratory on the same piece of fossilised wood from the basalt in the drill core returned a finite ‘age’. The laboratories’ staff when questioned had neither hesitation nor difficulties in calculating the quoted 13C-corrected radiocarbon ‘ages’, which they staunchly defended as valid. Thus the 14C ‘age’ of the fossilised wood from the drill core would appear to be 44,000–45,500 years BP, whereas the fossilised wood samples from the ventilation shaft appear much younger. The age differences in Table 1 are incongruous, given that the fossilised wood is supposed to have all been derived from the same trees, but the quantities of carbon analysed being so small might result in such large variations. Perhaps an averaged age would be more appropriate, and that would give the fossilised wood a radiocarbon ‘age’ of around 37,500 years BP.

Table 1. Radiocarbon (14C) analyses

of the Crinum fossilised wood samples. SAMPLE

LAB LAB CODE

CONVENTIONAL 14C AGE

δ13CPDB (‰) AGE (YEARS BP)

1 SIGMA ERROR

Wood in Drill Core Geochron ANSTO

GX-20798-AMS >35,620 — -25.7

0ZB472 44,700 950 -25.78

Other Wood Geochron GX-20087-AMS 29,544 759 -25.1

Other Wood ANSTO OZB473 37,800 3,450 -26.16

Notes: (1) Ages quoted are 14C ages not calendar ages. (2) The Geochron dates are based on the Libby half-life (5570 years) for 14C. The errors stated are ± 1σ as judged by the analytical data alone. Their modern standard is 95% of the activity of N.B.S. Oxalic Acid. The ages are referenced to the year AD 1950. (3) The ANSTO ages have been rounded according to the convention of Polach and Robertson.14

The possibility of contamination is also an important consideration which was raised with the laboratories’ staff. For example, recent microbial and fungal activity long after the wood was buried, including spores and dust in the laboratories, might have contaminated the fossilised wood with various amounts of radiocarbon to produce these different 14C ‘ages’. However, the responses were unhesitatingly unanimous that there would be no such contamination problem.15,16 Modern fungi or bacteria in fact derive their carbon from the organic material they live on and don’t get it from the atmosphere, so they would have the same ‘age’ as their host.16 Furthermore, the lab procedure followed in sample preparation would remove the cells and any waste products from either fungi or bacteria. Samples are treated first with hot dilute hydrochloric acid to remove any carbonates, and then with hot dilute caustic soda to remove any humic acids or other organic contaminants.17 After subsequent washing and drying, they are combusted to recover carbon dioxide for the radiocarbon analyses. However, pieces of the same fossilised wood from the basalt in the drill core, and also pieces of the fossilised wood recovered during excavation of the ventilation shaft, were analysed by each laboratory and the results are comparable. The radiocarbon ‘age’ depends on the amount of residual radiocarbon left in the sample from the time of its incorporation in the growing wood. This is usually expressed as ‘percent modern carbon’, which is how much modern carbon it would require to be added to the sample, assuming no 14C to begin with, to yield an ‘age’ equivalent to the calculated radiocarbon ‘age’. It is thus a measure of the sensitivity to sample contamination. In these samples the percent modern carbon was 0.9 % and 0.4 % for the ANSTO analyses, but between 1.0 and 2.5 % for the Geochron analyses. It has been suggested that any unavoidable contamination (laboratory dust and airborne fungal spores) would only amount to at most 0.2 % modern carbon, which would have a negligible effect on any analyses of 1.0 % modern carbon or more.18 Thus if such contamination were inadvertently present it would potentially have a noticeable effect on only one of the radiocarbon analyses, but even in that instance the ANSTO laboratory confidently reported the resultant 14C ‘age’ as valid and reliable. Recent research has focussed on the dating of ‘old’ materials and the problems of contamination.19 Radio-carbon analyses of ‘14C-dead’ charcoal from sediments said to be greater than 50,000 years old using the conventional acid-base pre-treatment and single combustion method have yielded ‘ages’ of only 34,820 to 50,360 years, suggesting such pre-treatment was inadequate to remove contamination. However, using a more severe acid-base-wet oxidation pre-treatment and stepped combustion, 14C analyses on the same charcoal yielded ‘ages’ of 37,720 to 55,860 years. This claimed ‘improvement’ is questionable, given that the vague ‘greater than’ 50,000 years ‘age’ for the sediments is based on optically stimulated luminescence (OSL) dating fraught with its own set of difficulties, and not on some external objective standard. Furthermore, the same study found that ‘geologically ancient’, ‘14C-dead’ graphite, even using the same severe pre-treatment, etc., still yielded 14C ‘ages’ of 59,280 to 67,730 years, which was interpreted as perhaps representing the limit attainable due to un-removable sample and lab contamination. Such an interpretation is required, of course, by the uniformitarian bias regarding the ‘antiquity’ of the graphite. On the other hand, it could be that the graphite is not ‘14C-dead’, and the 14C in it is there because the graphite is in fact not all that old. Therefore, such a study neither imposes limits on the supposed antiquity of samples that can be 14C ‘dated’, nor verifies that sample and lab contamination is necessarily still a problem after the appropriate pre-treatment. Thus it cannot be argued that this fossilised wood was too ‘old’ to be 14C ‘dated’, and/or that the 14C ‘ages’ obtained were due to contamination. Furthermore, whereas there is some variation in the 14C ‘ages’ of the Crinum fossilised wood samples as measured by the laboratories, the reported δ 13CPDB results, the measured differences between the 13C/12C ratios in the samples compared to Pee Dee Belemnite (in the last column of Table 1), are extremely uniform. Thus, they are essentially the same, with the average value of -25.69 ‰ (per mil) being totally consistent with the analysed carbon in the fossilised wood representing organic carbon from wood which belonged to terrestrial plants,20 and not from contamination. Basalt petrography and geochemistry Even at the hand specimen scale it is evident that the basalt (which enclosed the fossilised wood) in the drill core is more altered and/or weathered than the basalt from the outcrop beside Crinum Creek. This was verified by thin section examination (Figures 27 and 28). The basalt in the drill core does, in fact, come from the zone of weathering (Figure 3) where percolating oxidizing ground water readily alters minerals and rock chemistry by dissolving and removing various elements. On the other hand, the basalt outcrop beside Crinum Creek is expected to be relatively fresh because the fact that the basalt outcrops signifies it has survived weathering.

Figure 27. Polarised light photomicrograph of basalt sample BCM-3 from Drillhole 05469 from close to the entombed

fossilised wood (Figure 12). The large (1.5 mm wide) grain in the top left corner is former olivine altered to chlorite and serpentine (green), goethite (brown) and iddingsite? (blue-green). Small (0.5–1 mm long) plagioclase laths (white) are scattered uniformly through the rock, but the clinopyroxene (probably augite) between the laths has been altered to chlorite with titanomagnetite grains (black) and iron oxide staining. (Approximately 60 times magnification.)

Figure 28. Polarised light photomicrograph of basalt sample BCW-2 from the large outcrop beside the waterhole in

Crinum Creek (Figure 13). Rounded, equidimensional grains (1.5–2 mm wide) of altered olivine and lath-like crystals (1.5–2 mm long) of olivine are scattered between plagioclase laths (1–1.5 mm long) with intergranular clinopyroxene (augite?) altered to chlorite and small altered titanomagnetite grains. (Approximately 60 times magnification). Very little trace of olivine is left in the basalt from the drill core. In thin section (Figure 27) all that is left of the olivine are the outlines of the former 1–1.5 mm wide grains, which have been altered to pale green chlorite, serpentine and goethite. The serpentine is evident from the framework/window structure stained by brown goethite, and the residual smaller grains of bright blue-green iddingsite(?). It is hard to estimate, but the original proportion of olivine in the rock could have been at least 10 %. The small (0.5–1 mm long) plagio-clase laths, of which 40–45 % of the rock consists, are still visible, but all the clinopyroxene (probably augite, and 35–40 % of the rock) has been altered to chlorite and heavily stained with goethite and other iron oxides. Titanomagnetite (5–10 %) would have made up the rest of what was probably a typical olivine basalt. In contrast, some relatively unaltered olivine is visible in thin section in the basalt from the outcrop beside Crinum Creek (Figure 28). However, the sample of massive basalt from deeper within the flow is somewhat less altered than the sample of vesicular basalt from the near the top of the flow. As well as rounded and equi-dimensional grains of altered olivine up to 1.5–2 mm wide, there are lath-like crystals of mostly fresh olivine up to 1.5–2 mm long, all recognised by their high birefringence and internal fractures. The rock consists of at least 10 % olivine. The plagioclase laths are generally larger (1–1.5 mm long) in this basalt and make up about 45 % of the rock, while the intergranular clinopyroxene (probably augite) is largely altered to chlorite and seems to be about 35 % of the rock. There is very little iron oxide staining — only of the altered olivine grains and some of the chloritised clinopyroxene. However, the titanomagnetite (around 10 % of the rock) has been altered to leucoxene and hematite(?). This rock is only slightly different in its mineralogical make-up and texture, but is still an olivine basalt similar to (but less altered than) that in the drill core. The major and selected trace element analyses of these basalts are listed in Table 2. The loss on ignition, which is a measure of the content of H2O and CO2 (CO2 from carbonates), in these basalts is moderate but consistent with the alteration and weathering (H2O in chlorite, serpentine) observed in thin section. However, considering the amount of goethite/iron oxide staining in the basalt from the drill core, particularly, the Fe2O3 (total Fe) content seems somewhat low and the Al2O3 content correspondingly high, but this may reflect the composition of the predominant chlorite alteration. Otherwise, the MgO contents of the outcrop samples are reasonably consistent with the presence in them of fresh olivine (particularly in the massive basalt from deeper in the flow), whereas the MgO content of the basalt in the drill core enclosing the fossilised wood is noticeably much lower, a result of the alteration of all the olivine. Furthermore, the TiO2 contents of all the basalt samples are depleted compared with analyses of comparable basalts in the Springsure area south of Emerald.21

SAMPLE BCW-1 BCW-2 BCM-2 BCM-3

SiO2 55.00 54.50 60.00 61.00

TiO2 1.42 1.39 1.65 1.68

Al2O3 15.00 14.50 17.00 17.50

Fe2O3 10.50 9.43 5.07 3.66

MnO 0.14 0.12 0.07 0.05

MgO 4.91 6.30 2.02 1.08

CaO 7.48 7.31 6.98 6.93

Na2O 3.57 3.57 3.71 3.91

K2O 0.60 0.59 0.83 0.88

P2O5 0.23 0.22 0.20 0.20

Lol 2.22 2.66 3.24 3.77

Total 101.07 100.59 100.77 100.66

Rb 9.50 10.00 19.00 20.50

Sr 220.00 260.00 300.00 340.00

Y 12.00 13.00 13.00 17.00

Hf 4.00 3.00 3.00 3.00

Zr 100.00 80.00 100.00 120.00

Nb 15.00 15.00 20.00 20.00

Ba 180.00 160.00 400.00 460.00

Sc 15.00 15.00 15.00 15.00

V 110.00 105.00 110.00 115.00

Cr 300.00 280.00 280.00 300.00

Co 40.00 40.00 20.00 20.00

Ni 110.00 130.00 45.00 60.00

Cu 65.00 45.00 35.00 50.00

Ga 17.00 18.00 21.00 23.00

Zn 300.00 180.00 160.00 140.00

Pb 12.00 8.00 6.00 6.00

Th 1.00 1.00 1.00 1.00

U 1.50 0.50 0.50 2.00

Sb 3.00 3.00 3.00 2.00

Mo 4.00 4.00 4.00 4.00

W 125.00 96.00 71.00 61.00

Ta 5.00 4.00 4.00 4.00

La 12.00 11.00 13.00 17.00

Ce 22.00 20.00 24.00 31.00

Pr 3.00 2.00 3.00 4.00

Nd 12.50 10.00 12.50 14.50

Sm 2.50 3.00 2.50 1.50

Eu 1.50 1.00 1.50 1.50

Gd 4.00 4.00 4.00 4.00

Tb 0.50 0.50 0.50 0.50

Dy 3.50 3.00 4.00 4.00

Ho 0.50 0.50 0.50 0.50

Er 2.00 2.00 2.00 2.00

Tm 1.00 1.00 1.00 1.00

Yb 1.00 1.00 1.00 2.00

Lu 0.50 0.50 0.50 0.50

Table 2. Major, trace and rare earth element analyses of the Crinum basalts. (Units: % major oxides; ppm trace and rare

earth elements).

However, the major anomaly is the high SiO2 contents of these olivine basalts, which would be expected to be in the 46–50 % range, consistent with the related basalts of the Springsure area.21 With SiO2 contents of 54.5–55 % (outcrop) and 60–61 % (drill core), these basalts actually plot on the total alkalis (Na2O + K2O) versus SiO2 (TAS) plot in the basaltic andesite and andesite fields respectively22 (Figure 29). On the other hand, whereas these major elements are highly mobile during alteration and weathering, many trace elements are relatively immobile and highly incompatible, and therefore, because they are retained once lavas crystallize, they can be used to discriminate original rock types even after alteration and weathering. Thus on the Zr/Ti versus Nb/Y dis-crimination diagram these olivine basalts correctly plot close together in the alkali basalt field23,24 (Figure 30). This would indicate then that Si was added during alteration and weathering and/or other major elements (Mg, Fe, Ca, Na, K, Mn) which are mobile were depleted relative to Si.

Figure 29. Total alkalis (Na2O + K2O) versus silica (SiO2) or TAS diagram (after Le Maitre et al.22) for classification of

volcanic rocks. The Crinum basalt samples plot in the basaltic andesite and andesite fields.

Figure 30. The Zr/Ti versus Nb/Y discrimination diagram for volcanic rocks and particularly basalts (after Winchester and

Floyd,23 and Pearce24). The Crinum olivine basalt samples correctly plot in the alkali basalt field. There are a number of normalized multi-element diagrams or incompatible element diagrams (spider diagrams) that are useful in geochemically characterizing basalts and for distinguishing their magma type and tectonic setting.24,25 These Tertiary olivine basalts at Crinum are readily classified as within-plate, continental alkali basalts, and this is verified by the steep negative slope and the matching shape of the ‘spidergrams’ in the MORB-normalized multi-element/incompatible element diagram25,26,27,28,29 (Figure 31). Indeed, the pattern of trace element concentrations in this diagram has affinities to that of ocean island basalts, which therefore suggests a similar source. However, the ‘spidergrams’ on the chondrite-normalized multi-element/incompatible element diagram (Figure 32) do not completely match that for ocean island basalts but are suggestive of additional lower continental crust influence, probably as contamination.25,27,28,29,30 One glaring anomaly is the very low relative P content of these basalts, but the Rb, Th and K are also lower than expected, which in the case of those elements could be explained by their mobility during alteration and weathering. On the other hand, the rare earth elements (REE) are regarded as amongst the least soluble trace elements and are relatively immobile during alteration and weathering,25 so the REE abundances in rocks produce characteristic ‘spidergrams’ on chondrite-normalized REE diagrams. The REE ‘spidergrams’ for these Crinum basalts are plotted in Figure 33 and are as expected for such alkali basalts — a negative slope due to light REE enrichment relative to heavy REE, and a positive Eu anomaly.25,31 The low relative Sm in the basalt from the drill core is unexpected and may indicate some Sm loss, which like the apparent Rb, Th and K losses could be significant for the respective radioisotopic systems.

Figure 31. The MORB (mid-ocean ridge basalt)-normalized multielement/ incompatible element diagram (after Pearce26)

showing ‘spidergrams’ for Crinum basalt samples BCM-3 and BCW-2. Normalizing values used are those of Pearce.24,26

Figure 32. The chondrite (chondritic meteorite)-normalized multi-element/ incompatible element diagram25 showing

‘spidergrams’ for Crinum basalt samples BCM-3 and BCW-2. Normalizing values used are those of Sun28 and Sun and McDonough.30

Figure 33. The chondrite (chondritic meteorite)-normalized REE (rare earth element) diagram25 showing ‘spidergrams’

for Crinum basalt samples BCM-3 and BCW-2. Normalizing values used are those of Boynton.31 Basalt K-Ar ‘dating’ The K-Ar ‘dating’ results for the Crinum basalts are listed in Table 3. The calculated ‘model ages’ range from 36.7 ± 1.2 Ma to 58.3 ± 2.0 Ma, which is an unacceptable outcome for analyses of two samples from the same lava flow intersected in the drill core. This problem of obtaining consistently acceptable ‘model ages’ is highlighted by the fact that the same sample from the outcrop (BCW-2) submitted to both laboratories yielded ‘model ages’ of 39.1 ± 1.5 Ma (Geochron) and 47.9 ± 1.6 Ma (AMDEL). Because the other sample from the outcrop (BCW-1) yielded a result between these two ‘model ages’ it is tempting to assign an averaged ‘model age’ of about 43.9 Ma to this basalt. For the basalt in the drill core an averaged ‘model age’ would be 47.5 Ma, which would appear to be consistent with it being an older flow (because it is at the base of this Tertiary sequence).

Table 3. Potassi

um-argon (K-Ar) isotopic analyses and age determinations on the Crinum

LAB CODE

K20 (wt%)

40K (ppm)

40Ar* (ppm) x 10-3

40Ar* (%)

Total40Ar (ppm)

4040* / Total40Ar

40Ar /36Ar

36Ar (ppm) x 10-5

40K /36Ar (x 103

)

40Ar* / 36Ar

MODEL AGE (Ma)

UNCERTAINTY (Ma) (one sigma)

basalts. SAMPLE

BCW-1 (outcrop) Amdel

0.548

0.654

1.725

4.40

0.039205 0.044 — — — — 44.9 1.1

0.547

0.653

1.724

4.40

0.039182 0.044 — — — — 44.8 1.1

BCW-2 (outcrop) Amdel

0.491

0.586

1.661

4.40

0.037750 0.044 — — — — 47.9 1.6

0.496

0.592

BCW-2 (outcrop)

Geochron (R-11800)

0.529

0.631

1.448

5.70

0.025404 0.057

314.0 8.09

7.802

17.898 39.1 1.5

BCM-2 (drill core)

Geochron (R-11798)

0.862

1.028

3.537

4.70

0.075255 0.047

311.0

24.19

4.249

14.617 58.3 2.0

BCM-3 (drill core)

Geochron (R-11799)

0.870

1.038

2.234

3.80

0.053789 0.038

307.5

17.49

7.687

11.685 36.7 1.2

Notes:

(1) The mean K values were used in the age calculations (2) 40Ar' denotes radiogenic 40Ar (3) Ages in Ma with error limits given for the analytical uncertainty at one standard deviation Constants: 40K = 0.01167 atom%, 40K/K = 1.193 x 10-4 g/g λβ = 4.962 x 10-10/year, λε = 0.581 x 10-10/year

However, when the fossilised wood was discovered at Crinum during excavation of the ventilation shaft the expected ‘age’ of the basalt was suggested as only 30 Ma,1,3 which would have been due to the published K-Ar whole-rock ‘model ages’ of 27.9 Ma and 32.7 Ma for comparable olivine basalt samples from outcrops of the same Tertiary basalt flows south of Emerald towards Springsure.32 It was argued there that this spread of ‘ages’ most probably reflected varying degrees of Ar leakage from the flows, which were suggested to be all at least 33 Ma, due to the alteration of the 5–10 % intersertal cryptocrystalline material in the basalt (and in some instances to the alteration of the olivine and/or the plagioclase).32 Nevertheless, because the alteration of those basalts was presumed to be deuteric and thus contemporaneous with consolidation of the lavas, and because of the general agreement of these ‘dates’ with those K-Ar ‘ages’ obtained from sanidine crystals in cogenetic rhyolites, it was concluded that there must have been no appreciable leakage of radiogenic Ar (40Ar*) from the whole-rock samples, the alteration products (in most cases) having retained almost all 40Ar* despite the fine grain size. Thus it is very likely the K-Ar ‘model ages’ obtained for the Crinum basalts (Table 3) are far too high. Both laboratories reported an abnormally high atmospheric Ar component in the analyses so that the ratios of 40Ar* to total 40Ar were quite low,33,34 and this was suggested as possibly due to the goethite and other fine-grained alteration products, including some glassy mesostasis. Yet if the experience with the comparable olivine basalts south of Emerald is valid, then there has probably been no appreciable 40Ar* leakage from the alteration products in these Crinum basalts, so the explanation for these unacceptable older ‘model ages’ must lie elsewhere. One possibility is loss of K during weathering, but this is discounted by the fact that there is more K in the more altered basalt in the drill core than in the less altered outcrop basalt. If this difference is due to the alteration process, then K may have in fact been thereby added to the basalt in the drill core. On the other hand, because the two basalt outcrop samples have approximately the same K concentration, while the two drill core basalt samples have higher, and identical, K concentrations (Table 3), the difference may reflect different primary K concentrations in the basalts when extruded. Another possibility is excess 40Ar* present initially in the lavas when extruded, inherited from the upper mantle source area of the basaltic magma, which has been demonstrated to be a persistent and widespread problem for the K-Ar ‘dating’ of volcanics, and crustal rocks generally.35 It is very significant, therefore, that even though both laboratories reported extreme levels of atmospheric Ar contamination, Geochron also reported with their analyses 40Ar/36Ar ratios much higher than the atmospheric 40Ar/36Ar ratio of 295.533 (Table 3). This implies excess 40Ar* in these basalts, which was not derived from in situ decay of parent 40K. Thus, because in the standard K-Ar ‘model age’ calculations used by the laboratories all the analysed 40Ar* in the samples was assumed to have been derived by in situ40K decay, when in fact some excess 40Ar* is present, then the resultant ‘model ages’ are probably too high. In any case, it is clear from close examination of the analytical results in Table 3 that the variations in 40Ar* between the samples beyond proportionality with 40K are primarily responsible for the variations in the K-Ar ‘model ages’. What the ‘correct age’ is for the Crinum basalts remains unclear, as does the validity of K-Ar ‘dating’. There was also too much scatter and not enough spread in the data to determine any isochron ‘ages’.

Table 4. Rubidium-strontium (Rb-Sr) isotopic

analyses of the Crinum basalts. SAMPLE

Rb (ppm)

87 (nm/g) Sr (ppm)

86Sr (nm/g)

87Sr/86Sr 87Sr/86Sr *

BCM-2 21.20 68.825 340.67 383.64 0.17940 0.704204 ±19

BCM-3 24.94 80.966 366.98 413.27 0.19592 0.704269 ± 20

BCW-1 13.66 44.365 306.20 344.83 0.12866 0.704160 ± 21

BCW-2 13.51 43.900 307.48 346.26 0.12678 0.704227 ± 25

Notes: (1) *Measured, present-day 87Sr/86Sr ratios (±2σ), normalized to 86Sr/88Sr = 0.1194. (2) The 87Sr/86Sr value for the N.B.S. Sr isotope standard (SRM 987) run with these samples was 0.170207 ± 26 (± 2σ).

Basalt Sr-Nd-Pb Isotopic Geochemistry The results from the Rb-Sr, Sm-Nd and Pb-Pb isotopic analyses of the same four basalt samples are listed in Tables 4, 5 and 6 respectively. These radioisotopic systems are, of course, regularly used for ‘dating’ of rocks and minerals, particularly with the isochron method. However, because of the long half-lives of these parent radioisotopes and the relatively young expected ‘age’ of these Tertiary Crinum basalts (about 30–33 Ma), these radioisotopic systems are usually unable to provide statistically meaningful results. Moreover, there is insufficient spread in the data, particularly the 87Sr/86Sr and 143Nd/144Nd ratios (Tables 4 and 5), to produce isochrons with slopes sufficient for ‘age’ calculations. Indeed, both the Rb-Sr and Sm-Nd data when plotted yield isochrons which are virtually horizontal. Furthermore, the resultant isochrons do not fit the data well and thus yield poor statistics, unacceptably large MSWDs, and 2σ errors which are larger than the ‘ages’ calculated from the isochrons. ‘Model age’ calculations also produce useless results. Where these isotopes prove useful, however, is in geochemical ‘fingerprinting’ of the mantle source area of the basalt magma. For example, when young oceanic basalts are plotted on an Nd-Sr isotope correlation diagram (Figure 34) they fall within a narrow sloping linear band across the diagram referred to as the ‘mantle array’.37,28,39 The Crinum basalts also plot within this ‘mantle array’, which has been attributed to a chondritic lower mantle source contaminated by mixing with melts from a depleted MORB (mid-ocean ridge basalt) source during ascent. However, on both the Nd-Sr isotope correlation diagram (Figure 34) and the εNd-Sr isotope correlation diagram37,40 (Figure 35) the Crinum basalts plot very close to the Bulk Earth mantle reservoir, which is regarded as the chemical composition of the Earth without the core (all of the Earth made up of only silicate minerals). The Crinum basalts also plot close to other continental basalts on the εNd-Sr isotope correlation diagram (Figure 35) and thus show no signs of crustal radiogenic Sr contamination. Furthermore, when Nd-Sr isotopic compositions of oceanic volcanics are plotted, there can be evidence of a second array different from the main mantle array (Figure 36). This shallow mixing line has been attributed to sediment recycling — the addition of subducted sediments with a crustal radiogenic Sr component due to the recycling of oceanic crust.37,41 However, the Crinum basalts plot in the main mantle array, which can also be interpreted as a mixing line attributed to the recycling of magmatically fractionated material such as ancient oceanic crust.

Figure 34. Nd-Sr isotope correlation diagram for oceanic volcanic rocks showing the linear correlation referred to as the

‘mantle array’ (after DePaolo and Wasserburg,38 and Dosso and Murthey39). The Crinum basalt samples plot in the ‘mantle array’ close to the ‘Bulk Earth’ composition, though slightly depleted.

Figure 35. eNd-Sr isotope correlation diagram for ocean floor, ocean island and continental basalts (after DePaolo and

Wasserburg).40 The Crinum basalt samples plot with other continental basalts along a linear correlation and near the ‘Bulk Earth’ composition, and no crustal radiogenic Sr contamination is evident in them, unlike other continental basalts which plot to the right of the linear correlation.

Figure 36. Plot of Nd-Sr isotope compositions of oceanic volcanic rocks showing two arrays — recycling of magmatically

fractionated material and sediment recycling (after Hofmann and White).41 The Crinum basalt samples plot near the centre line of the magmatic fractionation array, and show no evidence of any contamination due to sediment recycling. The Pb isotopic geochemistry of these Crinum basalts, on the other hand, is enigmatic. When the Pb isotopic compositions of young ocean island basalts (OIBs) are plotted on a 207Pb-206Pb ‘isochron’ diagram they define a series of linear arrays to the right of the geochron 28,37 (Figure 37). The geochron is the isochron connecting the assumed primordial Pb isotopic composition (that of the troilite from the Canyon Diablo meteorite) with the Pb isotopic compositions of iron and stony meteorites and terrestrial pelagic sediment (regarded as a Bulk Earth composition), which defines the supposed 4.57 Ga age of the Earth.42 The distribution of these OIB Pb-Pb arrays to the right of the geochron presents a problem for the understanding of evolutionary models of Pb isotopes in the Earth as a whole, particularly as the slopes of these OIB arrays correspond to apparent Pb-Pb ‘ages’ of between 1.0 and 2.5 Ga.37Intriguingly, the Pb isotopic compositions of the Crinum basalts also define a linear array to the right of the geochron, with its slope corresponding to an apparent Pb-Pb ‘age’ of 5.07 ± 0.27 Ga (though the MSWD is too large for this ‘result’ to have any statistical significance).

Figure 37. Pb-Pb ‘isochron’ diagram showing linear arrays of data defined by ocean island basalts (after Sun).28 The

Geochron was defined by Patterson.42 The Crinum basalt samples define a linear array, the slope of which corresponds to an apparent Pb-Pb ‘age’ of 5.07 ± 0.27 Ga. These OIB linear Pb-Pb isotopic arrays have been inter-preted in three principal ways — as resulting from discrete mantle differentiation events;43 as the products of two-component mixing processes;44 or resulting from continuousevolution of reservoirs with changing µ (238U/204Pb) values.45 The steep slope of the linear array produced by the Crinum basalts clearly reflects different µ values. The two drill-core samples of the basalt plot close together with a similar µ value, but the two basalt outcrop samples have widely divergent µ values, even though they probably represent the same flow. This difference cannot be the result of alteration or weathering, because the outcrop samples have suffered very little alteration and weathering compared to the drill-core samples. Besides, Pb isotopes have been shown to be unperturbed by alteration and weathering,46 so the difference must be a primary feature. Furthermore, this linear array cannot be the product of a discrete mantle differentiation event because its apparent Pb-Pb ‘age’ is older than the Earth itself, unless the Pb isotopes are not recording ‘ages’. On the other hand, two com-ponent mixing is discounted by the Nd-Sr isotopic correlations which indicate a fairly homogeneous mantle source and no crustal radiogenic Sr contamination, that is, no mixing of a crustal component with the mantle reservoir. It is thus concluded that the Pb-Pb isotopic linear array of these Tertiary Crinum basalts is a primary geochemical feature of their otherwise homogeneous mantle source and has no ‘age’ significance. Discussion The identification of the fossilised wood as probably belonging to the genus Melaleuca and of the fossilised leaf as probably belonging to the family Lauraceae is consistent. Both living types are found in Australia today in wet environments, where a variety of trees grow adjacent to one another. An example of a Melaleuca today is the tea-tree, while Lauraceae grow today in wet rainforest, such as that on the Lamington Plateau near the Queensland-New South

Wales border, in-land behind the Gold Coast. Thus this fossilised wood and the leaf imprint suggest a reasonably wet and humid environment in the Crinum area in the recent past. This is in marked contrast to the climate and environment in the area today. The landscape is well-drained and dry for much of the year, and dominated byEucalyptus, with Bauhinia and Casuarina trees growing along Crinum Creek. Most of the rain falls in the summer months from tropic/sub-tropical storms which pass inland. Melaleuca and Lauraceae definitely do not grow in the Crinum area today.

However, Lauraceae leaf fossils are common in localised early Tertiary (Eocene) deposits scattered across Australia, from Anglesea on the Victorian coast west of Melbourne, to Moranbah in central Queensland, the Lake Eyre area in northern South Australia (which is desolate and arid today), and West Dale in the south-west of Western Australia.13 An analogous extant flora to that found fossilised at Anglesea is that at Noah Creek on Queensland’s northern tropical coast. The best documented of these fossil floras is at Nerriga in New South Wales (140 km east of Canberra), where fossilised Lauraceae leaves have generally been mummified, in contrast to the leaf impression at Crinum.12 At Moranbah in the northern Bowen Basin, about 145 km north of Crinum, fossilised Lauraceae leaves occur in clay capped by basalt, dated radiometrically and by pollen accompanying the fossilised leaves as of Eocene ‘age’.13 The 43.9 Ma and 47.5 Ma K-Ar ‘model ages’ obtained on the Crinum basalts are thus consistent with the enclosed Lauraceae leaf impression and Melaleuca fossilised wood at Crinum being also of Eocene age.On the other hand, as already noted, due to the well-established and published K-Ar ‘model ages’ of 27.9 Ma and 32.7 Ma for comparable olivine basalt samples from outcrops of the same Tertiary basalt flows south of Emerald,32 it is very likely that these K-Ar ‘model ages’ for the Crinum basalts are far too high. Excess 40Ar*, not derived from in situ decay of parent 40K and therefore present in the basalts initially, inherited from the magma source area, is suggested as the culprit. If these conclusions are correct, then the Crinum basalts and the enclosed fossilised wood and leaf impression would be early Oligocene in age (in conventional terms), a little younger than the Moranbah fossil flora.The chronological framework for regional volcanism also puts constraints on the ‘age’ of the Crinum basalts.47,48 When the K-Ar ‘model ages’ of all the volcanic rocks of Eastern Australia and their geographical locations are plotted there appears to be a consistent pattern of sub-parallel linear trends along which the volcanism has occurred at progressively younger ‘ages’ in a south-south-west direction.48,49 Thus there is a trend line of volcanism running from Cape Hillsborough on the central Queensland coast (33 Ma) south-south-west through Nebo in the northernmost Bowen Basin (32 Ma), North Clermont (31 Ma) and South Clermont (28–29 Ma) in the central Bowen Basin, to the Springsure area (27 Ma) south of Emerald, and it appears this trend line continues south-south-west through younger centres of volcanism in western New South Wales and central Victoria. The Crinum basalts appear by proximity and field relations to be related to, and part of, the volcanic centres and lava fields of South Clermont and Springsure,32,47 which would make their ‘age’ around 28 Ma, and the fossilised wood and leaf middle Oligocene (in conventional terms).The explanation given for this, and the other sub-parallel, south-south-westerly younging trends of volcanism, is the drift of the Australian plate over as many as seven stationary hotspots/mantle plumes producing hotspot trails similar to the classical hotspot trail along the chain of Hawaiian Islands.49,50 The direction of the younging trend and the rate of plate drift is said to be determined by the sea-floor spreading in the Southern Ocean and Coral Sea. Plate motion in the Tertiary-Recent has essentially been northwards as Australia separated from Antarctica, the drift rate being calculated from radioisotopic dating of this hotspot volcanism and ocean floor basalts related to sea-floor spreading. On the other hand, the hotspots/mantle plumes are regarded as being related to magma sources formed at the sea-floor spreading rift in the Coral Sea due to thermal anomalies in the mantle. The location of the volcanism itself at particular sites is considered as being related to structural weaknesses, including basin margins (relevant to the western margin of the Bowen Basin in the Clermont area), faults and major lineaments (perhaps linked to transform faults in the Tasman Sea related to sea-floor spreading and plate motion).The mineralogy, the major, trace and rare earth element geochemistry, and the Sr-Nd-Pb isotopic geochemistry are all consistent with these basalts being hotspot/mantle-plume-derived, within-plate, continental alkali basalts, as indicated also by the tectonic setting. The isotopic geochemistry suggests a mantle source for the Crinum basalts without any recycled crustal component and the tectonic setting confirms this. The hotspot/mantle plume source developed beneath oceanic crust in a sea-floor spreading setting remote from the influence of terrigenous sediments and their crustal isotopic signatures. It has been suggested that as much as 15 % or more partial melting of upper mantle rock must have occurred to supply these alkali basalts,49 resulting in recycling of magmatically fractionated material as implied by their isotopic geochemistry. Such partial melting may well have been triggered by upward flow of a volatile-rich fluid and accompanying heat from deeper in the mantle,51 the volatiles including excess 40Ar*.All the field evidence indicates that the wood was fossilised as a result of being entombed in the lowermost of these Tertiary alkali basalt flows at Crinum. The trees were apparently rooted in the Permian siltstone at the Tertiary land surface over which the lava flowed. Without doubt, the wood must be the same age as the basalt which entombed it. However, an apparent conflict arises because the fossilised wood contains radiocarbon which yields a 14C ‘age’ of around 37,500 years BP, whereas the basalt has been labelled ‘Tertiary’ with a K-Ar ‘age’ of 47.5 Ma (the basalt in the drill core enclosing the fossilised wood), though this latter ‘result’ should probably be around 30 Ma due to the inclusion of excess 40Ar* in the basalt. The reliability of K-Ar ‘dating’ is, of course, questioned, and the true age of the basalt based on radioisotopic dating remains unclear. The ‘acceptable’ 30 Ma ‘age’ is simply a product of correlation with other K-Ar ‘ages’ for comparable nearby basalts and the regional chronological framework,32,47 all of which is based on uniformitarian assumptions.Quite obviously, the radiocarbon ‘age’ for the fossilised wood is drastically short of the 30 Ma or more for the basalt, when they should both be the same ‘age’. Of course, uniformitarian geologists would probably not have even tested this fossilised wood for radiocarbon, because they would not expect any to be in it. No detectable 14C should have remained in the fossilised wood if it is older than about 55,000 years (10 half-lives of 5570 years), and the fossilised wood is supposedly at least 30 Ma, the ‘age’ of the basalt. Because measurable radiocarbon has been unequivocally demonstrated to be in this fossilised wood, uniformitarian geologists would assume this to be due somehow to contamination. But such a criticism is totally unjustified for the reasons already discussed, including the percent modern carbon in the samples and the extreme uniformity and consistency of the δ 13CPDB values. Thus the radiocarbon in the fossilised wood may be a better guide to the ‘age’ of the basalt than the K-Ar ‘dating’. The results in the context of the Flood model

In the Creation/Flood framework for Earth history, the observation that these trees were probably growing on a land surface that in relative terms existed very late in Earth history after many fossil-bearing strata (the Permian marine fossiliferous strata and coal seams) had been catastrophically laid down would make these trees post-Flood. Furthermore, the identification of the fossilised wood as probably Melaleuca and the leaf imprint as Lauraceae implies a wet environment (perhaps rainforest) where today it is relatively dry (before clearing, probably dry schlerophyll). This is consistent with this land surface and the trees being immediate post-Flood, when the climate was still drying out after the Flood. Thus the basalt lava flowed across this post-Flood land surface, and so, like the fossilised wood it entombed, it is less than 4,500 years old. In this framework, the radiocarbon in the fossilised wood has not provided the true age of the fossilised wood and the enclosing basalt, but it clearly demonstrates that they cannot be millions of years old. An excessively large finite radiocarbon ‘age’ for this fossilised wood is neither inconsistent nor unexpected within the Creation/Flood framework of Earth history. Engulfed by the basalt lava flow less than 4,500 years ago, this Crinum fossilised wood contains less than the expected amount of about 4,500 years worth of radiocarbon. During the Flood and the immediate post-Flood periods, the Earth’s stronger, but fluctuating, magnetic field would have more effectively shielded the Earth from the incoming cosmic ray flux, which in turn would have resulted in a lower radiocarbon production

rate.52 Thus there would have been much less radiocarbon in the atmosphere back then, and much less in the vegetation. Since the laboratories calculated the 14C ‘ages’ for the fossilised wood samples based on the assumption that the level of atmospheric radiocarbon in the past has been roughly the same as the level in 1950, the resultant radiocarbon ‘ages’ are very much greater than the true ages. Furthermore, the Flood also buried a lot of carbon. Thus the stable 12C would not have been totally replaced in the biosphere after the Flood, whereas 14C would have been regenerated in the atmosphere (from cosmic ray bombardment of nitrogen) and then in the biosphere. So the 14C/12C ratios in the pre-Flood organic materials (that is, organic materials that grew before the Flood but were buried during the Flood) and in immediate post-Flood organic materials (such as this Crinum fossilised wood), would have been much higher than today’s 14C/12C ratio. Using today’s ratio for calculating radiocarbon dates thus provides too high a calibration and yields inflated ‘ages’. Finally, the tectonic setting and origin of the Crinum basalt is not inconsistent within the Creation/Flood model of Earth history. Given that plate tectonics occurred catastrophically during the Flood, with metres per second rates of plate movements initiated by thermal runaway subduction connected to sea-floor spreading by mantle-wide convective flow,53,54,55 it is to be expected that plate movements slowed dramatically during the closing phase of the Flood but continued, finally decelerating to today’s rates some years after the Flood. Thus the final stages of movement of the Australian plate into its current position could have occurred in the immediate post-Flood period. If the Flood/post-Flood boundary were to be placed at the Cretaceous/Tertiary boundary55 or somewhere soon thereafter in the early Tertiary, then by the early Oligocene (the conventional age of the Crinum basalt), trees would have again been growing on a wet but drying out, post-Flood landscape in the Crinum area. With the Australian plate also drifting northwards over a stationary hotspot/mantle plume, which was generated by residual convective volatile-rich fluid flow from deeper in the mantle, a structural weakness in the crust allowed magma from the partial melting of the upper mantle, to erupt as outpourings of the basalt lavas that engulfed trees and other vegetation in their path. Conclusions

The fossilised wood found entombed in a Tertiary basalt flow during excavation of the upcast ventilation shaft at the Crinum Colliery in central Queensland was identified as probably Melaleuca and yielded a radiocarbon ‘age’ of about 37,500 years BP. A leaf imprint found in the basalt was identified as probably Lauraceae, which like Melaleuca suggests a wetter environment than in the Crinum area today. The δ13CPDB values measured in the wood were uniform, averaging -25.69 ‰, consistent with the organic carbon in the fossilised wood being that of terrestrial plants. Thus the measured radiocarbon pertains to organic carbon remaining in the fossilised wood, and is not due to any contamination. The basalt which entombed the fossilised wood, while showing alteration due to weathering, is an olivine-bearing alkali basalt. The basalt’s incompatible trace and rare earth element geochemistry though is unaffected by weathering and is characteristic of within-plate continental alkali basalts, in this case with some affinities to ocean island basalts consistent with a mantle source. The basalt yielded conventional K-Ar ‘model ages’ ranging from 36.7 ± 1.2 Ma to 58.3 ± 2.0 Ma. The averaged ‘model age’ of 47.5 Ma was excessively old compared to the expected ‘age’ of around 30 Ma, based on published K-Ar ‘model ages’ of 27.9 Ma and 32.7 Ma for comparable basalts to the south of Crinum which are believed to be contemporaneous. Available evidence indicates the excessively old ‘ages’ are due to excess 40Ar* in the basalt which was not derived from in situ decay of parent 40K but inherited by the lava from its source. The Nd-Sr isotope geochemistry of the basalt is consistent with a homogeneous mantle source potentially involving the recycling of magmatically fractionated material such as older oceanic crust, but with no crustal radiogenic Sr contamination. The basalt also yields a Pb-Pb isotopic linear array with a slope corresponding to an apparent Pb-Pb ‘age’ of 5.07 ± 0.27 Ga (but with poor statistics), which is only significant as a primary geochemical feature of its mantle source. In its tectonic setting, this basalt was erupted due to hotspot/mantle plume volcanism as the Australian plate moved northwards. All the Crinum observations and data are best explained within the Creation/Flood model of Earth history. The trees were growing in the immediate post-Flood period on a landscape that was drying out. After catastrophic plate movements during the Flood, the decelerating Australian plate drifted over a hotspot/mantle plume which produced outpourings of basalt lavas that engulfed the trees. The presence of the radiocarbon in the fossilised wood demonstrates that the enclosing basalt cannot be millions of years old and that the radioisotopic ‘dating’ is grossly in error. While not providing the true age, the excessive radiocarbon ‘age’ is consistent with a stronger magnetic field and changes in atmospheric 12C levels around the Earth during and immediately after the Flood. Acknowledgements This study would not have been possible without the co-operation and help of Greg Chalmers, then Chief Project Engineer for the Crinum Mine Project of BHP Australia Coal Pty Ltd. Greg supplied the fossilised wood samples, the relevant drill cores, and copies of geological plans and sections, and hosted a visit to the Crinum Colliery.

Rapid Rocks

Granites … They Didn’t Need Millions of Years of Cooling by Dr. Andrew A. Snelling and John Woodmorappe on December 1, 1998

Originally published in Creation 21, no 1 (December 1998): 42-44. The timescale and conditions for the formation and cooling of granites are totally consistent with a 6,000–7,000 year-old earth and a global cataclysmic flood 4,500–5,000 years ago. Shop Now

An oft-repeated objection to the earth’s being only 6,000–7,000 years old is that large bodies of magma (molten rock) supposedly require millions of years to accumulate and cool inside the earth’s upper crust to form granites.1,2,3 Exposed at the earth’s surface today due to erosion, these large bodies of granites (plutons) sometimes cover hundreds of square kilometres. It is thought that up to 86% of the once-molten rocks which have intruded into the upper crust are granites. Rapid injection

Deep in the lower crust, the temperatures sometimes reach 700–900°C. This is high enough to melt the rocks locally, particularly if there are high pressures, thus generating large ‘blobs’ of granitic magmas. Recent research indicates that the amount of water which can dissolve in granitic magmas increases with depth because of increased pressure.4Thus more than 10% of the magma weight may be dissolved water.Once molten, the ‘blobs’ of magma are ‘lighter’ than the surrounding rocks so the magma tries to rise, not slowly as large ‘blobs’ as once thought, but squeezed through fractures to be rapidly injected into the upper crust.5,6 The water in the magma makes it less viscous (more fluid), greatly helping its flow into and along fractures.7 Calculations indicate that the magma could ascend at more than 800m per day.8 At that rate, the 6,000 cubic kilometre Cordillera Blanca pluton of north-west Peru could have been formed by magma injected from more than 30km depth through a 6m wide and 10 km long fracture conduit in only 350 years.9Plutons exposed at the earth’s surface were once thought to extend many kilometres down into the lower crust. This would imply that an enormous amount of heat needed to be dissipated as the original magmas cooled, thus requiring millions of years. However, geophysical investigations have revealed that many plutons are only a few kilometres thick, and some are made up of thin (100–1,000m) sheets stacked on top of one another10—for example, the Harney Peak Granite pluton that includes Mt Rushmore in the Black Hills, South Dakota, where the famous president’s heads are carved.11 This discovery of itself greatly diminishes the cooling ‘problem.’ Rapid water cooling

Figure 1. Cooling of a pluton

by (a) conduction and (b) convection. The sizes of the arrows are proportional to the rate of heat flow to the surface. Convection dissipates the heat along fractures very quickly. Research has also shown that the higher the water content of a magma, the faster it will cool.12 This is simply explained. As the magma cools and the granite crystallizes, the contained water comes out of solution. But it is still very hot and confined as steam by the surrounding cooling granite, and the country rock. As continued cooling occurs and more water is released, the pressure inside the forming

pluton increases to the point where the water can no longer be confined, so it is driven by the heat outwards towards the crystallized granite at the pluton’s margins and escapes into the surrounding country rocks by fracturing the granite.13In so doing it takes heat with it outwards along fractures also in the country rocks (Figure 1). At the same time, cooler water in the country rocks can seep inwards into the pluton, where it is heated and then circulates out again, taking more heat energy with it. Thus what is known as hydrothermal circulation is established.14 As the cooling front advances deeper and deeper into the heart of the hot pluton, the cracking and hydrothermal circulation also move inwards, and thus the pluton rapidly cools.Previously, it had been assumed that cooling of plutons was only by way of conduction. So it is not surprising that calculations suggested millions of years were needed (Figure 1). That process can be likened to the cooling of a hot potato which is surrounded by a thick blanket. The heat from inside the potato takes a lot of time to work its way to the surface of the potato, and then to work its way through the blanket. Now suppose that we remove the blanket. The potato will cool more rapidly. Now let us slice the potato. Immediately, we see steam come out, and rise in a column. This indicates that not only is heat rapidly leaving the potato, but the heat transfer now is mostly by convection. It is the circulation of air near the potato which is largely responsible for its cooling. Of course, if we want to cool the potato still faster, we can pour ice-cold water into it after we slice it.In many ways, the buried pluton is like that hot potato. If only conductive cooling is allowed, heat can only work its way out slowly from within the pluton, through the thick layers of rock enclosing it, and to the surface (Figure 1). Now consider what would happen if the thick layers of enclosing rocks became cracked. Water would naturally percolate through the rocks, and this would speed up the cooling of the pluton. The very heat supplied by the pluton would help drive the circulation of water, and hence the ‘carrying-away’ of the pluton’s own heat (Figure 1). Now let us take the analogy of the potato further. Permit not only the surrounding rock layers to crack, but also allow the pluton itself to crack as it cools. This makes it possible for ground water to percolate right into the hottest regions of the very interior of the ‘hot potato’ pluton.How rapidly then does cooling occur? Based on mathematical cooling models, the time to cool a large pluton falls from several million years to only a few thousand, at most.15,16,17 The most recent models actually enable the cooling to be computer-simulated,18,19 but the timescale for cooling is still only hundreds to a few thousand years, depending on the sizes of plutons.20 Cracking and cooling

Is there evidence that ancient plutons have been largely cooled by convective water cooling? Definitely. The rock layers in contact with granites often contain chemicals which show that water has been greatly involved in cooling of the granites.21,22 Virtually all plutons are dissected by cracks of various sizes.23 In fact, it is next to impossible to locate uncracked granites! Many granitic bodies contain mineral-filled cracks, clearly proving that water has once flowed through them (the minerals crystallized out from a water solution). Furthermore, under special lighting, seemingly-intact granite samples show previously-filled channels between the major mineral components.24 Some granitic minerals, such as quartz, show evidence of having cooled under fluctuating temperatures. This is all consistent with rapid water-induced cooling, not slow-and-even cooling over millions of years.To begin with, the amount of heat to be dissipated by rapidly-cooling plutons is not great. A large granite body will heat to boiling point only about its equivalent mass in water. This means that there is plenty of water on earth to have carried away the heat of cooling plutons. Most of the earth’s water

would be unaffected by the heat of the world’s plutons undergoing cooling during and shortly after the Flood. Nor would rapidly-cooling plutons cause excessive local heating. Simple computations show that the heat given off at the surface by a large granite body cooling in 3000 years would be only half the rate of the heat emitted in a modern geothermal field in

Iceland.25 Conclusions

Millions of years are not necessary for the formation and cooling of granite plutons. New evidence shows that thick plutons are not the result of one-time slow intrusion of great amounts of magma into the earth’s upper crust. Instead, they are the result of rapidly-injected coalescing sheets of magma. Each of these sheets probably at least partly cooled independent of the other sheets, thereby greatly accelerating cooling. Less than 3,000 years would be needed to cool most plutons, and the vital ingredient is water in the magma and in the surrounding rocks. Thus the timescale and conditions for the formation and cooling of granites are totally consistent with a 6,000–7,000 year-old earth and a global cataclysmic flood 4,500–5,000 years ago.

“Rapid” Granite Formation?

by Dr. Andrew A. Snelling on August 1, 1996 Originally published in Journal of Creation 10, no 2 (August 1996): 175-177. Abstract Contrary evidence pointing to relatively rapid, even catastrophic, formation of granites is now beginning to surface. One of the persistent scientific objections to the Earth being young (6,000–7,000 years old rather than 4.5 billion years), and the Flood being a year–long, mountain–covering, global event, has been the apparent evidence that the large bodies of granite rocks found today at the Earth’s surface took millions of years to cool from magmas. However, contrary evidence pointing to relatively rapid, even catastrophic, formation of granites is now beginning to surface.Granites are crystalline rocks that occur over large areas, sometimes exposed over hundreds of square kilometres. Deep in the Earth’s crust, the temperatures are sometimes high enough to melt the rocks, particularly if there are applied high pressures due to tectonic forces (earth movements). The theory has been that large ‘blobs’ of magma are thus generated at 750–900° C, and because they are ‘lighter’ than the surrounding rocks the ‘blobs’ rise like balloon–shaped diapirs into the cooler upper crust. There they crystallise as granites.Young1 has insisted that an immense granitic batholith like that of southern California required a period of about one million years in order to crystallise completely, an estimate repeated by Hayward.2 A survey of the technical literature, however, yields estimates of even greater time–spans. Pitcher sums it all up: ‘My guess is that a granitic magma pulse generated in a collisional orogen may, in a complicated way involving changing rheologies of both melt and crust, take 5–10 Ma to generate, arrive, crystallize and cool to the ambient crustal temperature.’3 Of course, there is the added time–span from cooling of the granite pluton within the Earth’s crust to its exposure at today’s land surface by uplift and erosion. Nevertheless, it should be kept in perspective that most recent estimates of these time–spans, including uplift and erosion, rely heavily on radiometric dating determinations and uniformitarian assumptions, and not just on the thermodynamics of crystallisation and heat flow/dissipation.So whence cometh the challenge to this hithertofore seemingly impregnable bastion of old-earthers? Surprisingly, the contrary evidence pointing to relatively rapid (the word ‘catastrophic’ has even been used!) formation of granites within the ranks of the ‘establishment’ itself! The geological fraternity always had a problem within the accepted ‘wisdom’ anyway—the so–called space problem. How does the balloon–shaped diapir find room to rise through the Earth’s crust and then the space to crystallise there (even at 2–5 km depth) in spite of the continual confining pressures? As Petford et al. point out,‘The established idea that granitoid magmas ascend through the continental crust as diapirs is being increasingly questioned by igneous and structural geologists.’4In promoting the idea that the long distance diapir transport of granitic magmas is not viable on thermal and mechanical grounds, Clemens and Mawer favoured the growth of plutons by dyke injection propagating along fractures.5 In other words, the magma is squeezed upwards as thin sheets through long, narrow fractures. Pitcher comments:‘what is particularly radical is their calculation that a sizeable pluton may be filled in about 900 years. This is really speedy!’6Petford et al. have gone further, with calculations which show that a crystal–free

granitoid melt at 900° C, with a water content of 1.5 weight per cent, a viscosity of 8x105 Pa s, a density of about 2,600 kg/m3, and a density contrast between magma and crust of 200 kg/m3, can be transported vertically through the crust a distance of 30 km along a 6 m wide dyke in just 41 days.7 This equates to a mean ascent rate of about 1 cm/sec. Petford et al. then apply their equations to the Cordillera Blanca batholith of north–west Peru and conclude that if its

estimated volume is 6,000 km3, then it could have been filled from a 10 km long dyke in only 350 years. Magma transport must be this fast through such a dyke so that the granitoid magma does not freeze due to cooling within the conduit as it is ascending, and Petford et al.therefore maintain that the dyke intrusion of granitoid magma occurs in response to fault slippage within the Earth’s crust. They stop short of accepting this 350 year rapid filling of this batholith, because that rate is orders of magnitude greater than the mean cavity–opening rates based on radiometric dates for the associated faults. So Petford et al. are constrained by the radiometric dates to conclude that intrusion of the batholith must have been very intermittent, the magma being supplied in brief, catastrophic pulses, while the conduit supposedly remained open for 3 million years.In a more recent study, Petford has dealt with the question of how and at what rate, does deep crustal or upper mantle rock melt to form granite magmas?8 This is, of course, the first step in the process of formation of granites. Petford suggests that, according to the best theoretical models, melted rock in the lower crust segregates via porous flow into fractures within the source rock (usually metamorphic) above a mafic intrusion to form veins. Local compaction of the surrounding matrix then allows the veins to enlarge as they fill further with melt, and the fluid–filled veins coalesce to form a dyke. At a certain critical melt-fraction per cent of the source rock, a threshold is reached where the critical dyke width is achieved. Once that critical dyke width is exceeded, ‘rapid (catastrophic) removal of the melt from source’ occurs. The veins collapse abruptly, only to be then refilled by continuing porous flow of more melt from the continuously applied heat to the source rock. Thus the process is repeated, the granitic melt being extracted and then ascending through dykes to the upper crust in rapid and catastrophic pulses.‘In the physical model presented here of rapid melt extraction followed by ascent of relatively small magma batches at rates orders of magnitude faster than chemical diffusion, the only significant magma reservoir will exist at the level of emplacement, provided that is that space can be made fast enough in the upper crust to accommodate the ascending magma batches.’9Rapid provision of the required space within the upper crust would not be a problem within the context of a catastrophic global Flood that involved catastrophic plate tectonics.10 However, Petford only postulates a maximum vein filling rate of about 2.5 m/yr for a grain size of 5 mm and a porosity of 50 %, a rate that seems comfortably slow enough for his uniformitarian time–scale.But now just to hand is an independent test of the slow (diapir) versus fast (dyke) models for emplacement of granitic magmas, based both on laboratory work and field observations. Brandon et al. chose the mineral epidote for study because it has a magmatic

origin in some granitic rocks and its stability in granitic magmas is restricted to pressures of >= 600 MPa (a depth of 21 km).11 Their experimental work has now shown that epidote dissolves rapidly in granitic melts at pressures of < 600 MPa. Indeed, for temperatures appropriate for granitic magmas (700–800° C) they found that epidote crystals (0.2–0.7 mm) would dissolve in a low-pressure granite melt within 3–200 years. Therefore, if magma transport from sources in the lower crust is slow (> 1,000 years), epidote will not be preserved within upper–crustal batholiths. Yet the authors are able to point to granitic rocks of the Front Range (Colorado) and the White Creek Batholith (British Columbia) in which epidote crystals are found, 0.5 mm wide crystals (in the case of the Front Range occurrence) that would dissolve at 800° C in less than 50 years. Brandon et al. state:‘Preservation of 0.5mm crystals therefore requires a transport rate from a pressure of 600 to 200 MPa of greater than 700 m year-1.’12They went on to calculate a maximum ascent rate of 1.4x104 m (or 14 km) per year for the epidote–bearing White Creek Batholic granitic magma. Therefore, since epidote is found preserved in granitic magmas crystallised at shallow levels, then granitic magma transport from the lower crust must be fast (very much less than 1,000 years). Furthermore, since the modelling of ascending diapirs indicates such magma transport rates are slow (0.3–50 m per year) and ascent times are 10,000–100,000 years,13,14 then the preservation of epidote crystals not only implies magma transport was rapid, but that the transport was via dykes rather than diapirs.What all this means is that much progress is currently being made by some establishment geologists (not all agree yet) with a catastrophic model for the ascent of granitic magmas. While their findings are drastically reducing the time–scales involved, even for granitic melt production in the lower crust, there is still some way to go for our apparent granite problem to be fully solved. Yet since their calculations are invariably always placed within a uniformitarian, radiometrically–determined, millions–of–years context, there appears to be no intrinsic obstacle to successful transposition of these findings to a total catastrophic context, such as catastrophic plate tectonics within a global Flood. This is not to ignore the cooling of the granite magma once it has been rapidly transported into place from deep in the crust, but as Pitcher reminds us,‘...it is salutary to note that his [Spera15] estimates of the time taken for solidification of a typical pluton from liquidus to solidus temperatures varies greatly with the assumed water content, decreasing ten-fold between 0.5 and 4 wt % [weight per cent] water.’16

Towards a Creationist Explanation of Regional Metamorphism

by Dr. Andrew A. Snelling on April 1, 1994 Originally published in Journal of Creation 8, no 1 (April 1994): 51-77. Abstract The ‘classical’ model for regional metamorphism presupposes elevated temperatures and pressures due to deep burial and deformation/tectonic forces over large areas over millions of years. Summary

The “classical” model for regional metamorphism presupposes elevated temperatures and pressures due to deep burial and deformation/tectonic forces over large areas over millions of years—an apparently insurmountable problem for the creationist framework. Furthermore, zones of index minerals are said to represent differences in temperatures and pressures, and therefore mineral reactions, across the regionally metamorphosed terrain. However, evidence is now mounting that such mineral reactions do not occur and diffusion is severely limited. Furthermore, rather than temperatures and pressures being the key factors, compositional variations within and between metamorphic minerals are shown to reflect patterns of original sedimentation.The metasedimentary sheaths surrounding stratiform sulphide orebodies have facilitated the study of regional metamorphic processes on a much smaller scale. Such ore bodies were produced by hydrothermal waters disgorging both sulphides and a variety of other minerals and chemicals onto the sea-floor, where they have been superimposed on “normal” marine sedimentation. Rapid fluctuations have resulted in zones of different clay and related minerals of varying compositions being found at scales of centimetres and metres. When subsequently metamorphosed, these patterns of sedimentation are reflected in zones identical to the “classical” zones of regional metamorphism, and yet minerals are together in the same assemblage that would normally be regarded as having formed under vastly different temperature and pressure conditions. Thus it is shown that these metamorphic minerals have been primarily formed from precursor minerals and materials by in situ transformation, and at only moderate temperatures and pressures or less. Indeed, several “remarkable” examples of precursor minerals/materials having survived the supposed highest grades of metamorphism over presumed millions of years are adequate testimony against the “classical” model of regional metamorphism.This leads to a proposal for a creationist explanation of regional metamorphism. Two major events within the creationist framework of earth history are capable of producing regionally metamorphosed terrains—the tectonism, catastrophic erosion and sedimentation during the formation of dry land in the beginning , and the catastrophic erosion and sedimentation, deep burial and rapid deformation/tectonics during the Flood. Catastrophic sedimentation linked to increased volcanic activity and release of hydrothermal waters during the Flood particularly would have aided the production of zones of sediments of differing clay and related minerals, while catastrophic burial and higher heat flow from that volcanism and hydrothermal activity would have aided the transformation of these precursor materials to produce the resultant index mineral (‘grade’) zones across these metamorphic terrains. Introduction

One of the seemingly most potent, oft-repeated objections to the young-earth Creation-Flood model of earth history is the supposed processes of metamorphism and the formation of metamorphic rocks. There are two major types of metamorphism—contact and regional. Contact metamorphism is basically the baking of rocks around an intruding and cooling magma and thus only involves elevated temperatures. Creationists must here not only explain how the surrounding sediments could have been metamorphosed rapidly, but how the magma cooled quickly enough within their young-earth time framework.However, it is not in the formation of contact metamorphic rocks that the most common metamorphism objections to the Creation-Flood model occur. Regional metamorphic rocks are believed to have been subjected to high pressures as well as high temperatures. This, in addition to the fact that they are always found over areas of hundreds of square kilometres, has led geologists to believe that regional metamorphism occurs when the parent rocks are buried to great depths. Consequently, at current rates of sedimentation the burial process itself would take many millions of years, but creationists can counter that problem by pointing to the increased rate of sedimentation to catastrophic levels during the Flood, when deep burial is envisaged to have been accomplished in only a matter of days or months. However, as pointed out by Wise,l the biggest problem lies again in the heat presumed to have been involved. Rapid burial beneath many kilometres of sediments would have produced virtually instantaneous pressure increases, but once again the evolutionist would argue that it takes too much time to heat the sediment. He would argue that it takes many millions of years to heat up sediments buried 20 kilometres beneath the earth’s surface. These problems and objections are not minor, nor can they simply be ignored. As Young has stated: “Much of the earth’s surface is immediately underlain by vast tracts of crystalline metamorphic rock. Much of the exposed rock of the eastern two-thirds of Canada consists of metamorphic rocks. The Blue Ridge Mountains of the southern Appalachians, the southern Piedmont, virtually all of New England, New York’s Manhattan Island, and nearly the entire

area between Philadelphia and Washington D.C., consist of metamorphic rock. So do large areas of the mountainous western parts of the United States and Canada. Metamorphic rocks also are widely exposed in other parts of the world such as Australia, Scandinavia, Siberia, and India.”2Young goes on to say that a great many of these crystalline metamorphic rocks are believed to be Precambrian in age, and so suggests that creationists might be tempted then to relegate such rocks to the activity of Creation. However, even if some metamorphic activity could be relegated to the Creation (for example, during Day Three), there is still evidence that many regionally metamorphosed rocks had to have been, according to the Creation-Flood model, formed during the Flood year and subsequently.Young points to the metamorphic terrain of the New England, USA, and quite rightly states that despite many of these rocks having been very severely heated and deformed, it is evident that they were chiefly of sedimentary and volcanic character prior to their metamorphism. Furthermore, the original sedimentary character of many of these rocks is, apart from differences from various compositional, textural and structural characteristics, firmly established by the discovery in places of several fossils (even if somewhat deformed) within these metamorphic rocks.3,4 Thus, on the basis of these contained fossils, creationists would argue that the sediments from which these metamorphic rocks developed were deposited during the Flood year. Young also points out that in southern New England the metamorphic rocks are unconformably overlain by unmetamorphosed fossiliferous sedimentary rocks, and so therefore Flood geologists are faced with the necessity of

concluding that the metamorphic rocks of New England metamorphosed during the time-span of less than one year. Click here for larger image (104.4k) Figure 1. Paleozoic regional metamorphism in New England and adjacent areas. Precambrian

rocks in eastern New England and of the New York City area not shown. Furthermore, quantification of what is involved seemingly adds to the problem. Since it has been possible to experimentally determine the range of stability of almost all important metamorphic minerals in terms of pressure and temperature, and the pressure and temperature at which many important metamorphic mineral reactions may occur, it can be concluded that the mineral assemblages of these New England rocks indicate that many of the precursor sedimentary and volcanic rocks must have been subjected to temperatures approaching 600°C and pressures of 5

kilobars.5 Such conditions are interpreted as implying that the sediments were buried under a load of rock 16-19 kilometres thick. Thus Young insists that Flood geologists are obliged to explain in terms of their model for earth history how it would have been possible in less than one year for the precursor sediments of these New England metamorphic rocks to have been deposited, then progressively buried to a depth of between 16 and 19 kilometres as they were first converted to sedimentary rocks. They subsequently, according to Young, had to be progressively metamorphosed as the temperatures rose to around 600°C, and then uplifted and eroded to eventually be exposed as metamorphic rocks at the earth’s surface today! Implications-Zones of Precursor Materials

As has now been shown, the evidence of some stratiform ore environments indicates that, even within a restricted and relatively uniform group of rocks such as the pelites, there may be sufficient constitutional variation to induce the development of a wide range of metamorphic minerals, indeed virtually all of the metamorphic minerals known, at a given temperature and pressure. This is precisely the conclusion reached by Yoder from experimental evidence on the MgO-Al2O3-SiO2-H2O system.94 Clearly, the system investigated by Yoder is very much simpler than the natural ones under consideration here, yet Yoder showed that at 600°C and 15,000psi it was possible to have assemblages within that restricted system corresponding to every one of the accepted metamorphic facies in stable equilibrium. He pointed out that earlier investigators such as Eskola95 had based their identification of metamorphic zones and facies on the assumption that the rocks they had chosen were an isochemical group. However, Yoder noted that his experiments showed that changes of a few percent in composition (including water) may produce great differences in mineralogy, and that mineralogical differences interpreted by Eskola and others as resulting from changes in temperature-pressure conditions might actually be, for the most part, results of subtle changes in bulk composition.Having thus stated explicitly that observed mineralogical differences between rocks of different metamorphic facies might be “the result of variation in bulk composition and need not represent variations of pressure and temperature”, it now seems ironic that Yoder should have gone on to say, “This conclusion, based on experimental fact, appears to be at variance with field observations”. The metapelitic rocks associated with many stratiform ores now clearly indicate, as did Yoder’s experiments, that differences in metamorphic mineral assemblages may be due entirely to variation in the constitution of the rocks, and need not, and at least in some cases do not, represent variations in pressure and temperature. The “field evidence” is there in the metasedimentary sheaths of stratiform ores. Far from being “at variance” with Yoder’s experimental results, it appears to confirm them.Thus the evidence suggests that there may well be an alternative, in the general sense, to Barrow’s interpretation which has become almost unassailable dogma in the geological literature. At least in some cases metamorphic mineral zones may reflect no more than subtle, but systematic, variations in the clay mineral assemblages of the original pelitic sediments, variations consequent upon sedimentary facies in turn stemming from the filling and shall owing of sedimentary basins and shelves, and from transgression and regression associated with epeirogenic changes in shelf and basin depths. Additional factors effecting such clay mineral assemblages may have been the contribution of particularly copious quantities of aluminium) and iron compounds through nearby calc-alkaline volcanism, and the prevailing climate. Warm waters, as in the tropics today for example, may have favoured the development of abundant chamosite in the appropriate facies, and hence, during subsequent metamorphism, the development of a pronounced and extensive garnet zone. Indeed, one suspects that it may be the sediments of calc-alkaline volcanic shelves developed under warm water (today’s tropical) conditions that eventually yield the clearest metamorphic mineral zonations.In such a context the broad zoning and separation of metamorphic minerals in “normal” sedimentary sequences, as compared with the tiny, “compressed” sequences of stratiform ore environments, has been on a scale large enough to be compatible with, and indeed to suggest, that the mineralogical changes stem from regional changes in temperatures and pressures. However, this breadth of scale has probably misled us, and the clue to this possibility that we have probably been misled is provided by the stratiform ores. This line of thought indicates:-Early developed sedimentary/diagenetic precursor materials of the kind postulated may lead to the regional development of metamorphic mineral zoning mimicking that due to prograde metamorphism.In some cases an interplay between early, cryptic zoning of such sedimentary/diagenetic precursors, and later zoning of true prograde metamorphic temperature-pressure conditions may lead to confusing patterns of mineralogical zonation including apparent grade reversals.The “patchy” rather than zonal distribution of the various metamorphic mineralogies so often found in the field, and instances in which patterns of metamorphic mineral occurrences appear to bear no relation to either structural or intrusive features, may be attributable to primary precursor

patterns rather than to variations in metamorphic grade.None of the foregoing should be misconstrued to imply that prograde metamorphism is not a response to increased temperatures and pressures within a given volume of sedimentary and/or other rock strata. That such metamorphism is indeed a P-T-X response (particularly a temperature-composition response) on a regional scale has been taken as well established and therefore self-evident. However, what has been emphasised is that development of metamorphic minerals may result not so much from the “bulk chemistry” of the parent pelitic material, as from the crystal structures and chemical compositions of the innumerable individual particles of which it is composed. If (a) regional metamorphism is substantially a response of these preexisting crystalline particles to a rise in temperatures, (b) the different crystal structures respond at different temperatures, and (c) such temperatures vary in space and time, then it may be expected that the various relevant metamorphic daughter products will develop in ordered patterns in space and time. That is, regional metamorphism may proceed to different “grades” that may reveal themselves by the areal distribution of different mineral assemblages and paragenetic sequences.At first sight this may appear to be exactly the current conventional view of regional metamorphic grade and mineral zonation. This, however, is not the case, and the principle involved may be illustrated by a reexamination of the Dalradian metamorphic terrain of Scotland (see Figure 2 again) and the regional metamorphic zones there as mapped and interpreted by Barrow. Those zones are currently regarded (and have been so regarded for 100 years) as reflecting the progressively changing response of pelitic rocks of essentially uniform bulk chemical composition to a rise in temperature that itself exhibited an ordered increase in space. Thus the mineralogical zonation from south-southeast to north-northwest of chlorite-to sillimanite-bearing assemblages is interpreted as indicating a general increase in regional metamorphic temperatures in a north-northwest direction. However, on the basis of the precursor principle as proposed by Stanton,96,97 and discussed here, metamorphic temperatures may not have been significantly different over the entire terrain affected; they may simply have been sufficiently high to convert all members of a group of precursor minerals, arranged in zones of premetamorphic origin, to their respective daughter products (see Figure 8 again).The words “sufficiently high” are chosen deliberately. It would be very surprising indeed if all precursors converted to their relevant metamorphic daughter products at similar temperatures. There can be little doubt that the various transformations, as distinct from simple grain growth being the mechanism involved, would take place at different temperatures. If this were indeed the case, then the different grades of metamorphism would be marked by the temperatures of precursor transformations rather than temperatures of intermineral reactions as conventionally visualised. Clearly, the interplay between zonal sedimentary/diagenetic patterns of precursor occurrence on the one hand, and different temperatures (and pressures) of transformation of these precursors on the other, may well be complex. It is likely, for example, that neoformed chlorite will assume a high degree of crystallinity, and illite transform to muscovite, at lower temperatures than siliceous chlorites might transform to almandine, or kaolinite-gibbsite mixed layers reorder to silliminite.98 However, the place of other potential transformations in terms of the “standard” pattern of regional metamorphic zonation (chlorite-biotite-garnet-kyanite-sillimanite) is quite unknown at this stage. Indeed, temperatures of any particular transformation may be influenced substantially by kinetic factors, as has already been suggested in the cases of sillimanite99 and cordierite,100 and this, together with palaeogeographical factors, might induce reversals and other deviations from “normal” zoning patterns. Implications- Only Up to Moderate Temperatures Required

We noted earlier that Stanton and Williams101 found significant differences in garnet compositions developed and preserved from one thin bed to the next on a scale of 1mm or less in a finely laminated garnet-quartzite in the Broken Hill metamorphic terrain, New South Wales. Furthermore, whereas garnet compositions varied grossly across bedding, they were completely uniform along beds, indicating that the observed finely layered compositional arrangement was a direct reflection of original bedding. In other words, they maintained that a chemical sedimentary feature of the finest scale had been preserved through a proposed period claimed to be at least 1.8 billion years, including a very high-grade metamorphic episode. However, it strains credulity to suppose that this original pattern of chemical sedimentation could have been preserved with the “utmost delicacy”, through a presumed period of 1.8 billion years through the claimed high temperatures and pressures of very high-grade metamorphism.What is equally amazing is the discovery by Stanton102 of distinctly hydrous “quartz” in well-bedded quartz-muscovite-biotite-almandine-spinel rocks also in the Broken Hill metamorphic terrain. Stanton comments that it seems “remarkable” that this silica could still retain such a notably hydrous nature (7-10% water) after 1.8 billion years that included relatively high-grade (that is, high temperatures and pressures) metamorphism! He also insists that this well-bedded unit in part represents chert that exhibits delicately preserved fine bedding in spite of being involved in high-grade metamorphism.So the quartz in this Broken Hill metamorphic rock unit was originally chemically-sedimented silica, deposited as a product of sea-floor hydrothermal exhalation as hydrous silica gel, that with diagenesis and aging dehydrated and transformed in situ to quartz—a metamorphic mineral. Thus it has not

been produced by any metamorphic reaction, being derived directly from an ancestral hydrous form of silica. Even any induced variable grain growth and coarsening due to presumed metamorphic heating has in no way obliterated the fine bedding. However, this is wishful thinking, that some of this hydrous quartz, that is supposed to be transformed in situ to quartz merely with the low temperatures of diagenesis and aging, should not only survive intact through a presumed period of 1.8 billion years, but the high temperatures and pressures of high-grade metamorphism. Surely, if this “remarkable” discovery proves anything at all, then it is that metamorphic quartz has not only been produced by dehydration and transformation in situ of precursor silica gel and/or chert, but that the temperatures, pressures and time-scales postulated are not necessarily required. Indeed, this discovery indicates that, since quartz does form from its hydrous silica precursor at the low temperatures of diagenesis, these claimed high-grade metamorphic rocks may not have suffered high temperatures and pressures at all!Stanton103 has concluded that if the regional metamorphic silicates do develop principally by transformation and grain growth, the problem of the illusive metamorphic reaction in the natural milieu is resolved. Preservation of what appear to be disequilibrium concentration gradients and mineral

assemblages follows naturally if the materials formed at low temperatures and pressures, particularly in wet sedimentary and sedimentary-hydrothermal depositional regimes, simply undergo early water loss followed by in situ solid-solid transformation with rising temperatures and pressures. There is no destabilising of large chemical domains (‘bulk chemistries’) leading to extensive diffusion, no widespread reaction tending to new equilibria among minerals that develop as groups in accordance with the requirements of the Phase Rule. Puzzled speculation that some metamorphic rocks might attain their mineral assemblages directly rather than through a series of mineral reactions, and hence without passing through each successive grade, appears to be answered. The common lack of evidence that “h igh-grade” zones have passed through all the mineral assemblages of the “lower-grade” zones, an inevitable corollary of the “progressive” nature of the conventional understanding of metamorphism, seems accounted for. The real metamorphic grade indicators are then not the hypothetical intermineral reactions usually postulated, but the relevant precursor transformations, which may be solid-solid or in some cases gel-solid. Of course, it would be going too far to maintain that there was no such thing as a regional metamorphic mineral reaction, or that regional metamorphic equilibrium was never attained. Nevertheless, such phenomena appear not to have anything like the dominating importance in regional metamorphism that is currently

assumed, and the role of metamorphic reactions in generating the bulk of regional metamorphic mineral matter is probably, quite contrary to present belief, almost negligible.The other key factor in elucidating regional metamorphic grades, zones and mineral compositions besides precursor mineral/sediment compositions would thus be the temperatures of precursor transformations, rather than the temperatures of presumed “classical” metamorphic mineral reactions. It is therefore highly significant that hydrous “quartz”, which should have been totally dehydrated at relatively low temperatures, is still found today with its water content in a “high-grade” metamorphic terrain. This is not an isolated occurrence. Many such examples indicate that such transformations do occur at low to moderate temperatures and pressures, and that the time-scales involved may not have been as long as suggested. Thus it is conceivable that regional metamorphic terrains with their zones of “classical” index minerals could have been produced as a result of catastroph ic sedimentation, burial and tectonic activities over short time-scales, the zones only being a reflection of variations in original sedimentation, as can be demonstrated in continental shelf depositional facies today Regional Metamorphism Within the Creationist Framework

In the creationist framework of earth history there is more than one episode capable of producing large regions of zoned metamorphic rocks. During the Creation it is not clear when the first rocks were created and formed, although of course the Scriptural record clearly states that dry land was formed and covered in soils ready for plants to grow in during Day Three. The earth itself was created on Day One, but we are only told that it was then covered in water. We can only speculate whether there was a rocky earth beneath differentiated at that point of time into a core, mantle and rocky exterior crust.104 Furthermore, the nature of any such early-formed rocky crust would be difficult to decipher from today’s surface exposures, because the rocks there have undergone changes due to the catastrophic events since. Nevertheless, we can clearly infer that the formation of the dry land must have involved both earth movements (tectonism), erosion of the emerging land surface due to the retreating waters, and deposition of sediments in the developing ocean basins. So at the very least there is here sedimentation capable of producing zones of sediments with subtle differences in bulk chemistry and mineralogy that would be precursors for accompanying or subsequent regional metamorphism. It is because tectonism accompanied this sedimentation that we cannot preclude the possibility that with such earth movements, plus deep burial of some of these sediments, some metamorphism in some regions may have accompanied this Day Three regression.Of course, there is no reason to assume that this sedimentation did not continue on into, and through, the pre-Flood era. Furthermore, any volcanism and tectonism that occurred during the Creation may also have continued on into the pre-Flood era, but obviously with an intensity and frequency subdued enough so as not to generate impossible living conditions for the residents of the pre-Flood world. Thus the pre-Flood continental shelves and ocean basins would have continued to accumulate a variety of sediments with zonal patterns of different clay and other minerals, perhaps not too dissimilar to those observed today and described earlier (for example, see Figure 7). There also seems no reason not to suppose that there was also sea-floor hydrothermal activity, with hot springs issuing forth a variety of chemicals to interact with the normal marine sedimentation. In the pre-Flood era there is wide scope for the development of sedimentation patterns that may have subsequently been metamorphosed, due to heat released and burial at the outset of the Flood producing temperatures sufficient to induce precursor transformations and regional zones that would mimic conventional “grades”. Nevertheless, it is suggested that the scope for metamorphism itself would have been somewhat limited in the pre-Flood era.It is, of course, the Flood event itself which provides perhaps the greatest scope for regional metamorphism within the creationist framework of earth history. With water eventually again covering the whole earth, catastrophic sedimentation occurred as the pre-Flood land surface was eroded away. The vast thicknesses of fossil-bearing strata are mute testimony to the deep burial of large volumes of sediments. The rock record also testifies to vast outpourings of lavas, so that volcanism on a global scale ensured the release of copious amounts of hydrothermal waters during sedimentation, and the sediments would also have included volcanic components.105 Tidal resonance of the global ocean’s waters would have ensured an episodic nature to sedimentation,106,107 and rapid deformation and tectonism would have ensured both elevated temperatures and pressures in thick sediment piles, as well as the potential for repeated cycles of sedimentation, metamorphism, erosion, sedimentation and then metamorphism again in regions that overlapped as this catastrophic activity shifted geographically. l08 Add to this the possibility of rapid plate tectonics with thermal runaway subduction, rapid rifting, and “rapid” continent-continent collisions as per conventional plate tectonics minus the evolutionary time-scale109-111 and one has a sufficient scenario for the various settings required for regional metamorphism. The range of induced pressures would have, of course, been short-lived, and the time-scales would have only allowed for moderate temperatures to be reached. However, as we have seen, the evidence presented now indicates that composition is the primary factor in metamorphism, and that the zoning of index minerals found across regionally metamorphosed terrains is dependent upon the presence and compositions of precursor minerals, and the temperatures at which those precursors are transformed.This overall scenario may be somewhat simplistic, but it does provide the “skeleton” of a creationist explanation for regional metamorphism. As was noted at the outset, the biggest problem creationists face with the conventional scenario for regional metamorphism is the heat presumed to have been involved,112 given that even with rapid burial beneath kilometres of sediments time is needed to produce that heat within the sediment pile. However, we have now seen that only moderate temperatures may be needed to transform the precursors into the index minerals of the zones of regional metamorphism, and such moderate temperatures would have conceivably been generated in the short time-scale in the Flood event described above, both due to the thicknesses of the sediment piles catastrophically accumulated, and due to the increased heat flow from the mantle because of rapid plate tectonics.113 This higher heat flow during the Flood also would have progressively raised ocean water temperatures. This has been confirmed by oxygen isotope analyses of foraminifera fossilised in the lowermost deep-sea sediments in today’s post-Flood ocean basins (such fossilised foraminifera building their tests in equilibrium with the waters at the time they lived, which would have been at the end of the Flood/beginning of the post-Flood era).114 So the waters trapped in the Flood sediments would have been warmer than the waters being trapped in sediments today, thus giving the buried sediments a “head start” in reaching the temperatures required for diagenesis, and then the moderate temperatures required for regional metamorphism.This demonstrated necessity for only moderate temperatures to transform precursors, even at the highest conventional “grades” also alleviates the conventional need, raised as an objection against Flood geology by Young,115to bury sediments under loads up to 16-19 kms thick to produce the presumed high temperatures and high pressures conventionally thought necessary for regional metamorphism. These conventionally postulated overlying thicknesses Young also posed as another problem, as they need to be then eroded away subsequent to that metamorphism so that the metamorphosed strata are now exposed at the earth’s surface again. Thus, given the primary importance of precursors and zones of different precursors in the sediments, it has now been demonstrated that the creationist framework with its short time-scale, and particularly the Flood event, appears to be able to cope with the moderate temperatures, pressures and depths of burial, plus the catastrophic loading and unloading (burial and erosion), required for regional metamorphism, and for the distribution of regionally metamorphosed rocks and their constituent “grade” zones that we see exposed on the earth’s surface today.

Metamorphic Zones and Facies

Like other terrains of regionally metamorphosed rocks in other parts of the world, the New England (USA) area has been carefully mapped and the rocks divided into metamorphic zones and facies according to their contents (see Figure 1 and Table 1).6 As already indicated, conventional uniformitarian thinking like that of Young envisages that in regions such as the New England sedimentary strata must have been subjected to elevated temperatures and pressures due to deep burial and deformation/tectonic forces over millions of years, and that the resultant mineralogical and textural formations are due to mineral reactions in the original sediments during those prevailing temperature-pressure conditions. Thus the mapped zones of strata, as in Figure 1, contain mineral assemblages that are believed to be diagnostic and confined to each zone respectively. It is assumed that these mineral assemblages reflect the metamorphic transformation conditions specific to each zone, so that by traversing across these metamorphic zones, from the chlorite zone to the sillimanite-K feldspar zone, higher metamorphic grades are progressively encountered, from low to high grade respectively. In the case of the New England area the original sedimentary strata were not just pelitic rocks, but included mafic igneous rocks, and carbonate units that had been metamorphosed into calc-silicates. Thus while the metamorphic zones are often more easily mapped in the field within the pelitic rocks, there is believed to be an approximate correlation with characteristic mineral facies developed in the associated mafic rocks and with index minerals found in the calc-silicates, as shown in Table 1.

Pelitic Rocks Mafic Rocks Calc-Silicate Rocks

Biotite zone Greenschist facies Talc, phlogopite

Garnet zone Epidote amphibolite facies Tremolite, actinolite, epidote, zoisite

Staurolite zone

Amphibolite facies

Diopside

Sillimanite zone Grossularite, scapolite

Sillimanite-K feldspar zone Hornblende-pyroxene granulite facies Forsterite

Table 1. Approximate correlation of mineral zones in pelitic rocks, as shown in Figure 1, with characteristic mineral facies

developed in associated mafic rocks and with the index minerals found in calc-silicate rocks. The lines that separate the different metamorphic zones, as depicted in Figure 1, are called isograds, and are defined as the line along which the index mineral or mineral pair characteristic of the next metamorphic zone first appears in rocks of similar composition. Such first appearances are believed to be dependent not only on externally imposed conditions of temperature, pressure, and the activities of components that have comparatively free mobility, such as water, but also on the original bulk compositions of the rocks. These isograds, of course, are ideally drawn on maps so as to minimise the effects of variations in initial bulk compositions which invariably occur due to the fact that these metamorphic zones and facies cross the boundaries between different original strata—for example, pelitic sedimentary rocks, with interbedded mafic igneous rocks and carbonates. It is envisaged that the mineral assemblages in these zones and facies are the result of mineral reactions, whereby the temperature and pressure conditions, along with active components like water, have induced the minerals in the original rocks to react and form new minerals. Thus, for example, it is envisaged that at the boundary between the biotite and garnet zones in typical pelitic rocks is the first appearance of the completed reaction:

Of course, such reactions will vary according to which minerals are available to react with one another in the original rocks, so for example, if the rock contained more aluminium the resultant reaction might be:

Considerable effort has therefore been expended to elucidate all possible reactions between minerals in the almost limitless potential variations in original bulk compositions.

Historically, the concept of metamorphic zones and facies was developed by Barrow as a result of his geological mapping of the metamorphic rocks and the mineral zones in them in the Scottish Highlands (see Figure 2).7-9 Barrow’s mineralogical zones, which he ascribed to the effect of systematically increasing temperature on the sedimentary rocks of the area he described, laid the foundation for, and formed the basis of, the concept of progressive regional metamorphism as we know it today. The terrain with which Barrow happened to be involved was restricted almost entirely to commonly occurring silicate rocks—primarily greywackes and subordinate pelites. Barrow was not concerned with metamorphic assemblages associated with metal ores of any kind, for he appears quite simply not to have encountered them. Had he encountered them he may have come to rather different conclusions with respect to the processes of regional metamorphism. It is now known that many ores are metamorphosed, and such ores and their environments yield clues to a better understanding of metamorphism in general, an understanding that may help to resolve some of the perceived conflicts between the current uniformitarian view of regional metamorphism and the young-earth Creation-Flood model.

Figure 2. Simplified regional representation of the metamorphic zones of the Grampian Caledonides, Scotland.

Although there have been some doubts expressed, it appears to be widely accepted amongst geologists that the achievement of chemical equilibrium in regional metamorphism is the rule rather than the exception. Metamorphic petrology today is based on the assumption that chemical equilibrium is virtually always attained and hence that mineral assemblages can be evaluated in the context of the Phase Rule. It appears to be generally accepted that diffusion occurs over distances large enough to permit mineral reactions to occur through large volumes of rock, and that with rise in temperature and pressure, such reactions occur in progressive fashion so that any particular set of pressure-temperature conditions comes to manifest itself through the development, in rocks of like chemical composition, of a particular set of metamorphic minerals. In this way grades of metamorphism and metamorphic gradients and zones are identified, and metamorphic rocks of different compositions are linked through the facies principle. Current Inherent Difficulties

This view of metamorphism is now so well established that it constitutes an essentially unquestioned basis for some very highly refined studies of relationships between mineral chemistry and metamorphic grade. These include studies of trace element abundances in individual minerals, trace element partitioning between mineral species, fractionation of stable isotopes, and related fields of investigation.However, there are some reasons to doubt whether the basic assumptions are as sound as they have been thought to be. More precise studies, on the scale of the microscope and particularly of the electron microprobe, are beginning to place severe limits on the distances involved in metamorphic diffusion. This is critical, because limits on diffusion set limits to the extent to which minerals may react, and this in turn limits the extent to which the metamorphic system can approach equilibrium.Writing in the same year as Barrow’s epic work, Harker10 set severe limits to the scale on which metamorphic diffusion might take place. From his observations of the delicate preservation of bedding in some metamorphosed strata, Harker concluded:- “… that within the mass of rock undergoing thermal metamorphism any transfer of material (other than volatile substances) is confined to extremely narrow limits, and consequently … the mineral formed at any point depends on the chemical composition of the rock mass within a certain very small distance around that point.”11 In the same year Harker and Marr,12 through their very careful consideration of metamorphic phenomena associated with the contact of the Shap Granite, concluded that in that case diffusion distances were probably of the order of “1/20 or 1/25 inch”13 (around 1mm).More recently, Turner and Verhoogen14 observed that what little evidence there is seems to indicate

that metamorphic diffusion is probably effective at most over distances measured in centimetres, over times of the order of millions of years. However, in the same year Chinner15 noted:- “The confinement of rocks of varying oxidation ratio to well-defined sedimentary bands suggests that the differences in oxygen content are of premetamorphic, diagenetic origin …”.16 In contrast, Carmichael17 has estimated diffusion limits of the order of 0.2mm–4.0mm. Thus in the century since Barrow’s and Harker’s early work, opinion on diffusion distances, concomitant material transfer, and resulting modification of rock compositions, has varied widely. Many investigators have assumed extensive diffusion and substantial material transfer, though careful mass-balance calculations by others have repeatedly indicated that in at least many cases diffusion distances have been very small. Opinion probably remains diverse, though Winkler has encapsulated the view of many modem investigators:- “There are many indications that rocks constitute a "closed " thermodynamic system during the short time required for metamorphic crystallization. Transport of material is generally limited to distances similar to the size of newly formed crystals. It has been observed frequently that minute chemical differences of former sediments are preserved during metamorphism. Metamorphism is essentially an isochemical process . . .” (emphasis his).18

Whether diffusion is in fact restricted to very small distances, and what, precisely, these distances are, is a critical matter for regional metamorphic petrogenesis. If, as indicated by Harker in 1893 and reiterated by Winkler in 1979, the chemical components of a metamorphic grain now occupying a given small domain are derived directly from those chemical components occupying that domain immediately prior to the onset of metamorphism, that metamorphic mineral must represent the in situ growth and/or transformation of a premetamorphic material of similar overall composition, or it must be one of two or more products of the in situ breakdown of premetamorphic material of appropriate composition.

If this is the case, and it follows not only from the considerations of Harker and Winkler, but also from all those whose findings have indicated metamorphic mineral growth to be isochemical on a fine scale, the implications for metamorphic petrogenesis are profound. The development of metamorphic minerals would stem from simple grain growth, ordering of randomly disposed structures, and solid-solid transformations, not from “mineral reactions” as these are currently visualised. Such metamorphic mineral development would be attained on no more, and perhaps often less, than a single grain scale, and the proposition that groups of minerals, on a thin-section scale, commonly represent “equilibrium assemblages” developed in accordance with the Phase Rule, would be seriously open to question.For the geologist studying ore deposits this question of diffusion distances, and the likelihood that metamorphic diffusion might induce short-range modification of rock compositions, is vital in the detailed consideration of metamorphic processes. There are some ore deposits that form as a primary part of the pelitic rocks in which they occur and which, hence, suffer any metamorphism that the latter may undergo. One approach to the elucidation of the physical and chemical conditions of formation of these ores is the consideration of their present chemical compositions. However, such an approach is soundly based only if present constitutional features are a close reflection of the original ones. This will not be the case if metamorphism has induced differential movement of components. Thus the ore petrologist is obliged to have a vital concern with the nature, and particularly the scale, of metamorphic diffusion.Such limitations on the distance of migration of the elements in metamorphism impose severe constraints on the extent of reaction and the opportunity for equilibration of mineral assemblages. Indeed, clear microscopical evidence of mineral reaction, as distinct from solid-solid transformations, such as the transformation of andalusite to kyanite, is usually very hard to find, even where minerals that might be expected to react lie in contact. Where good microscopical evidence for a fact or process exists, in whatever field of science, it is usual for this to be presented photographically (for example, Vernon19). It therefore seems significant that of the three great metamorphic texts in English of recent years20-22 none shows a single photograph illustrating the destruction of one mineral and the concomitant development of another. Two other texts of a specialist nature on metamorphic textures23 and metamorphic processes24 also do not have any photographs of any mineral transformations, although the former text has photographs of textures and some “reaction rims and coronas”. Mineral aggregates said to indicate particular reactions commonly present an equivocal picture, and in most cases, the postulated product-reactant grouping does not, within that group, yield a balanced chemical equation with respect to all elements.25 What seems the best evidence, that is, two or more “products” habitually replacing what could be seen to be formerly juxtaposed “reactants”, the whole yielding a balanced equation, seems very difficult to find.

Quite frequently some minerals present in a rock, for example, quartz and muscovite, might have been expected to have reacted prior to the achievement of the metamorphic grade indicated by the presence of an associated mineral, in this case sillimanite, but there is no unambiguous microscopical evidence indicating that they have done so. Such difficulties led Carmichael26 to propose the operation of “metasomatic cation-exchange”, though it is difficult to see how such a mechanism can be reconciled better than any other mechanism with limits set by diffusion. Certainly, evidence of reaction should be preserved along isograds, but even here it seems to elude us. This almost general absence of direct evidence of reaction has led some observers27-29 to suggest that metamorphic rocks may attain their mineral assemblages directly, rather than by a series of mineral reactions, and hence without passing through each successive grade. When viewed in a detached way it may be seen that any evidence for mineral reactions is really largely circumstantial. On traversing a metamorphic terrain we find that as one mineral diminishes and disappears another appears to take its place, and so it has been assumed that there must have been a reaction leading to the demise of the first mineral and the generation of the second. There are, however, other reasons why one mineral might give way to another in a spatial sense.Coupled with doubts concerning the reality of many postulated reactions are doubts on equilibrium. The preservation of zoning in garnets, for example, revealed so spectacularly in the past 20 years by the electron microprobe, has been an indication that, even at high grades of metamorphism, equilibrium may remain unattained even in a single crystal. The significance of this has often been minimised on the grounds that diffusion in garnet is probably sluggish due to the complex close-packed structure and strong bonding of the garnet crystal. However, evidence of the preservation of compositional inhomogeneities in other minerals, including sulphides30 is now mounting, indicating that compositional equilibrium may not have been attained even in the most sensitive crystal structures, and even where these are subjected to the highest grades of metamorphism. Ore Deposits in Metasedimentary Rocks

There are two principle categories of ore deposits in sedimentary and metasedimentary rocks: those that, prior to any post-depositional deformation, are concordant and those that are discordant with respect to the bedding of the containing rocks.The discordant group are those referred to as veins that occupy openings, frequently faults, that cut across bedding. The materials in the veins have been introduced from elsewhere in liquid and gaseous solutions, and they have built up by accretion on the walls of the openings concerned. Frequently the solutions and gases have not only yielded the minerals of the ores, they have also caused alteration of the walls of the opening. Such alteration may extend some metres into the enclosing rocks and is commonly referred to as wall-rock alteration, an almost ubiquitous accompaniment of vein formation. Common products of this alteration are sericite, chlorite, quartz, kaolinite and pyrite. In all cases both ore and alteration are the products of materials manifestly introduced from elsewhere and superimposed on the geological environment of the original opening.The concordant group of deposits are those now usually referred to as “conformable” or “stratiform” ores. The ore minerals, usually sulphides, have the appearance of being an integral, and hence normal, component of the sedimentary or metasedimentary rocks in which they occur, being simply grains within a granular rock. The orebodies are usually lens-shaped and grossly elongated, with their long dimensions parallel to the stratification of the enclosing rocks, and they themselves commonly display good internal bedding which may usually be demonstrated to be continuous with that of the enclosing pelitic sediment.In a manner that appears somewhat analogous to the wall-rock alteration zones around discordant or vein ores, many stratiform deposits contain, and are immediately ensheathed by, metapelitic rocks displaying distinctive metamorphic mineral assemblages. These assemblages are sometimes quite complex and exotic and include all of sericite, chlorite, garnet; metamorphic pyroxenes, amphiboles and olivines; staurolite, sillimanite and most of the other well-known metamorphic minerals.Because the materials of discordant/vein ores are so demonstrably introduced, and that at some discrete time “after the formation of the host rocks, it was for a long time thought that the materials of the concordant/stratiform ores must, simply because they were ores, have likewise been introduced. Because they were clearly not formed by the filling of openings it was concluded that they formed by a process of metasomatic replacement. At the same time the rather unusual metamorphic mineral assemblages that often occurred within and surrounding concordant/stratiform orebodies were identified also as “metasomatic” and equated with the zones of wall-rock alteration so commonly associated with the discordant/vein ores. However, it is now generally accepted that most of these concordant/stratiform ores have not developed by replacement of preexisting, lithified sedimentary or metasedimentary rocks, the sulphides of these ores having been laid down as fine chemical precipitates as part of the original sediments themselves. Indeed, such modern-day analogues have been found and observed forming on the sea-floor associated with hydrothermal springs.31-36 These ores are, as of course they have the appearance of being, intrinsic parts of the rocks in which they occur, and they have shared the whole of the latter’s history.This being the case, the somewhat unusual metamorphic mineral assemblages within and surrounding the ores can no longer be ascribed to late-stage metasomatic activity associated with ore deposition by hydrothermal replacement. They must result from the metamorphism of the sedimentary materials laid down with, and adjacent to, the sulphide precipitates. Thus they are genuine metamorphic rocks, even if unusual, and are likely to be just as significant in the study of metamorphic phenomena as the metamorphosed pelitic rocks observed by Barrow, Harker and their many modern counterparts.37-39These stratiform orebodies and their enclosing metapelites often provide very sharp chemical and mineralogical contrasts down to a very small scale, such contrasts being commonly preserved in the very ordered form of the earlier fine bedding of the sediment concerned. Such ores represent high, and usually highly fluctuating, concentrations of particular elements and minerals set in a medium of very much lower concentrations of these elements and minerals. For example, a stratiform orebody may contain 15% Pb, whereas the enclosing rocks a few centimetres away normally only contain parts per million Pb. In the ore Fe may be in excess of 40%, whereas immediately outside the orebody the Fe concentration usually decreases to less than 10%. Expressed mineralogically, the orebody contains abundant galena whereas the surrounding strata contain none. Similarly, the ore-beds and their sheath may contain abundant chlorite, garnet and other metamorphic minerals that are absent from, or very much less abundant in, the enclosing rocks. In addition to this highly localised nature of the metamorphic minerals these also occur in a bedded arrangement; that is, metamorphism of the rock and the development of the metamorphic minerals in many cases has not led to the disruption of the original bedding or other sedimentary structures. Thus these orebodies provide unusually good opportunities for studying the incidence of individual metamorphic mineral species and of compositional variations in them, and the relation of this to the original features of sedimentation. As a result they also provide good opportunities for studying distances over which concentration equilibria are attained, and hence instances over which metamorphic diffusion has occurred. Evidence of Regional Metamorphic Processes From Stratiform Ore Environments The Extent of Metamorphic Diffusion

It seems reasonable to expect that the maximum distances of the diffusion would be indicated by the distance over which compositional homogeneity is achieved on a small scale between, and within, individual crystalline grains of an individual mineral species. Stratiform ores and their envelopes provide some striking examples of the preservation of compositional

inhomogeneities over very small distances. The following examples occur in assemblages that include garnet, staurolite and sillimanite, that is, “high-grade metamorphic” assemblages in which diffusion would be expected to have operated to the maximum extent.Beginning with the relatively gross scale of centimetres, Stanton and Vaughan40,41 have studied variations in garnet compositions associated with the Pegmont orebody in northwest Queensland. Close examination of Figure 3 shows that over a distance of 23cm, between 357.03m and 357.26m in drill core PD31, substantial variations exist in the compositions of garnet grains. Furthermore, at each of the three sample points concerned there was also substantial variation in garnet grain compositions within each single electron microprobe section concerned. Yet garnet is not the only mineral to exhibit such short range variations of this general kind in this particular orebody. For example, FeO/MnO weight percent in manganiferous fayalitic olivine was found to vary from 10 to 24 weight percent then back to

10 weight percent again over a distance of less than a metre. Click here for larger image Figure 3. Variation in divalent cation composition of almandine garnets at eight points over a

total down-core distance of 1.08 m in diamond drill-hole PD31 through the fringe of the ore horizon at Pegmont, Queensland. Note the gross variation in garnet composition over the 23

cm interval from 357.03 m yo 357.26 m. Rows of filled circles at each depth position indicate variation in composition observed in each individual probe section.On a somewhat finer scale Stanton and Williams42 investigated the preservation of garnet compositions as related to bedding in a finely laminated garnet-quartzite (a variant of a banded iron formation) from Broken Hill, New South Wales. They found significant differences in garnet compositions developed and preserved from one thin bed to the next on a scale of 1mm or less. However, systematic microanalyses showed that whereas garnet compositions varied grossly across bedding they were, within the high order of accuracy of the analyses, completely uniform along beds, indicating that the observed finely layered compositional arrangement was a direct reflection of original bedding. That is, a chemical sedimentary feature of the finest scale had been preserved through a proposed period claimed to be at least 1.8 billion years, and through a metamorphic episode generally regarded as of very high grade.43On an even finer scale, there is clear evidence of within-grain inhomogeneities in some of the minerals associated with stratiform ores, the presence of these inhomogeneities indicating limits to diffusion within a single crystal grain during high grade metamorphism. For example, metamorphism of the Mount Misery stratiform orebody near Einasleigh, North Queensland, has produced an assemblage which includes andradite, hornblende and epidote.44-45Pairs of analyses from single grains of andradite (0.05mm apart) and epidote (0.20mm apart) reveal compositional differences that are substantial. In neither of these or other examples does it appear that these differences are due to segregation or exsolution resulting from a tendency for the achievement of a lower energy state by the gathering of elements into structural domains within the crystals. Neither do they represent visible zoning. Instead, they appear to be patchy inhomogeneities that probably represent earlier individual grains of slightly different composition that have amalgamated to become one larger grain as a result of grain boundary movement during metamorphism.The maintenance of such clear compositional disequilibrium between and within grains of single mineral species, and the preservation of this disequilibrium on such a fine scale through the highest supposed grades of metamorphism, seems to indicate that, at least in some cases, metamorphic diffusion is limited not only to distances of a fraction of a millimetre but also to distances less than the grain sizes of the minerals concerned. Mineral Reactions

With the development of very extensive assemblages of metamorphic minerals within what are relatively very small volumes it might be expected that metamorphosed stratiform ores and their envelopes would provide, better perhaps than almost any other metapelitic environment, good textural evidence of mineral reactions. This, however, they do not seem to do.In the ore environs at Broken Hill, New South Wales, quartz and muscovite occur together in rocks also containing sillimanite, but the muscovite exhibits its characteristic sub-idiomorphic, sharply defined, platy form and shows no sign of reacting with the adjacent quartz to form sillimanite and K-feldspar,46 as would normally be expected according to the frequently quoted reaction

Similarly, muscovite-biotite and muscovite-biotite-quartz aggregates are common, but show no sign of reaction in situto form garnet (or cordierite) and K-feldspar, although they might have been expected to have done so at the grade of metamorphism that appears to have been achieved. Similarly, in the Mt Misery orebody chlorite, muscovite and quartz occur in contact in samples whose apparent high-grade nature is indicated by the presence of abundant staurolite and sillimanite or kyanite, but in spite of the high iron content of the chlorites47 there is no textural evidence of the three reacting to produce biotite, or cordierite-biotite, which they might be expected to have done given the over-all apparently high-grade assemblages of the rocks concerned.Stanton reported that his examination of many thin sections of rocks from these, and similar metamorphosed stratiform ore environments, has failed to yield clear micro-structural evidence of mineral reactions. Indeed, there appears to be no unequivocal indication, in the development of corrosion features, reaction rims or pseudomorphs, that minerals that might have been expected to react with each other have done so, nor does there seem to be any clear micro-structural indication of reactions through which the higher grade minerals have formed. Given that some stratiform ore zones possess a very wide range of metamorphic minerals within volumes of a few cubic centimetres, it might have been expected that evidence of such reactions would be found here even if they could be found nowhere else. The inference is that metamorphic mineral reactions, as these are currently visualised, are unlikely to have been a significant factor in the development of these particular extensive metamorphic mineral assemblages. Attainment of Metamorphic Equilibrium

Probably the most basic of all the assumptions in the current consensus about metamorphic rocks and metamorphism is that prograde mineral assemblages as those now observed reflect the attainment of chemical equilibrium. It seems widely accepted that, because of the supposed long periods of presumed millions of years available, lag effects were not significant and thus the various mineral phases present developed and were preserved in accordance with the Phase Rule. On the other hand, because of the lack of these presumed long periods of time in the young-earth Creation-Flood model we would expect chemical/metamorphic equilibrium not to have been attained. Thus it is highly significant that from time to time evidence of doubt about the attainment of metamorphic equilibrium has appeared in the literature. In 1925 Tilley,48 referring to chloritoid-andalusite schists of the Broken Hill area, noted: “One rock … is described as containing in thin slice, quartz, muscovite, biotite, andalusite, sillimanite, chloritoid, chlorite, garnet, magnetite and tourmaline. Such a mineral association is clearly one in which equilibrium is far from being completely attained, and the associations bear witness to this great departure from equilibrium conditions.”

Atherton,49 in examining variations in garnet, biotite and chlorite compositions in medium-grade pelitic rocks from the Dalradian, noted: “Biotites 1 and 2 from rocks of higher grade have very similar Mg/Mg+Fe values; so do the rocks, but the chlorite values are different. The reason for this is not clear. However, the host rock chlorite 2 is thinly banded and chlorite tends to be confined to the quartzose portions, in which case the analyzed chlorite may include material from a subsystem of a different composition to the whole.” Blackburn,50 working on high-grade gneisses from the Grenville Province of Ontario (Canada), concluded that the volumes over which metamorphic equilibrium was established in rocks of this kind were limited to a few cubic centimetres at most, and might be directionally related to foliation. Similar estimates, based on the mineral chemistry of coexisting

phases, as well as on the simple coexistence of such phases, have been expressed by many other investigators.51-58 Click here for larger image Figure 4. Zoning patterns in eight garnets in diamond drill-hole PD 31 through the

fringe of the ore horizon at Pegmont, Queensland. These garnets are in the lower iron formation unit and the variations observed are over the small interval 356.82m to 357.44m (see Figure 3). Compositional variation (y-axis) is expressed in terms of Fe, Ca, Mn, and Mg cation numbers; the x-axis indicates the size of the garnets (mm) and the relative positions of the probe analysis. An ideal opportunity to further investigate whether metamorphic equilibrium has been attained is afforded by some of the assemblages that occur within, and immediately adjacent to, some metamorphosed stratiform ores. In most cases the ores and their enclosing metasedimentary sheaths have been extensively drilled, and continuous, spatially well-controlled, samples are thus available for study in a highly systematic way.A lack of short-range equilibrium between grains of a single mineral species during growth is quite spectacularly illustrated by the differences in zoning patterns developed in garnets, for example, in drill-hole PO 31 from the Pegmont ore deposit, Queensland (Figure 3). Vaughan and Stanton have examined, using the electron microprobe, the patterns of zoning developed in garnets of the several beds of garnet quartzite within an iron formation encountered in this hole.59 Figure 4 shows the results obtained on eight garnets within three beds 15cm and 8cm apart respectively. The zoning patterns present a complex picture and are widely divergent. There is both “normal” Mn-Fe zonation (Mn-

enriched, Fe-depleted core relative to the rim) and “reverse” zonation (Mn-depleted, Fe-enriched core relative to the rim), although Ca also contributes to zoning. These zoning patterns vary sharply over short distances, and therefore if these zones developed during metamorphic growth they were apparently not in equilibrium when they did so.The most striking evidence of the apparent lack of metamorphic equilibrium is, however, provided by the total assemblages of the ore zones of deposits in metasedimentary rocks. Table 2 gives those associated with six such occurrences—the Gorob orebody in Namibia, the Gamsberg deposit in Namaqualand (South Africa ), the Broken Hill deposit (A-lode) in New South Wales, the Pegmont and Einasleigh (Mount Misery deposits) in Queensland, and the Geco deposit in Ontario (Canada).60Each of the metamorphic mineral assemblages in these ore zones is extensive, and in most cases they cover the whole spectrum of metamorphic index minerals of all the presumed zones of progressive regional metamorphism. Yet each assemblage is contained within what is, compared to the regional scale of the classical metamorphic zones, almost an infinitesimally small volume of rock. For example, the whole of the Mount Misery assemblage occurs in a single diamond drill-hole within a core length of 20m, and a major portion of the whole assemblage can be found within a single thin section.61 The assemblage at Gorob is contained within a core length of 3m, and again a major part of it can be observed in almost any individual thin section. Obviously, not all of the minerals listed in Table 2 as occurring in a given ore zone are found in mutual contact, though the majority are so found in each case. Exhaustive examination of the Gorob metapelites shows, for example, that quartz, chlorite, muscovite, biotite, almandine, staurolite and kyanite all occur within a single homogeneous thin section and in mutual contact. While there is certainly a tendency for the various minerals to occur as different groupings, that is, different “assemblages”, from one small metasedimentary unit to the next, the propensity for extensive groupings of minerals to occur together is very clear.

Gorob (Namibia)

Gamsberg (South Africa)

Broken-Hill (A-lode) (Australia)

Pegmont (Australia)

Einasleigh (Australia)

Geco (Canada)

sillimanite sillimanite sillimanite sillimanite sillimanite sillimanite

K-feldspar K-feldspar K-feldspar andalusite staurolite K-feldspar

kyanite olivine olivine K-feldspar andesine staurolite

staurolite clinopyroxene staurolite staurolite scapolite hornblende

cordierite orthopyroxene hornblende clinopyroxene clinopyroxene cordierite

anthophyllite pyroxenoids hedenbergite and related pyroxenoids hornblende hornblende gedrite

almandine grunerite grunerite grunerite andradite biotite

biotite codierite almandine biotite almandine muscovite

muscovite almandine biotite muscovite actinolite chlorite

chlorite andradite muscovite chlorite epidote kaolinite

prehnite biotite chlorite greenalite biotite sudoitic chlorite

quartz zoisite quartz quartz muscovite quartz

clinozoisite chlorite

muscovite stilpnomelane

chlorite prehnite

quartz laumonite

chamosite

quartz

Table 2. Silicate mineral assemblages of some exhalative stratiform orebodies and their metasedimentary sheaths.

Significance of the Metapelites Associated With Stratiform Ores All of the ores that have just been considered in connection with diffusion, reaction and equilibrium have been metamorphosed to high grade; all contain abundant garnet, staurolite, and sillimanite or kyanite. They thus show that even at what are currently regarded as high grades of metamorphism of pelitic rocksmetamorphic diffusion is, at least in some cases, confined to distances of a small fraction of a millimetre,microscopic evidence of metamorphic reactions is usually poor and ambiguous, or absent, andthe whole spectrum of metamorphic index minerals may occur within centimetres of each other, indicating either that metamorphic mineral equilibrium is not established even over very small distances, or that some factor other than, or additional to, temperature and pressure is responsible for the development of these minerals.The confinement of metamorphic diffusion to minuscule distances indicates that the metamorphic minerals now occupying a given domain in space must have grown from materials that previously occupied that domain, so that what is now present in any small segment of a metamorphic rock must be a close constitutional (that is, compositional and crystal-structural) reflection of what previously occupied the space concerned. Furthermore; the coexistence of the whole spectrum of metamorphic index minerals in such confined spaces indicates that, given a temperature and pressure sufficient to induce mineralogical change, there is some other factor that is of dominating importance in determining what minerals will develop. There seems no doubt that this is composition, the constitutions of the minute volumes of material from which each metamorphic mineral grain develops.It has of course long been recognised that compositional variation is an important factor in the development of a given metamorphic mineral assemblage. Indeed, the development of a particular set of metamorphic minerals has always been considered as being dependent on pressure (P), temperature (T) and composition (X). However, it has been thought that by taking a particular group of rocks of essentially uniform composition, such as the “argillaceous” rocks,62-64 the composition X could be made essentially a constant; that is, observation could be restricted to what was regarded, to a first approximation, as an isochemical system, so that variations in mineralogy became independent of rock composition and could be regarded substantially as indicators of variations in temperature and pressure.A careful study of the literature shows, however, that this assumption of constancy of composition in argillaceous rocks has been an uneasy one. Repeatedly, different investigators have suggested that “anomalous” occurrences of index minerals and resulting “reversals” of zones might be due to minor vagaries of parent rock composition; that the composition of the original argillaceous rocks might not have been so constant that the subsequent assemblages of metamorphic minerals reflected only variations in temperature and pressure. However, these doubts and hesitations have generally been stated relatively unobtrusively, and so have had no significant effect on mainstream thought.Now, however, the evidence of the metapelites associated with stratiform ores confirms these doubts, putting them instead into a position of primary importance. Whole-rock analyses of the different lithological units and bands at Gorob, Mount Misery, Broken Hill and Pegmont show these to vary in composition from one to another very substantially over very short distances, even though the original rocks in all cases appear to have been pelitic.65 The total volumes of rock concerned have been far too small to have sustained differences in temperature, pressure, or partial pressures of volatiles, over any significant period of time. The huge array of metamorphic minerals displayed in each case must, therefore, reflect variations in the compositions of the parent shales. It appears that the sedimentary environments of formation of the stratiform ores have been such as to induce marked and sudden changes in sediment constitution from one bed to the next, and it is this that led to the development of such extensive metamorphic mineral assemblages in such very small volumes of rock.What significance has this to our understanding of metamorphic grade and progressive regional metamorphism? It indicates, as was pointed out by Yoder in 1952,66 that differences between metamorphic mineral assemblages may be, in at least some cases, entirely a result of variations in the bulk compositions of the parent rocks, and need not represent variations in temperature and pressure at all. It also thus indicates that the metamorphic zones described by Barrow and thought by him to reflect changing intensity of thermal metamorphism, could in fact result from subtle but systematic compositional changes in the pelitic rocks concerned. Precursors

If, as the evidence from the metamorphic mineral assemblages associated with stratiform ores suggests, metamorphic minerals may represent essentially in situ transformations of earlier sedimentary-diagenetic materials, what might those precursor materials have been? There are a number of possibilities, some of which, particularly in the case of some of these simpler “low-grade” metamorphic minerals, are already well recognised.The chlorite of many metamorphic rocks may have been incorporated in the original sediments as fine chloritic detritus, or it may have originated as fine volcanic glass that was subsequently converted to montmorillonite and then, by iron and magnesium fixation, to chlorite. Sericite and muscovite may have been contributed to the original sediments as fine illite, or it may represent sea floor and diagenetic illitisation of kaolinite and other clay minerals. The biotite of metasedimentary rocks may have been detrital, derived by erosion from granitic and older metamorphic rocks; or pyroclastic, derived from dacitic and related volcanism; or it may be derived by potassium fixation and structural reordering from marine glauconite.67 It has already been suggested68-70 that at least many of the almandine garnets of metamorphosed sediments may derive from marine chamosites, much of the zoning in the garnet stemming from the original oolitic structures of the chamosites. Although garnet contains a little more silica than do most chamosites, dispersed fine chemical silica within chamosite grains could readily supply the balance (Figure 5).71 Possible precursors of staurolite (and cordierite) are by no means obvious, but marine degradation of, for example, calc-alkaline volcanic hornblendes might well yield mixed-layer clay-chlorite minerals similar to some of those noted in volcanic clay deposits of Japan.72 Granules of such materials, with finely admixed chemical silica, as in the case of the chamosites above, in turn may be converted during compaction and metamorphism to cordierite.

Figure 5. Al2O3-SiO2-M2+O relations in garnets from

Broken Hill and Mount Misery (dots) and in chamosites from Mount Misery and in the literature (open circles). The aluminium silicate (Al2SiO5) polymorphs may in turn be derived from kaolinite, halloysite and related alumino-silicate clays, sometimes in combination with hydrothermal-sedimentary diaspore, boehmite and gibbsite. It has previously been suggested73,74 that sillimanite might be generated by desilication and dehydration of kaolinite. It is possible, however, that fibrolite, which may in some cases be a precursor of sillimanite, is derived preferentially from the fibrous or tubular member of the kaolinite family, halloysite. This clay mineral is generated particularly in volcanic areas as the result of degradation of feldspars by acid (sulphate-bearing) hydrothermal solutions75 and has been found in abundance in a number of the Japanese volcanic hydrothermal clay deposits. Development of sillimanite from halloysite might occur by a desilication-dehydration process analogous to that indicated for kaolinite, or by the ordering of halloysite with associated gibbsite, or with excess gibbsite in its structure. In work on minerals present in the metamorphosed

“alteration zone” associated with the Geco orebody (Ontario, Canada), Stanton76 found three materials, whose identities were not obvious under the microscope, that commonly occurred in association with sillimanite, and electron microprobe analyses indicated that these were alumino-silicates. The most abundant of these alumino-silicate materials associated with the sillimanite occurs as dark, extremely fine-grained clots, which give low analytical totals (90-98% ) indicative of some water content, and plot on an Al2O3-SiO2diagram as shown in Figure 6. A lighter coloured, less fine-grained member

of the trio gives even lower analytical totals and plots very close to the position of halloysite. Figure 6. Al2O3-SiO2 weight percent

relations in the three classes of hydrous “alumino-silicate” minerals intimately associated with sillimanite in the Gleco Mine, Manitouwadge, Ontario. Points for kaolinite, halloysite, pyrophyllite, sillimanite and mullite are included for reference. There seems no likelihood that these materials reflect weathering or hydrothermal breakdown of sillimanite to clay minerals, since the drill core in which they occur comes from deep beneath a heavily glaciated, and little-weathered, terrain. Neither is there any evidence of alteration in associated sulphide or silicate minerals (such as biotite), and the microcrystalline material tends strongly to occur at the centres, not the peripheries, of aggregates of clear, sharp sillimanite

crystals. Similarly, there is no evidence of retrogression in associated biotite, almandine and staurolite. Thus the fact that these microcrystalline alumino-silicate materials plot in an unmistakable trend intermediate between halloysite/kaolinite and sillimanite seems to give a strong indication that here preserved in an incomplete state is evidence of the prograde transformation of halloysitic/kaolinitic precursor materials to sillimanite.On this general basis it may be suggested that the three Al2SiO5 polymorphs, sillimanite, kyanite and andalusite, may in some cases each owe their development in metamorphic rocks to nucleation and growth from a specific clay mineral of the kaolinite group, perhaps with additional influence imposed by associated aluminium hydroxides—gibbsite, boehmite and diaspore. If this were the case, the occurrence of particular Al2SiO5 polymorphs would thus be substantially a reflection of the compositions and crystal structures of precursors, and would have little or no pressure-temperature connotation. This does not, however, contradict the careful consideration of the problem of the Al2SiO5polymorphs,77,78 or experiments79,80 which may be accepted as impeccable. Nevertheless, this evidence does strongly suggest that there are alternative ways of generating these minerals, just as there are alternative ways of producing many other minerals.Stanton81 has provided numerous examples of minerals found in metamorphic rocks that have been, or can be, produced from simple or complex precursors of near identical compositions, and even at low temperatures. Consequently, the development of a particular metamorphic mineral assemblage can thus be seen to have devolved from constitutional features in the widest sense, that is, not only from simple “bulk chemistry”, but from this in combination with the detailed features of the precursor crystal structure or mixtures of structures. The nature of such structures, and particularly of the mixed layering of clays - chlorites -Al/Fe oxides/hydroxides- zeolites, and of the admixture of these with amorphous SiO2 and silica/ alumina gels, is likely to be just as important as, or even more important than, “bulk composition” in the development of a particular metamorphic mineral. Possible Reasons for the Extensive Assemblages Associated with some Stratiform Ores

Having established that metamorphic mineral assemblages, can be, indeed must be, derived by transformation in situfrom simple and complex precursors as exemplified in the metasedimentary sheaths surrounding stratiform sulphide ores, it is now necessary to explain how these remarkably extensive metamorphic mineral assemblages of the stratiform ore environments develop, and the reasons for the great variations in composition of the original sediments that these mineral assemblages reflect.It appears that most stratiform ores are formed by the contribution of mineral-bearing hot springs to the sea floor in areas of volcanic activity. The waters of such hot springs today are, of course, at a relatively high temperature, are also slightly acidic, and have a high dissolved solid content and low Eh. As they disgorge onto the sea floor they encounter the water of the sea which is cold, slightly alkaline, possesses relatively low dissolved solids, and which mayor may not have a low Eh (oxidation potential). Added to this, the output of the hot springs is likely to be some- what pulsatory, and the motion of the sea water likely to vary with variation of the slow bottom currents of the locality concerned, these two factors leading to a fluctuating interplay between the warm, acidic and concentrated waters of the hydrothermal regime and the cold, alkaline and dilute waters of the normal marine regime. It is this interplay, the encounter of warm, concentrated hydrothermal solutions with cold, dilute sea water, that leads to the precipitation of the ore minerals, and it is its fluctuating nature that leads to the development of the bedding of the stratiform ores.However, the contribution of the springs involves more than the ore minerals. As well as iron, calcium and other metal compounds, it usually includes substantial quantities of silica, alumina, and silica-alumina gels, the basic materials of the clay minerals and, through its acidic nature, it also involves the variable breakdown of detrital feldspars and other minerals to a variety of clays within the surrounding sea floor sediments. This activity may continue on well after the deposition of the stratiform orebody itself, and may thus lead to the accumulation of sediments not only of highly varying chemical composition, but also containing a wide variety of clay and associated chemical/detrital minerals.Thus, sea-floor hydrothermal environments of ore formation, involving as they inevitably do, rapid fluctuations in the chemical and physical state of the mud-water interface, are likely to produce short-range changes of substantial chemical and crystal-structural significance in the sediments to which they are contributing, particularly to rapid variations in clay mineral assemblages, as sediments accumulate. Changes between dominantly kaolinitic, halloysitic, illitic, chamositic, montmorillonitic, chloritic, glauconitic and related clay mineral sedimentation, changes that usually take place only over substantial distances and over substantial stratigraphic intervals in “normal” marine sedimentation, may take place with extreme rapidity, and on a very local scale, in the marine-hydrothermal regime. Thus if individual metamorphic minerals are essentially direct derivatives of specific clay, chlorite, mixed-layer clay and mixed-layer clay-chlorite and zeolitic mineral precursors, the sea-floor hydrothermal regime may generate over very small distances and over minute stratigraphic intervals the beginnings of a wide range of metamorphic minerals, such as is usually observed to develop only over substantial distances and over substantial stratigraphic intervals in “normal” marine pelitic sequences. Clay Mineral Facies in the Marine-Shelf Environment

The small-scale sedimentary environments of stratiform ores such as those described thus indicate that the larger-scale regional metamorphic zones in pelitic rocks could have stemmed in many cases from semi-regional variations in clay and related mineral assemblages consequent upon the variations in the nature and conditions of sedimentation.The tendency of the clay and related layered silicate minerals to develop zonal patterns of distribution during shelf sedimentation is wel l established. Smoot,82 working in the Chester Series of the Mississippian sediments of Illinois, observed that clay minerals were distributed in a regular pattern of essentially concentric zones which developed outwards from what he interpreted as a delta onto an open marine shelf. He considered this distribution of clay minerals to be essentially a depositional, rather than a diagenetic, feature, the coarser kaolinite having settled closer “in-shore”, whereas the finer material remained suspended for some distance “out to sea”, thus adsorbing K+ and being “transformed” to illite, which settled as sediment “further from the shore”. Thus Millot83 and de Segonzac84 both supported the suggestion that kaolinite, in tending to deposit as larger crystals closer to its interpreted continental source, may be a palaeogeographical indicator of supposed old shorelines.In considering the development of glauconite by the marine degradation of detrital biotite, Galliher85 pointed out that in the sediments of Monterey Bay, California, biotite-rich sandy sediments laid down in near-shore zones were facies of glauconite muds deposited further out to sea. Similarly, in studying clays being delivered to the present Gulf of Mexico, Griffen86 showed that a combination of current action and clay particle size led to an ordered distribution of the different clay species, which in turn yielded a gradation facies pattern of clay minerals parallel to the coastline. Figure 7, which shows the degrees of mixing of clay types from several rivers flowing into the Gulf of Mexico,

illustrates the scale and nature of clay mineral zoning in the near-shore, modern sediments of the Gulf. Click here for larger image Figure 7. Zonal pattern of mixing of different clay types around portion of the coast of the

Gulf of Mexico. “Apalachicola-type clay” refers to the clay mineral suite contributed to the Gulf by the Apalachicola River, as distinct from those contributed by the Mississippi and Mobile Rivers. The Liassic (Jurassic) chamositic ironstones of England and Germany have been noted as occurring as a boundary facies between sandstone and shales, giving way laterally to sandstones on what has been interpreted as the shallower margin, and to silty shales

towards what has been interpreted as deeper water.87 Thus it has been proposed that the ironstones developed as a near-shore facies, and that they were an accompaniment to pronounced delta formation, the chamosite-rich zones representing the pro-delta facies. Ellison,88 in his interpretation of the Middle Silurian sediments of the eastern USA, suggested that a ferruginous facies occurred near-shore between the presumed palaeoshoreline and a carbonate reef facies. This ferruginous facies constitutes a clear zonal development of iron-rich sediment containing abundant chamosite as well as iron oxides. In a detailed study of the clay minerals of the iron-rich facies, Schoen89 showed that chamosite, illite and chlorite were all abundant, the illite being detrital, the chlorite diagenetic, and the chamosite a primary, syngenetic precipitate. Similarly, Porrenga90 found that the iron-rich minerals in the modern sediments of the Niger delta of West Africa displayed a clear zoning of goethite, chamosite and glauconite- parallel to the shoreline. This is clearly significant, because it is the “clay minerals”, chamosite and glauconite, that are the possible precursors to garnet and biotite respectively.Along the South American shelf receiving sediments from the Amazon River, Gibbs91 found a clear zoning of clay minerals developed both along and across the shelf, which he attributed quite simply to sorting by size. Jeans92likewise found distinctive zoning of clay mineral assemblages amongst the sedimentary megafacies in the Triassic Keuper Marl, Tea Green Marl and Rhaetic Sediments in England. Two principal assemblages were recognised:- a detrital assemblage of mica with minor chlorite which occurred throughout the sediments investigated; and a “neoformed” assemblage of magnesium-rich clay minerals with a limited occurrence apparently related to certain megafacies cycles that had presumably resulted from the interpreted transgression and regression of lighter, normal marine waters over heavier, highly saline Mg-rich waters of a restricted hypersaline environment.

Thus, whatever the cause -variation in the nature of the source materials being eroded; differential settling due to systematic differences in particle size or of flocculation; systematic variations in adsorption and “neoformation” sea- floor alteration and agradation; variations in climatic conditions and temperatures during sedimentation; or marine transgression or regression -it is clear that the incidence of different clay minerals in near-shore, and presumed near-shore, marine sediments commonly acquires distinct zoned patterns. The details of these patterns are not entirely constant, and there is considerable overlap, but there does seem to be a widespread tendency for the sediments to develop broad facies patterns not only in the size and nature of their coarser components, but also, though less obviously, in the nature of the clay minerals that these sediments contain.The facies of clay mineral sedimentation on volcanic shelves appear to be poorly studied, but it is envisaged that volcanic contributions to adjacent shelf areas may well modify and enhance features of clay mineral distribution, and hence may have considerable significance in the metamorphic response of the sediments concerned. In areas of sedimentation adjacent to calc-alkaline volcanism and hydrothermal activity, it is likely that kaolinite is joined by halloysite and one or more of gibbsite, diaspore and boehmite. Considerable hydrothermal iron could also be added to the sediments, and this presumably would favour the generation of chamosite and glauconite in sedimentary facies, similar to the pattern found in the Niger delta. Erosion of deeply weathered hinterlands, particularly those characterised by extensive laterite-bauxite, would also lead to the gross contribution of ferriferous and aluminous material, and the addition of chamositic and glauconitic, and iron-rich chlorite, zones to the more common kaolinite-, illite-, and smectite-rich clay mineral facies patterns.Thus with the superimposition of a substantial component of iron, in somewhat greater-than-usual amounts of aluminous matter, on what might be referred to as “normal” patterns of clay mineral sedimentation, we may visualise the development of a clay mineral zoning during sedimentation such as is depicted in Figure 8(a). It should now be recalled that all of these minerals in this pattern have been proposed as principle precursor materials of the common metamorphic index minerals. Figure 8(b) shows the metamorphic mineral zonation that would, if these precursor-product relationships are valid, derive from the sedimentary clay mineral zonation depicted in Figure 8(a). It should be noted that under such circumstances the given mineralogical zone may be confined to a single stratum on a local scale, a single stratum may encompass several zones, and that mineralogical (metamorphic) zones may develop at a high angle to bedding and hence cut across later developed fold structures. For the pelitic rocks, on this basis, metamorphic facies may reflect sedimentary facies, as the latter manifest

themselves in subtle variations in clay mineral assemblages. Click here for larger image Figure 8. (a) Idealized representation of notably aluminum- and iron-rich clays and

clay type materials that might develop in the warm waters of a tropical shelf to which seaboard calc-alkaline volcanic and hydrothermal activity were contributing. (b), (c) Similarly idealized representation of metamorphic mineral zones that might result from essentially isochemical regional metamorphism with concomitant

precursor metamorphic mineral transformation, of the original pattern of detrital, sedimentary and diagenetic clays as in (a). Note that the original clay mineral facies boundaries and their derived metamorphic zones cut across bedding, and hence would be transgressive to later fold structures. A Creationist Alternative to the Uniformitarian Interpretation As was noted at the outset, the concept of regional metamorphic zones and facies was initially developed by Barrow, and later by Kennedy, their interpretation of the metamorphic mineral zonation in the Dalradian of the Scottish Highlands being depicted in a somewhat simplified fashion in Figure 2. It would appear that Barrow was, very reasonably, conscious of the intrusive igneous rocks that cut the

Dalradian rocks further to the north, and interpreted the somewhat concentric zonation as a thermal effect. However, there were in fact two possible explanations, not one, that he could have utilized, namely:- that the zones reflected increasing grades of metamorphism of rocks of constant composition, as he concluded, or that they reflected a more or less constant metamorphism of rocks of systematically, but subtly, changing constitution. Whether Barrow saw only one possibility, or whether he saw the two and deliberately chose the first, we shall never know. However, there is now this further evidence provided by stratiform ore environments that suggests that the second alternative merits very serious consideration. In the Pegmont deposit (northwest Queensland), for example, Stanton and Vaughan93 have presented what seems clear evidence that progressive change in metamorphic mineral assemblages and metamorphic mineral chemistry are, in those instances at least, a direct consequence of sedimentary facies. Changes in principal element abundances, as revealed in a series of drill-holes, from the centre to the edge of the Pegmont Basin represent a pattern of chemical sedimentation that must have developed in a shallow depression on the sea floor. The original materials of the chemical sediments were probably iron-rich clays and chlorites such as greenalite, minnesotaite and chamosite, together with goethite, and minor sulphide increasing in abundance towards the center. Conclusions

A careful search of the metamorphic petrology literature reveals that in recent years doubts have been expressed regarding the basic assumptions of the “classical” or conventional explanation for regional metamorphism. Precise microscope and electron microprobe studies now indicate that there are severe limits on the distances involved in metamorphic diffusion, which in turn imposes severe constraints on both the extent of supposed mineral reactions and the opportunity for equilibration of mineral assemblages. Even where different minerals are found side-by-side, that conventional wisdom would expect to have reacted, no evidence of such mineral reactions can be found. Furthermore, the preservation of very fine scale zoning patterns within single crystals indicates that, even at the supposed highest grades of metamorphism, equilibrium has not been attained even within single crystals. One is thus forced to conclude that the chemical components of a metamorphic grain now occupying a given small domain are derived directly from those chemical components occupying that domain immediately prior to the onset of metamorphism - in other words, the metamorphic mineral must represent the in situ growth and/or transformation of a pre-metamorphic material of similar

overall composition.These conclusions are strikingly confirmed by the array, assemblages and compositions of metamorphic minerals found within and surrounding stratiform sulphide orebodies. Since these ores have now been demonstrated to have formed due to hydrothermal springs on the sea-floor, the enclosing rocks with their metamorphic assemblages must represent original pelitic sediments produced in concert with “normal” marine sedimentation. Studying the assemblages of mineral species and their compositional variations in these metasedimentary sheaths shows that original sedimentary features even at the finest scale (1mm or less) have been preserved through claimed millions of years and the supposed highest “grades” of metamorphism. Furthermore, there is no clear micro-structural evidence of mineral reactions and metamorphic equilibrium has not been established. Indeed, the whole spectrum of index minerals

characteristic of the presumed zones of regional metamorphism occurs within centimetres of each other. It is thus concluded that the key factor in the development of a particular set of metamorphic minerals is the composition, not just the bulk chemistry, of the pelitic rock, and the detailed features of precursor materials, their crystal structures and their compositions.Therefore, these stratiform ores and their metamorphic assemblages reflect original sedimentation in sea-floor hydrothermal environments mixing with “normal” marine sedimentation, the clay and other minerals in the sediments being the precursors to the metamorphic assemblages now present. Extension of this precursor principle to wider zones of sedimentation reveals that both in present-day marine shelf environments and in the depositional environments reflected in a number of “ancient” sedimentary basins, there are wide zones of pelitic sediments containing different clay and related mineral assemblages, such that if these were metamorphosed they would result in metamorphic mineral assemblages that would mimic the zones of regional metamorphism with their characteristic index minerals.Furthermore, it has been demonstrated that these transformations of precursor minerals/materials into metamorphic mineral assemblages can occur at low to moderate temperatures. Some of these metamorphic minerals have been found with remnants of their precursor materials alongside, the two coexisting in rocks that are supposed to have experienced the highest “grade” of metamorphism. The most extreme example, the presence of distinctly hydrous “quartz” in high-grade metamorphic rocks, even after 1.8 billion years and such metamorphism, can only mean that temperatures were low to moderate and the time-scale was very short. Thus it is feasible to conclude that the classical zones of regional metamorphism represent zonal patterns of the original sedimentation, and that the precursor clay and associated minerals have undergone transformation to metamorphic mineral assemblages at low to moderate temperatures and pressures. Furthermore, this implies that the depths of burial required were considerably less, and consequently the time-scales as well.Creationists can therefore explain regional metamorphism within their time framework on the basis of catastrophic sedimentation, deep burial and rapid deformation/tectonics, with accompanying low to moderate temperatures and pressures, particularly during the Flood, but also during the tectonism, erosion and sedimentation of the emerging land surface during the Creation. Volcanism on a global scale, and thus the release of copious amounts of hydrothermal waters, during sedimentation would have produced zones of different precursor materials, and also provided heat for metamorphism during the Flood year. Catastrophic erosion caused by the retreating Flood waters would also have left previously-buried metamorphic rocks exposed at the earth’s surface today.Thus the major objections raised, on the basis of the conventional explanation of regional metamorphism, against the young-earth Creation-Flood model of earth history are answerable, and an alternative creationist explanation has been outlined on the basis of observational and experimental realities. Further work is, of course, needed to quantify the conditions required for precursor transformations, while various mineralogical and textural issues in metamorphic petrology, and in microstructural analysis of phases of deformation, need to be dealt with to make this creationist explanation comprehensive. Acknowledgment

The ideas I have expressed in this paper have been greatly influenced by the research of Professor Richard Stanton of the University of New England, Armidale (New South Wales, Australia). This research is acknowledged without implying that Professor Stanton would support the creationist conclusions—he would not. Some Remaining Problems to be Solved

It would be misleading to give the impression that no problems remain to be solved. Far from it. While the “skeleton” of this creationist scenario for regional metamorphism, based as it is on observational and experimental realities, is both conceivable and feasible, the “bones” need “fleshing out” and the principles enunciated here need to be applied specifically from region to region of metamorphic rocks across the earth’s surface today, and vertically and time-wise down through the rock record.And some problems about the rocks and minerals themselves also remain to be resolved. For example, at what specific temperatures and pressures are the various pre-cursors transformed? Obviously, the answer to that question will enable quantification of the temperatures, pressures and depths of burial required for regional metamorphism within the creationist framework. Also, how do porphyroblasts develop in the many cases where diffusion has been restricted? Are they products of transformation of large particles, for example, impure chamosite ooliths and particles in the case of garnet, products of transformation of concretions and related products developed by post-sedimentation and diagenetic processes, a derivation that would account for many “spotty” porphyroblasts, and porphyroblasts that straddle bedding planes, or products of later inhibition-dependent and orientation-dependent coarsening?116 These processes would readily account for porphyroblasts of a given mineral in a matrix of its own kind, for example, quartz porphyroblasts in quartz-rich metapelites, and for porphyroblasts that straddle bedding planes. These mechanisms would also account for porphyroblasts related to, or developed after, tectonic deformation. Another group of problems lies in relationships between metamorphic minerals and phases of deformation. It seems likely that some interpretations of metamorphic microstructures may require revision, although there has been some recent vigorous discussion on some aspects of this issue.117-124 However, it remains to be seen whether or not apparent sequences of development of metamorphic minerals may be attributed, more simply, to differences in their deformational behaviour and in their variable propensity to anneal and to undergo secondary grain growth in the metallurgical sense. Thus there is still a lot of work for creationists to do in dealing with many of the mineralogical and textural issues in metamorphic petrology from the short time-scale perspective, including conventional experimental studies on mineral stabilities and reactions. Only then will we have developed a comprehensive explanation of regional metamorphism within the creationist framework for earth history.

Australia’s Burning Mountain

A Challenge to Evolutionary Time by Dr. Andrew A. Snelling on March 1, 1993

Originally published in Creation 15, no 2 (March 1993): 42-46. For as long as anyone can remember Mt Wingen has been burning, with an acrid smell of sulphur in the fumes issuing from cracks along its summit. Australia’s Aboriginal inhabitants had known about this burning mountain for many years before the European settlers reached the area, but soon after they came this spectacle attracted scientific attention. The earliest European visitors to describe the phenomenon, Reverend C.P.N. Wilton (between 1828 and 1832) and Sir Thomas Mitchell (in 1829 and 1831), correctly recognized its cause, although this burning mountain became widely known overseas at that time as a volcano or pseudo-volcano.1 Burning coal

Burning Mountain is located five kilometres (about 3 miles) north of the village of Wingen on a major highway between Brisbane and Sydney. Sydney is about 200 kilometres (125 miles) to the south. But Burning Mountain is not a volcano,

Australia being fortunate in not having any volcanoes still active today. Instead, within Mt Wingen is a layer of coal that is burning, having been set alight by natural means.The coal layer (or seam) and associated sandstone, shale and claystone layers at Mt Wingen are called the Koogah Formation, and assigned an Early Permian ‘age’ according to evolutionary terminology.2 Below the Koogah Formation are the thick lavas of the Werrie Basalt, which is also assigned an Early Permian evolutionary ‘age’. Overlying the Koogah Formation are alternating layers of conglomeratic mudstones and sandstones containing fossilized shellfish (brachiopods and pelecypods), together called the Bickham Formation. These geological relationships can be seen easily in the geological cross-section of Figure 1, which depicts these rock units as they are seen where a west-flowing creek transects the Mt Wingen ridge 1.5 kilometres (less than a mile) north of Burning Mountain.3 Subsidence and fused rocks

The ‘burnt-out’ zone extends north-easterly for at least 6.5 kilometres (4 miles) from the present zone of burning at Burning Mountain. The land surface above the ‘burnt-out’ zone is characterized by subsidence features such as fractures, closely-spaced parallel faulting, small grabens (fault-bounded gullies) and open gash-like fissures, which appear to have been controlled by the jointing system in the rocks of the Koogah Formation.4Small, collapsed, chaotically broken areas containing highly altered and fused rocks may represent ‘chimneys’ through which high-temperature burning gases escaped (see Figure 1 again). Fused sandstones associated with these ‘chimneys’ contain rare high-temperature forms of the common mineral quartz and another high-temperature mineral in a rock glass of slaggy, vesicular (bubbly) appearance.Elsewhere in the ‘burnt-out’ area the highly refractory (high-temperature) kaolinite-bearing claystones, which originally were underneath the unburnt coal layer, have been relatively little affected by the burning of the coal (see Figure 2). A thin zone of the claystone just below the burnt coal layer (see Figure 2 again) has been converted to the mineral mullite, a very common refractory form of aluminium silicate.5 However, the kaolinite-bearing claystone above the burnt coal layer, which was subject to the full effects of burning gases, has been more extensively altered to the high-temperature forms of quartz and aluminium silicate (including mullite). A blast-furnace effect

Experimental work, including laboratory ‘firing’ and fusion tests on the ‘natural starting materials’ suggests that temperatures of up to 1700°C must have been attained in the burning zones in order to account for these and other alteration effects due to thermal metamorphism.6, 7As a consequence of the burning of the coal layer a variety of thermal and chemical replacement effects and mineralogical phenomena occur, as has already been described above.The area on Burning Mountain which is presently burning is a highly fissured zone heated to red-white heat over an area of less than 100 square metres.8, 9 Intake of air through the fissures appears to have resulted in a blast-furnace effect being added to the natural combustion of the coal and its gases 30 metres (almost 100 feet) below the surface. Fissures are continuing to open in as yet unburnt ground immediately south of the present area of thermal activity as underground collapse occurs.Heated aqueous fumes emanating from the burning area deposit a sinter composed of hematite (an iron oxide) and high-temperature forms of quartz, encrusted with elemental sulphur which has come from the sulphide minerals, chiefly pyrite (iron sulphide), found in the coal. It is for this reason that the fumes have a pungent sulphur smell, while condensate from these fumes is highly acidic and strongly sulphatic.10For many years these open fissures in the ‘vent’ area were used to extract water and gases for the production of a liquid and an ointment with supposed medicinal value.11 These products were sold until the 1960s. The visitor in those days would have been confronted with an array of various pipes and ducts over the fissures. How did the fire start?

But how did this coal seam get ignited and for how long has it been burning? It has been estimated that the burning front has been moving southward at a rate of approximately one metre (more than 3 feet) every year and has moved about 6,000 metres (nearly 4 miles) to its present position.12 Thus, if the coal has burned in the past at the current rate, then the fire started probably at most about 6,000 years ago. Even allowing for variations in the rate, the evidence certainly indicates that it has been burning for a few thousand years, not millions.Those prepared to hazard a guess have suggested that the coal seam may have been ignited naturally through a lightning strike, a forest fire, or more probably through spontaneous combustion, the latter phenomenon being known to occasionally occur in coal mines today.13However, spontaneous combustion of coal seams today is not known to occur where a coal seam is weathering in outcrop at the surface. On the contrary, spontaneous combustion occurs where coal has been freshly exposed in mine workings, whether in an open pit or in underground tunnels, the heat which ignites the coal being generated by a rapid drying out and oxidation of the coal constituents because they have been rapidly exposed to the elements by the mining process.

As for the other suggested mechanisms for igniting the coal, namely, a lightning strike or a forest fire, again simple reasoning exposes the improbability of these explanations. To begin with, any coal exposed at the land surface as outcrop would be highly weathered due to the way coal rapidly oxidizes and weathers when exposed to the elements at the earth’s surface. It is not that a lightning strike or a forest fire could not ignite an outcropping coal seam, but the weathered nature of the exposed coal would make ignition more difficult. But that is not the only problem. Once ignited at the surface the fire has to burn along the coal seam under the ground, having first to pass through the water table. There the seam would be saturated with water, so the fire

Figure 1 Cross section through Mt Wingen, 1.5km north of the present burning zone, showing the geological strata in the mountain particularly the burning coal layer (seam) (after Rattigan).

would almost certainly be extinguished. Added to that, as any fire moved along a coal seam down under the ground the supply of oxygen necessary for the burning process would continually decrease. Admittedly, if the fire became established under the ground, the rocks above the burnt-out coal would tend to fracture and collapse, thus allowing air down into the burning zone, as appears to be the case on Burning Mountain. But to achieve that situation any fire ignited at the surface has to overcome the other hurdles of passing through the weathered zone and the water table with a diminishing air supply initially. A volcanic intrusion? So if these explanations for the igniting of this underground coal fire beneath Burning Mountain are either tenuous or virtually impossible, how are we to explain this phenomenon? There is one other explanation that has been hinted at subtly in one of the few scientific papers written about this site, but herein lies the challenge for uniformitarian/evolutionary geologists and their millions-of-years timescale. One geologist, a staff member at the time at the University of Newcastle (New South Wales), observed where previously molten volcanic rock has cut through the coal seam at some time in the past and cooled (Figure 2).14, 15 Now it is well known that such molten rock can be intruded at temperatures around 1000°C causing thermal metamorphic effects in the rocks it intrudes, while the intense heat radiates outwards from the molten rock as it cools over subsequent weeks and months. In other places, such molten rock intrusions through coal seams have been known to have either severely metamorphosed the coal or ignited it. This then is the most likely mechanism for the igniting of the burning coal under Mt Wingen. Furthermore, since this appears to have happened less than 6,000 years ago, this intrusion would have been sufficiently close to the surface for fractures to supply the necessary air to the ignited coal to keep it burning. Evolutionary time challenged

So when was the last volcanic activity in this area according to the evolutionary timescale? This molten rock which cross-cuts the coal seam could hardly have come from the same volcano that poured out the basalts of the Werrie Basalt, because those basalts underlie the coal seam of the Koogah Formation and are thus much older than this intrusive volcanic rock (in evolutionary geologic terms). Besides, the Werrie Basalt is said to be of ‘Permian’ age, that is, supposedly over 260 million years old.16, 17The closest volcanic activity to Mt Wingen that occurred after formation of the coal seam is that responsible for the Liverpool Range Basalts, less than 5 kilometres (3 miles) to the north and to the west18 The same basalts are found to the north-east of Mt Wingen also. But these basalts have been dated using the potassium-argon radioactive method as 38 million to 41 million years old.19 Today they cover an area of approximately 6000 square kilometres (almost 2,620 square miles) and are in places up to 800 metres (over 2,600 feet) thick, so they represent an enormous outpouring of molten lavas.20 Thus it seems likely that these small intrusions of similar composition in the nearby Mt Wingen area are related to the same volcano and volcanic event. Indeed, there are intrusive rocks of related composition and the same ‘age’ about 80 kilometres (49.5 miles) to the south,21 and other intrusives about 20 kilometres (12.5 miles)22 and 50 kilometres (31 miles)23, 24 to the south, so volcanic activity has been widespread through this region.However, this would imply that if this intrusive rock at Burning Mountain is supposedly 38 million to 41 million years old, then it must have ignited the coal seam at that time. This is clearly impossible, for we have seen that observational evidence in the present is only consistent with the coal having been burning for less than 6000 years. Consequently, if this intrusive rock ignited the coal then it can’t be millions of years old. Is it any wonder then that Burning Mountain is a challenge to the evolutionary timescale, a challenge which is ignored by geologists generally? Because of the bias generated by their evolutionary indoctrination, they cannot allow evidence like this to challenge their time framework. On the other hand, the evidence is totally consistent with residual volcanic activity sometime after the Flood having ignited this coal seam under Burning Mountain only thousands of years ago.

Figure 2 The burning area today on top of Mt Wingen. There is ‘smoke’ coming out of the ground and the surrounding white sinter.

When Was the Ice Age in Biblical History?

Special Feature by Dr. Andrew A. Snelling and Mike Matthews on April 1, 2013

The Bible doesn’t say, “And then there was an Ice Age.” Yet it does give us the big picture of human history—as well as some critical details—which help us narrow down when the ice built up and then melted away. Just down the road from Cincinnati in the north central USA is Big Bone Lick, “the cradle of American paleontology.” The discovery of huge bones from mastodons, giant sloths, and other Ice Age creatures sparked the first scientific expedition to collect vertebrate fossils in North America. In 1807 President Thomas Jefferson sent General William Clark (of “Lewis and Clark” fame) to gather bones and ship them to the White House. Among the treasures Clark found were spear points. After two centuries of research, we now have enough information to begin recreating scenes from the rise and fall of the Ice Age. As a massive ice sheet expanded over Canada, it drove out most living things, and then it continued to push south into the Ohio valley. Eventually, the heavy snows stopped and the earth warmed. Once the ice began to melt, animals returned to Big Bone Lick, along with spear-wielding humans. Museums worldwide depict similar scenes from this unique era.But it is still difficult to interpret the earth’s dynamic past based on present, slow processes. During the Ice Age the earth’s landscapes, forests, and grasslands bore little resemblance to our own. Indeed, the thick ice sheets drew so much water out of the ocean that large tracts of ocean floor became dry ground. Herds of animals wandered across a 1,000-mile-wide grassy plain that stretched from Asia across the Bering Strait to North America, and people actually lived in the lowlands between England and Europe. (Fishermen in the North Sea sometimes dredge up their stone tools, which look surprisingly similar to those found at Big Bone Lick!)Many pieces of the “Ice Age puzzle” remain unsolved, but one thing is sure. Based on the Bible, we can be certain that the changes occurred within just a few human generations—not over millions of years. What follows is only a benchmark based on our starting parameters. When Did the Ice Age Begin?

The Bible gives us many clues to help us nail down the real time frame of the Ice Age. For example, when did it begin? Bible Fact: Eight Generations from the Flood to AbrahamThe Bible gives us an inerrant chronology for marking historical events. It tells exactly how many human generations passed from the Flood to Abraham’s birth: eight.1 God’s judgment occurred at Babel sometime during the days of Peleg, who was the fourth generation after the Flood 2

Click chart to enlarge. The Bible also reveals that humanity stayed at the plains around Babel until “the Lord scattered them abroad over the face of all the earth” 3 This means that at least three generations passed between the Flood and the first appearance of

humans in Africa, Asia, and Europe. Meanwhile, the animals on the Ark had already fulfilled God’s command to “abound on the earth, and be fruitful and multiply”. 4The Bible also tells us precisely how many years passed from Peleg’s birth to Abraham’s birth. According to the most-often used Hebrew version of the Old Testament (the Masoretic text),5 the total is 190 years.6 Each generation lasted about thirty years until Abraham’s father, Terah. He waited seventy years to have children, so you could say he waited two generations, making a total of either five or six generations from Babel to Abraham.With this information, can we set an approximate date for the start of the Ice Age? Geological Fact: Growth of Arctic Ice Sheets

The “Ice Age” is an informal expression. So first it is necessary to define the term before discussing its timeline.In secular thinking the Ice Age does not refer to the first formation of ice on the planet. Indeed, forests grew on Antarctica and the Arctic before ice began to form.7 Drilling down through Antarctica’s ice sheet, scientists have found in sediment layers beneath the ice sheet fossils of a subtropical rainforest, complete with palm trees and macadamia trees. For these to grow, the land would have to be frost-free for a brief time after the Flood.As the earth cooled, however, grasslands expanded on the continent, while the forests changed to deciduous trees and tundra. Finally, the whole continent was covered by ice, which marked the beginning of the post-Flood cool-down. In the old-earth view, all this took place millions of years before the Ice Age and without a global Flood.The “Ice Age” actually refers only to the period when great ice

sheets arose in the Northern Hemisphere, well after the Antarctic ice sheet had formed (see above map). The deposits from this time period—caused by moving ice and melting waters—are technically known as the Pleistocene. According to old-age assumptions about radiometric dating, the deposits were laid between 2.6 million years and 11,700 years ago (9,700 BC). As the term Ice Age is used in science publications, its end does not refer to the melting of the ice sheets, but

to the rising world temperatures that started the dramatic and relentless retreat of the ice.Though this range is clearly not accurate because it lies outside the Bible’s total timeline of 6,000 years, several lines of evidence support the choice of the Pleistocene layers for the Ice Age. Anywhere that these layers have been tested by radiometric dating, the ages fall within this range. Also, the plants and animals associated with these layers fit the Pleistocene. Indeed, the woolly mammoth (Mammuthus primigenius) and the saber-tooth cat (Smilodon fatalis)—descendants of the original elephant and cat kinds on the Ark—first occur in these layers and disappear at the end of this time frame, except for a few holdouts on a remote Russian island. (See “Why Were the Animals So Big?” p. 56, which discusses how the first elephant and cat kinds on the Ark might produce all this variety during the Ice Age.)Apart from Antarctica and a few high mountain chains, sediments deposited before the Ice Age do not show signs of cold-weather environments or ice sheet activity. Indeed, the world appears to have been a pretty balmy place until the Ice Age.Knowing these things, how can we use the human history described in the Bible to shed light on the Ice Age’s beginning? Well, for one thing, no human tools or fossils appear anywhere on the earth until found in deposits from the beginning of the Ice Age.8 Since their earliest remains suddenly appear throughout the Old World (Asia, Africa, and Europe), it appears that these are the people who scattered from Babel.So it is reasonable to conclude that the start of the Ice Age in the Northern Hemisphere (the Pleistocene) roughly coincides with the Babel judgment, around a century or so after the Flood (perhaps 2250 BC).Who knows, perhaps the Ice Age was part of God’s plan to keep people from quickly resettling in one place again. The unpredictable climate would have made it difficult for anyone to settle down and raise seasonal crops in the years immediately following Babel’s dispersion. When Did the Ice Age End?

The Bible also sheds light on the Ice Age’s end, though in an indirect way. If we can determine the dates of the first cities built after Babel, including Ur, and then show their relationship with dates for the last human and animal remains from the Ice Age, we can establish approximately when the Ice Age ended. Bible Fact: Thriving Cities by Abraham’s Day

The Bible mentions that some very important cities were established by Abraham’s day and continued to thrive throughout Old Testament times. For instance, the city of Abraham’s nativity was Ur. Abraham later passed through many other cities in Mesopotamia (modern Iraq and Syria), Canaan, and Egypt. Since Abraham grew up in Ur, we know that it must have been founded before his birth.Another important clue is the Bible’s reference to several familiar domesticated animals, such as camels, oxen, and donkeys, which Abraham and his contemporaries owned. These domestic animals are not the same species as Ice Age fossils of the same created kinds, and they do not appear until cities are well established. (The camels found earlier in the fossil record were not anything you would want to ride!) It appears that most wild versions of these beasts of burden were extinct by Abraham’s time, along with many other Pleistocene mammals (like wild horses in the Americas). Archaeological Fact: No Cities Associated with Ice Age Remains

The fossil and archaeological record offers us a phenomenal wealth of data from thousands and thousands of sites on every continent. In case after case, radiocarbon dating confirms a general pattern. While the “radiocarbon ages” are wrong because they exceed the Bible’s timeline, the relative ages are useful. If something dates at 40,000 radiocarbon years and something else at 20,000 or 5,000, we know the first find is older than the second, and so on.9Radiocarbon dating shows that every fossil from the Ice Age predates anything from the earliest known human settlements. Several cities have been continuously inhabited since Abraham’s day, so it’s not likely that we’re just missing evidence. 10 Many large mammals specifically designed for cold weather went extinct when the Ice Age ended, in a period known as the “Ice Age extinction event” (see “Mystery of the Megafauna Extinction,” p. 57). We are also able to date human fossils and other remains from the earliest human settlements around the world.In no case do these settlements, including Ur, date as early as the end of the Ice Age. At the time of Ur’s settlement it was a port city on the Persian Gulf, but this gulf did not even exist during the Ice Age. Only later did the melting ice sheets raise the ocean enough to flood into the area and fill the gulf.11 What Were People Doing During the Ice Age?

Archaeologists have found thousands of campsites and small settlements where the people lived after the Babel dispersion during the Ice Age. These early pioneers were daring explorers and settlers, quickly reaching as far as Australia and the Americas. Everywhere they went, they found unfamiliar plants, weather cycles, soils, and wild animals. Cast off from the pampered life of the city, the tiny bands had to invent whole new ways of doing things, including living off the land while caring for their children. Bible Fact: The Whole Earth Is Settled

The Bible does not reveal much about the biology and geology of the Ice Age, but it does tell us about the languages, culture, and migrations of the people of that time. They began as a united people with one language, capable of accomplishing great feats. But God recognized the danger of unity without obedience to His word, so He scattered the people from Babel.Twice the Bible repeats that “the Lord scattered them abroad from there over the face of all the earth”. Notice that this was the Lord’s doing. This supernatural event is essential for a proper understanding of human history. Yet without God’s written Word archaeologists would have no way of knowing this happened.Archaeological Fact: Brief

Appearance of Neanderthals, Woolly Mammoths, and “Stone Age” VillagesThe fossil and archaeological record gives us a wealth of amazing detail about the creatures that people met and the places where they lived.Various species of the saber-tooth cat (such as Smilodon fatalis) began appearing as the Ice Age got underway, though not in the areas first settled by humans. The woolly mammoth (Mammuthus primigenius) did not appear until later, but as the cold increased and grasslands spread across northern Asia and North America, its numbers quickly filled the grassy plains. Humans soon followed in their steps.Another interesting development during the Ice Age was the appearance of Neanderthal people, whose range was restricted to Europe and the Near East. Like all other humans, they were descendants of the people who scattered from Babel. Their remains do not appear until the middle of the Ice Age, and they disappeared as the glaciers reached their maximum and the cold, dry weather reached its worst.12Their short, squat bodies were better suited for the cold than the taller, thinner bodies of their contemporaries, the Cro-Magnon people (other descendants of Babel people), who looked like us. The Neanderthals used heavy spears to hunt woodland animals, but these woods began disappearing at the height of the Ice Age, to be replaced by grasslands or barren tundra. The Cro-Magnon, in contrast, made finely crafted arrows and other weapons that enabled them to hunt more easily on the open plains. The vast number of the Cro-Magnon campsites and fossils indicate these men and women were more successful at adapting to the changes.Sometime after the demise of Neanderthal people, the first “stone age” villages begin appearing all over the Old World. We find them by the thousands, in some instances spread over several acres, and apparently predating any “cities” we know of.It is hard to imagine such extreme changes in weather, landscapes, and vegetation during the rapid Ice Age and the years that followed. Some lush places in the north were stricken by drought, while monsoons filled the Sahara Desert with lakes and grasslands, attracting rhinoceroses, crocodiles, and human settlers. For a time at the end of the Ice Age, the drenched Nile Valley was not even habitable (at least, no human artifacts or villages have been found from this time). The great cities of Memphis and Luxor did not arise until many years later.

The toolmaking technology that archaeologists find is not a record of millions of years of human advancement. These improvements could easily happen within decades after Babel. Same Stone Tools, Different Views Stone tools and other artifacts from the Ice Age do not come with signs on them telling us their age and significance. Depending on your starting assumptions, you can reach very different conclusions, even if you start with the very same facts. Consider one interesting example. Everywhere we find the earliest known stone tools—in Europe, Asia, and Africa—they have the same basic design, called Acheulean tools.* This type of tool appears in most Ice Age layers. Then suddenly, near the end, lots of new styles were adopted, such as the smaller Mousterian blades associated with Neanderthals. If you believe the Ice Age lasted 2.6

million years, then you must assume human beings were making the same basic tools for at least 50,000 generations before any new ideas were invented. That scenario does not quite fit what we know about human ingenuity. God’s Word gives us a different picture of human history. The earth is only six thousand years old, and humans lived here since the first week. We would expect the people who scattered from Babel to share many of the same technological skills. They also lived longer than we do, sometimes over four centuries. So they could pass down technology to many generations. In fact, it is conceivable that most of the stone tool innovations occurred within a single generation.*Andrew Snelling and Mike Matthews, “When Did Cavemen Live?” Answers, April–June 2012, pp. 50–55. Putting It All TogetherWhy did people wait so long after Babel to build cities and farm again? Problems included the tiny populations, the threat of skirmishes, and the changing climates. We also know from the fossil record that they faced constant flooding, dust storms, supervolcanoes, massive earthquakes, meteorites, and downpours of snow or rain on a scale never before seen. It was much safer to live off the land and gather wild grains and game, as people still do in harsh environments. On top of those problems was God’s supernatural intervention to scatter the small groups of families over the face of the earth. The very purpose of this judgment, after all, was to limit mankind’s ability to “do whatever they imagine.” And it was clearly successful!Big Bone Lick is a stark reminder of this difficult time in earth history. The “lick” was a salt deposit that appeared as the ice sheets began retreating. Animals came to lick the salt and then got trapped in the boggy ground. Humans arrived in the area later, at the end of the Ice Age. Their weapons show up in the fossil record about the same time that the large Ice Age mammals went extinct—around 2100–2000 BC. Only later would various cultures begin building pyramid-like mounds and well-defined cities in the Americas, as they did elsewhere in the world. We still have a lot to learn. But we know for certain that the Bible sheds light that puts our world into perspective, including the Ice Age. In fact, it is essential to a right understanding of reality. That extends to modern worries, such as global warming and endangered species, because our understanding of the future is built upon our correct understanding of the past. If mankind would only take God’s Word to heart, it would transform our thinking in every area, and open up amazing new vistas in science and archaeology.

ASTRO GEOLOY

Moon Dust and the Age of the Solar System

by Dr. Andrew A. Snelling and David Rush on April 1, 1993 Originally published in Journal of Creation 7, no 1 (April 1993): 2-42. Abstract

Using a figure published in 1960 of 14,300,000 tons per year as the meteoritic dust influx rate to the earth, creationists have argued that the thin dust layer on the moon’s surface indicates that the moon, and therefore the earth and solar system, are young. Furthermore, it is also often claimed that before the moon landings there was considerable fear that astronauts would sink into a very thick dust layer, but subsequently scientists have remained silent as to why the anticipated dust wasn’t there. An attempt is made here to thoroughly examine these arguments, and the counter arguments made by detractors, in the light of a sizable cross-section of the available literature on the subject.Of the techniques that have been used to measure the meteoritic dust influx rate, chemical analyses (of deep sea sediments and dust in polar ice), and satellite-borne detector measurements appear to be the most reliable. However, upon close examination the dust particles range in size from fractions of a micron in diameter and fractions of a microgram in mass up to millimetres and grams, whence they become part of the size and mass range of meteorites. Thus the different measurement techniques cover different size and mass ranges of particles, so that to obtain the most reliable estimate requires an integration of results from different techniques over the full range of particle masses and sizes. When this is done, most current estimates of the meteoritic dust influx rate to the earth fall in the range of 10, 000-20, 000 tons per year, although some suggest this rate could still be as much as up to 100,000 tons per year.Apart from the same satellite measurements, with a focusing factor of two applied so as to take into account differences in size and gravity between the earth and moon, two main techniques for estimating the lunar meteoritic dust influx have been trace element analyses of lunar soils, and the measuring and counting of microcraters produced by impacting micrometeorites on rock surfaces exposed on the lunar surface. Both these techniques rely on uniformitarian assumptions and dating techniques. Furthermore, there are serious discrepancies between the microcrater data and the satellite data that remain unexplained, and that require the meteoritic dust influx rate to be higher today than in the past. But the crater-saturated lunar highlands are evidence of a higher meteorite and meteoritic dust influx in the past. Nevertheless the estimates of the current meteoritic dust influx rate to the moon’s surface group around a figure of about 10,000 tons per year.Prior to d irect investigations, there was much debate amongst scientists about the thickness of dust on the moon. Some speculated that there would be very thick dust into which astronauts and their spacecraft might “disappear”, while the majority of scientists believed that there was minimal dust cover. Then NASA sent up rockets and satellites and used earth-bound radar to make measurements of the meteoritic dust influx, results suggesting there was only sufficient dust for a thin layer on the moon. In mid-1966 the Americans successively soft-landed five Surveyor spacecraft on the lunar surface, and so three years before the Apollo astronauts set foot on the moon NASA knew that they would only find a thin dust layer on the lunar surface into which neither the astronauts nor their spacecraft would “disappear”. This was confirmed by the Apollo astronauts, who only found up to a few inches of loose dust.The Apollo investigations revealed a regolith at least several metres thick beneath the loose dust on the lunar surface. This regolith consists of lunar rock debris produced by impacting meteorites mixed with dust, some of which is of meteoritic origin. Apart from impacting meteorites and micrometeorites it is likely that there are no other lunar surface processes capable of both producing more dust and transporting it. It thus appears that the amount of meteoritic dust and meteorite debris in the lunar regolith and surface dust layer, even taking into account the postulated early intense meteorite and meteoritic dust bombardment, does not contradict the evolutionists’ multi-billion year timescale (while not proving it). Unfortunately, attempted counter-responses by creationists have so far failed because of spurious arguments or faulty calculations. Thus, until new evidence is forthcoming, creationists should not continue to use the dust on the moon as evidence against an old age for the moon and the solar system.Shop Now Introduction

One of the evidences for a young earth that creationists have been using now for more than two decades is the argument about the influx of meteoritic material from space and the so-called “dust on the moon” problem. The argument goes as follows: “It is known that there is essentially a constant rate of cosmic dust particles entering the earth’s atmosphere from space and then gradually settling to the earth’s surface. The best measurements of this influx have been made by Hans Pettersson, who obtained the figure of 14 million tons per year.1 This amounts to 14 x 1019 pounds in 5 billion years. If we assume the density of compacted dust is, say, 140 pounds per cubic foot, this corresponds to a volume of 1018 cubic feet. Since the earth has a surface area of approximately 5.5 x 1015 square feet, this seems to mean that there should have accumulated during the 5-billion- year age of the earth, a layer of meteoritic dust approximately 182 feet thick all over the world! There is not the slightest sign of such a dust layer anywhere of course. On the moon’s surface it should be at least as thick, but the astronauts found no sign of it (before the moon landings, there was considerable fear that the men would sink into the dust when they arrived on the moon, but no comment has apparently ever been made by the authorities as to why it wasn’t there as anticipated). Even if the earth is only 5,000,000 years old, a dust layer of over 2 inches should have accumulated. Lest anyone say that erosional and mixing processes account for the absence of the 182-foot meteoritic dust layer, it should be noted that the composition of such material is quite distinctive, especially in its content of nickel and iron. Nickel, for example, is a very rare element in the earth’s crust and especially in the ocean. Pettersson estimated the average nickel content of meteoritic dust to be 2.5 per cent, approximately 300 times as great as in the earth’s crust. Thus, if all the meteoritic dust layer had been dispersed by uniform mixing through the earth’s crust, the thickness of crust involved (assuming no original nickel in the crust at all) would be 182 x 300 feet, or about 10 miles! Since the earth’s crust (down to the mantle) averages only about 12 miles thick, this tells us that practically all the nickel in the crust of the earth would have been derived from meteoritic dust influx in the supposed (5 x 109 year) age of the earth!”2 This is indeed a powerful argument, so powerful that it has upset the evolutionist camp. Consequently, a number of concerted efforts have been recently made to refute this evidence.3-9 After all, in order to be a credible theory,evolution needs plenty of time (that is, billions of years) to occur because the postulated process of transforming one species into another certainly can’t be observed in the lifetime of a single observer. So no evolutionist could ever be happy with evidence that the earth and the solar system are less than 10,000 years old.

But do evolutionists have any valid criticisms of this argument? And if so, can they be answered? Criticisms of this argument made by evolutionists fall into three categories:- The question of the rate of meteoritic dust influx to the earth and moon, The question as to whether NASA really expected to find a thick dust layer on the moon when their astronauts, landed, and The question as to what period of time is represented by the actual layer of dust found on the moon. Dust Influx to the Earth Petterson’s Estimate The man whose work is at the centre of this controversy is Hans Pettersson of the Swedish Oceanographic Institute. In 1957, Pettersson (who then held the Chair of Geophysics at the University of Hawaii) set up dust-collecting units at 11,000 feet near the summit of Mauna Loa on the island of Hawaii and at 10,000 feet on Mt Haleakala on the island of Maui. He chose these mountains because “occasionally winds stir up lava dust from the slopes of these extinct volcanoes, but normally the air is of an almost ideal transparency, remarkably free of contamination by terrestrial dust.”10 With his dust-collecting units, Pettersson filtered measured quantities of air and analysed the particles he found. Despite his description of the lack of contamination in the air at his chosen sampling sites, Pettersson was very aware and concerned that terrestrial (atmospheric) dust would still swamp the meteoritic (space) dust he collected, for he says: “It was nonetheless apparent that the dust collected in the filters would come preponderantly from terrestrial sources.”11Consequently he adopted the procedure of having his dust samples analysed for nickel and cobalt, since he

reasoned that both nickel and cobalt were rare elements in terrestrial dust compared with the high nickel and cobalt contents of meteorites and therefore by implication of , meteoritic dust also.Based on the nickel analysis of his collected dust, Pettersson finally estimated that about 14 million tons of dust land on the earth annually. To quote Petterson again: “Most of the samples contained small but measurable quantities of nickel along with the large amount of iron. The average for 30 filters was 14.3 micrograms of nickel from each 1,000 cubic metres of air. This would mean that each 1,000 cubic metres of air contains .6 milligram of meteoritic dust. If meteoritic dust descends at the same rate as the dust created by the explosion of the Indonesian volcano Krakatoa in 1883, then my data indicate that the amount of meteoritic dust landing on the earth every year is 14 million tons. From the observed frequency of meteors and from other data Watson (F.G. Watson of Harvard University) calculates the total weight of meteoritic matter reaching the earth to be between 365,000 and 3,650,000 tons a year. His higher estimate is thus about a fourth of my estimate, based upon theHawaiian studies. To be on the safe side, especially in view of the uncertainty as to how long it takes meteoritic dust to descend, I am inclined to find five million tons per year plausible.”12

Now several evolutionists have latched onto Pettersson’s conservatism with his suggestion that a figure of 5 million tons per year is more plausible and have thus promulgated the idea that Pettersson’s estimate was “high”,13 “very speculative”,14 and “tentative”.15 One of these critics has even gone so far as to suggest that “Pettersson’s dust- collections were so swamped with atmospheric dust that his estimates were completely wrong”16 (emphasis mine). Others have said that “Pettersson’s samples were apparently contaminated with far more terrestrial dust than he had accounted for.”17 So what does Pettersson say about his 5 million tons per year figure?: “The five-million-ton estimate also squares nicely with the nickel content of deep-ocean sediments. In 1950 Henri Rotschi of Paris and I analysed 77 samples of cores raised from the Pacific during the Swedish expedition. They held an average of. 044 per cent nickel. The highest nickel content in any sample was .07 per cent. This, compared to the average .008- per-cent nickel content of continental igneous rocks, clearly indicates a substantial contribution of nickel from meteoritic dust and spherules. If five million tons of meteoritic dust fall to the earth each year, of which 2.5 per cent is nickel, the amount of nickel added to each square centimetre of ocean bottom would be .000000025 gram per year, or .017 per cent of the total red-clay sediment deposited in a year. This is well within the .044-per-cent nickel content of the deep-sea sediments and makes the five- million-ton figure seem conservative.”18 In other words, as a reputable scientist who presented his assumptions and warned of the unknowns, Pettersson was happy with his results. But what about other scientists who were aware of Pettersson and his work at the time he did it? Dr Isaac Asimov’s comments,19 for instance, confirm that other scientists of the time were also happy with Pettersson’s results. Of Pettersson’s experiment Asimov wrote:- “At a 2-mile height in the middle of the Pacific Ocean one can expect the air to be pretty free of terrestrial dust. Furthermore, Pettersson paid particular attention to the cobalt content of the dust, since meteor dust is high in cobalt whereas earthly dust is low in it.”20 Indeed, Asimov was so confident in Pettersson’s work that he used Pettersson’s figure of 14,300,000 tons of meteoritic dust falling to the earth’s surface each year to do his own calculations. Thus Asimov suggested: “Of course, this goes on year after year, and the earth has been in existence as a solid body for a good long time: for perhaps as long as 5 billion years. If, through all that time, meteor dust has settled to the earth at the same rate as it does, today, then by now, if it were undisturbed, it would form a layer 54 feet thick over all of the earth.”21 This sounds like very convincing confirmation of the creationist case, but of course, the year that Asimov wrote those words was 1959, and a lot of other meteoritic dust influx measurements have since been made. The critics are also quick to point this out - “. ..we now have access to dust collection techniques using aircraft, high-altitude balloons and spacecraft. These enable researchers to avoid the problems of atmospheric dust which plagued Pettersson.”22

However, the problem is to decide which technique for estimating the meteoritic dust influx gives the “true” figure. Even Phillips admits this when he says: “(Techniques vary from the use of high altitude rockets with collecting grids to deep-sea core samples. Accretion rates obtained by different methods vary from 102 to 109 tons/year. Results from identical methods also differ because of the range of sizes of the measured particles.”23 One is tempted to ask why it is that Pettersson’s 5-14 billion tons per year figure is slammed as being “tentative”, “very speculative” and “completely wrong”, when one of the same critics openly admits the results from the different, more modern methods vary from 100 to 1 billion tons per year, and that even results from identical methods differ? Furthermore, it should be noted that Phillips wrote this in 1978, some two decades and many moon landings after Pettersson’s work!

(a) Small Size In Space (<0.1 cm)

Penetration Satellites 36,500-182,500 tons/yr

Al26 (sea sediment) Rare Gases Zodiacal Cloud (i) (ii)

73,000-3,650,000 tons/yr <3,650,000 tons/yr 91,500-913,000 tons/yr 73-730 tons/yr

(b) Cometary Meteors (104-102g) In Space

Cometary Meteors 73,000 tons/yr

(c) “Any" Size in Space

Barbados Meshes (i) Spherules (ii) Total Winter (iii) Total Annual Balloon Meshes Airplane Filters Balloons (i) Dust Counter (ii) Coronograph Ni (Antarctic ice) Ni (sea sediment) Os (sea sediment) CI36 (sea sediment) Sea-sediment Spherules

< 110 tons/yr <730 tons/yr <220,000 tons/yr <200,000 tons/yr <91 ,500 tons/yr 3,650,000 tons/yr 365,000 tons/yr 3,650,000-11,000,000 tons/yr <3,650,000 tons/yr 110,000 tons/yr 1,825,000 tons/yr 365-3,650 tons/yr

(d) Large Size in Space

Airwaves Meteorites

36,500 tons/yr 365-3,650 tons/yr

Table 1. Measurements and estimates of the meteoritic dust influx to the earth. (The data are adapted from Parkin and

Tilles,24 who have fully referenced all their data sources.) (All figures have been rounded off.) Other Estimates, Particularly by Chemical Methods In 1968, Parkin and Tilles summarised all the measurement data then available on the question of influx of meteoritic (interplanetary) material (dust) and tabulated it.24 Their table is reproduced here as Table 1, but whereas they quoted influx rates in tons per day, their figures have been converted to tons per year for ease of comparison with Pettersson’s figures. Even a quick glance at Table 1 confirms that most of these experimentally-derived measurements are well below Pettersson’s 5-14 million tons per year figure, but Phillips’ statement (quoted above) that results vary widely, even from identical methods, is amply verified by noting the range of results listed under some of the techniques. Indeed, it also depends on the experimenter doing the measurements (or estimates, in some cases). For instance, one of the astronomical methods used to estimate the influx rate depends on calculation of the density of the very fine dust in space that causes the zodiacal light. In Table 1, two estimates by different investigators are listed because they differ by 2-3 orders of magnitude. On the other hand, Parkin and Tilles’ review of influx measurements, while comprehensive, was not exhaustive, there being other estimates that they did not report. For example, Pettersson25 also mentions an influx estimate based on meteorite data of 365,000-3,650,000 tons/year made by F. G. Watson of Harvard University (quoted earlier), an estimate which is also 2-3 orders of magnitude different from the estimate listed by Parkin and Tilles and reproduced in Table 1. So with such a large array of competing data that give such conflicting orders-of-magnitude different estimates, how do we decide which is the best estimate that somehow might approach the “true” value? Another significant research paper was also published in 1968. Scientists Barker and Anders were reporting on their measurements of iridium and osmium concentration in dated deep-sea sediments (red clays) of the central Pacific Ocean Basin, which they believed set limits to the influx rate of cosmic matter, including dust.26 Like Pettersson before them, Barker and Anders relied upon the observation that whereas iridium and osmium are very rare elements in the earth’s crustal rocks, those same two elements are present in significant amounts in meteorites.

Element Sampling Site Accretion Rate (tons/year)*

Ni Fe Ni Ni Fe Ni Ir Ir Os .

Surface Surface Pacific sediment Pacific sediment Stratosphere Antarctic ice Pacific sediment Pacific sediment Pacific sediment .

40,000,000 200,000,000 3,000,000 40,000,000 <100,000 <100,000 80,000 60,000 <50,000

* Normalized to the composition of C1 carbonaceous chondrites (one class of meteorites).

Table 2. Estimates of the accretion rate of cosmic matter by chemical methods (after Barker and Anders,26 who have fully

referenced all their data sources). Their results are included in Table 2 (last four estimates), along with earlier reported estimates from other investigators using similar and other chemical methods. They concluded that their analyses, when compared wit iridium concentrations in meteorites (C1 carbonaceous chondrites), corresponded to a meteoritic influx rate forth entire earth of between 30,000 and 90,000 tons per year. Furthermore, they maintained that a firm upper limit on the influx rate could be obtained by assuming that all the iridium and osmium in deep-sea sediments is of cosmic origin. The value thus obtained is between 50,000 and 150,000 tons per year. Notice, however, that these scientists were careful to allow for error margins by using a range of influx values rather than a definitive figure. Some recent authors though have quoted Barker and Anders’ result as 100,000 tons, instead of 100,000 ± 50,000 tons. This may not seem a rather critical distinction, unless we realise that we are talking about a 50% error margin either way, and that’s quite a large error margin in anyone’s language regardless of the magnitude of the result being quoted. Even though Barker and Anders’ results were published in 1968, most authors, even fifteen years later, still quote their influx figure of 100,000 ± 50,000 tons per year as the most reliable estimate that we have via chemical methods. However, Ganapathy’s research on the iridium content of the ice layers at the South Pole27 suggests that Barker and Anders’ figure underestimates the annual global meteoritic influx. Ganapathy took ice samples from ice cores recovered by drilling through the ice layers at the US Amundsen-Scott base at the South Pole in 1974, and analysed them for iridium. The rate of ice accumulation at the South Pole over the last century or so is now particularly well established, because two very reliable precision time markers exist in the ice layers for the years 1884 (when debris from the August 26,1983 Krakatoa volcanic eruption was deposited in the ice) and 1953 (when nuclear explosions began depositing fission products in the ice). With such an accurately known time reference framework to put his iridium results into, Ganapathy came up with a global meteoritic influx figure of 400,000 tons per year, four times higher than Barker and Anders’ estimate from mid-Pacific Ocean sediments. In support of his estimate, Ganapathy also pointed out that Barker and Anders had suggested that their estimate could be stretched up to three times its value (that is, to 300,000 tons per year) by compounding several unfavorable assumptions. Furthermore, more recent measurements by Kyte and Wasson of iridium in deep-sea sediment samples obtained by drilling have yielded estimates of 330,000-340,000 tons per year.28 So Ganapathy’s influx estimate of 400,000 tons of meteoritic material per year seems to represent a fairly reliable figure, particularly because it is based on an accurately known time reference framework. Estimates via Aircraft and Spacecraft Methods So much for chemical methods of determining the rate of annual meteoritic influx to the earth’s surface. But what about the data collected by high-flying aircraft and spacecraft, which some critics29,30 are adamant give the most reliable influx estimates because of the elimination of a likelihood of terrestriat dust contamination? Indeed, on the basis of the dust collected by the high-flying U-2 aircraft, Bridgstock dogmatically asserts that the influx figure is only 10,000 tonnes per year.31,32 To justify his claim Bridgstock refers to the reports by Bradley, Brownlee and Veblen,33 and Dixon, McDonnel1 and Carey34 who state a figure of 10,000 tons for the annual influx of interplanetary dust particles. To be sure, as Bridgstock says,35 Dixon, McDonnell and Carey do report that “. ..researchers estimate that some 10,000 tonnes of them fall to Earth every year.”36 However, such is the haste of Bridgstock to prove his point, even if it means quoting out of context, he obviously didn’t carefully read, fully comprehend, and/or deliberately ignored all of Dixon, McDonnell and Carey’s report, otherwise he would have noticed that the figure “some 10,000 tonnes of them fall to Earth every year” refers only to a special type of particle called Brownlee particles, not to all cosmic dust particles. To clarify this, let’s quote Dixon, McDonnell and Carey: “Over the past 10 years, this technique has landed a haul of small fluffy cosmic dust grains known as ‘Brownlee particles’ after Don Brownlee, an American researcher who pioneered the routine collection of particles by aircraft, and has led in their classification. Their structure and composition indicate that the Brown lee particles are indeed extra-terrestrial in origin (see Box 2), and researchers estimate that some 10,000 tonnes of them fall to Earth every year. But Brownlee particles represent only part of the total range of cosmic dust particles”37 (emphasis mine). And further, speaking of these “fluffy” Brownlee particles: “The lightest and fluffiest dust grains, however, may enter the atmosphere on a trajectory which subjects them to little or no destructive effects, and they eventually drift to the ground. There these particles are mixed up with greater quantities of debris from the larger bodies that burn up as meteors, and it is very difficult to distinguish the two”38 (emphasis ours).

What Bridgstock has done, of course, is to say that the total quantity of cosmic dust that hits the earth each year according to Dixon, McDonnell and Carey is 10,000 tonnes, when these scientists quite clearly stated they were only referring to a part of the total cosmic dust influx, and a lesser part at that. A number of writers on this topic have unwittingly made similar mistakes. But this brings us to a very crucial aspect of this whole issue, namely, that there is in fact a complete range of sizes of meteoritic material that reaches the earth, and moon for that matter, all the way from large meteorites metres in diameter that produce large craters upon impact, right down to the microscopic-sized “fluffy” dust known as Brownlee particles, as they are referred to above by Dixon, McDonnell, and Carey. And furthermore, each of the various techniques used to detect this meteoritic material does not necessarily give the complete picture of all the sizes of particles that come to earth, so researchers need to be careful not to equate their influx measurements using a technique to a particular particle size range with the total influx of meteoritic particles. This is of course why the more experienced researchers in this field are always careful in their records to stipulate the particle size range that their measurements were made on.

Figure 1. The mass ranges of interplanetary

(meteoritic) dust particles as detected by various techniques (adapted from Millman39). The particle penetration, impact and collection techniques make use of satellites and rockets. The techniques shown in italics are based on lunar surface measurements. Millman39 discusses this question of the particle size ranges over which the various measurement techniques are operative. Figure 1 is an adaptation of Millman’s diagram. Notice that the chemical techniques, such as analyses for iridium in South Pole ice or Pacific Ocean deep-sea sediments, span nearly the full range of meteoritic particles sizes, leading to the conclusion that these chemical techniques are the most likely to give us an estimate closest to the “true” influx figure. However, Millman40 and Dohnanyi41 adopt a different approach to obtain an influx estimate. Recognising that most of the measurement techniques only measure the influx of particles of particular size ranges, they combine the results of all the techniques so as to get a total influx estimate that represents all the particle size ranges. Because of overlap between techniques, as is obvious from Figure 1, they plot the relation between the cumulative number of particles measured (or cumulative flux) and the mass of the particles being measured, as derived from the various measurement techniques. Such a plot can be seen in Figure 2. The curve in Figure 2 is the weighted mean flux curve obtained by comparing, adding together and taking the mean at anyone mass range of all the results obtained by the various measurement

techniques. A total influx estimate is then obtained by integrating mathematically the total mass under the weighted mean flux curve over a given mass range. Figure 2. The relation between the cumulative

number of particles and the lower limit of mass to which they are counted, as derived from various types of recording - rockets, satellites, lunar rocks, lunar seismographs (adapted from Millman39). The crosses represent the Pegasus and Explorer penetration data. By this means Millman42 estimated that in the mass range 10-12 to 103g only a mere 30 tons of meteoritic material reach the earth each day, equivalent to an influx of 10,950 tons per year. Not surprisingly, the same critic (Bridgstock) that erroneously latched onto the 10,000 tonnes per year figure of Dixon, McDonnell and Carey to defend his (Bridgstock’s) belief that the moon and the earth are billions of years old, also latched onto Millman’s 10,950 tons per year figure.43 But what Bridgstock has failed to grasp is that Dixon, McDonnell and Carey’s figure refers only to the so-called Brownlee particles in the mass range of 10-12 to 10-6g, whereas Millman’s figure, as he stipulates himself, covers the mass range of 10-12 to 103g. The two figures can in no way be compared as equals that somehow support each other because they are not in the same

ballpark since the two figures are in fact talking about different particle mass ranges. Furthermore, the close correspondence between these two figures when they refer to different mass ranges, the 10,000 tonnes per year figure of Dixon, McDonnell and Carey representing only 40% of the mass range of Millman’s 10,950 tons per year figure, suggests something has to be wrong with the techniques used to derive these figures. Even from a glance at the curve in Figure 2, it is obvious that the total mass represented by the area under the curve in the mass range 10-6 to 103g can hardly be 950 or so tons per year (that is, the difference between Millman’s and Dixon, McDonnell and Carey’s figures and mass ranges), particularly if the total mass represented by the area under the curve in the mass range 10-12 to 10-6g is supposed to be 10,000 tonnes per year (Dixon, McDonnell and Carey’s figure and mass range). And Millman even maintains that the evidence indicates that two-thirds of the total mass of the dust complex encountered by the earth is in the form of particles with masses between 10-6.5 and 10-3.5g, or in the three orders of magnitude 10-6, 10-5 and 10-4g, respectively,44 outside the mass range for the so-called Brownlee particles. So if Dixon, McDonnell and Carey are closer to the truth with their 1985 figure of 10,000 tonnes per year of Brownlee particles (mass range 10-12 to 10-6g), and if two-

thirds of the total particle influx mass lies outside the Brownlee particle size range, then Millman’s 1975 figure of 10,950 tons per year must be drastically short of the “real” influx figure, which thus has to be at least 30,000 tons per year. Millman admits that if some of the finer dust partlcles do not register by either penetrating or cratering, satellite or aircraft collection panels, it could well be that we should allow for this by raising the flux estimate. Furthermore, he states that it should also be noted that the Prairie Network fireballs (McCrosky45), which are outside his (Millman’s) mathematical integration calculations because they are outside the mass range of his mean weighted influx curve, could add appreciably to his flux estimate.46 In other words, Millman is admitting that his influx estimate would be greatly increased if the mass range used in his calculations took into account both particles finer than 10-12g and particularly particles greater than l03g.

Figure 3. Cumulative flux of meteoroids and related

objects into the earth’s atmosphere having a mass of M(kg) (adapted from Dohnanyi41). His data sources used to derive this plot are listed in his bibliography. Unlike Millman, Dohnanyi47 did take into account a much wider mass range and smaller cumulative fluxes, as can be seen in his cumulative flux plot in Figure 3, and so he did obtain a much higher total influx estimate of some 20,900 tons of dust per year coming to the earth. Once again, if McCrosky’s data on the Prairie Network fireballs were included by Dohnanyi, then his influx estimate would have been greater. Furthermore, Dohnanyi’s estimate is primarily based on supposedly more reliable direct meas- urements obtained using collection plates and panels on satellites, but Millman maintains that such satellite penetration methods may not be registering the finer dust particles because they neither penetrate nor crater the collection panels, and so any influx estimate based on such data could be underestimating the “true” figure. This is particularly significant since Millman also highlights the evidence that there is another concentration peak in the mass range 10-13 to 10-14g at the lower end of the theoretical effectiveness of satellite penetration data collection (see Figure 1 again). Thus even Dohnanyi’s influx estimate is probably well below the “true” figure. Representativeness and Assumptions This leads us to a consideration of the representativeness both physically and statistically of each of the influx measurement dust collection techniques and the influx estimates derived from them. For instance, how representitive is a sample of dust collected on the small plates mounted on a small satellite or U-2 aircraft compared with the enormous volume of space that the sample is meant to represent? We have already seen how Millman

admits that some dust particles probably do not penetrate or crater the plates as they are expected to and so the final particle count is thereby reduced by an unknown amount. And how representative is a drill core or grab sample from the ocean floor? After all, aren’t we analysing a split from a 1-2 kilogram sample and suggesting this represents the tonnes of sediments draped over thousands of square kilometres of ocean floor to arrive at an influx estimate for the whole earth?! To be sure, careful repeat samplings and analyses over several areas of the ocean floor may have been done, but how representative both physically and statistically are the results and the derived influx estimate?Of course, Pettersson’s estimate from dust collected atop Mauna Loa also suffers from the same question of representativeness. In many of their reports, the researchers involved have failed to discuss such questions. Admittedly there are so many potential unknowns that any statistical quantification is well-nigh impossible, but some discussion of sample representativeness should be attempted and should translate into some “guesstimate” of error margins in their final reported dust influx estimate. Some like Barker and Anders with their deep-sea sediments48 have indicated error margins as high as ±50%, but even then such error margins only refer to the within and between sample variations of element concentrations that they calculated from their data set, and not to any statistical “guesstimate” of the physical representativeness of the samples collected and analysed. Yet the latter is vital if we are trying to determine what the “true” figure might be. But there is another consideration that can be even more important, namely, any assumptions that were used to derive the dust influx estimate from the raw measurements or analytical data. The most glaring example of this is with respect to the interpretation of deep-sea sediment analyses to derive an influx estimate. In common with all the chemical methods, it is assumed that all the nickel, iridium and osmium in the samples, over and above the average respective contents of appropriate crustal rocks, is present in the cosmic dust in the deep-sea sediment samples. Although this seems to be a reasonable assumption, there is no guarantee that it is completely correct or reliable. Furthermore, in order to calculate how much cosmic dust is represented by the extra nickel, iridium and osmium con- centrations in the deep-sea sediment samples, it is assumed that the cosmic dust has nickel, iridium and osmium concentrations equivalent to the average respective concentrations in Type I carbonaceous chondrites (one of the major types of meteorites). But is that type of meteorite representative of all the cosmic matter arriving at the earth’s surface? Researchers like Barker and Anders assume so because everyone else does! To be sure there are good reasons for making that assumption, but it is by no means certain the Type I carbonaceous chondrites are representative of all the cosmic material arriving at the earth’s surface, since it has been almost impossible so far to exclusively collect such material for analysis. (Some has been collected by spacecraft and U-2 aircraft, but these samples still do not represent that total composition of cosmic material arriving at the earth’s surface since they only represent a specific particle mass range in a particular path in space or the upper atmosphere.)

However, the most significant assumption is yet to come. In order to calculate an influx estimate from the assumed cosmic component of the nickel, iridium and osmium concentrations in the deep-sea sediments it is necessary to determine what time span is represented by the deep-sea sediments analysed. In other words, what is the sedimentation rate in that part of the ocean floor sampled and how old therefore are our sediment samples? Based on the uniformitarian and evolutionary assumptions, isotopic dating and fossil contents are used to assign long time spans and old ages to the sediments. This is seen not only in Barker and Anders’ research, but in the work of Kyte and Wasson who calculated influx estimates from iridium measurements in so-called Pliocene and Eocene-Oligocene deep-sea sediments.49 Unfortunately for these researchers, their influx estimates depend absolutely on the validity of their dating and age assumptions. And this is extremely crucial, for if they obtained influx estimates of 100,000 tons per year and 330,000-340,000 tons per year respectively on the basis of uniformitarian and evolutionary assumptions (slow sedimentation and old ages), then what would these influx estimates become if rapid sedimentation has taken place over a radically shorter time span? On that basis, Pettersson’s figure of 5-14 million tons per year is not far-fetched! On the other hand, however, Ganapathy’s work on ice cores from the South Pole doesn’t suffer from any assumptions as to the age of the analysed Ice samples because he was able to correlate his analytical results with two time-marker events of recent recorded history. Consequently his influx estimate of 400,000 tons per year has to be taken seriously. Furthermore, one of the advantages of the chemical methods of influx estimating, such as Ganapathy’s analyses of iridium in ice cores, is that the technique in theory, and probably in practice, spans the complete mass range of cosmic material (unlike the other techniques - see Figure 1 again) and so should give a better estimate. Of course, in practice this is difficult to verify, statistically the likelihood of sampling a macroscopic cosmic particle in, for example, an ice core is virtually nonexistent. In other words, there is the question” of representativeness again, since the ice core is taken to represent a much larger area of ice sheet, and it may well be that the cross sectional area intersected by the ice core is an anomalously high or low concentration of cosmic dust particles, or in fact an average concentration -who knows which? Finally, an added problem not appreciated by many working in the field is that there is an apparent variation in the dust influx rate according to the latitude. Schmidt and Cohen reported50 that this apparent variation is most closely related to geomagnetic latitude so that at the poles the resultant influx is higher than in equatorial regions. They suggested that electromagnetic interactions could cause only certain charged particles to impinge preferentially at high latitudes. This may well explain the difference between Ganapathy’s influx estimate of 400,000 tons per year from the study of the dust in Antarctic ice and, for example, Kyte and Wasson s estimate of 330,000-340,000 tons per year based on iridium measurements in deep-sea sediment samples from the mid-Pacific Ocean. Further Estimates

A number of other workers have made estimates of the meteoritic dust influx to the earth that are often quoted with some finality. Estimates have continued to be made up until the present time, so it is important to contrast these in order to arrive at the general consensus.In reviewing the various estimates by the different methods up until that time, Singer and Bandermann5l argued in 1967 that the most accurate method for determining the meteoritic dust influx to the earth was by radiochemical measurements of radioactive Al26 in deep-sea sediments. Their confidence in this method was because it can be shown that the only source of this radioactive nuclide is interplanetary dust and that therefore its presence in deep-sea sediments was a more certain indicator of dust than any other chemical evidence. From measurements made others they concluded that the influx rate is 1250 tons per day, the error margins being such that they indicated the influx rate could be as low as 250 tons per day or as high as 2,500 tons per day. These figures equate to an influx rate of over 450,000 tons per year, ranging from 91,300 tons per year to 913,000 tons per year. They also defended this estimate via this method as opposed to other methods. For example, satellite experiments, they said, never measured a concentration, nor even a simple flux of particles, but rather a flux of particles having a particular momentum or energy greater than some minimum threshold which depended on the detector being used. Furthermore, they argued that the impact rate near the earth should increase by a factor of about 1,000 compared with the value far away from the earth. And whereas dust influx can also be measured in the upper atmosphere, by then the particles have already begun slowing down so that any vertical mass motions of the atmosphere may result in an increase in concentration of the dust particles thus producing a spurious result. For these and other reasons, therefore, Singer and Bandermann were adamant that their estimate based on radioactive Al26 in ocean sediments is a reliable determination of the mass influx rate to the earth and thus the mass concentration of dust in interplanetary space. Other investigators continued to rely upon a combination of satellite, radio and visual measurements of the “different particle masses to arrive at a cumulative flux rate. Thus in 1974 Hughes reported52 that “from the latest cumulative influx rate data the influx of interplanetary dust to the earth’s surface in the mass range 10-13 - 106g is found to be 5.7 x 109 g yr-1”, or 5,700 tons per year, drastically lower than the Singer and Bandermann estimate from Al26 in ocean sediments. Yet within a year Hughes had revised his estimate upwards to 1.62 x 1010 g yr-1, with error calculations indicating that the upper and lower limits are about 3.0 and 0.8 x 1010g yr-1 respectively.53 Again this was for the particle mass range between 10-13g and 106 g, and this estimate translates to 16,200 tons per year between lower to upper limits of 8,000 - 30,000 tons per year. So confident now was Hughes in the data he had used for his calculations that he submitted an easier-to-read account of his work in the widely-read, popular science magazine, New Scientist.54 Here he again argued

that “as the earth orbits the sun it picks up about 16,000 tonnes of interplanetary material each year. The particles vary in size from huge meteorites weighing tonnes to small microparticles less than 0.2 micron in diameter. The majority originate from decaying comets.”

Figure 4. Plot of thecumulative flux of interplanetary matter (meteorites, meteors, and meteoritic dust, etc.) into the earth’s

atmosphere (adapted from Hughes54). Note that he has subdivided the debris into two modes of origin - cometary and asteroidal - based on mass, with the former category being further subdivided according to detection techniqes. From this plot Hughes calculated a flux of 16,000 tonnes per year. Figure 4 shows the cumulative flux curve built from the various sources of data that he used to derive his calculated influx of about 16,000 tons per year. However, it should be noted here that using the same methodology with similar data Millman55 had in 1975, and Dohnanyi56 in 1972, produced influx estimates of 10,950 tons per year and 20,900 tons per year respectively (Figures 2 and 3 can be compared with Figure 4). Nevertheless, it could be argued that these two estimates still fall within the range of 8,000 -30,000 tons per year suggested by Hughes. In any case, Hughes’ confidence in his estimate is further illustrated by his again quoting the same 16,000 tons per year influx figure in a paper published in an authoritative book on the subject of cosmic dust.58 Meanwhile, in a somewhat novel approach to the problem, Wetherill in 1976 derived a meteoritic dust influx estimate by looking at the possible dust production rate at its source.59 He argued that whereas the present sources of meteorites are probably multiple, it being plausible that both comets and asteroidal bodies of several kinds contribute to the flux of meteorites on the earth, the immediate source of meteorites is those asteroids, known as Apollo objects, that in their orbits around the sun cross the earth’s orbit. He then went on to calculate the mass yield of meteoritic dust (meteoroids) and meteorites from the fragmentation and cratering of these Apollo asteroids. He found that the combined yield from both crate ring and complete fragmentation to be 7.6 x 1010g yr-l, which translates into a figure of 76,000 tonnes per year. Of this figure he calculated that 190 tons per year would represent meteorites in the mass range of 102 - 106g, a figure which compared well with terrestrial meteorite mass impact rates obtained by various other calculation methods, and also with other direct measurement data, including observation of the actual meteorite flux. This figure of 76,000 tons per year is of course much higher than those estimates based on cumulative flux calculations such as those of Hughes,60 but still below the range of results gained from various chemical analyses of deep-sea sediments, such as those of Barker and Anders,61 Kyte and Wasson,62 and Singer and Bandermann,63 and of the Antarctic ice by Ganapathy.64 No wonder a textbook in astronomy compiled by a worker in the field and published in 1983 gave a figure for the total meteoroid flux of about 10,000 - 1,000,000 tons per year.65 In an oft-quoted paper published in 1985, Griin and his colleagues66 reported on yet another cumulative flux calculation, but this time based primarily on satellite measurement data. Because these satellite measurements had been made in interplanetary space, the figure derived from them, would be regarded as a measure of the interplanetary dust flux. Consequently, to calculate from that figure the total meteoritic mass influx on the earth both the gravitational increase at the earth and the surface area of the earth had to be taken into account. The result was an influx figure of about 40 tons per day, which translates to approximately 14,600 tons per year. This of course still equates fairly closely to the influx estimate made by Hughes.67 As well as satellite measurements, one of the other major sources of data for cumulative flux calculations has been measurements made using ground-based radars. In 1988 Olsson-Steel68 reported that previous radar meteor observations made in the VHF band had rendered a flux of particles in the 10-6 - 10-2g mass range that was anomalously low when compared to the, fluxes derived from optical meteor observations or satellite measurements. He therefore found that HF radars were necessary in order to detect the total flux into the earth’s atmosphere. Consequently he used radar units near Adelaide and Alice Springs in Australia to make measurements at a number of different frequencies in the HF band. Indeed, Olsson-Steel believed that the radar near Alice Springs was at that time the most powerful device ever used for meteor detection, and be- cause of its sensitivity the meteor count rates were extremely high. From this data he calculated a total influx of particles in the range 10-6 - 10-2g of 12,000 tons per year, which as he points out is almost

identical to the flux in the same mass range calculated by Hughes.69,70 He concluded that this implies that, neglecting the occasional asteroid or comet impact, meteoroids in this mass range dominate the total flux to the atmosphere, which he says amounts to about 16,000 tons per year as calculated by Thomas et al.71

In a different approach to the use of ice as a meteoritic dust collector, in 1987 Maurette and his colleagues72 reported on their analyses of meteoritic dust grains extracted from samples of black dust collected from the melt zone of the Greenland ice cap. The reasoning behind this technique was that the ice now melting at the edge of the ice cap had, during the time since it formed inland and flowed outwards to the melt zone, been collecting cosmic dust of all sizes and masses. The quantity thus found by analysis represents the total flux over that time period, which can then be converted into an annual influx rate. While their analyses of the collected dust particles were based on size fractions, they relied on the mass-to-size relationship established by Griin et al.73 to convert their results to flux estimates. They calculated that each kilogram of black dust they collected for extraction and analysis of its contained meteoritic dust corresponded to a collector surface of approximately 0.5 square metres which had been exposed for approximately 3,000 years to meteoritic dust infall. Adding together their tabulated flux estimates for each size fraction below 300 microns yields a total meteoritic dust influx estimate of approximately 4,500 tons per year, well below that calculated from satellite and radar measurements, and drastically lower than that calculated by chemical analyses of ice. However, in their defense it can at least be said that in comparison to the chemical method this technique is based on actual identification of the meteoritic dust grains, rather than expecting the chemical analyses to represent the meteoritic dust component in the total samples of dust analysed. Nevertheless, an independent study in another polar region at about the same time came up with a higher influx rate more in keeping with that calculated from satellite and radar measurements. In that study, Tuncel and Zoller74 measured the iridium content in atmospheric samples collected at the South Pole. During each 10-day sampling period, approximately 20,000-30,000 cubic metres of air was passed through a 25-centimetre-diameter cellulose filter, which was then submitted for a wide range of analyses. Thirty such atmospheric particulate samples were collected over an 11 month period, which ensured that, seasonal variations were accounted for. Based on their analyses they discounted any contribution of iridium to their samples from volcanic emissions, and concluded that iridium concentrations in their samples could be used to estimate both the meteoritic dust component in their atmospheric particulate samples and thus the global meteoritic dust influx rate. Thus they calculated a global flux of 6,000 -11,000 tons per year. In evaluating their result they tabulated other estimates from the literature via a wide range of methods, including the chemical analyses of ice and sediments. In defending their estimate against the higher estimates produced by those chemical methods, they suggested that samples (particularly sediment samples) that integrate large time intervals include in addition to background dust particles the fragmentation products from large bodies. They reasoned that this meant the chemical methods do not discriminate between background dust particles and fragmentation products from large bodies, and so a significant fraction of the flux estimated from sediment samples may be due to such large body impacts. On the other hand, their estimate of 6,000-11,000 tons per year for particles smaller than 106g they argued is in reasonable agreement with estimates from satellite and radar studies. Finally, in a follow-up study, Maurette with another group of colleagues75 investigated a large sample of micrometeorites collected by the melting and filtering of approximately 100 tons of ice from the Antarctic ice sheet. The grains in the sample were first characterised by visual techniques to sort them into their basic meteoritic types, and then selected particles were submitted for a wide range of chemical and isotopic analyses. Neon isotopic analyses, for example, were used to confirm which particles were of extraterrestrial origin. Drawing also on their previous work they concluded that a rough estimate of the meteoritic dust flux, for particles in the size range 50-300 microns, as recovered from either the Greenland or the Antarctic ice sheets, represents about a third of the total mass influx on the earth at approximately 20,000 tons per year.

Scientist(s) (year)

Technique Influx Estimate (tons/year)

Petterson (1960) Ni in atmospheric dust 14,300,000

Barker and Anders (1968) Ir and Os in deep-sea sediments

100,000 (50,000 - 150,000)

Ganapathy (1983) Ir in Antarctic ice 400,000

Kyte and Wasson (1982) Ir in deep-sea sediments 330,000 - 340,000

Millman (1975) Satellite, radar, visual 10,950

Dohnanyi (1972) Satellite, radar, visual 20,900

Singer and Bandermann (1967) Al26 in deep-sea sediments

456,000 (91,300 - 913,000)

Hughes (1975 - 1978) Satellite, radar, visual

16,200 (8,000 - 30,000)

Wetherill (1976) Fragmentation of Apollo asteroids 76,000

Grün et al. (1985) Satellite data particularly 14,600

Olsson-Steel (1988) Radar data primarily 16,000

Maurette et al. (1987) Dust from melting Greenland ice 4,500

Tuncel and Zoller (1987) Ir in Antarctic atmospheric particulates 6,000 - 11,000

Maurette et al. (1991) Dust from melting Antarctic ice 20,000

Table 3. Summary of the earth’s meteoritic dust influx estimates via the different measurement techniques.

Conclusion Over the last three decades numerous attempts have been made using a variety of methods to estimate the meteoritic dust influx to the earth. Table 3 is the summary of the estimates discussed here, most of which are repeatedly referred to in the literature. Clearly, there is no consensus in the literature as to what the annual influx rate is. Admittedly, no authority today would agree with Pettersson’s 1960 figure of 14,000,000 tons per year. However, there appear to be two major groupings -those chemical methods which give results in the 100,000-400,000 tons per year range or thereabouts, and those methods, particularly cumulative flux calculations based on satellite and radar data, that give results in the range 10,000-20,000 tons per year or thereabouts. There are those that would claim the satellite measurements give results that are too low because of the sensitivities of the techniques involved, whereas there are those on the other hand who would claim that the chemical methods include background dust particles and fragrnentation products. Perhaps the “safest” option is to quote the meteoritic dust influx rate as within a range. This is exactly what several authorities on this subject have done when producing textbooks. For example, Dodd76 has suggested a daily rate of between 100 and 1,000 tons, which translates into 36,500-365,000 tons per year, while Hartmann,77 who refers to Dodd, quotes an influx figure of 10,000-1 million tons per year. Hartmann’s quoted influx range certainly covers the range of estimates in Table 3, but is perhaps a little generous with the upper limit. Probably to avoid this problem and yet still cover the wide range of estimates, Henbest writing in New Scientist in 199178 declares: “Even though the grains are individually small, they are so numerous in interplanetary space that the Earth sweeps up some 100,000 tons of cosmic dust every year.79 Perhaps this is a “safe” compromise! However, on balance we would have to say that the chemical methods when reapplied to polar ice, as they were by Maurette and his colleagues, gave a flux estimate similar to that derived from satellite and radar data, but much lower than Ganapathy’s earlier chemical analysis of polar ice. Thus it would seem more realistic to conclude that the majority of the data points to an influx rate within the range 10,000-20,000 tons per year, with the outside possibility that the figure may reach 100,000 tons per year. Dust Influx to the Moon Van Till et al. suggest: “To compute a reasonable estimate for the accumulation of meteoritic dust on the moon we divide the earth’s accumulation rate of 16,000 tons per year by 16 for the moon’s smaller surface area, divide again by 2 for the moon’s smaller gravitational force, yielding an accumulation rate of about 500 tons per year on the moon.”80 However, Hartmann81 suggests a figure of 4,000 tons per year from his own published work,82 although this estimate is again calculated from the terrestrial influx rate taking into account the smaller surface area of the moon. These estimates are of course based on the assumption that the density of meteoritic dust in the area of space around the earth-moon system is fairly uniform, an assumption verified by satellite measurements. However, with the US Apollo lunar exploration missions of 1969-1972 came the opportunities to sample the lunar rocks and soils, and to make more direct measurements of the lunar meteoritic dust influx. Lunar Rocks and Soils

One of the earliest estimates based on actual moon samples was that made by Keays and his colleagues,83 who analysed for trace elements twelve lunar rock and soil samples brought back by the Apollo 11 mission. From their results they concluded that there was a meteoritic or cometary component to the samples, and that component equated to an influx rate of 2.9 x 10-9g cm-2 yr-l of carbonaceous-chondrite-like material. This equates to an influx rate of over 15,200 tons per year. However, it should be kept in mind that this estimate is based on the assumption that the meteoritic component represents an accumulation over a period of more than 1 billion years, the figure given being the anomalous quantity averaged over that time span. These workers also cautioned about making too much of this estimate because the samples were only derived from one lunar location. Within a matter of weeks, four of the six investigators published a complete review of their earlier work along with some new data.84 To obtain their new meteoritic dust influx estimate they compared the trace element contents of their lunar soil and breccia samples with the trace element contents of their lunar rock samples. The assumption then was that the soil and breccia is made up of the broken-down rocks, so that therefore any trace element differences between the rocks and soils/breccias would represent material that had been added to the soils/breccias as the rocks were mechanically broken down. Having determined the trace element content of this “extraneous component” in their soil samples, they sought to identify its source. They then assumed that the exposure time of the region (the Apollo 11 landing site or Tranquillity Base) was 3.65 billion years, so in that time the proton flux from the solar -wind would account for some 2% of this extraneous trace elements component in the soils, leaving the remaining 98% or so to be of meteoritic (to be exact, “particulate’) origin. Upon further calculation, this approximate 98% portion of the extraneous component seemed to be due to an approximate 1.9% admixture of carbonaceous-chondrite-like material (in other words, meteoritic dust of a particular type), and the quantity involved thus represented, over a 3.65 billion year history of soil formation, an average influx rate of 3.8 x 10-9gcm-2 yr-l, which translates to over 19,900 tons per year. However, they again added a note of caution because this estimate was only based on a few samples from one location. Nevertheless, within six months the principal investigators of this group were again in print publishing further results and an updated meteoritic dust influx estimate.85 By now they had obtained seven samples from the Apollo 12 landing site, which included two crystalline rock samples, four samples from core “drilled” from the lunar regolith, and a soil sample. Again, all the samples were submitted for analyses of a suite of trace elements, and by again following the procedure outlined above they estimated that for this site the extraneous component represented an admixture of about 1.7% meteoritic dust material, very similar to the soils at the Apollo 11 site. Since the trace element content of the rocks at the Apollo 12 site was similar to that at the Apollo 11 site, even though the two sites are separated by 1,400 kilometres, other considerations aside, they concluded that this

“spatial constancy of the meteoritic component suggests that the influx rate derived from our Apollo 11 data, 3.8 x 10-

9gcm-2yr-l, is a meaningful average for the entire moon.”86 So in the abstract to their paper they reported that “an average meteoritic influx rate of about 4 x 10-9 per square centimetre per year thus seems to be valid for the entire moon. ”87 This latter figure translates into an influx rate of approximately 20,900 tons per year. Ironically, this is the same dust influx rate estimate as for the earth made by Dohnanyi using satellite and radar measurement data via a cumulative flux calculation.88 As for the moon’s meteoritic dust influx, Dohnanyi estimated that using “an appropriate focusing factor of 2,” it is thus half of the earth’s influx, that is, 10,450 tons per year.89Dohnanyi defended his estimate, even though in his words it “is slightly lower than the independent estimates” of Keays, Ganapathy and their colleagues. He suggested that in view of the uncertainties involved, his estimate and theirs were “surprisingly close”. While to Dohnanyi these meteoritic dust influx estimates based on chemical studies of the lunar rocks seem very close to his estimate based primarily on satellite measurements, in reality the former are between 50% and 100% greater than the latter. This difference is significant, reasons already having been given for the higher influx estimates for the earth based on chemical analyses of deep- sea sediments compared with the same cumulative flux estimates based on satellite and radar measurements. Many of the satellite measurements were in fact made from satellites in earth orbit, and it has consequently been assumed that these measurements are automatically applicable to the moon. Fortunately, this assumption has been verified by measurements made by the Russians from their moon-orbiting satellite Luna 19, as reported by Nazarova and his colleagues.90 Those measurements plot within the field of near-earth satellite data as depicted by, for example, Hughes.91 Thus there seems no reason to doubt that the satellite measurements in general are applicable to the meteoritic dust influx to the moon. And since Nazarova et al.’s Luna 19 measurements are compatible with Hughes’ cumulative flux plot of near-earth satellite data, then Hughes, meteoritic dust influx estimate for the earth is likewise applicable to the moon, except that when the relevant focusing factor, as outlined and used by Dohnanyi,92 is taken into account we obtain a meteoritic dust influx to the moon estimate from this satellite data (via the standard cumulative flux calculation method) of half the earth’s figure, that is, about 8,000-9,000 tons per year. Lunar Microcraters

Apart from satellite measurements using various techniques and detectors to actually measure the meteoritic dust influx to the earth-moon system, the other major direct detection technique used to estimate the meteoritic dust influx to the moon has been the study of the microcraters that are found in the rocks exposed at the lunar surface. It is readily apparent that the moon’s surface has been impacted by large meteorites, given the sizes of the craters that have resulted, but craters of all sizes are found on the lunar surface right down to the micro-scale. The key factors are the impact velocities of the particles, whatever their size, and the lack of an atmosphere on the moon to slow down (or burn up) the meteorites. Consequently, provided their mass is sufficient, even the tiniest dust particles will produce microcraters on exposed rock surfaces upon impact, just as they do when impacting the windows on spacecraft (the study of microcraters on satellite windows being one of the satellite measurement techniques). Additionally, the absence of an atmosphere on the moon, combined with the absence of water on the lunar surface, has meant that chemical weathering as we experience it on the earth just does not happen on the moon. There is of course still physical erosion, again due to impacting meteorites of all sizes and masses, and due to the particles of the solar wind, but these processes have also been studied as a result of the Apollo moon landings. However, it is the microcraters in the lunar rocks that have been used to estimate the dust influx to the moon.Perhaps one of the first attempts to try and use microcraters on the moon’s surface as a means of determining the meteoritic dust influx to the moon was that of Jaffe,93 who compared pictures of the lunar surface taken by Surveyor 3 and then 31 months later by the Apollo 12 crew. The Surveyor 3 spacecraft sent thousands of television pictures of the lunar surface back to the earth between April 20 and May 3, 1967, and subsequently on November 20, 1969 the Apollo 12 astronauts visited the same site and took pictures with a hand camera. Apart from the obvious signs of disturbance of the surface dust by the astronauts, Jaffe found only one definite change in the surface. On the bottom of an imprint made by one of the Surveyor footpads when it bounced on landing, all of the pertinent Apollo pictures showed a particle about 2mm in diameter that did not appear in any of the Surveyor pictures. After careful analysis he concluded that the particle was in place subsequent to the Surveyor picture-taking. Furthermore, because of the resolution of the pictures any crater as large as 1.5mm in diameter should have been visible in the Apollo pictures. Two pits were noted along with other particles, but as they appeared on both photographs they must have been produced at the time of the Surveyor landing. Thus Jaffe concluded that no meteorite craters as large as 1.5 mm in diameter appeared on the bottom of the imprint, 20cm in diameter, during those 31 months, so therefore the rate of meteorite impact was less than 1 particle per square metre per month. This corresponds to a flux of 4 x 10-7 particles m-2sec-1 of particles with a mass of 3 x 10-8g, a rate near the lower limit of meteoritic dust influx derived from spacecraft measurements, and many orders of magnitude lower than some previous estimates. He concluded that the absence of detectable craters in the imprint of the Surveyor 3 footpad implied a very low meteoritic dust influx onto the lunar surface.With the sampling of the lunar surface carried out by the Apollo astronauts and the return of rock samples to the earth, much attention focused on the presence of numerous microcraters on exposed rock surfaces as another means of calculating the meteoritic dust influx. These microcraters range in diameter from less than 1 micron to more than 1 cm, and their ubiquitous presence on exposed lunar rock sur- faces suggests that microcratering has affected literally every square centimetre of the lunar surface. However, in order to translate quantified descriptive data on microcraters into data on interplanetary dust particles and their influx rate, a calibration has to be made between the lunar microcrater diameters and the masses of the particles that must have impacted to form the craters. Hartung et al.94 suggest that several approaches using the results of laboratory

cratering experiments are possible, but narrowed their choice to two of these approaches based on microparticle accelerator experiments. Because the crater diameter for any given particle diameter increases proportionally with increasing impact velocity, the calibration procedure employs a constant impact velocity which is chosen as 20km/sec. Furthermore, that figure is chosen because the velocity distribution of interplanetary dust or meteoroids based on visual and radar meteors is bounded by the earth and the solar system escape velocities, and has a maximum at about 20km/sec, which thus conventionally is considered to be the mean velocity for meteoroids. Particles impacting the moon may have a minimum velocity of 2.4km/sec, the lunar escape velocity, but the mean is expected to remain near 20km/sec because of the relatively low effective crosssection of the moon for slower particles. Inflight velocity measurements of micron-sized meteoroids are generally consistent with this distribution. So using a constant impact velocity of 20km/sec gives a calibration relationship between the diameters of the impacting particles and the diameters of the microcraters. Assuming a density of 3g/cm3 allows this calibration relationship to be between the diameters of the microcraters and the masses of the impacting particles.After determining the relative masses of micrometeoroids, their flux on the lunar surface may then be obtained by correlating the areal density of microcraters on rock surfaces with surface exposure times for

those sample rocks. In other words, in order to convert crater populations on a given sample into the interplanetary dust flux the sample’s residence time at the lunar surface must be known.95 These residence times at the lunar surface, or surface exposure times, have been determined either by Cosmogenic Al26 radioactivity measurements or by cosmic ray track density measurements,96 or more often by solar-flare particle track density measurements.97On this basis Hartung et al.98 concluded that an average minimum flux of particles 25 micrograms and larger is 2.5 x 10-6 particles per cm2 per year on the lunar surface supposedly over the last 1 million years, and that a minimum cumulative flux curve over the range of masses 10-12 - 10-4g based on lunar data alone is about an order of magnitude less than independently derived present-day flux data from satellite-borne detector experiments. Furthermore, they found that particles of masses 10-7 - 10-4g are the dominant contributors to the cross-sectional area of interplanetary dust particles, and that these particles are largely responsible for the exposure of fresh lunar rock surfaces by superposition of microcraters. Also, they suggested that the overwhelming majority of all energy deposited at the surface of the moon by impact is delivered by particles 10 -6 - 10-2g in mass.A large number of other studies have been done on microcraters on lunar surface rock samples and from them calculations to estimate the meteoritic dust (micrometeoroid) influx to the moon. For example, Fechtig et al. investigated in detail a 2cm2 portion of a particular sample using optical and scanning electron microscope (SEM) techniques. Microcraters were measured and counted optically, the results being plotted to show the relationship between microcrater diameters and the cumulative crater frequency. Like other investigators, they found that in all large microcraters 100-200 microns in diameter there were on average one or two “small” microcraters about 1 micron in diameter within them, while in all “larger” microcraters (200-1,000 microns in diameter), of which there are many on almost all lunar rocks, there are large numbers of these “smaller” microcraters. The counting of these “small” microcraters within the “larger” microcraters was found to be statistically significant in estimating the overall microcratering rate and the distribution of particle sizes and masses that have produced the microcraters, because, assuming an unchanging impacting particle size or energy distribution with time, they argued that an equal probability exists for the case when a large crater superimposes itself upon a small crater, thus making its observation impossible, and the case when a small crater superimposes itself upon a larger crater, thus enabling the observation of the small crater. In other words, during the random cratering process, on the average, for each small crater observable within a larger microcrater, there must have existed one small microcrater rendered unobservable by the subsequent formation of the larger microcrater. Thus they reasoned it is necessary to correct the number of observed small craters upwards to account for this effect. Using a correction factor of two they found that their resultant microcrater size distribution plot agreed satisfactorily with that found in another sample by Schneider et al.100 Their measuring and counting of microcraters on other samples also yielded size distributions similar to those reported by other investigators on other samples.Fechtig et al. also conducted their own laboratory simulation experiments to calibrate microcrater size with impacting particle size, mass and energy. Once the cumulative microcrater number for a given area was calculated from this information, the cumulative meteoroid flux per second for this given area was easily calculated by again dividing the cumulative microcrater number by the exposure ages of the samples, previously determined by means of solar-flare track density measurements. Thus they calculated a cumulative meteoroid flux on the moon of 4 (±3) x 10-5 particles m-2 sec-1, which they suggested is fairly consistent with in situ satellite measurements. Their plot comparing micrometeoroid fluxes derived from lunar microcrater measurements with those attained from various satellite experiments (that is, the cumulative number of particles per square metre per second across the range of particle masses) is reproduced in Figure 5.Mandeville101 followed a similar procedure in studying the microcraters in a breccia sample collected at the Apollo 15 landing site. Crater numbers were counted and diameters measured. Calibration curves were experimentally derived to relate impact velocity and microcrater diameter, plus impacting particle mass and microcrater diameter. The low solar-flare track density suggested a short and recent exposure time, as did the low density of microcraters. Consequently, in their calculating of the cumulative micrometeoroid flux they assumed a 3,000-year exposure time because of this measured solar-flare track density and the assumed solar-track production rate. The resultant cumulative particle flux was 1.4 x 10-5 particles per square metre per second for particles greater than 2.5 x 10-10g at an impact velocity of 20km/sec, a value which again appears to be in close agreement with flux values obtained by satellite measurements, but at the lower end of the cumulative flux curve

calculated from microcraters by Fechtig et al. Figure 5. Comparison of

micrometeoroid fluxes derived from lunar microcrater measurements (cross-hatched and labelled “MOON’) with those obtained in various satellite in situ experiments (adapted from Fechtig et al.99) The range of masses/sizes has been subdivided into dust and meteors. Unresolved Problems Schneider et al.102 also followed the same procedure in looking at microcraters on Apollo 15 and 16, and Luna 16 samples. After counting and measuring microcraters and calibration experiments, they used both optical and scanning electron microscopy to determine solar-flare track densities and derive solar-flare exposure ages. They plotted their resultant cumulative meteoritic dust flux on a flux versus mass diagram, such as Figure 5, rather

than quantifying it. However, their cumulative flux curve is close to the results of other investigators, such as Hartung et al.103Nevertheless, they did raise some serious questions about the microcrater data and the derivation of it, because they found that flux values based on lunar microcrater studies are generally less than those based on direct measurements made by satellite-borne detectors, which is evident on Figure 5 also. They found that this discrepancy is not readily resolved but may be due to one or more factors. First on their list of factors was a possible systematic error existing in the solar-flare track method, perhaps related to our present-day knowledge of the solar-flare particle flux. Indeed, because of uncertainties in applying the solar-flare flux derived from solar-flare track records in time-control led situations such as the Surveyor 3 spacecraft, they concluded that these implied their solar-flare exposure ages were systematically too low by a

factor of between two and three. Ironically, this would imply that the calculated cumulative dust flux from the microcraters is systematically too high by the same factor, which would mean that there would then be an even greater discrepancy between flux values from lunar microcrater studies and the direct measurements made by the satellite-borne detectors. However, they suggested that part of this systematic difference may be because the satellite-borne detectors record an enhanced flux due to particles ejected from the lunar surface by impacting meteorites of all sizes. In any case, they argued that some of this systematic difference may be related to the calibration of the lunar microcraters and the satellite-borne detectors. Furthermore, because we can only measure the present flux, for example by satellite detectors, it may in fact be higher than the long-term average, which they suggest is what is being derived from the lunar microcrater data. Morrison and Zinner104 also raised questions regarding solar-flare track density measurements and derived exposure ages. They were studying samples from the Apollo 17 landing area and counted and measured microraters on rock sample surfaces whose original orientation on the lunar surface was known, so that their exposure histories could be determined to test any directional variations in both the micrometeoroid flux and solar-flare particles. Once measured, they compared their solar-flare track density versus depth profiles against those determined by other investigators on other samples and found differences in the steepnesses of the curves, as well as their relative positions with respect to the track density and depth values. They found that differences in the steepnesses of the curves did not correlate with differences in supposed exposure ages, and thus although they couldn’t exclude these real differences in slopes reflecting variations in the activity of the sun, it was more probable that these differences arose from variations in observational techniques, uncertainties in depth measurements, erosion, dust cover on the samples, and/or the precise lunar surface exposure geometry of the different samples measured. They then suggested that the weight of the evidence appeared to favour those curves (track density versus depth profiles) with the flatter slopes, although such a conclusion could be seriously questioned as those profiles with the flatter slopes do not match the Surveyor 3 profile data even by their own admission.,Rather than calculating a single cumulative flux figure, Morrison and Zinner treated the smaller microcraters separately from the larger microcraters, quoting flux rates of approximately 900 0.1 micron diameter craters per square centimetre per year and approximately 10 -15 x 10-6 500 micron diameter or greater craters per square centimetre per year. They found that these rates were independent of the pointing direction of the exposed rock surface relative to the lunar sky and thus this reflected no variation in the micrometeorite flux directionally. These rates also appeared to be independent of the supposed exposure times of the samples. They also suggested that the ratio of microcrater numbers to solar-flare particle track densities would make a convenient measure for comparing flux results of different laboratories/investigators and varying sampling situations. Comparing such ratios from their data with those of other investigations showed that some other investigators had ratios lower than theirs by a factor of as much as 50, which can only raise serious questions about whether the microcrater data are really an accurate measure of meteoritic dust influx to the moon. However, it can’t be the microcraters themselves that are the problem, but rather the underlying assumptions involved in the determination/estimation of the supposed ages of the rocks and their exposure times.Another relevant study is that made by Cour-Palais,105 who examined the heat-shield windows of the command modules of the Apollo 7 - 17 (excluding Apollo 11) spacecrafts for meteoroid impacts as a means of estimating the interplanetary dust flux. As part of the study he also compared his results with data obtained from the Surveyor 3 lunar-lander’s TV shroud. In each case, the length of exposure time was known, which removed the uncertainty and assumptions that are inherent in estimation of exposure times in the study of microcraters on lunar rock samples. Furthermore, results from the Apollo spacecrafts represented planetary space measurements very similar to the satellite-borne detector techniques, whereas the Surveyor 3 TV shroud represented a lunar surface detector. In all, Cour-Palais found a total of 10 micrometeoroid craters of various diameters on the windows of the Apollo spacecrafts. Calibration tests were conducted by impacting these windows with microparticles for various diameters and masses, and the results were used to plot a calibration curve between the diameters of the micrometeoroid craters and the estimated masses of the impacting micrometeoroids. Because the Apollo spacecrafts had variously spent time in earth orbit, and some in lunar orbit also, as well as transit time in interplanetary space between the earth and the moon, correction factors had to be applied so that the Apollo window data could be taken as a whole to represent measurements in interplanetary space. He likewise applied a modification factor to the Surveyor 3 TV shroud results so that with the Apollo data the resultant cumulative mass flux distribution could be compared to results obtained from satellite-borne detector systems, with which they proved to be in good agreement.He concluded that the results represent an average micrometeoroid flux as it exists at the present time away from the earth’s gravitational sphere of influence for masses < l0-7g. However, he noted that the satellite-borne detector measurements which represent the current flux of dust are an order of magnitude higher than the flux supposedly recorded by the lunar microcraters, a record which is interpreted as the “prehistoric” flux. On the other hand he, corrected the Surveyor 3 results to discount the moon’s gravitational effect and bring them into line with the interplanetary dust flux measurements made

by satellite- borne detectors. But if the Surveyor 3 results are taken to represent the flux at the lunar surface then that flux is currently an order of magnitude lower than the flux recorded by the Apollo spacecrafts in interplanetary space. In any case, the number of impact craters measured on these respective spacecrafts is so small that one wonders how statistically representative these results are. Indeed, given the size of the satellite-borne detector systems, one could argue likewise as to how representative of the vastness of interplanetary space are these detector results. Figure 6. Cumulative fluxes (numbers of

micrometeoroids with mass greater than the given mass which will impact every second on a square metre of exposed surface one astronomical unit from the sun) derived from satellite and lunar microcrater data (adapted from Hughes106).

Others had been noticing this disparity between the lunar microcrater data and the satellite data. For example, Hughes reported that this disparity had been known “for many years’.106 His diagram to illustrate this disparity is shown here as Figure 6. He highlighted a number of areas where he saw there were problems in these techniques for measuring micrometeoroid influx. For example, he reported that new evidence suggested that the meteoroid impact velocity was about 5km/sec rather than the 20km/ sec that had hithertofore been assumed. He suggested that taking this into account would only move the curves in Figure 6 to the right by factors varying with the velocity dependence of microphone response and penetration hole size (for the satellite-borne detectors) and crater diameter (the lunar microcraters), but because these effects are only functions of meteoroid momentum or kinetic energy their use in adjusting the data is still not sufficient to bring the curves in Figure 6 together (that is, to overcome this disparity between the two sets of data). Furthermore, with respect to the lunar microcrater data, Hughes pointed out that two other assumptions, namely, the ratio of the diameter of the microcrater to the diameter of the impacting particle being fairly constant at two, and the density of the particle being 3g per cm3, needed to be reconsidered in the light of laboratory experiments which had shown the ratio decreases with particle density and particle density varies with mass. He suggested that both these factors make the interpretation of microcraters more difficult, but that “the main problem” lies in estimating the time the rocks under consideration have remained exposed on the lunar surface. Indeed, he pointed to the assumption that solar activity has remained constant in the past, the key assumption required for calculation of an exposure age, as “the real stumbling block” - the particle flux could have been lower in the past or the solar-flare flux could have been higher. He suggested that because laboratory simulation indicates that solarwind sputter erosion is the dominant factor determining microcrater lifetimes, then knowing this enables the micrometeoroid influx to be derived by only considering rock surfaces with an equilibrium distribution of microcraters. He concluded that this line of research indicated that the micrometeoroid influx had supposedly increased by a factor of four in the last 100,000 years and that this would account for the disparity between the lunar microcrater data and the satellite data as shown by the separation of the two curves in Figure 6. However, this “solution”, according to Hughes, “creates the question of why this flux has increased” a problem which

appears to remain unsolved.In a paper reviewing the lunar microcrater data and the lunar micrometeoroid flux estimates, Hörz et al.107 discuss some key issues that arise from their detailed summary of micrometeoroid fluxes derived by various investigators from lunar sample analyses. First, the directional distribution of micrometeoroids is extremely non-uniform, the meteoroid flux differing by about three orders of magnitude between the direction of the earth’s apex and anti-apex. Since the moon may only collect particles greater than 1012g predominantly from only the apex direction, fluxes derived from lunar microcrater statistics, they suggest, may have to be increased by as much as a factor of p for comparison with satellite data that were taken in the apex direction. On the other hand, apex-pointing satellite data generally have been corrected upward because of an assumed isotropic flux, so the actual anisotropy has led to an overestimation of the flux, thus making the satellite results seem to represent an upper limit for the flux. Second, the micrometeoroids coming in at the apex direction appear to have an average impact velocity of only 8km/sec, whereas the fluxes calculated from lunar microcraters assume a standard impact velocity of 20km/sec. If as a result corrections are made, then the projectile mass necessary to produce any given microcrater will increase, and thus the moon-based flux for masses greater than 10-10g will effectively be enhanced by a factor of approximately 5. Third, particles of mass less than 10 -12g generally appear to have relative velocities of at least 50km/sec, whereas lunar flux curves for these masses are based again on a 20km/sec impact velocity. So again, if appropriate corrections are made the lunar cumulative micrometeoroid flux curve would shift towards smaller masses by a factor of possibly as much as 10. Nevertheless, Hörz et al. conclude that “as a consequence the fluxes derived from lunar crater statistics agree within the order of magnitude with direct satellite results if the above uncertainties in velocity and directional distribution are considered.” Although these comments appeared in a review paper published in 1975, the footnote on the first page signifies that the paper was presented at a scientific meeting in 1973, the same meeting at which three of those investigators also presented another paper in which they made some further pertinent comments. Both there and in a previous paper, Gault,

Hörz and Hartung108,109 had presented what they considered was a “best” estimate of the cumulative meteoritic dust flux based on their own interpretation of the most reliable satellite measurements. This “best” estimate they expressed mathematically in the form N=l.45m-0.47 l0-13<m<l0-7, N=9.l4 x l0-6m-l.213 l0-7<m<l03. Figure 7. The micrometeoroid flux

measurements from spacecraft experiments which were selected to define the mass-flux distribution (adapted from Gault et al.109) Also shown is the incremental mass flux contained within each decade of m, which sum to approximately 10,000 tonnes per year. Their data sources used are listed in their bibliography. They commented that the use of two such exponential expressions with the resultant discontinuity is an artificial representation for the flux and not intended to represent a real discontinuity, being used for mathematical simplicity and for convenience in computational procedures. They also plotted this cumulative flux presented by these two exponential expressions, together with the incremental mass flux in each decade of particle mass, and that plot is reproduced here as Figure 7. Note that their flux curve is based on what they regard as the most reliable satellite measurements. Note also, as they did, that the fluxes

derived from lunar rocks (the microcrater data) “are not necessarily directly comparable with the current satellite or photographic meteor data.” 110 However, using their cumulative flux curve as depicted in Figure 7, and their histogram plot of incremental mass flux, it is possible to estimate (for example, by adding up each incremental mass flux) the cumulative mass flux, which comes to approximately 2 x 10-9gcm-2yr-1 or about 10,000 tons per year. This is the same estimate that they noted in their concluding remarks:- “We note that the mass of material contributing to any enhancement, which the earth-moon system is currently sweeping up, is of the order of 1010g per year.”111

Having derived this “best” estimate flux from their mathematical modelling of the “most reliable satellite measurements’ their later comments in the same paper seem rather contradictory:- “If we follow this line of reasoning, the basic problem then reduces to consideration of the validity of the ‘best’ estimate flux, a question not unfamiliar to the subject of micrometeoroids and a question not with- out considerable historical controversy. We will note here only that whereas it is plausible to believe that a given set of data from a given satellite may be in error for any number of reasons, we find the degree of correlation between the various spacecraft experiments used to define the ‘best’ flux very convincing, especially when consideration is given to the different techniques employed to detect and measure the flux. Moreover, it must be remembered that the abrasion rates, affected primarily by microgram masses, depend almost exclusively on the satellite data while the rupture times, affected only by milligram masses, depend exclusively on the photographic meteor determinations of masses. It is extremely awkward to explain how these fluxes from two totally different and independent techniques could be so similarly in error. But if, in fact, they are in error then they err by being too high, and the fluxes derived from lunar rocks are a more accurate description of the current near- earth micrometeoroid flux.”(emphasis theirs )112 One is left wondering how they can on the one hand emphasise the lunar microcrater data as being a more accurate description of the current micrometeoroid flux, when they based their “best” estimate of that flux on the “most reliable satellite measurements”. However, their concluding remarks are rather telling. The reason, of course, why the lunar

microcrater data is given such emphasis is because it is believed to represent a record of the integrated cumulative flux over the moon’s billions-of- years history, which would at face value appear to be a more statistically reliable estimate than brief point-in-space satellite-borne detector measurements. Nevertheless, they are left with this unresolved discrepancy between the microcrater data and the satellite measurements, as has already been noted. So they explain the microcrater data as presenting the “prehistoric” flux, the fluxes derived from the lunar rocks being based on exposure ages derived from solar- flare track density measurements and assumptions regarding solar-flare activity in the past. As for the lunar microcrater data used by Gault et al., they state that the derived fluxes are based on exposure ages in the range 2,500 - 700,000 years, which leaves them with a rather telling enigma. If the current flux as indicated by the satellite measurements is an order of magnitude higher than the microcrater data representing a “prehistoric” flux, then the flux of meteoritic dust has had to have increased or been enhanced in the recent past. But they have to admit that “if these ages are accepted at face value, a factor of 10 enhancement integrated into the long term average limits the onset and duration of enhancement to the past few tens of years.” They note that of course there are uncertainties in both the exposure ages and the magnitude of an enhancement, but the real question is the source of this enhanced flux of particles, a question they leave unanswered and a problem they pose as the subject for future investigation. On the other hand, if the exposure ages were not accepted, being too long, then the microcrater data could easily be reconciled with the “more reliable satellite measurements”. Other Techniques Only two other micrometeoroid and meteor influx measuring techniques appear to have been tried. One of these was the Apollo 17 Lunar Ejecta and Micrometeorite Experiment, a device deployed by the Apollo 17 crew which was specifically designed to detect micrometeorites.113 It consisted of a box containing monitoring equipment with its outside cover being sensitive to impacting dust particles. Evidently, it was capable not only of counting dust particles, but also of measuring their masses and velocities, the objective being to establish some firm limits on the numbers of microparticles in a given size range which strike the lunar surface every year. However, the results do not seem to have added to the large database already established by microcrater investigations.

The other direct measurement technique used was the Passive Seismic Experiment in which a seismograph was deployed by the Apollo astronauts and left to register subsequent impact events.114 In this case, however, the particle sizes and masses were in the gram to kilogram range of meteorites that impacted the moon’s surface with sufficient force to cause the vibrations to be recorded by the seismograph. Between 70 and 150 meteorite impacts per year were recorded, with masses in the range 100g to 1,000 kg, implying a flux rate of log N = -1.62 -1.16 log m, where N is the number of bodies that impact the lunar surface per square kilometre per year, with masses greater than m grams.115 This flux works out to be about one order of magnitude less than the average integrated flux from microcrater data. However, the data collected by this experiment have been used to cover that particle mass range in the development of cumulative

flux curves (for example, see Figure 2 again) and the resultant cumulative mass flux estimates. Figure 8. Constraints on the flux of micrometeoroids and larger objects according to a variety of independent lunar

studies (adapted from Hörz et al.107) Conclusion Hörz et al. summarised some of the basic constraints derived from a variety of independent lunar studies on the lunar flux of micrometeoroids and larger objects.116 They also plotted the broad range of cumulative flux curves that were bounded by these constraints (see Figure 8). Included are the results of the Passive Seismic Experiment and the direct measurements of micrometeoroids encountered by spacecraft windows. They suggested that an upper limit on the flux can be derived from the mare cratering rate and from erosion rates on lunar rocks and other cratering data. Likewise, the negative findings on the Surveyor 3 camera lens and the perfect preservation of the footpad print of the Surveyor 3 1anding gear (both referred to above) also define an upper limit. On the other hand, the lower limit results from the study of solar and galactic radiation tracks in lunar soils, where it is believed the regolith has been reworked only by micrometeoroids, so because of presumed old undisturbed residence times the flux could not have been significantly lower than that indicated. The “geochemical”, evidence is also based on studies of the lunar soils where the abundance of trace elements are indicative of the type and amount of meteoritic contamination. Hörz et al. suggest that strictly, only the passive seismometer, the Apollo windows and the mare craters yield a cumulative mass distribution. All other parameters are either a bulk measure of a meteoroid mass or energy, the corresponding “flux” being calculated via the differential mass-distribution obtained from lunar microcrater investigations (‘lunar rocks , on Figure 8). Thus the corresponding arrows on Figure 8 may be shifted anywhere along the lines defining the “upper” and “lower” limits. On the other hand, they point out that the Surveyor 3 camera lens and footpad analyses define points only.

Scientist(s) (year)

Technique Influx Estimate (tons/year)

Hartmann (1983)

Calculated from estimates of influx to the earth 4,000

Keays et al. (1970) Geochemistry of lunar soil and rocks 15,200

Ganapathy et al. (1970) Geochemistry of lunar soil and rocks 19,900

Dohnanyi (1971,1972) Calculated from satellite, radar data 10,450

Nazarova et al. (1973) Lunar orbit satellite data 8,000 - 9,000

by comparison with Hughes (1975) Calculated from satellite, radar data (4,000 - 15,000)

Gault, et al. (1972, 1973)

Combination of lunar microcrater and satellite data 10,000

Table 4. Summary of the lunar meteoritic dust influx estimates.

Table 4 summarises the different lunar meteoritic dust estimates. It is difficult to estimate a cumulative mass flux from Hörz et al.’s diagram showing the basic constraints for the flux of micrometeoroids and larger objects derived from independent lunar studies (see Figure 8), because the units on the cumulative flux axis are markedly different to the units on the same axis of the cumulative flux and cumulative mass diagram of Gault et al. from which they estimated a lunar meteoritic dust influx of about 10,000 tons per year. The Hörz et al. basic constraints diagram seems to have been partly

constructed from the previous figure in their paper, which however includes some of the microcrater data used by Gault et al. in their diagram (Figure 7 here) and from which the cumulative mass flux calculation gave a flux estimate of 10,000 tons per year. Assuming then that the basic differences in the units used on the two cumulative flux diagrams (Figures 7 and 8 here) are merely a matter of the relative numbers in the two log scales, then the Gault et al. cumulative flux curve should fall within a band between the upper and lower limits, that is, within the basic constraints, of Hörz et al.’s lunar cumulative flux summary plot (Figure 8 here). Thus a flux estimate from Hörz et al.’s broad lunar cumulative flux curve would still probably centre around the 10,000 tons per year estimate of Gault et al. In conclusion, therefore, on balance the evidence points to a lunar meteoritic dust influx figure of around 10,000 tons per year. This seems to be a reasonable, approximate estimate that can be derived from the work of Hörz et al., who place constraints on the lunar cumulative flux by carefully drawing on a wide range of data from various techniques. Even so, as we have seen, Gault et al. question some of the underlying assumptions of the major measurement techniques from which they drew their data - in particular, the lunar microcrater data and the satellite measurement data. Like the “geochemical” estimates, the microcrater data depends on uniformitarian age assumptions, including the solar-flare rate, and in common with the satellite data, uniformitarian assumptions regarding the continuing level of dust in interplanetary space and as influx to the moon. Claims are made about variations in the cumulative dust influx in the past, but these also depend upon uniformitarian age assumptions and thus the argument could be deemed circular. Nevertheless, questions of sampling statistics and representativeness aside, the figure of approximately 10,000 tons per year has been stoutly defended in the literature based primarily on present-day satellite-borne detector measurements. Finally, one is left rather perplexed by the estimate of the moon’s accumulation rate of about 500 tons per year made by Van Till et al.117 In their treatment of the “moon dust controversy”, they are rather scathing in their comments about

creationists and their handling of the available data in the literature. For example, they state: “The failure to take into account the published data pertinent to the topic being discussed is a clear failure to live up to the codes of thoroughness and integrity that ought to characterize professional science.”118 And again: “The continuing publication of those claims by young- earth advocates constitutes an intolerable violation of the standards of professional integrity that should characterize the work of natural scientists.”119

Having been prepared to make such scathing comments, one would have expected that Van Till and his colleagues would have been more careful with their own handling of the scientific literature that they purport to have carefully scanned. Not so, because they failed to check their own calculation of 500 tons per year for lunar dust influx with those estimates that we have seen in the same literature which were based on some of the same satellite measurements that Van Till et al. did consult, plus the microcrater data which they didn’t. But that is not all - they failed to check the factors they used for calculating their lunar accumulation rate from the terrestrial figure they had established from the literature. If they had consulted, for example, Dohnanyi, as we have already seen, they would have realised that they only needed to use a focusing factor of two, the moon’s smaller surface area apparently being largely irrelevant. So much for lack of thoroughness! Had they surveyed the literature thoroughly, then they would have to agree with the conclusion here that the dust influx to the moon is approximately 10,000 tons per year. Pre-Apollo Lunar Dust Thickness Estimates

The second major question to be addressed is whether NASA really expected to find a thick dust layer on the moon when their astronauts landed on July 20, 1969. Many have asserted that because of meteoritic dust influx estimates made by Pettersson and others prior to the Apollo moon landings, that NASA was cautious in case there really was a thick dust layer into which their lunar lander and astronauts might sink. Early Speculations

Asimov is certainly one authority at the time who is often quoted. Using the 14,300,000 tons of dust per year estimate of Pettersson, Asimov made his own dust on the moon calculation and commented: “But what about the moon? It travels through spacewith us and although it is smaller and has a weaker gravity, it, too, should sweep up a respectable quan tity of micrometeors. To be sure, the moon has no atmosphere to friction the micrometeors to dust, but the act of striking the moon’s surface should develop a large enough amount of heat to do the job. Now it is already known, from a variety of evidence, that the moon (or at least the level lowlands) is covered with a layer of dust. N o one, however, knows for sure how thick this dust may be. It strikes me that if this dust is the dust of falling micrometeors, the thickness may be great. On the moon there are no oceans to swallow the dust, or winds to disturb it, or life forms to mess it up generally one way or another. The dust that forms must just lie there, and if the moon gets anything like the earth’s supply, it could be dozens of feet thick. In fact, the dust that strikes craters quite probably rolls down hill and collects at the bottom, forming ‘drifts’ that could be fifty feet deep, or more. Why not? I get a picture, therefore, of the first spaceship, picking out a nice level place for landing purposes coming slowly downward tail-first … and sinking majestically out of sight.”120

Asimov certainly wasn’t the first to speculate about the thickness of dust on the moon. As early as 1897 Peal121 was speculating on how thick the dust might be on the moon given that “it is well known that on our earth there is a considerable fall of meteoric dust.” Nevertheless, he clearly expected only “an exceedingly thin coating” of dust. Several estimates of the rate at which meteorites fall to earth were published between 1930 and 1950, all based on visual observations of meteors and meteorite falls. Those estimates ranged from 26 metric tons per year to 45,000 tons per year.122 In 1956 Öpik123 estimated 25,000 tons per year of dust falling to the earth, the same year Watson124estimated a total accumulation rate of between 300,000 and 3 million tons per year, and in 1959 Whipple125 estimated 700,000 tons per year.However, it wasn’t just the matter of meteoritic dust falling to the lunar surface that concerned astronomers in their efforts to estimate the thickness of dust on the lunar surface, since the second source of pulverised material on the moon is the erosion of exposed rocks by various processes. The lunar craters are of course one of the most striking features of the moon and initially astronomers thought that volcanic activity was responsible for them, but by about 1950 most investigators were convinced that meteorite impact was the major mechanism involved.126 Such impacts pulverise large amounts of rock and scatter fragments over the lunar surface. Astronomers in the 1950s agreed that the moon’s surface was probably covered with a layer of pulverised material via this process, because radar studies were consistent with the conclusion that the lunar surface was made of fine particles, but there were no good ways to estimate its actual thickness.Yet another contributing source to the dust layer on the moon was suggested by Lyttleton in 1956,127 He suggested that since there is no atmosphere on the moon, the moon‘s surface is exposed to direct radiation, so that ultraviolet light and x-rays from the sun could slowly erode the surface of exposed lunar rocks and reduce them to dust, Once formed, he envisaged that the dust particles might be kept in motion and so slowly “flow” to lower elevations on the lunar surface where they would accumulate to form a layer of dust which he suggested might be “several miles deep”. Lyttleton wasn’t alone, since the main proponent of the thick dust view in British scientific circles was Royal Greenwich astronomer Thomas Gold, who also suggested that this loose dust covering the lunar surface could present a serious hazard to any spacecraft landing on the moon.128 Whipple, on the other hand, argued that the dust layer would be firm and compact so that humans and vehicles would have no trouble landing on and moving across the moon’s surface.129 Another British astronomer, Moore, took note of Gold’s theory that the lunar seas “were covered with layers of dust many kilometres deep” but flatly rejected this. He commented: “The disagreements are certainly very marked. At one end of the scale we have Gold and his supporters, who believe in a dusty Moon covered in places to a great depth; at the other, people such as myself, who incline to the view that the dust can be no more than a few centimetres deep at most. The only way to clear the matter up once and for all is to send a rocket to find out.”150 So it is true that some astronomers expected to find a thick dust layer, but this was no means universally supported in the astronomical community. The Russians too were naturally interested in this question at this time because of their involvement in the “space race”, but they also had not reached a consensus on this question of the lunar dust. Sharonov,131 for example, discussed Gold’s theory and arguments for and against a thick dust layer, admitting that “this theory has become the object of animated discussion.” Nevertheless, he noted that the “majority of selenologists” favoured the plains of the lunar “seas’ (mares ) being layers of solidified lavas with minimal dust cover. Research in the Early 1960s

The lunar dust question was also on the agenda of the December 1960 Symposium number 14ofthe International Astronomical Union held at the Puikovo Observatory near Leningrad. Green summed up the arguments as follows: “Polarization studies by Wright verified that the surface of the lunar maria is covered with dust. However, various estimates of the depth of this dust layer have been proposed. In a model based on the radioastronomy techniques of Dicke and Beringer and others, a thin dust layer is assumed, Whipple assumes the covering to be less than a few meters’ thick. On the other hand, Gold, Gilvarry, and Wesselink favor a very thick dust layer. … Because no polar homogenization of lunar surface details can be demonstrated, however, the concept of a thin dust layer appears more reasonable. … Thin dust layers, thickening in topographic basins near post-mare craters, are predicted for mare areas.”132

In a 1961 monograph on the lunar surface, Fielder discussed the dust question in some detail, citing many of those who had been involved in the controversy. Having discussed the lunar mountains where he said “there may be frequent pockets of dust trapped in declivities” he concluded that the mean dust cover over the mountains would only be a

millimetre or so.133 But then he went on to say, “No measurements made so far refer purely to marebase materials. Thus, no estimates of the composition of maria have direct experimental backing. This is unfortunate, because the interesting question ‘How deep is the dust in the lunar seas?’ remains unanswered.” In 1964 a collection of research papers were published in a monograph entitled The Lunar Surface Layer, and the

consensus therein amongst the contributing authors was that there was not a thick dust layer on the moon’s surface. For example, in the introduction, Kopal stated that “this layer of loose dust must extend down to a depth of at least several centimeters, and probably a foot or so; but how much deeper it may be in certain places remains largely conjectural.”134 In a paper on “Dust Bombardment on the Lunar Surface”, McCracken and Dubin undertook a comprehensive review of the subject, including the work of Öpik and Whipple, plus many others who had since been investigating the meteoritic dust influx to the earth and moon, but concluded that “The available data on the fluxes of interplanetary dust particles with masses less than 104gm show that the material accreted by the moon during the past 4.5 billion years amounts to approximately 1 gm/cm2 if the flux has remained fairly constant.”135 (Note that this statement is based on the uniformitarian age constraints for the moon.) Thus they went on to say that “The lunar surface layer thus formed would, therefore, consist of a mixture of lunar material and interplanetary material (primarily of cometary origin) from 10cm to 1m thick. The low value for the accretion rate for the small particles is not adequate to produce large-scale dust erosion or to form deep layers of dust on the moon. …”.136 In another paper, Salisbury and Smalley state in their abstract: “It is concluded that the lunar surface is covered with a layer of rubble of highly variable thickness and block size. The rubble in turn is mantled with a layer of highly porous dust which is thin over topographic highs, but thick in depressions. The dust has a complex surface and significant, but not strong, coherence.”137 In their conclusions they made a number of predictions. “Thus, the relief of the coarse rubble layer expected in the highlands should be largely obliterated by a mantle of fine dust, no more than a few centimeters thick over near-level areas, but meters thick in steep- walled depressions. …The lunar dust layer should provide no significant difficulty for the design of vehicles and space suits. …”138 Expressing the opposing view was Hapke, who stated that “recent analyses of the thermal component of the lunar radiation indicate that large areas of the moon may be covered to depths of many meters by a substance which is ten times less dense than rock. …Such deep layers of dust would be in accord with the suggestion of Gold.”139 He went on: “Thus, if the radio-thermal analyses are correct, the possibility of large areas of the lunar surface being covered with thick deposits of dust must be given serious consideration.”140 However, the following year Hapke reported on research that had been sponsored by NASA, at a symposium on the nature of the lunar surface, and appeared to be more cautious on the dust question. In the proceedings he wrote: “I believe that the optical evidence gives very strong indications that the lunar surface is covered with a layer of fine dust of unknown thicknes.”141 There is no question that NASA was concerned about the presence of dust on the moon’s surface and its thickness. That is why they sponsored intensive research efforts in the 1960s on the questions of the lunar surface and the rate of meteoritic dust influx to the earth and the moon. In order to answer the latter question, NASA had begun sending up rockets and satellites to collect dust particles and to measure their flux in near-earth space. Results were reported at symposia, such as that which was held in August 1965 at Cambridge, Massachusetts, jointly sponsored by NASA and the Smithsonian Institution, the proceedings of which were published in 1967.142 A number of creationist authors have referred to this proceedings volume in support of the standard creationist argument that NASA scientists had found a lot of dust in space which confirmed the earlier suggestions of a high dust influx rate to the moon and thus a thick lunar surface layer of dust that would be a danger to any landing spacecraft. Slusher, for example, reported that he had been involved in an intensive review of NASA data on the matter and found “that radar, rocket, and satellite data published in 1976 by NASA and the Smithsonian Institution show that a tremendous amount of cosmic dust is present in the space around the earth and moon.”143 (Note that the date of publication was incorrectly reported as 1976, when it in fact is the 1967 volume just referred to above.) Similarly, Calais references this same 1967 proceedings volume and says of it, “NASA has published data collected by orbiting satellites which confirm a vast amount of cosmic dust reaching the vicinity of the earth-moon system.”144,145 Both these assertions, however, are far from correct, since the reports published in that proceedings volume contain results of measurements taken by detectors on board spacecraft such as Explorer XVI, Explorer XXIII, Pegasus I and Pegasus II, as well as references to the work on radio meteors by Elford and cumulative flux curves incorporating the work of people like Hawkins, Upton and Elsässer. These same satellite results and same investigators’ contributions to

cumulative flux curves appear in the 1970s papers of investigators whose cumulative flux curves have been reproduced here as Figures 3, 5 and 7, all of which support the 10,000 - 20,000 tons per year and approximately 10,000 tons per year estimates for the meteoritic dust influx to the earth and moon respectively - not the “tremendous” and “vast” amounts of

dust incorrectly inferred from this proceedings volume by Slusher and Calais. Pre-Apollo Moon Landings

The next stage in the NASA effort was to begin to directly investigate the lunar surface as a prelude to an actual manned landing. So seven Ranger spacecraft were sent up to transmit television pictures back to earth as they plummeted toward crash landings on selected flat regions near the lunar equator.146 The last three succeeded spectacularly, in 1964 and 1965, sending back thousands of detailed lunar scenes, thus increasing a thousand-fold our ability to see detail. After the first high-resolution pictures of the lunar surface were transmitted by television from the Ranger VII spacecraft in 1964, Shoemaker147 concluded that the entire lunar surface was blanketed by a layer of pulverised ejecta caused by repeated impacts and that this ejecta would range from boulder-sized rocks to finely-ground dust. After the remaining Ranger crash-landings, the Ranger investigators were agreed that a debris layer existed, although interpretations varied from virtually bare rock with only a few centimetres of debris (Kuiper, Strom and Le Poole) through to estimates of a layer from a few to tens of metres deep (Shoemaker).148 However, it can’t be implied as some have done149 that Shoemaker was referring to a dust layer that thick that was unstable enough to swallow up a landing spacecraft. After all, the consolidation

of dust and boulders sufficient to support a load has nothing to do with a layer’s thickness. In any case, Shoemaker was describing a surface layer composed of debris from meteorite impacts, the dust produced being from lunar rocks and not from falling meteoritic dust.But still the NASA planners wanted to dispel any lingering doubts before committing astronauts to a manned spacecraft landing on the lunar surface, so the soft-landing Surveyor series of spacecraft were designed and built However, the Russians just beat the Americans when they achieved the first lunar soft-landing with their Luna 9 spacecraft. Nevertheless, the first American Surveyor spacecraft successfully achieved a soft-landing in mid- 1966 and returned over 11,000 splendid photographs, which showed the moon’s surface in much greater detail than ever before.150 Between then and January 1968 four other Surveyor spacecraft were successfully landed on the lunar surface and the pictures obtained were quite remarkable in their detail and high resolution, the last in the series (Surveyor 7) returning 21,000 photographs as well as a vast amount of scientific data. But more importantly, “as each spindly, spraddle-legged craft dropped gingerly to the surface, its speed largely negated by retrorockets, its three footpads sank no more than an inch or two into the soft lunar soil. The bearing strength of the surface measured as much as five to ten pounds per square inch, ample for either astronaut or landing spacecraft.”151 Two of the Surveyors carried a soil mechanics surface sampler which was used to test the soil and any rock fragments within reach. All these tests and observations gave a consistent picture of the lunar soil. As Pasachoff noted: “It was only the soft landing of the Soviet Luna and American Surveyor spacecraft on the lunar surface in 1966 and the photographs they sent back that settled the argument over the strength of the lunar surface; the Surveyor perched on the surface without sinking in more than a few centimeters.”152152 Moore concurred, with the statement that “up to 1966 the theory of deep dust-drifts was still taken seriously in the United States and there was considerable relief when the soft-Ianding of Luna 9 showed it to be wrong.”153 Referring to Gold’s deep-dust theory of 1955, Moore went on to say that although this theory had gained a considerable degree of respectability, with the successful soft-landing of Luna 9 in 1966 “it was finally discarded.”154 So it was in May

1966 when Surveyor I landed on the moon three years before Apollo 11 that the long debate over the lunar surface dust layer was finally settled, and NASA officials then knew exactly how much dust there was on the surface and that it was capable of supporting spacecraft and men. Since this is the case, creationists cannot say or imply, as some have,155-160 that most astronomers and scientists expected a deep dust layer. Some of course did, but it is unfair if creationists only selectively refer to those few scientists who predicted a deep dust layer and ignore the majority of scientists who on equally scientific grounds had predicted only a thin dust layer. The fact that astronomy textbooks and monographs acknowledge that there was a theory about deep dust on the moon,161,162 as they should if they intend to reflect the history of the development of thought in lunar science, cannot be used to bolster a lop-sided presentation of the debate amongst scientists at the time over the dust question, particularly as these same textbooks and monographs also indicate, as has already been quoted, that the dust question was settled by the Luna and Surveyor soft-landings in 1966. Nor should creationists refer to papers like that ofWhipple,163 who wrote of a “dust cloud” around the earth, as if that were representative of the views at the time of all astronomers. Whipple’s views were easily dismissed by his colleagues because of subsequent evidence. Indeed, Whipple did not continue promoting his claim in subsequent papers, a clear indication that he had either withdrawn it or been silenced by the overwhelming response of the scientific community with evidence against it, or both. The Apollo Lunar Landing

Two further matters need to be also dealt with. First, there is the assertion that NASA built the Apollo lunar lander with large footpads because they were unsure about the dust and the safety of their spacecraft. Such a claim is, inappropriate given the success of the Surveyor soft-landings, the Apollo lunar lander having footpads which were proportionally similar to the relative sizes of the respective spacecraft. After all, it stands to reason that since the design of Surveyor spacecraft worked so well and survived landing on the lunar surface that the same basic design should be followed in the Apollo lunar lander. As for what Armstrong and Aldrin found on the lunar surface, all are agreed that they found a thin dust layer .The transcript of Armstrong’s words as he stepped onto the moon are instructive: “I am at the foot of the ladder. The LM [lunar module ] footpads are only depressed in the surface about one or two inches, although the surface appears. to be very, very fine grained, as. you get close to it. It is almost like a powder. Now and then it is very fine. I am going to step off the LM now. That is one small step for man, one giant leap for mankind.”164164 Moments later while taking his first steps on the lunar surface, he noted: “The surface is fine and powdery. I can - I can pick it up loosely with my toe. It does adhere in fine layers like powdered charcoal to the sole and sides. of my boots. I only go in a small fraction of an inch, maybe an eighth of an inch, but I can see the footprints. of my boots and the treads in the fine sandy particles.‘ And a little later, while picking up samples of rocks and fine material, he said: “This is very interesting. It is a very soft surface, but here and there where I plug with the contingency sample collector, I run into a very hard surface, but it appears to be very cohesive material of the same sort. I will try to get a rock in here. Here’s a couple.”165 So firm was the ground, that Armstrong and Aldrin had great difficulty planting the American flag into the rocky and virtually dust-free lunar surface. The fact that no further comments were made about the lunar dust by NASA or other scientists has been taken by some166-168 to represent some conspiracy of silence, hoping that some supposed unexplained problem will go away. There is a perfectly good reason why there was silence - three years earlier the dust issue had been settled and Armstrong and Aldrin only confirmed what scientists already knew about the thin dust layer on the moon. So because it wasn’t a problem just before the Apollo 11 landing, there was no need for any talk about it to continue after the successful exploration of the lunar surface. Armstrong himself may have been a little concerned about the constituency and strength of the lunar surface as he was about to step onto it, as he appears to have admitted in subsequent interviews,169 but then he was the one on the spot and about to do it, so why wouldn’t he be concerned about the dust, along with lots of other related issues. Overn’s Testimony

Finally, there is the testimony of Dr William Overn.170,171 Because he was working at the time for the Univac Division of Sperry Rand on the television sub-system for the Mariner IV spacecraft he sometimes had exchanges with the men at the Jet Propulsion Laboratory (JPL) who were working on the Apollo program. Evidently those he spoke to were assigned to the Ranger spacecraft missions which, as we have seen, were designed to find out what the lunar surface really was like; in other words, to investigate among other things whether there was a thin or thick dust layer on the lunar surface. In Bill’s own words:

“I simply told them that they should expect to find less than 10,000 years’ worth of dust when they got there. This was based on my creationist belief that the moon is young. The situation got so tense it was suggested I bet them a large amount of money about the dust. … However, when the Surveyor spacecraft later landed on the moon and discovered there was virtually no dust, that wasn’t good enough for these people to pay off their bet. They said the first landing might have been a fluke in a low dust area! So we waited until ,.,. astronauts actually landed on the moon. …”172 Neither the validity of this story nor Overn’s integrity is in question. However, it should be noted that the bet Overn made with the JPL scientists was entered into at a time when there was still much speculation about the lunar surface, the Ranger spacecraft just having been crash-landed on the moon and the Surveyor soft-landings yet to settle the dust issue. Furthermore, since these scientists involved with Overn were still apparently hesitant after the Surveyor missions, it suggests that they may not have been well acquainted with NASA’s other efforts, particularly via satellite measurements, to resolve the dust question, and that they were not “rubbing shoulders with” those scientists who were at the forefront of these investigations which culminated in the Surveyor soft-landings settling the speculations over the dust. Had they been more informed, they would not have entered into the wager with Overn, nor for that matter would they have seemingly felt embarrassed by the small amount of dust found by Armstrong and Aldrin, and thus conceded defeat in the wager. The fact remains that the perceived problem of what astronauts might face on the lunar surface was settled by NASA in 1966 by the Surveyor soft-landings. Moon Dust and the Moon’s Age

The final question to be resolved is, now that we know how much meteoritic dust falls to the moon’s surface each year, then what does our current knowledge of the lunar surface layer tell us about the moon’s age? For example, what period of time is represented by the actual layer of dust found on the moon? On the one hand creationists have been using the earlier large dust influx figures to support a young age of the moon, and on the other hand evolutionists are satisfied that the small amount of dust on the moon supports their billions-of-years moon age. The Lunar Regolith

To begin with, what makes up the lunar surface and how thick is it? The surface layer of pulverised material on the moon is now, after on-site investigations by the Apollo astronauts, not called moon dust, but lunar regolith, and the fine materials in it are sometimes referred to as the lunar soil. The regolith is usually several metres thick and extends as a continuous layer of debris draped over the entire lunar bedrock surface. The average thickness of the regolith on the maria is 4-5m, while the highlands regolith is about twice as thick, averaging about 10m.173 The seismic properties of the regolith appear to be uniform on the highlands and maria alike, but the seismic signals indicate that the regolith consists of discrete layers, rather than being simply “compacted dust”. The top surface is very loose due to stirring by micrometeorites, but the lower depths below about 20cm are strongly compacted, probably due to shaking during impacts. The complex layered nature of the regolith has been studied in drill-core samples brought back by the Apollo missions. These have clearly revealed that the regolith is not a homogeneous pile of rubble. Rather, it is a layered succession of ejecta blankets.174 An apparent paradox is that the regolith is both well mixed on a small scale and also displays a layered structure. The Apollo 15 deep core tube, for example, was 2.42 metres long, but contained 42 major textural units from a few millimetres to 13cm in thickness. It has been found that there is usually no correlation between layers in adjacent core tubes, but the individual layers are well mixed. This paradox has been resolved by recognising that the regolith is continuously “gardened” by large and small meteorites and micrometeorites. Each impact inverts much of the microstratigraphy and produces layers of ejecta, some new and some remnants of older layers. -The new surface layers are stirred by micrometeorites, but deeper stirring is rarer. The result is that a complex layered regolith is built up, but is in a continual state of flux, particles now at the surface potentially being buried deeply by future impacts. In this way, the regolith is turned over, like a heavily bombarded battlefield. However, it appears to only be the upper 0.5 - l mm of the lunar surface that is subjected to intense churning and mixing by the meteoritic influx at the present time. Nevertheless, as a whole, the regolith is a primary mixing layer of lunar materials from all points on the moon with the incoming meteoritic influx, both meteorites proper and dust.

Figure 9. Processes of erosion on the lunar surface today appear to be extremely slow compared with the processes on

the earth. Bombardment by micrometeorites is believed to be the main cause. A large meteorite strikes the surface very rarely, excavating bedrock and ejecting it over thousands of square kilometres, sometimes as long rays of material radiating from the resulting crater. Much of the meteorite itself is vaporized on impact, and larger fragments of the debris produce secondary craters. Such an event at a mare site pulverizes and churns the rubble and dust that form the regolith.

Accompanying base surges of hot clouds of dust. gas and shock waves might compact the dust into breccias. Cosmic rays continually bombard the surface. During the lunar day ions from the solar wind and unshielded solar radiation impinge on the surface. (Adapted from Eglinton et al.176) Lunar Surface Processes

So apart from the influx of the meteoritic dust, what other processes are active on the moon’s surface, particularly as there is no atmosphere or water on the moon to weather and erode rocks in the same way as they do on earth? According to Ashworth and McDonnell, “Three major processes continuously affecting the surface of the moon are meteor impact, solar wind sputtering, and thermal erosion.”175 The relative contributions of these processes towards the erosion of the lunar surface depend upon various factors, such as the dimensions and composition of impacting bodies and the rate of meteoritic impacts and dust influx, These processes of erosion on the lunar surface are of course extremely slow compared with erosion processes on the earth, Figure 9, after Eglinton et al.,176 attempts to illustrate these lunar surface erosion processes.Of these erosion processes the most important is obviously impact erosion, Since there is no atmosphere on the moon, the incoming meteoritic dust does not just gently drift down to the lunar surface, but instead strikes at an average velocity that has been estimated to be between 13 and 18 km/sec,177 or more recently as 20 km/sec,178 with a maximum reported velocity of 100 km/sec.179 Depending not ,ony on the velocity but on the mass of the impacting dust particles, more dust is produced as debris.A number of attempts have been made to quantify the amount of dust-caused erosion of bare lunar rock on the lunar surface. Hörz et al.180 suggested a rate of 0.2-0.4mm/106 year (or 20-40 x 10-9cm/yr) after examination of

micrometeorite craters on the surfaces of lunar rock samples brought back by the Apollo astronauts. McDonnell and Ashworth181 discussed the range of erosion rates over the range of particle diameters and the surface area exposed. They thus suggested that a rate of 1-3 x 10-7cm/yr (or 100-300 x 10-9cm/yr), basing this estimate on Apollo moon rocks also, plus studies of the Surveyor 3 camera. They later revised this estimate, concluding that on the scale of tens of metres impact erosion accounts for the removal of some 10-7cm/yr (or 100x 10-9cm/yr) of lunar material.182 However, in another paper, Gault et al.183 tabulated calculated abrasion rates for rocks exposed on the lunar surface compared with observed erosion rates as determined from solar-flare particle tracks. Discounting the early satellite data and just averaging the values calculated from the best, more recent satellite data and from lunar rocks, gave an erosion rate esti mate of 0.28cm/106yr (or 280 x 10-9cm/yr), while the average of the observed erosion rates they found from the literature was 0.03cm/106yr (or 30 x 10-9cm/yr). However, they naturally favoured their own “best” estimate from the satellite data of both the flux and the consequent abrasion rate, the latter being 0.1 cm/106yr (or 100 x 10-9cm/ yr), a figure identical with that ofMcDonnell and Ashworth. Gault et al. noted that this was higher, by a factor approaching an order of magnitude, than

the “consensus’ of the observed values, a discrepancy which mirrors the difference between the meteoritic dust influx estimates derived from the lunar rocks compared with the satellite data.These estimates obviously vary from one to another, but 30-100 x 10-9cm/yr would seem to represent a “middle of the range” figure. However, this impact erosion rate only applies to bare, exposed rock. As McCracken and Dubin have stated, once a surface dust layer is built up initially from the dust influx and impact erosion, this initial surface dust layer would protect the underlying bedrock surface against continued erosion by dust particle bombardment.184 If continued impact erosion is going to add to the dust and rock fragments in the surface layer and regolith, then what is needed is some mechanism to continually transport dust away from the rock surfaces as it is produced, so as to keep exposing bare rock again for continued impact erosion. Without some active transporting process, exposed rock surfaces on peaks and ridges would be worn away to give a somewhat rounded moonscape (which is what the Apollo astronauts found), and the dust would thus collect in thicker accumulations at the bottoms of slopes. This is illustrated in Figure 9.So bombardment of the lunar surface by micrometeorites is believed to be the main cause of surface erosion. At the Current rate of removal, however, it would take a million years to remove an approximately 1mm thick skin of rock from the whole lunar surface and convert it to dust. Occasionally a large meteorite strikes the surface (see Figure 9 again), excavating through the dust down into the bedrock and ejecting debris over thousands of square kilometres sometimes as long rays of material radiating from the resulting crater. Much of the meteorite itself is vaporised on impact, and larger fragments of the debris create secondary craters. Such an event at a mare site pulverises and churns the rubble and dust that forms the regolith.The solar wind is the next major contributor to lunar surface erosion. The solar wind consists primarily of protons, electrons, and some alpha particles, that are continuously being ejected by the sun. Once again, since the moon has virtually no atmosphere or magnetic field, these particles of the solar wind strike the lunar surface unimpeded at velocities averaging 600 km/sec, knocking individual atoms from rock and dust mineral lattices. Since the major components of the solar wind are H+ (hydrogen) ions, and some He (helium) and other elements, the damage upon impact to the crystalline structure of the rock silicates creates defects and voids that accommodate the gases and other elements which are simultaneously implanted in the rock surface. But individual atoms are also knocked out of the rock surface, and this is called sputtering or sputter erosion. Since the particles in the solar wind strike the lunar surface with such high velocities, “one can safely conclude that most of the sputtered atoms have ejection velocities higher than the escape velocity of the moon.”185 There would thus appear to be a net erosional mass loss from the moon to space via this sputter erosion. As for the rate of this erosional loss, Wehner186 suggested a value for the sputter rate of the order of 0.4 angstrom (Å)/yr. However, with the actual measurement of the density of the solar wind particles on the surface of the moon, and lunar rock samples available for analysis, the intensity of the solar wind used in sputter rate calculations was downgraded, and consequently the estimates of the sputter rate itself (by an order of magnitude lower). McDonnell and Ashworth187 estimated an average sputter rate of lunar rocks of about 0.02Å/yr, which they later revised to 0.02-0.04Å/yr.188 Further experimental work refined their estimate to 0.043Å/yr,189 which was reported in Nature by

Hughes.190 This figure of 0.043 Å/yr continued to be used and confirmed in subsequent experimental work,191although Zook192 suggested that the rate may be higher, even as high as 0.08Å/yr.193 Even so, if this sputter erosion rate continued at this pace in the past then it equates to less than one centimetre of lunar surface lowering in one billion years. This not only applies to solid rock, but to the dust layer itself, which would in fact decrease in thickness in that time, in opposition to the increase in thickness caused by meteoritic dust influx. Thus sputter erosion doesn’t help by adding dust to the lunar surface, and in any case it is such a slow process that the overall effect is minimal. Yet another potential form of erosion process on the lunar surface is thermal erosion, that is, the breakdown of the lunar surface around impact/crater areas due to the marked temperature changes that result from the lunar diurnal cycle. Ashworth and McDonnell194 carried out tests on lunar rocks, submitting them to cycles of changing temperature, but found it “impossible to detect any surface changes”. They therefore suggested that thermal erosion is probably “not a major force.” Similarly, McDonnell and Flavill195 conducted further experiments and found that their samples showed no sign of “degradation or enhancement” due to the temperature cycle that they had been subjected to. They reported that

“the conditions were thermally equivalent to the lunar day-night cycle and we must conclude that on this scale thermal cycling is a very weak erosion mechanism.‘ The only other possible erosion process that has ever been mentioned in the literature was that proposed by Lyttleton196 and Gold.197 They suggested that high-energy ultraviolet and x-rays from the sun would slowly pulverize lunar rock to dust, and over millions of years this would create an enormous thickness of dust on the lunar surface. This was proposed in the 1950s and debated at the time, but since the direct investigations of the moon from the mid- 1960s onwards, no further mention of this potential process has appeared in the technical literature, either for the idea or against it. One can only assume that either the idea has been ignored or forgotten, or is simply ineffective in producing any significant erosion, contrary to the suggestions of the original proposers. The latter is probably true, since just as with impact erosion the effect of this radiation erosion would be subject to the critical necessity of a mechanism to clean rock surfaces of the dust produced by the radiation erosion. In any case, even a thin dust layer will more than likely simply absorb the incoming rays, while the fact that there are still exposed rock surfaces on the moon clearly suggests that Lyttleton and Gold’s radiation erosion process has not been effective over the presumed millions of years, else all rock surfaces should long since have been pulverized to dust. Alternately, of course, the fact that there are still exposed rock surfaces on the moon could instead mean that if this radiation erosion process does occur then the moon is quite young. “Age” Considerations

So how much dust is there on the lunar surface? Because of their apparent negligible or non-existent contribution, it may be safe to ignore thermal, sputter and radiation erosion. This leaves the meteoritic dust influx itself and the dust it generates when it hits bare rock on the lunar surface (impact erosion). However, our primary objective is to determine whether the amount of meteoritic dust in the lunar regolith and surface dust layer, when compared to the current meteoritic dust influx rate, is an accurate indication of the age of the moon itself, and by implication the earth and the solar system also.Now we concluded earlier that the consensus from all the available evidence, and estimate techniques employed by different scientists, is that the meteoritic dust influx to the lunar surface is about 10,000 tons per year or 2x10-9g cm-2yr-1. Estimates of the density of micrometeorites vary widely, but an average value of 19/cm3 is commonly used. Thus at this apparent rate of dust influx it would take about a billion years for a dust layer a mere 2cm thick to accumulate over the lunar surface. Now the Apollo astronauts apparently reported a surface dust layer of between less than 1/8 inch (3mm)and 3 inches (7.6cm). Thus, if this surface dust layer were composed only of meteoritic dust, then at the current rate of dust influx this surface dust layer would have accumulated over a period of between 150 million years (3mm) and 3.8 billion years (7.6cm). Obviously, this line of reasoning cannot be used as an argument for a young age for the moon and therefore the solar system.However, as we have already seen, below the thin surface dust layer is the lunar regolith, which is up to 5 metres thick across the lunar maria and averages 10 metres thick in the lunar highlands. Evidently, the thin surface dust layer is very loose due to stirring by impacting meteoritic dust (micrometeorites), but the regolith beneath which consists of rock rubble of all sizes down to fines (that are referred to as lunar soil) is strongly compacted. Nevertheless, the regolith appears to be continuously “gardened” by large and small meteorites and micrometeorites, particles now at the surface potentially being buried deeply by future impacts. This of course means then that as the regolith is turned over meteoritic dust particles in the thin surface layer will after some time end up being mixed into the lunar soil in the regolith below. Therefore, also, it cannot be assumed that the thin loose surface layer is entirely composed of meteoritic dust, since lunar soil is also brought up into this loose surface layer by impacts.However, attempts have been made to estimate the proportion of meteoritic material mixed into the regolith. Taylor198 reported that the meteoritic compositions recognised in the maria soils turn out to be surprisingly uniform at about 1.5% and that the abundance patterns are close to those for primitive unfractionated Type I carbonaceous chondrites. As described earlier, this meteoritic component was identified by analysing for trace elements in the broken-down rocks and soils in the regolith and then assuming that any trace element differences represented the meteoritic material added to the soils. Taylor also adds that the compositions of other meteorites, the ordinary chondrites, the iron meteorites and the stony-irons, do not appear to be present in the lunar regolith, which may have some significance as to the origin of this meteoritic material, most of which is attributed to the influx of micrometeorites. It is unknown what the large crater-forming meteorites

contribute to the regolith, but Taylor suggests possibly as much as 10% of the total regolith. Additionally, a further source of exotic elements is the solar wind, which is estimated to contribute between 3% and 4% to the soil. This means that the total contribution to the regolith from extra-lunar sources is around 15%. Thus in a five metre thick regolith over the maria, the thickness of the meteoritic component would be close to 60cm, which at the current estimated meteoritic influx rate would have taken almost 30 billion years to accumulate, a timespan six times the claimed evolutionary age of the moon. The lunar surface is heavily cratered, the largest crater having a diameter of 295kms. The highland areas are much more heavily cratered than the maria, which suggested to early investigators that the lunar highland areas might represent the oldest exposed rocks on the lunar surface. This has been confirmed by radiometric dating of rock samples brought back by the Apollo astronauts, so that a detailed lunar stratigraphy and evolutionary geochronological framework has been constructed. This has led to the conclusion that early in its history the moon suffered intense bombardment from scores of meteorites, so that all highland areas

presumed to be older than 3.9 billion years have been found to be saturated with craters 50-100 km in diameter, and beneath the 10 metre-thick regolith is a zone of breccia and fractured bedrock estimated in places to be more than 1 km thick.199 Figure 10. Cratering history of the moon (adapted from Taylor200). An aeon represents a billion years on the evolutionists’

time scale, while the vertical bar represents the error margin in the estimation of the cratering rate at each data point on the curve. Following suitable calibration, a relative crater chronology has been established, which then allows for the cratering rate through lunar history to be estimated and then plotted, as it is in Figure 10.200 There thus appears to be a general correlation between crater densities across the lunar surface and radioactive “age” dates. However, the crater densities at the various sites cannot be fitted to a straightforward exponential decay curve of meteorites or asteroid populations.201 Instead, at least two separate groups of objects seem to be required. The first is believed to be approximated by the present-day meteoritic flux, while the second is believed to be that responsible for the intense early bombardment claimed to be about four billion years ago. This intense early bombardment recorded by the crater-saturated surface of the lunar highland areas could thus explain the presence of the thicker regolith (up to 10 metres) in those areas.It follows that this period of intense early bombardment resulted from a very high influx of meteorites and thus meteoritic dust, which should now be recognisable in the regolith. Indeed, Taylor202 lists three types of meteoritic debris in the highlands regolith- the micrometeoritic component, the debris from the large-crater-producing bodies, and the material added during the intense early bombardment. However, the latter has proven difficult to quantify. Again, the use of trace element ratios has enabled six classes of ancient meteoritic components to be identified, but these do not correspond to any of the currently known meteorite classes, both iron and chondritic. It would appear that this material represents the debris from the large projectiles responsible for the saturation cratering in the lunar highlands during the intense bombardment early in the moon’s history. It is this early intense bombardment with its associated higher influx rate of meteoritic material that would account for not only the thicker regolith in the lunar highlands, but the 12% of meteoritic component in the thinner regolith of the maria that we have calculated (above) would take up to 30 billion years to accumulate at the current meteoritic influx rate. Even though the maria are believed to be younger than the lunar highlands and haven’t suffered the same saturation cratering, the cratering rate curve of Figure 10 suggests that the meteoritic influx rate soon after formation of the maria was still almost 10 times the current influx rate, so that much of the meteoritic component in the regolith could thus have more rapidly accumulated in the early years after the maria’s formation. This then removes the apparent accumulation timespan anomaly for the evolutionists’ timescale, and suggests that the meteoritic component in the maria regolith is still consistent with its presumed 3 billion year age if uniformitarian assumptions are used. This of course is still far from satisfactory for those young earth creationists who believed that uniformitarian assumptions applied to moon dust could be used to deny the evolutionists’ vast age for the moon.Given that as much as 10% of the maria regolith may have been contributed by the large crater-forming meteorites,203impact erosion by these large crater-producing meteorites may well have had a significant part in the development of the regolith, including the generation of dust, particularly if the meteorites strike bare lunar rock. Furthermore, any incoming meteorite, or micrometeorite for that matter, creates a crater much bigger than itself,204 and since most impacts are at an oblique angle the resulting secondary cratering may in fact be more important205 in generating even more dust. However, to do so the impacting meteorite or micrometeorite must strike bare exposed rock on the lunar surface. Therefore, if bare rock is to continue to be available at the lunar surface, then there must be some mechanism to move the dust off the rock as quickly as it is generated, coupled with some transport mechanism to carry it and accumulate it in lower areas, such as the maria. Various suggestions have been made apart from the obvious effect of steep gradients, which in any case would only produce local accumulation. Gold, for example, listed five possibilities,206 but all were highly speculative and remain unverified. More recently, McDonnell207 has proposed that electrostatic charging on dust particle surfaces may cause those particles to levitate across the lunar surface up to 10 or more metres. As they lose their charge they float back to the surface, where they are more likely to settle in a lower area. McDonnell gives no estimate as to how much dust might be moved by this process, and it remains somewhat tentative. In any case, if such transport mechanisms were in operation on the lunar surface, then we would expect the regolith to be thicker over the maria because of their lower elevation. However, the fact is that the regolith is thicker in the highland areas where the presumed early intense bombardment occurred, the impact-generated dust just accumulating locally and not being transported any significant distance.Having considered the available data, it is inescapably clear that the amount of meteoritic dust on the lunar surface and in the regolith is not at all inconsistent with the present meteoritic dust influx rate to the lunar surface operating, over the multi-billion year time framework proposed by evolutionists, but including a higher influx rate in the early history of the moon when intense bombardment occurred producing many of the craters on the lunar surface. Thus, for the purpose of “proving” a young moon, the meteoritic dust influx as it appears to be currently known is at least two orders of magnitude too low. On the other hand, the dust influx rate has, appropriately enough, not been used by evolutionists to somehow “prove” their multi-billion year timespan for lunar history. (They have recognised some of the problems and uncertainties and so have relied more on their radiometric dating of lunar rocks, coupled with wide- ranging geochemical analyses of rock and soil samples, all within the broad picture of the lunar stratigraphic succession.) The present rate of dust influx does not, of course, disprove a young moon. Attempted Creationist Responses

Some creationists have tentatively recognised that the moon dust argument has lost its original apparent force. For example, Taylor(Paul)208 follows the usual line of argument employed by other creationists, stating that based on published estimates of the dust influx rate and the evolutionary timescale, many evolutionists expected the astronauts to find a very thick layer of loose dust on the moon, so when they only found a thin layer this implied a young moon. However, Taylor then admits that the case appears not to be as clear cut as some originally thought, particularly because evolutionists can now point to what appear to be more accurate measurements of a smaller dust influx rate compatible with their timescale. Indeed, he says that the evidence for disproving an old age using this particular process is weakened, but that furthermore, the case has been blunted by the discovery of what is said to be meteoritic dust within the regolith. However, like Calais,209,210 Taylor points to the NASA report211 that supposedly indicated a very large amount of cosmic dust in the vicinity of the earth and moon (a claim which cannot be substantiated by a careful reading of the papers published in that report, as we have already seen). He also takes up DeYoung’s comment212 that because all evolutionary theories about the origin of the moon and the solar system predict a much larger amount of incoming dust in the moon’s early years, then a very thick layer of dust would be expected, so it is still missing. Such an argument cannot be sustained by creationists because, as we have seen above, the amount of meteoritic dust that appears to be in the regolith seems to be compatible with the evolutionists’ view that there was a much higher influx rate of meteoritic dust early in the moon’s history at the same time as the so-called “early intense bombardment”.

Indeed, from Figure 10 it could be argued that since the cratering rate very early in the moon’s history was more than 300 times today’s cratering rate, then the meteoritic dust influx early in the moon’s history was likewise more than 300 times today’s influx rate. That would then amount to more than 3 million tons of dust per year, but even at that rate it would take a billion years to accumulate more than six metres thickness of meteoritic dust across the lunar surface, no doubt mixed in with a lesser amount of dust and rock debris generated by the large-crater-producing meteorite impacts. However, in that one billion years, Figure 10 shows that the rate of meteoritic dust influx is postulated to have rapidly declined, so that in fact a considerably lesser amount of meteoritic dust and impact debris would have accumulated in that supposed billion years. In other words, the dust in the regolith and the surface layer is still compatible with the evolutionists’ view that there was a higher influx rate early in the moon’s history, so creationists cannot use that to shore up this considerably blunted argument.Coupled with this, it is irrelevant for both Taylor and DeYoung to imply that because evolutionists say that the sun and the planets were formed from an immense cloud of dust which was thus obviously much thicker in the past, that their theory would thus predict a very thick layer of dust. On the contrary, all that is relevant is the postulated dust influxafter the moon’s formation, since it is only then that there is a lunar surface available to collect the dust, which we

can now investigate along with that lunar surface. So unless there was a substantially greater dust influx after the moon formed than that postulated by the evolutionists (see Figure 10 and our calculations above), then this objection also cannot be used by creationists.De Young also adds a second objection in order to counter the evolutionists’ case. He maintains that the revised value of a much smaller dust accumulation from space is open to question, and that scientists continue to make major adjustments in estimates of meteors and space dust that fall upon the earth and moon.213 If this is meant to imply that the current dust influx estimate is open to question amongst evolutionists, then it is simply not the case, because there is general agreement that the earlier estimates were gross overestimates. As we have seen, there is much support for the current figure, which is two orders of magnitude lower than many of the earlier estimates. There may be minor adjustments to the current estimate, but certainly not anything major.While De Young hints at it, Taylor (Ian)214 is quite open in suggesting that a drastic revision of the estimated meteoritic dust influx rate to the moon occurred straight after the Apollo moon landings, when the astronauts , observations supposedly debunked the earlier gross over-estimates, and that this was done quietly but methodically in some sort of deliberate way. This is simply not so. Taylor insinuates that the Committee for Space Research (COSPAR) was formed to work on drastically downgrading the meteoritic dust influx estimate, and that they did this only based on measurements from indirect techniques such as satellite-borne detectors, visual meteor counts and observations of zodiacal light, rather than dealing directly with the dust itself. That claim does not take into account that these different measurement techniques are all necessary to cover the full range of particle sizes involved, and that much of the data they employed in their work was collected in the 1960s before the Apollo moon landings. Furthermore, that same data had been used in the 1960s to produce dust influx estimates, which were then found to be in agreement with the minor dust layer found by the astronauts subsequently. In other words, the data had already convinced most scientists before the Apollo moon landings that very little dust would be found on the moon, so there is nothing “fishy” about COSPAR’s dust influx estimates just happening to yield the exact amount of dust actually found on the moon’s surface. Furthermore, the COSPAR scientists did not ignore the dust on the moon’s surface, but used lunar rock and soil samples in their work, for example, with the study of lunar microcraters that they regarded as representing a record of the historic meteoritic dust influx. Attempts were also made using trace element geochemistry to identify the quantity of meteoritic dust in the lunar surface layer and the regolith below.A final suggestion from De Young is that perhaps there actually is a thick lunar dust layer present, but it has been welded into rock by meteorite impacts.215 This is similar and related to an earlier comment about efforts being made to re-evaluate dust accumulation rates and to find a mechanism for lunar dust compaction in order to explain the supposed absence of dust on the lunar surface that would be needed by the evolutionists’ timescale216 For support, Mutch217 is referred to, but in the cited pages Mutch only talks about the thickness of the regolith and the debris from cratering, the details of which are similar to what has previously been discussed here. As for the view that the thick lunar dust is actually present but has been welded into rock by meteorite impacts, no reference is cited, nor can one be found. Taylor describes a “mega-regolith” in the highland areas218 which is a zone of brecciation, fracturing and rubble more than a kilometre thick that is presumed to have resulted from the intense early bombardment, quite the opposite to the suggestion of meteorite impacts welding dust into rock. Indeed, Mutch,219 Ashworth and McDonnell220 and Taylor221 all refer to turning over of the soil and rubble in the lunar regolith by meteorite and micrometeorite impacts, making the regolith a primary mixing layer of lunar materials that have not been welded into rock. Strong compaction has occurred in the regolith, but this is virtually irrelevant to the issue of the quantity of meteoritic dust on the lunar surface, since that has been estimated using trace element analyses.Parks222 has likewise argued that the disintegration of meteorites impacting the lunar surface over the evolutionists’ timescale should have produced copious amounts of dust as they fragmented, which should, when added to calculations of the meteoritic dust influx over time, account for dust in the regolith in only a short period of time. However, it has already been pointed out that this debris component in the maria regolith only amounts to 10%, which quantity is also consistent with the evolutionists, postulated cratering rate over their timescale. He then repeats the argument that there should have been a greater rate of dust influx in the past, given the evolutionary theories for the formation of the bodies in the solar system from dust accretion, but that argument is likewise negated by the evolutionists having postulated an intense early bombardment of the lunar surface with a cratering rate, and thus a dust influx rate, over two orders of magnitude higher than the present (as already discussed above). Finally, he infers that even if the dust influx rate is far less than investigators had originally supposed, it should have contributed much more than the 1.5%’s worth of the 1-2 inch thick layer of loose dust on the lunar surface. The reference cited for this percentage of meteoritic dust in the thin loose dust layer on the lunar surface is Ganapathy et al.223 However, when that paper is checked carefully to see where they obtained their samples from for their analytical work, we find that the four soil samples that were enriched in a number of trace elements of meteoritic origin came from depths of 13-38 cms below the surface, from where they were extracted by a core tube. In other words, they came from the regolith belowthe 1-2 inch thick layer of loose dust on the

surface, and so Parks’ application of this analytical work is not even relevant to his claim. In any case, if one uses the current estimated meteoritic dust influx rate to calculate how much meteoritic dust should be within the lunar surface over the evolutionists’ timescale one finds the results to be consistent, as has already been shown above.Parks may have been influenced by Brown, whose personal correspondence he cites. Brown, in his own publication,224has stated that “if the influx of meteoritic dust on the moon has been at just its present rate for the last 4.6 billion years, then the layer of dust should be over 2,000 feet thick.” Furthermore, he indicates that he made these computations based on the data contained in Hughes225 and Taylor.226This is rather baffling, since Taylor does not commit himself to a meteoritic dust influx rate, but merely refers to the work of others, while Hughes concentrates on lunar microcraters and only indirectly refers to the meteoritic dust influx rate. In any case, as we have already seen, at the currently estimated influx rate of approximately 10,000 tons per year a mere 2 cm thickness of meteoritic dust would accumulate on the lunar surface every billion years, so that in 4.6 billion years there

would be a grand total of 9.2 cm thickness. One is left wondering where Brown’s figure of 2,000 feet (approximately 610 metres) actually came from? If he is taking into account Taylor’s reference to the intense early bombardment, then we have already seen that, even with a meteoritic dust influx rate of 300 times the present figure, we can still comfortably account for the quantity of meteoritic dust found in the lunar regolith and the loose surface layer over the evolutionists’ timescale. While defence of the creationist position is totally in order, baffling calculations are not. Creation science should always be good science; it is better served by thorough use of the technical literature and by facing up to the real data with sincerity, as our detractors have often been quick to point out. Conclusion

So are there any loopholes in the evolutionists’ case that the current apparent meteoritic dust influx to the lunar surface and the quantity of dust found in the thin lunar surface dust layer and the regolith below do not contradict their multi-billion year timescale for the moon’s history? Based on the evidence we currently have the answer has to be that it doesn’t look like it. The uncertainties involved in the possible erosion process postulated by Lyttleton and Gold (that is, radiation erosion) still potentially leaves that process as just one possible explanation for the amount of dust in a young moon model, but the dust should no longer be used as if it were a major problem for evolutionists. Both the lunar surface and the lunar meteoritic influx rate seem to be fairly well characterised, even though it could be argued that direct geological investigations of the lunar surface have only been undertaken briefly at 13 sites (six by astronauts and seven by unmanned spacecraft) scattered across a portion of only one side of the moon.Furthermore, there are some unresolved questions regarding the techniques and measurements of the meteoritic dust influx rate. For example, the surface exposure times for the rocks on whose surfaces microcraters were measured and counted are dependent on uniformitarian age assumptions. If the exposure times were in fact much shorter, then the dust influx estimates based on the lunar microcraters would need to be drastically revised, perhaps upwards by several orders of magnitude. As it is, we have seen that there is a recognised discrepancy between the lunar microcrater data and the satellite-borne detector data, the former being an order of magnitude lower than the latter. Hughes227explains this in terms of the meteoritic dust influx having supposedly increased by a factor of four in the last 100,000 years, whereas Gault et al.228 admit that if the ages are accepted at face value then there had to be an increase in the meteoritic dust influx rate by a factor of 10 in the past few tens of years! How this could happen we are not told, yet according to estimates of the past cratering rate there was in fact a higher influx of meteorites, and by inference meteoritic dust, in the past. This is of course contradictory to the claims based on lunar microcrater data. This seems to leave the satellite-borne detector measurements as apparently the more reliable set of data, but it could still be argued that the dust collection areas on the satellites are tiny, and the dust collection timespans far too short, to be representative of the quantity of dust in the space around the earth-moon system. Should creationists then continue to use the moon dust as apparent evidence for a young moon, earth and solar system? Clearly, the answer is no. The weight of the evidence as it currently exists shows no inconsistency within the evolutionists’ case, so the burden of proof is squarely on creationists if they want to argue that based on the meteoritic dust the moon is young. Thus it is inexcusable for one creationist writer to recently repeat verbatim an article of his published five years earlier,229,230 maintaining that the meteoritic dust is proof that the moon is young in the face of the overwhelming evidence against his arguments. Perhaps any hope of resolving this issue in the creationists, favour may have to wait for further direct geological investigations and direct measurements to be made by those manning a future lunar surface laboratory, from where scientists could actually collect and measure the dust influx, and investigate the characteristics of the dust in place and its interaction with the regolith and any lunar surface processes. Conclusions

Over the last three decades numerous attempts have been made using a variety of methods to estimate the meteoritic dust influx to both the earth and the moon. On the earth, chemical methods give results in the range of 100,000-400,000 tons per year, whereas cumulative flux calculations based on satellite and radar data give results in the range 10,000-20,000 tons per year. Most authorities on the subject now favour the satellite data, although there is an outside possibility that the influx rate may reach 100,000 tons per year. On the moon, after assessment of the various techniques employed, on balance the evidence points to a meteoritic dust influx figure of around 10,000 tons per year.Although some scientists had speculated prior to spacecraft landing on the moon that there would be a thick dust layer there, there were many scientists who disagreed and who predicted that the dust would be thin and firm enough for a manned landing. Then in 1966 the Russians with their Luna 9 spacecraft and the Americans with their five successful Surveyor spacecraft accomplished soft-landings on the lunar surface, the footpads of the latter sinking no more than an inch or two into the soft lunar soil and the photographs sent back settling the argument over the thickness of the dust and its strength. Consequently, before the Apollo astronauts landed on the moon in 1969 the moon dust issue had been settled, and their lunar exploration only confirmed the prediction of the majority, plus the meteoritic dust influx measurements that had been made by satellite-borne detector systems which had indicated only a minor amount.Calculations show that the amount of meteoritic dust in the surface dust layer, and that which trace element analyses have shown to be in the regolith, is consistent with the current meteoritic dust influx rate operating over the evolutionists’ timescale. While there are some unresolved problems with the evolutionists’ case, the moon dust argument, using uniformitarian assumptions to argue against an old age for the moon and the solar system, should for the present not be used by creationists. Acknowledgements Research on this topic was undertaken spasmodically over a period of more than seven years by Dr Andrew Snelling. A number of people helped with the literature search and obtaining copies of papers, in particular, Tony Purcell and Paul Nethercott. Their help is acknowledged. Dave Rush undertook research independentl yon this topic while studying and working at the Institute for Creation Research, before we met and combined our efforts. We, of course, take responsibility for the conclusions, which unfortunately are not as encouraging or complimentary for us young earth creationists as we would have liked.

Solar Neutrinos—The Critical Shortfall Still Elusive

by Dr. Andrew A. Snelling on December 1, 1997

Originally published in Journal of Creation 11, no 3 (December 1997): 253-254. Abstract

Neutrinos have fascinated physicists since they were ‘invented’ 67 years ago Shop Now [Ed. note: while the argument in this paper was cogent given the information then available, subsequent information has

superseded it, meaning that the shortfall problem seems to have been solved. Therefore creationists should no longer use this as an ‘ age’ argument — see more detail.] Neutrinos have fascinated physicists since they were ‘invented’ 67 years ago. In β-decay, a nucleus of one element spontaneously changes into the nucleus of a neighbouring element in the periodic table, emitting an electron (or sometimes an anti-electron or ‘positron’). To their shock, the scientists found that some energy appeared to vanish in these decays. The solution proposed by Wolfgang Pauli in 1930 was that the missing energy was carried away by a new particle, so ephemeral as to be almost undetectable. In 1955 Clyde Cowan and Fred Reines proved Pauli right by observing the neutrino. The problem facing experimenters is that neutrinos are so difficult to detect. For example, on average, the neutrinos emitted in β-decay can typically traverse 100 light-years thickness of lead unscathed! 1Life on Earth is made possible by the energy from the Sun. It is believed that it takes about a million years for energy (apart from that carried by neutrinos) supposedly produced by nuclear reactions near the centre of the Sun to make its way to the surface and be radiated. It takes the neutrinos born in those claimed nuclear reactions about 8 minutes to arrive here, so they should tell us what is happening at the centre of the Sun today. This is one of the main reasons why physicists have built large detectors underground — to look for solar neutrinos.The first experiment by Ray Davis operated for over twenty years in the Homestake mine in South Dakota (USA) measured less than half the expected flux of neutrinos. A large tank was filled with 380,000 litres of dry-cleaning fluid and located in the deep mine to reduce background. The incoming solar neutrinos convert some of the chlorine atoms in the fluid into argon (this is nearly the inverse of β-decay), so the task of Davis and his team was to measure the number of argon atoms produced. Figure 1 shows the numbers of argon atoms counted by the experiment over 20 years, the count rate falling well short of that expected.2 They expected an average of 1.5 atoms per day, but only measured an average of about 0.5 atoms per day. Finding one atom of argon in a tank containing over 1031 atoms of chlorine is not easy, so it was not surprising that some doubted the Davis result.Subsequently another experiment, in the Kamiokande mine in western Japan, used a very different technique and confirmed the Davis result. The team of scientists involved observed the scattering of neutrinos on electrons in a large tank filled with ultra-pure water, the photons produced being detected via amplification of their conversion to a small electric current. This Japanese experiment was also able to follow the Sun as it traversed the sky, much as a telescope can track a star, and it confirmed that the Sun does produce neutrinos but the number detected was again too small.Both experiments were sensitive to neutrinos with relatively high energy supposedly produced in rare nuclear reactions, whereas the nuclear reactions claimed to produce most solar energy give lower energy neutrinos, which these experiments would not have recorded. Now that has changed, with new experiments sensitive to those crucial low energy neutrinos starting to report results. However, these new experiments are also recording too few neutrinos, in this case about half the expected number.Understandably, the solar astronomers and physicists remain baffled by this consistent critical shortfall in the neutrinos expected and measured. Since the nuclear reactions they believe are producing the bulk of the solar energy, and hence the bulk of the associated neutrinos, are very well understood, the predictions of the expected neutrino flux here on Earth are very reliable. So why are they not detected in sufficient numbers?Now the depth of the dilemma has intensified. In its first months of operation, a new neutrino detector with unprecedented sensitivity has confirmed yet again that solar neutrinos are only about half as common as researchers predict when they combine nuclear physics with profiles of the Sun’s internal temperature and pressure.3 The Super-Kamiokande detector, a 50 million litre water tank one kilometre underground in the Kamiokande mine, ‘catches’ roughly 10 neutrinos daily.Since the efficiency of the claimed nuclear reaction responsible strongly depends on temperature, astronomers could conceivably explain away the shortfall by positing that the Sun's core is slightly cooler than thought. However, since helioseismology has ‘pinned down’ the Sun’s central temperature (15.6 million degrees Kelvin), this ‘out’ is no longer viable. Instead, physicists now favour the hypothesis that neutrinos may ‘oscillate’, spontaneously transmutating between different varieties (electron, muon and tau neutrinos) and thus changing their properties en route from the Sun’s core to the Earth.4,5 Allied to this is a recent added twist — the neutrinos may supposedly undergo decay — but this requires abandoning the almost sacrosanct ‘relativity principle’.6 Only further years of experiments will begin to test these attempts at explaining this critical shortfall in the solar neutrinos detected.So ‘after 10 years, no one has yet explained all the data on neutrinos.’7 Of course there’s one explanation not considered — perhaps the reason for the critical shortfall is that nuclear reactions are not solely responsible for producing the Sun’s energy. But such an explanation would be tantamount to an admission that we really don’t yet know how the Sun operates, which would clearly be embarrassing. And if we don’t understand how our nearest star operates, how can the astronomers be so sure how all the other stars ‘evolved’ and now operate? As candidly admitted by David Malin, head research scientist at the Anglo-Australian Telescope, in a recent interview on Australian ABC radio, ‘How little we really know!’8

Galaxy-Quasar ‘Connection’ Defies Explanation by Dr. Andrew A. Snelling on December 1, 1997

Originally published in Journal of Creation 11, no 3 (December 1997): 254-255. Shop Now Astronomers have known for decades about the strange ‘connection’ between the galaxy NGC4319 and the quasar Markarian 205 (see Figure 1, below).1 Without any explanation so far, astronomers are still baffled, and with good reason. Figure 1 is a reproduction of an isophote image of the galaxy and quasar made by superposing a number of photographic plates taken by Halton Arp using the 200-inch Palomar telescope.2 The image clearly shows that a luminous ‘bridge’

connects the two objects which is distinct and well away from any ‘pixel [picture element] bleeding’.3 Figure 1: This isophote image of the galaxy NGC 4319 (above) and the quasar Markarian 205 (below), made by superimposing a number of photographic plates taken by Halton Arp using the 200-inch Palomar telescope, clearly shows the luminous bridge connecting the two objects (north is up, east is left). This photo appears in Arp, Ref. 2 and Arp et al., Ref. 3. So what is baffling about such a clear linkage between this galaxy and its apparently close neighbouring quasar? The ‘basic’ problem is that the galaxy and the quasar have discordant red-shifts, which according to the standard (Doppler) red-shift interpretation means that the galaxy is receding at a velocity of 1800km/sec, whereas the quasar is travelling at 21,000km/sec. Thus, according to the Hubble law, the galaxy is 107 million light years away and the quasar is 12 times further away at 1.2 billion light years! Obviously, this simply cannot be, because the galaxy and the quasar are clearly connected together by a ‘bridge’, probably of luminous gas filaments. They give every appearance of existing together. Some critics have claimed that the bridge is only an illusion, but Arp and

his colleagues have staunchly defended the reality of this connection for many years, and Arp’s photography (Figure 1) has documented it. Ignoring this cosmological ‘anomaly’ won’t make it go away! Perhaps red-shifts may not be connected with recession velocities and so may not be a reliable index to distances in an expanding universe after all. These are very fundamental questions to our understanding of the universe. In the words of astronomer William Kaufmann: ‘If Arp is correct [about red-shifts not being distance indicators], if his observations are confirmed, he will have single-handedly shaken all modern astronomy to its very foundations. If he is right, one of the pillars of modern astronomy and cosmology will come crashing down in a turmoil unparalleled since Copernicus dared to suggest that the sun, not the earth, was at the center of the solar system.’4 James Waterhouse is thanked for bringing this unresolved ‘anomaly’ to our attention, and for providing the reproduction for Figure 1.

Saturn’s Rings—Short-Lived and Young

by Dr. Andrew A. Snelling on April 1, 1997

Originally published in Journal of Creation 11, no 1 (April 1997): 1. Abstract Creationists have long argued that the rings of Saturn are less than 1 million years old, in spite of evolutionists’ claims that the planet is 4.5–5.0 billion years old, the same as the rest of the Solar System.1 The rings are made up of rock and ice fragments that are being drawn closer and closer to Saturn’s surface by the planet’s gravitational pull. Shop Now

Astronomers have long believed that Saturn’s rings were formed when a moon or comet about 200 km across was shattered by an impact close to the planet, leaving a mass of debris. This impact, it is suggested, happened no more than 100 million years ago.2It was in 1852 that Otto Struve noted in the Memoirs of the St Petersburg Academy of Sciences3 there had been changes in the widths of the rings and a progressive decrease in the width of the gap between the planet and the inner edge of ring B, relative to the combined width of ring A. Old drawings and descriptions were used to evaluate this ratio—Huygens (1657), Huygens and Cassini (1695), Bradley (1719), Herschel (1799) and W. Struve (1826)—results indicating a rapid approach of the inner edges of the rings toward Saturn, while the outer edge of the outermost ring (ring A) had changed little.Now an international team of scientists (French, US and Canadian) using the Hubble Space Telescope have shown that the innermost rings are losing water ‘relatively rapidly’. Indeed, the water is disappearing ‘so fast’, the team believes that it would all have gone already if the rings were more than about 30 million years old.4News of the rings’ mortality didn’t come as a surprise to the scientific community.5 Astronomers had suspected that the rain of microscopic meteorites that pelts every body in the Solar System was rapidly eroding the rings, and they already had the indirect evidence that ring debris is falling into the planet. But this first direct evidence of the infall could tell astronomers just how fast the rings are eroding, placing direct bounds on the lifespan of Saturn’s rings—and, by extension, the less showy rings of the other giant planets.Thus, astronomers now believe that water evaporates from the particles making up the rings when micrometeorites crash into them. The fate of the water molecules depends upon their charge and distance from the planet. Neutral molecules fall back onto the rings’ surfaces, but charged (ionised) particles spiral along magnetic field lines. Beyond the outer edge of the inner ring, the field lines carry them away from the planet, but at lower altitudes the field lines guide them down to Saturn. ‘This result is the first evidence of significant water precipitation flux from the rings of Saturn onto its atmosphere’.6Determining just how fast ring water is streaming into Saturn and thus how long the rings have been around will take more work and some calculations of how fast the water is being removed from the stratosphere.7 A high flux would be the most direct evidence that Saturn’s rings are ‘short-lived’. If Saturn’s spectacular rings are ‘very young’8 and ‘short-lived’, then it’s ‘only by luck’, they say, that they are around for us human beings to marvel at. Furthermore, the ‘catastrophic event’ needed to make rings as massive as these—the shattering of a small moon by a comet or the disruption of a passing giant comet by Saturn’s gravity—is only likely to happen just once in the planet’s life-time, say the scientists.This realization that the dazzling rings of Saturn could be a ‘rare sight’9 does not bother us. The evidence is increasingly mounting that the Flood was accompanied by catastrophism throughout the Solar System (for example, impact cratering), and thus we would expect Saturn’s rings to be ‘very young’.

That Matter of the Shrinking Sun

by Dr. Andrew A. Snelling on September 1, 1989 Originally published in Creation 11, no 4 (September 1989): 45-47. We should be skeptical about the Skeptics and their arguments, as this article shows in the matter of the shrinking sun. Creationists are often accused by evolutionists of not quoting, or referring to, other scientists’ work accurately or in context. This is particularly so when the doubts of an evolutionist can be misconstrued to imply he’s given up evolution. Such impressions are never intentional. What our opponents forget is that quoting other scientists’ work and statements is

common practice, and conventionally such quotes are never intended to imply anything more about the authors’ beliefs, etc., than what is so stated in the statements quoted.What is more serious is complete misrepresentation, particularly if a proper reading of a scientist’s work clearly indicates that scientist’s position on the issue being discussed. Under such circumstances unintentional misrepresentation should never occur. But if misrepresentation does occur, it raises serious questions about the intent of the scientist quoting another’s statements. In my experience, most creationists try to be exceptionally careful in this area. Misrepresentation

However, one would least expect to see blatant misrepresentation in a book whose authors claim that creationists misquote, make basic errors, misrepresent, etc. But such is the case in the Skeptics’ book, in the article on page 22 entitled, ‘Is the sun shrinking?’ Quite correctly the Skeptic author reported ‘Gilliland (1981) has examined much of the data available from the early 18 th century up to now. He concluded that the major change in size has been a periodic oscillation, with the sun shrinking and expanding over a 76 year cycle, with the last maximum occurring around 1911. However the experimental scatter in the observations (see Gilliland 1981, fig. 3 on p. 1149) is such that fairly sophisticated mathematical techniques were required to extract this information.’ However, when the Skeptic author says that ‘Gilliland stated that there was also the possibility of a steady shrinkage of about a tenth the rate proposed by Eddy and Boornazian, but that the experimental errors were such that zero shrinkage was also possible’, he is ascribing to Gilliland doubts which Gilliland did not have. This misrepresentation is rather blatant since Gilliland says in his abstract, or summary of the main points and conclusions in his paper: ‘A secular decrease of about 0.1 second of arc per century over the last 265 years is also likely from an objective analysis of the available data’ (p. 1144).1 This is no claim of possible zero shrinkage. Furthermore, in the body of his paper Gilliland says rather sternly and critically of his colleagues: ‘In the partially justified, but perhaps overzealous, criticism of the early Eddy and Boornazian (1979) claims there is a distinct possibility that much smaller but still fundamentally important (any trend less than -0.004 second of arc per century is faster than the Kelvin-Helmholtz gravitational contraction rate) secular trends are being inadvertently disclaimed’ (p. 1150). Negative Trend

Further down the same page he says: ‘Given the many problems with the data sets, one is inexorably led to the conclusion that a negative secular solar radius trend has existed since AD 1700, but the preponderance of current evidence indicates that such is likely to be the case.’ And: ‘Thus, with allowance for possible systematic errors in both the meridian circle and Mercury transit timing observations, a negative secular trend of solar radius is still supported.’ But the misrepresentation and errors don’t stop here. The author in the Skeptics’ article goes on to refer to Stephenson’s 1970 paper on ‘The Earliest Known Record of a Solar Eclipse’2 and says: ‘In any attempt to use these early records additional complications arise due to the gradual slowing down of the earth’s speed of rotation, due to friction from tides. This would lead to an accumulated time error of 8 or 9 hours by July 17, 709 BC, the date of the earliest recorded total eclipse.’

Now while the Skeptic author is not attributing this accumulated time error of eight or nine hours by July 17, 709 BC to Stephenson, his figures are none the less very wrong, since a straightforward reading of Stephenson’s paper gives the correct figure: ‘Accurate computation of an ancient solar eclipse for a given place is limited by the non-uniformity of the Earth’s rotation and the tidal recession of the Moon from the Earth. Irregularities in the Earth’s rotation are chiefly the result of tides, but other causes are changes in sea level and electromagnetic coupling between the core and mantle of the Earth. A computation of a solar eclipse which ignores these effects may be in error by up to about 4h in time and 50 per cent in phase near 1300 BC’ (p. 651). Total Eclipse?

The Skeptic author then goes on to give the reader the impression that when ‘Stephenson (1982, p. 161) in fact concludes that observation supports a rate of shrinkage of about 0.16 seconds of arc per century’ etc., ‘that observation’ is the one in the previous sentence when the Skeptic author says, referring to the total eclipse of July 17, 709 BC, ‘At this time the sun cannot have been much, if any, larger than at present or the eclipse would not have been a total one.’ While this latter statement may be true, the impression left with the reader is that Stephenson on p. 161 of his 1982 paper on ‘Historical Eclipses’3 discusses the total eclipse of July 17, 709 BC. Nothing could be further from the truth. Nowhere on p. 161 does Stephenson even mention the July 17, 709 BC total eclipse, and when he does talk about a rate of shrinkage of about 0.16 second of arc per century Stephenson only derives that conclusion from the ‘six total solar eclipses from AD 1715 to 1925’ as well as ‘the observed duration of 30 transits of Mercury’. Stephenson only mentions the July 17, 709 BC total eclipse once in his whole paper, and that is in a table on p. 157 where no mention is made of any comparison of the sun’s size between then and now.And what of Stephenson’s shrinkage rate of 0.16 second of arc per century? The Skeptic author says the error in this figure is about 0.14 second of arc per century ‘so that there is no solid evidence of shrinkage’ and ‘this agrees with Gilliland’s conclusion’. While he is correctly reporting Stephenson’s shrinkage result of 0.16± 0.14 second of arc per century, it is wrong for both the Skeptic author and Stephenson to say that there is

no solid evidence of shrinkage or that this is ‘essentially a null result’ (Stephenson, p. 151). Such statements are misleading at best and dishonest at worst. The calculated shrinkage rate of 0.16± 0.14 second of arc per century is not no

shrinkage, but says that there is shrinkage at a rate of somewhere between 0.02 and 0.30 second of arc per century. This is exactly what Gilliland meant when he said, as quoted earlier, that many colleagues, in their rush to criticize those who claimed the sun was shrinking, were overlooking or inadvertently disclaiming a much smaller but still fundamentally important long-term shrinkage trend. That’s why Gilliland confidently suggested a shrinkage rate of almost 0.2 second of arc per century for the sun’s diameter (0.1 second of arc per century for the solar radius). Solid Evidence

To be sure, Stephenson’s results agree with Gilliland’s conclusion, but the Skeptic author again misrepresents Gilliland when he states ‘there is no solid evidence of shrinkage. This agrees with Gilliland’s conclusion.’ Gilliland did have solid

evidence of shrinkage and concluded the above small rate of almost 0.2 second of arc per century, very close to Stephenson’s 0.16 and within the 0.02–0.30 range that is the correct Stephenson result, Stephenson’s misleading reporting notwithstanding. So how does the Skeptic author answer his own question: ‘Is the sun shrinking?’ He says: ‘To answer the question posed in the title of this section—the sun oscillates up and down in size, but there is very little evidence of steady shrinkage.’ Note that the ‘no solid evidence of shrinkage’ at the end of his previous paragraph has become ‘there is very little evidence of shrinkage’. Of course he’s wrong since both authors whose work he has drawn from (i.e. Gilliland and

Stephenson) agree that there is evidence of a shrinkage rate of around 0.16–0.20 second of arc per century within the range of 0.02–0.30 second of arc per century to account for the error margins. Indeed, as we have repeatedly seen, Gilliland is adamant that ‘one is inexorably led to the conclusion that a negative secular solar radius trend has existed since AD 1700.’ Glaring Errors

How dare the Skeptic author conclude with the comment that ‘any creationist arguments based on such shrinkage should be treated with caution indeed’ when in the space of less than one page he, the Skeptic author, has repeatedly and blatantly misrepresented other scientists’ conclusions and made glaring errors in order to attempt a refutation of creationist arguments.We have every reason in fact to be skeptical about the Skeptics and their attempts at answering the powerful creationist arguments if this is the level of their use and abuse of science, other scientists’ work, and the ethics of writing. Unsuspecting readers should be clearly warned not to be fooled.But why should the Skeptic author want the answer to his question to be that there is no shrinkage of the sun and no solid, or little, evidence of steady shrinkage?Because even if we take Stephenson’s bottom-of-the-range figure of a mere 0.02 second of arc per century (tiny shrinkage indeed), this means that, using the evolutionists’ own uniformitarian assumption of extrapolating this shrinkage rate backwards in time, just as they extrapolate further back 10–15 billion years to the ‘big bang’, only 100 million years ago the sun would have been too large for life to exist on earth!But this won’t do for the Skeptic author

who, like other evolutionists, believes life has been on this earth for at least three billion years, so the sun must not be shrinking. Notice that his conclusion is not based on the evidence, since we have just seen that the solid evidence does support a small shrinkage rate, but on his a priori commitment to evolution, that is, his starting belief in evolution before he even looked at the evidence. Yes, we should be skeptical about the Skeptics and their arguments.

GOLD

A Little Bit of Heaven on Earth

by Dr. Andrew A. Snelling on December 8, 2010; last featured October 13, 2013 Shop Now Gold has fascinated people since earliest times. It has always been valued because of its warm color, glistening beauty, durability, and ease of shaping into exquisite jewelry. Nations have acquired and treasured it, traded and warred over it. Due to its rarity, gold’s principal function has been as currency and as the preferred way to store wealth. Created for Eternity

The gold have many properties that make it so valuable. It does not rust or tarnish. Fire does not destroy gold but only makes it purer. It can be alloyed to other metals, like copper, to add strength without losing beauty. Gold is easy to shape. Under the right conditions, 1 ounce (28 g) can be stretched into a wire 60 miles (100 km) long, or hammered into a big sheet, 100 feet by 100 feet (30 m x 30 m), to cover the dome of a fancy building.Another amazing quality of gold is that it essentially lasts forever. In fact, we can safely conclude that most of the gold mined since the Flood is still readily available (in active use or hoarded). The total amount has not changed; it has just been recycled into jewelry, tooth fillings,

computer components, and lots more.This means that we can estimate the total amount of gold that has ever been mined: about 180,779 tons (164,000 m. tons).1 If gathered into one location, this treasure hoard would fill a seven story office building, 66 feet (20 m) high and 66 feet square (6 m2). Primary and Secondary Deposits as a Result of the Flood

During the Flood, catastrophic plate tectonics reshaped and rebuilt the earth’s crust into multiple new continents with new mountains.2 At this time, gold returned to rocks near the earth’s surface. Though the details differ, the processes had a few things in common. Initially hot acid waters3 in deep crustal rocks dissolved the gold, and molten magma and volcanic waters carried it toward the surface (Figure 1). This hot material then entered into cracks in the rocks near the earth’s surface.

Common Types of Gold Deposits Primary gold deposits occur where hot acid waters dissolved metals deep in the earth and then rose toward the surface, carrying the metals with them.Secondary gold deposits occur where rain and other natural forces eroded primary deposits and then washed the gold to other places (called placer deposits).Some primary deposits are associated with volcanic activity during the Flood. As the earth’s plates collided, the plates melted, sending hot magma and hot water toward the surface. This hot water was rich in gold, copper, and other metals.Other gold deposits are found in pre-Flood rocks. These deposits were formed during Creation During the Flood, some of these deposits were changed under great heat and pressure and then pushed to the surface.As it cooled, the gold remained in place, either associated with certain large granite bodies (often with copper) or in veins and orebodies.4After these “primary gold deposits” were put in place, heavy rains and other natural forces eroded many of the rocks. Because gold is very heavy and resistant to corrosion, it settled out into what are called “placer deposits.” These secondary gold deposits include the gold particles found at Sutter’s Mill, which sparked the California gold rush in 1849.Most placer deposits formed at the end of the Flood when the retreating waters drastically eroded the landscape. Indeed, most of the Flood-generated primary and secondary deposits formed during the closing stages of the Flood, especially during the building of the Rockies, Andes, Himalayas, European Alps, and other related mountain ranges. Primary and Secondary Deposits During Creation .

That explains Flood-related gold deposits, but we also find gold in pre-Flood sedimentary layers.5 What event could possibly explain these gold-filled sediments before the Flood washed over the earth? The answer: the Creation moment. To properly understand this oft-overlooked period of young history, let’s look more closely at perhaps the world’s most famous gold deposit—the Witwatersrand.Until recently the Witwatersrand sedimentary basin of South Africa accounted for about 40% of all known gold (and 45% of total gold production). Like a great sea reef rising gently above the surrounding landscape, the Witwatersrand is a ridge running some 60 miles (100 km) in a broad arc across South Africa’s interior. Among locals, it is known simply as “the reef” (or “rand” in Afrikaans).This is a massive placer deposit, similar to the ones described above but on a much bigger scale. Placers get their name because water transported the gold particles into their new place, mingled with silt and sometimes, as in this case, with pebbles too. But how did such a large “reef” appear? Secular geologists argue that the “Golden Arc” was once the edge of a huge inland lake, where gold-laden sediments settled for millions of years.Separation of land and water . This was a dramatic event in earth history, as the pre-Flood supercontinent was built. It seems that all land was initially buried under the original globe-covering waters. Then the supercontinent raised above the ocean surface, water rushed off the land and caused massive erosion, decimating many of the earlier primary gold deposits, concentrating it into placer deposits.Around 1,700 years later, the global Flood laid down new fossil-bearing layers atop these deposits, and the mountain-building processes at the end of the Flood pushed some of these lower layers to the surface.So we have now seen the main periods of history when gold was deposited. A total of 65% of known, mineable gold deposits are in rocks associated with Creation .6 Less than 2% of known gold deposits were produced in the “post-Creation, pre-Flood” rocks. About 33% of the remaining known gold deposits lie in Flood-related rocks. Still Being Deposited Today

We see some of these processes at work today, but at a much smaller scale. The Creation and the Flood were one-time events that produced unique conditions that would never be repeated, vastly increasing the speed and scale of new deposits.Some might claim that gold in granites and related vein deposits and ore bodies requires more time to form than was available during the year-long global Flood catastrophe. However, accumulated evidences now indicate granites formed and cooled rapidly. Metal-laden hot waters would have been expelled from the granites during a crucial, final stage in the process of their formation, quickly producing deposits of gold and other precious metals.7Furthermore, we can see gold being deposited rapidly today. At the giant, volcanically produced Ladolam gold deposit at Lihir in Papua New Guinea, volcanic waters are still depositing gold at a rate of 52 pounds (24 kg) per year.8 At this rate, this giant gold deposit (containing 3 million pounds [1.3 million kg] of gold) would have formed in about 55,000 years. “Ancient” ore fluids had 100-1,000 times more gold in them,9 and the Flood upheaval would have released such volcanic fluids at much faster rates.All the gold is still available today, just in different types of deposits. Ever since people explored the land of Havilah, man has mined and treasured gold. In the past, it has usually been the metal of kings, palaces, priests, and temples, including Israel’s Tabernacle and Solomon’s Temple. Nuggets of Knowledge . . . One cubic foot of gold weighs more than half a ton.

The ocean waters contain an estimated 10 billion tons of gold (along with most other elements). That’s over 1 ton per person.Pure gold does not easily corrode, it does a good job conducting electricity and heat, and it has a high melting point at 1,948°F (1064°C). So it has many applications in medicine, engineering, aerospace, and the chemical industry. The largest gold nugget ever found was about 25 inches (60 cm) long and 10 inches (31 cm) wide, weighing in at approximately 160 pounds (72 kg). Two Australian men found “the Welcome Stranger” in 1869 under a tree, 2 inches underground. In modern U.S. dollars, it would be worth well over $3.5 million.The largest stockpile of gold today is held at the Federal Reserve Bank of New York. The underground vault holds around 550,000 gold bars total, worth $485 billion U.S. as of November 2010. (Around 95% of the gold in the Federal Reserve Bank is owned by non-USA governments.) The vault was built on solid bedrock, which was necessary to support the gold’s weight of 5,000 metric tons.

CRYSTALS

Shape-Shifting Silicon Semi-Technical

by Dr. Andrew A. Snelling on October 1, 2014

Rob Lavinsky, irocks.com

The exotic shapes and vivid colors of crystals are often what first attract the wonder of children and draw them into studying geology. That’s what happened to me. When I was nine years old on a family vacation in Tasmania—the island state off Australia’s southeastern coast—I saw a piece of shiny mineral on a mine’s waste pile. I was instantly hooked. I eagerly talked about this treasure at my next grade four “show and tell” session, and this chalcopyrite (copper ore) became the first member of my rock and mineral collection. So why do minerals have so many different shapes and colors? A small set of basic building blocks were created, out of which the earth could provide the amazing variety of minerals we need to build places to live and grace our lives with beautiful gems. The marvelous stability and interlocking properties of minerals, which have such an amazing variety of applications—from the yellow paint on our kitchen walls to the glass in our windows. The Crucial Role of Silicon Atoms The earth’s crust is composed of many different elements, but 75% of the crust consists of just two elements: silicon and oxygen. These are the basic building blocks

of the ground under our feet.When isolated, silicon is invaluable to modern life. For instance, it’s the basic ingredient in computer chips. Imagine that—the most important element in modern technology is the most common on the planet (apart from oxygen).When silicon combines with oxygen, the true marvel of its versatility shines. Out of nearly 5,000 minerals known to exist, over 25% are silicates (minerals whose crystals are composed of arrays of atoms based around silicon atoms). Silicate minerals are so abundant that about 92% of the earth’s crustal rocks are made up of them.How can so many shapes and colors come from just one element? The answer is its incredible ability to combine with other elements in many different ways. Like Tinkertoys, silicon can combine into rows, rings, sheets, or complex three-dimensional structures. First, A Little Chemistry

Just as carbon is the basic building block of living things, silicon is the basic building block of the nonliving earth. To appreciate the wisdom behind their design, it’s necessary to understand a little basic chemistry.

Figure 1: Elemental Building Blocks Just as carbon is the basic building block of living things, silicon is the basic building block of the earth. Both elements are on the same column of the Periodic Table, the only nonmetal elements in this column. Their special properties allow them to combine easily with other elements.Look closely at the Periodic Table of Elements (Figure 1). Silicon (symbol Si) is element 14 on the table, and is in the same column as carbon (C), element 6. Silicon and carbon are the only nonmetal elements in this column, with special properties that allow them to combine easily with other elements.Both carbon and silicon atoms have spots for eight electrons in their outer shells, but only four of these spots are filled with their own electrons. This configuration enables other atoms to hook into the empty spots. Carbon, for instance, links together with oxygen, hydrogen, and other atoms to form the complex organic molecules of life, such as DNA.In the same way, silicon has four electrons in its outer shell, which it readily shares with oxygen (O) atoms. Oxygen likes to fill all four empty spots, resulting in a triangular pyramid. The silicon atom is in the middle, and an oxygen atom sits at each of the four corners. This is an incredibly stable, flexible building material. The chemical formula is technically SiO4, and the formal name of this basic building block is the silica tetrahedron. A Thousand Combinations, for Work and Pleasure

These little pyramid blocks of silica tetrahedra can be linked together and stacked in almost every imaginable combination. But geologists recognize six major classes: isolated, couplets, rings, chains, sheets, and frameworks (3D structures).The different combinations make possible the multifaceted shapes of crystals. The colors are more complicated. Adding other elements produces different colors, though indirectly. The colors aren’t inherent in the atoms, but they change the way light passes through the minerals.In most cases, the tetrahedra are formed out of silicon and oxygen atoms, but sometimes in some terahedra an aluminum atom is substituted for the silicon atom. Other major elements that frequently join the tetrahedra are iron, magnesium, sodium, potassium, calcium, and to a lesser extent titanium and manganese. Sometimes trace elements can join, too, like chromium, beryllium, lithium, and boron—producing interesting and colorful variations.Changing the combination of elements gives each mineral not just new shapes and colors, but also new properties. In fact, the same elements can produce either cheap building materials or precious gems, depending on their arrangement. While this is not intended to be an earth science lesson, all believers should become familiar with a few highlights, which will enable them to share the glories of their Creator with people who don’t know Him. Figure 2 Limitless Possibilities Silicon form basic four-sided molecule with oxygen that would be the building block of earth. From this single molecule, called a silcon tetrahedron, there are over two thousand minerals that are essential to modern life and industry.

photos thinkstockphotos.com and Rob Lavinsky, irocks.com Single (Nesosilicates) Let’s start simple. Single pyramids, or tetrahedra (Figure 2), can be linked by magnesium and iron atoms to form the dense, green mineral called olivine. Olivine is the major mineral in the earth’s mantle, which lies between the core and the outer skin or crust and is 1,796 miles (2,890 km) thick.1 Amazingly, olivine also comes in a gem variety, called peridot. Another common mineral in this class is garnet. Its beautiful shape, called a dodecahedron, makes it a popular gem. In this class is another famous mineral, the topaz. At 8 on a scale of 1 to 10, this densely packed gem is the third-hardest mineral. Couplets (Sorosilicates) Another class of silicate minerals consists of couplets (Figure 2) linked by calcium, aluminum, and iron atoms. Many minerals fall into this class, such as epidote and zoisite (see photos), but none are well-known. Rings (Cyclosilicates)

Now it starts to get really interesting. Six silica tetrahedra can join into rings (Figure 2). The best-known mineral in this class is beryl, formed when the rings are linked together by beryllium and aluminum atoms. The six-sided rings produce distinctive six-sided crystals that can get really massive. The largest crystal ever discovered—of any type of mineral—is a beryl from Madagascar, 59 feet (18 m) long and 12 feet (3.5 m) in diameter. Beryl is a source of beryllium, a lightweight metal used in special high-tech alloys. Beryl also comes in two beautiful gem varieties: emerald2 and aquamarine. Chains (Inosilicates)

When the silica pyramids are joined together in single chains (Figure 2), they form an important class of minerals known as pyroxenes. The most prevalent example of these is the common black specks, called augite, which appear in basalt walls on buildings. Another variety of pyroxene, called jadeite, is a major source of the precious gem jade. This mineral is made by combining with sodium and aluminum. Think about this marvelous transformation: you get green jade by combining the silicon in computer chips with table salt (sodium) and aluminum!If the silica building blocks are joined together in double chains (Figure 2), then they form a common type of mineral known as amphiboles. Many different varieties exist because five different atoms (magnesium, iron, aluminum, calcium, and sodium) can be used to link the double chains together. If all five atoms are involved, the result is hornblende, a common black mineral, sometimes found in granites. Another dual-chain mineral, called nephrite, provides another variety of jade.The double-chain crystal structure can also produce long, thin fibers. That’s what happens in asbestos minerals. Once considered a cheap building material, asbestos was banned after doctors discovered the fibers can clog lungs. But these same fibers, if woven into cloth, are still used in fireproof clothing that protects our firefighters. Amazingly, one of the six asbestos minerals (riebeckite) produces the valuable “tiger’s eye” gem. Sheets (Phyllosilicates) Silica tetrahedra can also be joined into sheets (Figure 2). What good is a “sheet” of mineral? These sheets form three of

the earth’s most common minerals—micas, talc, and clay minerals. All three are vital to industry. The black mica (biotite) and the white mica (muscovite) are common in granites and metamorphic rocks, such as schists. Micas can be peeled apart like the pages of a book, so they’re not always good for building materials or gems.3Muscovite sheets, because of their transparency and ability to withstand heat, were once used as windows in wood-burning heaters and stoves. Another sheet silicate is talc. We get talcum (“baby”) powder from this mineral. Common clays are also sheet silicate minerals. We call these “clay minerals” because they break down easily into clays. They have an abundance of uses. Kaolinite, for example, is a “filler” in glossy paper and house paints. When you buy paint at the store, an essential ingredient is sheets of silica and oxygen atoms connected by aluminum!

Frameworks (Tectosilicates) The most elaborate form of silica tetrahedra is a three-dimensional structure called a framework (see diagram). These are the most abundant minerals in the earth’s crust, making up 63% of its rocks. One example is quartz, whose chemical formula is SiO2. This mineral is the basis of the glass used in windows, bottles, and jars, and lately, fiber optics. It also comes in gem varieties, such as amethyst, agate, and opal.4 The other example of framework silica is feldspar. Along with building materials, this mineral is also useful in making glass, as well as soaps, cements, tar roofing, paper, and pottery. Unlike in quartz, which consists simply of silicon and oxygen, aluminum atoms must substitute for some silicon atoms in feldspar. This substitution results in an imbalance of the electron charge, which is compensated for by adding potassium atoms in alkali feldspar, or calcium and sodium atoms in plagioclase, to restore the balance. Plagioclase is actually the most common mineral on earth.

Rubies & Sapphires

by Dr. Andrew A. Snelling on April 1, 2010; last featured January 5, 2011

Diamonds may get all the attention, but rubies and sapphires are the first choice of kings and the affluent because of their extreme rarity. Only special conditions, initiated by the Flood, could have produced these rare beauties. Shop Now In our culture most attention is focused on the glamour of diamonds, but two colorful gems—rubies and sapphires—are actually much rarer and more valuable. Since no one was present to observe how these precious gems formed, creation geologists are carefully investigating the chemistry of the gems and the “crime scene” where they are found. With these clues, along with the young history of the earth, these sleuths have reconstructed an amazing story of these gems’ origin. What Are Rubies and Sapphires? Rubies and sapphires are varieties of the same mineral, called corundum. This hard mineral, composed of aluminum and oxygen (Al2O3), comes in many different forms and degrees of clarity. Only the rarer, clearer crystals are classified as rubies or sapphires, based on their

color.1

Of most interest is the source of corundum’s hardness. Corundum is the second hardest natural mineral, after diamonds. Because of its hardness, corundum is used as a natural grinding material, called emery in powdered form. (Emery is commonly found in emery boards—the disposable files used to trim fingernails.)Great heat and pressure were required to transform the original source materials into this hard mineral. Such an amazing transformation must have occurred in the heat of the earth’s interior, but where and when? Where Are Rubies and Sapphires Found?

The modern location of rubies and sapphires gives us a clue about the place of their formation. We find them in only a few places, mainly southern Asia and eastern Africa. What took place inside the earth to form these gems and then transport them to the surface?The answer varies from place to place, but the basic story remains the same. At some point in the past, source rocks inside the earth’s crust were subjected to intense pressures and high temperatures, causing the atoms to recombine into new metamorphic (“changed”) rocks, which included rubies and sapphires. Later the moving crustal plates and erupting volcanoes carried these rocks to the surface.The details differ in each place. Some rubies and sapphires are found in high-grade metamorphic rocks, called gneisses and granulites, located in Sri Lanka, India, Madagascar, and eastern Africa. In most cases, they formed at depths of 6–18 miles (10–29 km) in the earth’s crust, as intense pressures and high temperatures (above 840°F [450°C]) transformed sedimentary (“water deposited”) rocks, such as siltstones and shales, into metamorphic rocks (Figure 1).2The best rubies, however, are found in marbles, particularly at mines in Myanmar but also in Vietnam, Afghanistan, Pakistan, and Nepal.3 These marbles formed when heat and pressure inside the earth changed, or “metamorphosed,” soft limestone.Sapphires are most commonly found in stream beds and other secondary deposits.2 To get there, the nearby rocks must have eroded away and washed down to their current location. The nearby rocks are made of basalts (rocks that came from basaltic magma in the upper mantle). We might assume that these basalts are the original source of the gems, but they don’t have the right chemistry. So where did these sapphires originate? They must have formed in the metamorphic rocks located in the earth’s crust, above the mantle. When the basaltic magma rose up though the crust, it “captured” the gems along the way. The magma then carried the gems to the surface. Later, as water and other natural forces broke down the basalts, the sapphires were released into alluvial deposits, where they are now mined.

Click picture to view a larger copy in PDF format. When Were Rubies and Sapphires Formed?

We know the composition of these gems and their location. But what special conditions could have created them in the first place and then moved them to the surface?Geologists have noticed that ruby and sapphire deposits are closely linked to major earth movements.4 Furthermore, they have identified three distinct episodes when these gems formed. These findings help us to place ruby and sapphire deposits at the correct times within the young framework of earth history. The global Flood, in particular, involved a series of catastrophic plate movements that would explain these gems.5The first episode was early in the year-long Flood catastrophe, when the African and Indian fragments of the pre-Flood supercontinent Rodinia rapidly collided.6 Pre-Flood and early Flood sedimentary and igneous rocks were buckled, squeezed, and heated, transforming them into the metamorphic gneisses and granulites that host the ruby and sapphire deposits of eastern Africa, Madagascar, India, and Sri Lanka. Then, according to the young model of earth history, when rapid crustal plate movements were quickly slowing down at the end of the Flood, the Indian plate collided with the Eurasian plate to form today’s Himalaya mountains. Limestones that had been deposited early in the Flood were then metamorphosed into the ruby-containing marbles of Myanmar, Vietnam, Nepal, Pakistan, and Afghanistan.During this same period, and extending into the early post-Flood era, residual hotspots in the earth’s upper mantle generated pockets of molten basalt around the globe. When the continental plates, now moving much more slowly, drifted over this molten basalt, the basalt magmas squeezed explosively through the fractured crust, erupting within hours as volcanoes at the earth’s surface.7 As this magma passed through the fractured metamorphic rocks, it plucked rock pieces and sapphires

from the walls and carried them to the surface.This catastrophic activity lasted through the final stages of the Flood and on into the post-Flood era, when new mountains were still rising and volcanoes exploding. Violent weather then rapidly sculpted the new surfaces. Wherever rocks were exposed to weathering and erosion, the indestructible rubies and sapphires were liberated from their hosts and washed into alluvial deposits, later to be mined and enjoyed by man. The post-Flood people who scattered from Babel had migrated across Asia to the places where they would find rubies and sapphires.If this interpretation is correct, the young age worldview explains why rubies and sapphires are so rare—their formation is restricted to unique conditions . The Value of Rubies & Sapphires

Rubies and sapphires are the most important colored gemstones in the gem trade, together accounting for over 50% of global gem production.1 Rubies are far less abundant than blue sapphires of similar quality and thus are of more value. Flawless, highly prized deep red rubies are seldom larger than three carats, and those that exceed ten carats are extremely rare. Large sapphires, in contrast, are relatively common, and numerous stones exceeding 100 carats have been found. (A carat is the unit of weight for gemstones, which is now internationally defined as equal to 0.2 gram, or 200 mg, or approximately 0.007 ounce.2)Transparent raw rubies and sapphires are commonly cut and faceted. Non-transparent stones of fine color are sometimes smoothly polished, not faceted, if there is indication that they might be star sapphires or rubies.Rubies and sapphires have

long been part of human history, dating back to Job, an early post-Babel patriarch around 2000 BC.3 Rubies in particular have been prized by monarchs as a symbol of their wealth and power. In ancient Sanskrit the name for rubies meant “queen of precious stones.” In the seventeenth century the King of Bijapur (now in modern India) owned a ruby that weighed over 50 carats. The German Emperor Rudolph II is reported to have possessed a ruby the size of a hen ’s egg. Rubies are the world’s most expensive gemstones, the best Burmese rubies being valued more than an equivalent-sized flawless diamond.1 The world record paid at auction for a ruby is U.S. $3.63 million in 1988 for a 15.97 carat Burmese ruby (U.S. $227,300 per carat). (By comparison, a 62 carat flawless diamond recently sold for just over U.S. $8 million, or U.S. $130,000 per carat.) The world record paid at auction for a blue sapphire is U.S. $3 million for a spectacular 62 carat rectangular-cut royal blue Burmese sapphire.

Microscopic Diamonds Confound Geologists

by Dr. Andrew A. Snelling on April 1, 1996

Originally published in Journal of Creation 10, no 1 (April 1996): 1-2. Tiny diamond grains discovered in high-grade metamorphic rocks (gneisses) from south-western Norway may force geologists to rethink cherished ideas about the Earth’s continental crust and processes. Discovered by an international team of Russian, Norwegian, British and US geoscientists,1 the diamond fragments at only 20–80 micrometres in size are too small to see without a microscope. Yet they have formed within the continental crust where they shouldn’t have!‘This is a spectacular discovery’, says diamond expert Stephen Haggerty of the University of Massachusetts in Amherst.2 According to all the geology textbooks, diamonds can only form in the Earth’s mantle at depths of more than 120 km (75 miles), where the exceedingly high pressures and temperatures—40 kbar and 900°C—squeeze carbon into the ultracompact crystal structure of diamond. The diamonds then reach the surface when explosive volcanic eruptions force the molten rock containing them up narrow conduits (pipes) through the crust.However, these Norwegian microdiamonds just do not comply with the textbooks! Whereas they should have been in volcanic mantle rocks, they were found in metamorphic rocks. Originally formed as ancient sedimentary deposits on the Earth’s surface, these layers of sediments are believed to have been compacted and cooked (400–450 million years ago!) when another continent (Laurentia) rammed into what is now Scandinavia (the ancient Baltica). Although such continental collisions (also expected to have occurred in a catastrophic plate tectonics Flood model3) are believed to be capable of metamorphosing crustal rocks, they are considered far too ‘docile’ for making diamonds. According to Dobrzhinetskaya et al.,4 geothermobarometry, textural

studies and fluid-inclusion analyses indicate that the high-pressure phase of metamorphism that produced these Norwegian gneisses involved conditions of 17–21 kbar and approximately 630–820°C. However, this is still not nearly enough to mould carbon into diamond, says Haggerty and conventional wisdom.Significantly, this Norwegian discovery is not the first, geologists having already reported finding examples of microdiamonds in metamorphic (crustal) rocks twice before, in 1990 in Kazakhstan5and in 1992 in eastern China.6While skeptical researchers questioned those earlier reports, this Norwegian discovery makes it harder for the geoscience community to ignore the obvious conclusion that diamonds may also form in crustal rocks.‘This really nails it’, says Haggerty. According to W. Gary Ernst of Stanford University,‘If these are well-documented diamonds, I exult. You can’t laugh it off anymore and say it’s one of a kind.’7 Dobrzhinetskaya et al. are cautious in their report and do not speculate how these crustal rocks could have been subjected to the mantle conditions claimed for diamond formation, yet Dobrzhinetskaya independently tries to explain the presence of these microdiamonds in these Norwegian metamorphic rocks.8 She suggests that the ancient continental collision forced pieces of the crust down to mantle depths temporarily, where carbon in the sedimentary layers then turned into diamonds before the crustal rocks rose back to the surface.While this theory would solve the ‘mystery’ of how the diamonds formed, Monastersky9 is absolutely right in pointing out that instead it raises another conundrum. Crustal rocks have a much lower density than mantle rocks, so therefore most geologists consider continental rocks too buoyant to be carried down into the mantle. Yet Ernest insists,

‘We don’t think crustal rocks can go down and come bobbing back up, but a few of them must have!’ Haggerty, however, suggests that the diamonds might have formed without a trip into the mantle. Industrial researchers, he notes, have learned how to grow extremely thin diamond films at very low pressures. Therefore, because the microdiamonds from Norway, Kazakhstan and China are so tiny, he speculates that they may have formed at pressures found in the crust. ‘We either have a major tectonic problem, or we have an entirely new way of making diamonds,’ says Haggerty.10 So should geologists now have to rewrite some basic textbooks as Monastersky concludes? No, not yet, because Haggerty, Ernst, Monastersky, and even Dobrzhinetskaya all overlook one key issue—Dobrzhinetskaya et al.11 admitted that they had not yet identified the microdiamonds in situ in the gneiss (they recovered them from crushed rock), and therefore they had no indisputable evidence to support either a metamorphic or an alluvial origin for the grains. That’s right—there’s still the possibility these micro-diamonds were deposited in the original sediments (by erosion from source rocks) before they were metamorphosed! In any case, the uniformitarian (slow-and-gradual) model of plate tectonics, which involves millions-of-years for continental collisions, is hard pressed to explain how crustal rocks could go down to mantle depths of 120 km and bob back up again. On the other hand, catastrophic plate tectonics during the Flood year12 with metres per second crustal movements would have inevitably resulted in violent continental collisions, the tremendous forces involved buckling crustal rocks to the extent of ramming some portions down to mantle depths. However, this would be short-lived, for as the crumpled collision zone ‘relaxed’ very soon after the impact, the lower density continental crustal rocks thus rammed into the mantle would rapidly rebound. No wonder geologists are confounded by these microdiamonds! Perhaps the ‘mystery’ surrounding them would be easily solved if they abandoned their uniformitarian presuppositions. Maybe catastrophic plate tectonics during the Flood is the better model for earth history?

Creating Opals

Opals in months—not millions of years! by Dr. Andrew A. Snelling on December 1, 1994

Originally published in Creation 17, no 1 (December 1940): 14-17. Shop Now Opals have fascinated people for centuries. As early as the first century AD, the Roman Pliny wrote of opals: ‘In them you shall see the living fire of ruby, the glorious purple of the amethyst, the sea-green of the emerald all glittering together in an incredible mixture of light.’ Mark Antony loved them, and is thought to have assaulted a senator to get a particularly nice one. Napoleon presented Josephine with ‘The Burning of Troy’, a magnificent red example. Shakespeare called them ‘that miracle and queen of gems’, and Queen Victoria of Great Britain made the new discoveries from far-off Australia a fashion necessity.Prized for their vivid hues, Australia’s renowned precious opals command retail prices from US$5 to $3,000 per carat, depending on quality. The finest opals have become more expensive than many other gems, and Australia is responsible for practically all of the world’s supply. (Mexico is the only other significant producer.) Coober Pedy, together with Andamooka and Mintabie, all in South Australia, account for approximately 70 percent of total world production. However, since 1988 the value of production from Lightning Ridge in New South Wales, with its famed high-quality black opal, has outstripped the South Australian fields.The opals are said to have formed millions of years ago (30 million years ago at Coober Pedy), although the host rocks are all claimed to be more than 65–70 million years old. And surprising as it may seem, the ingredients of opal are commonplace stuff. Water in the ground carrying dissolved silica (similar to the glass in windows) is said to have seeped through beds of sand and grit, where the silica particles are deposited in cracks. As the water subsequently evaporated, the silica particles became ‘cemented’ together to form the opal. Light bending around the silica produces the variety of glowing colours. Fossils made of opal

Even fossils found in the host rocks have not escaped the percolating silica-rich groundwaters. Occasionally, bones, seashells and seed pods are found fossilized by having been ‘turned’ into opal. Perhaps the most famous example in recent years is ‘Eric’ the pliosaur (a marine reptile), which was the subject of high-profile public fund-raising by The Australian Museum in Sydney in order to purchase these opalized bones from the Coober Pedy miner who found them in 1987. ‘Eric’ is said to be about 100 million years old. No wonder then, in most people’s minds, because of these claimed time scales, and because of the almost universal perception/indoctrination that geological processes are almost always slow and gradual, opals ‘must’ have taken a long time to form in the ground. ‘Not so’, says Len Cram, a Lightning Ridge ‘bush’ scientist who earned his Ph.D. for his opal research. Secret of ‘growing’ opals Len has discovered the secret that has enabled him to actually ‘grow’ opals in glass jars stored in his wooden shed laboratory, and the process takes only a matter of weeks! (See: Snelling, A., Growing opals—Australian style! Creation 12(1):10–15, 1989.) Len’s man-made opals are so good that even experienced Lightning Ridge miners

can’t tell the difference between them and opals found in the ground. Furthermore, scientists from Australia’s CSIRO (Commonwealth Scientific and Industrial Research Organisation) can’t distinguish Len’s opal from natural opal even under an electron microscope—they look identical!

No, Len is not about to disclose the formula and ‘flood’ the world with man-made opals. His quest has always been to find out how opal forms so as to discredit uniformitarian (slow and gradual) geological theories. He believes the opals took only a few months to form within suitable portions of the thick sediment layers laid down catastrophically during the Flood, and his experiments undeniably demonstrate that this was feasible.All it takes is an electrolyte (a chemical solution that conducts electricity), a source of silica and water, and some alumina and feldspar. The basic ingredient in Len’s ‘recipe’ is a chemical called tetraethylosilicate (TEOS for short), which is an organic molecule containing silica. The amount of alumina which turns to aluminium oxide determines the hardness of the opal.The opal-forming process is one of ion exchange, a chemical process that involves building the opal structure ion by ion (an ion is an electrically charged atom, or group of atoms [molecule]). The process starts at some point and spreads until all the critical ingredients, in this case the electrolyte, are used up. Within a matter of weeks of this initial formation, the newly forming opal has beautiful colour patterns, but it still has a lot of water in it. Slowly over months, further chemical changes take place, the silica gel consolidating as the water is ‘squeezed’ out.Len can now ‘grow’ opal in natural Lightning Ridge opal dirt, the sandy grit in which the natural opals are found. Once the electrolyte is mixed into the opal dirt, colour starts to form within four to six days. Seams of opal then actually grow, identical in shape and form to that found in the ground, some with colour and some without, the process taking about three months. Thus seam opal is not necessarily a sedimentary deposit in previously existing cracks in the opal dirt. Rather, the chemical reaction which ‘creates’ the opal makes the seam from the opal dirt itself where no crack or seam previously existed. Len says this achievement is a ‘world first’, and that viscosity evidently plays a major role in this crucial ion-exchange process. Rapid opals fit the young timescale

Len’s experiments not only provide an explanation of how opals form, but the short timescale of only a matter of years is consistent with the young age framework and can readily account for the field observations of natural opal in its host rocks. Furthermore, this means that his short timescale also applies to the fossilization process. The bones of ‘Eric’ the pliosaur (for example) need not have taken thousands or millions of years to fossilize. The most likely explanation of their preservation via opalization is now therefore the same replacement (ion-exchange) process that Len has so graphically demonstrated in his glass jars, and that takes only months to years.So the evolutionary ‘stories’ of opal formation and fossilization slowly over thousands and millions of years have to be rewritten. Since pliosaurs and other creatures need to be buried catastrophically to ensure their subsequent fossilization, the rock layers hosting the opals and opalized bones are best explained by catastrophic deposition during the global Flood. Chemical processes then took over to form the opals in the rock layers and opalize the bones in the months and years that followed.

Diamonds—Evidence of Explosive Geological Processes

Evidence of Explosive Geological Processes by Dr. Andrew A. Snelling on December 1, 1993

Originally published in Creation 16, no 1 (December 1993): 42-45. Diamonds have been highly prized throughout history, being regarded as symbols of wealth and power. Shop Now The prized value has a lot to do with the appearance of cut gem-quality diamonds and their hardness. On the scale of hardness of minerals and natural materials diamonds are rated as the hardest—hence their industrial uses. Ironically however, diamonds are merely one physical form of the element carbon, another being graphite, which is of course quite soft, black and relatively unattractive. To many it is an enigma that an element like carbon could occur in such starkly contrasting physical forms. An Aboriginal ‘myth’

Like many other native peoples around the world, the Australian Aborigines have stories about events in their history, including what had to be geological events. Their stories include one of a flood, the breakup of the continents, and a morning star.1 Of course, these traditions are usually dismissed as either simply religious beliefs, mythology, or the primitive explanation of local natural phenomena. Yet it is apparent that these stories, stripped of their grotesque elements and embellishments, are simply technically unsophisticated eyewitness accounts of real events. Thus it is significant that the Aborigines in the East Kimberleys of far northern Western Australia have a story associated with the Argyle diamond deposit which is in their tribal area. They say that the place where the diamond deposit is found is where the Barramundi (a large fish found in northern Australian estuaries) jumped out of the ground during the ‘Dreamtime’ (the time in which the earth received its present form, and cycles of life and nature were initiated).This story of course has generally been accepted as fanciful native mythology, with no basis in fact, because the diamond deposit is supposed to be millions of years old. But could it be that these Aboriginal people actually saw this diamond deposit form in the recent past? Since diamond deposits appear to have formed by what can best be described as explosive volcanism, it would certainly seem that their description fits such an event.

Diamond deposits

Diamond deposits are found in only a few isolated and restricted locations around the world where particular rock types occur. Figure 1 shows the location of the economic primary deposits, which are located in what are known geologically as ‘cratonic areas’, that appear to be the old foundational basement rocks on which the continents have been built.2 Historically, diamonds have been found and mined in southern Africa, from where sprang the DeBeers empire that grew to essentially control the world diamond market. However, today the largest deposits are found in Siberia, but the world’s largest diamond mine is at Argyle in northern Western Australia, the deposit whose formation the Aborigines appear to have witnessed. This mine currently produces 25 million carats of diamonds a year, about 30% of the world’s production.3Diamond deposits are termed primary when found

in the host rocks that have brought them from deep in the earth’s interior to the surface. The two host rock types in which significant quantities of diamond occur are called kimberlite (named after the best-known and earliest-mined diamond deposits at Kimberley in South Africa) and lamproite. Secondary diamond deposits are formed from these primary host rocks due to weathering and transportation by surface erosion processes. Because diamonds are so hard they survive

weathering and erosion to end up in either gravels or alluvium, and even on beaches, as along the west coast of Namibia, southern Africa. Host rock transport

Careful scientific investigations have revealed that diamonds have come from deep in the earth to the surface extremely rapidly. Identification of a rock as kimberlite or lamproite does not guarantee that it will contain economic quantities of diamonds. There are two reasons for this.4 It is now accepted by most geologists specializing in the study of diamond deposits that the diamonds themselves are crystals that are foreign to these rocks, that is, they were not part of the original rock material. Additionally, during the process of bringing the diamonds from inside the earth to the surface, in these rocks the diamonds may revert to graphite and/or be chemically dispersed and so be eliminated. Therefore, a given barren kimberlite or lamproite may never have contained diamonds, due to its failure to incorporate diamonds in it before its passage to the earth’s surface, or any diamonds originally present may have been completely destroyed during their passage upwards. Current research has thus shown that kimberlites and lamproites are merely vehicles which transport diamonds from deep inside the earth to the surface.Kimberlites and lamproites could broadly be classified as volcanic rocks. They appear to have been produced from molten (and melted) rocks derived from the mantle below the earth’s outer crust.5 However, they have unusual compositions that set them apart from other volcanic rocks. The generalized three-dimensional shape of kimberlite and lamproite rock masses is depicted in Figure 2.6 This shape is usually called a pipe, but the uppermost part towards the land surface can be splayed out to make the shape more like a champagne glass. At depth the pipe narrows down and connects with a system of deep fractures. It is along these fractures that the molten rock forced its way upwards.

Diamond formationKimberlites and lamproites often contain fragments of other rocks types that have been ‘broken off and picked up’ during the passage of the molten rock from the earth’s interior to the surface. Amongst these foreign rock fragments are pieces of the probable source rocks that melted to form the molten masses of kimberlites and lamproites. Laboratory studies of the minerals in these rock fragments suggest that they formed at temperatures of 900–1400°C (approximately 1630–2500°F) and pressures of 50–80 kilobars (approximately 370–600 tons force per square inch). Such conditions evidently exist in the earth’s upper mantle at a depth of 150–250km (approximately 90–155 miles),7and are also the conditions under which diamond is known to be stable. At shallower depths, where temperatures and pressures are lower, diamonds are not stable and any carbon present will occur as graphite. This implies that diamonds had to form at depths of more than 150km (about 90 miles) below the earth’s surface in the upper mantle. Current ideas about diamond formation differ with respect to the postulated source of the carbon.8 Some researchers believe that diamonds form from carbon in methane or other hydrocarbon gases that ascend through the upper mantle from deeper inside the earth. Other scientists suggest that the carbon has come from the earth’s surface (and may even be ultimately of biological origin), presumably having been deeply buried and ‘pushed’ to these depths as a result of upheavals in the earth’s crust (explainable as due to the Flood). In either case, it appears that the formation of a primary diamond deposit depends upon there having developed diamond–bearing horizons at depths greater than 150km in the ‘root zones’ of the continental foundation areas. Below in the upper mantle proper, localized melting of the rocks produced molten ‘blobs’ of kimberlite and lamproite compositions, which in their molten state were then ‘lighter’ (less dense and relatively buoyant) than the surrounding mantle rocks. As a consequence these molten ‘blobs’ (magmas) began to rise along fractures upwards towards the earth’s crust. If these molten ‘blobs’ passed through diamond–bearing horizons in the continental ‘root zones’, then diamond crystals may have become incorporated into the magmas, which then transported them into the crust and up to the earth’s surface.

A rapid ascent However, once these ‘blobs’ of molten magma containing diamonds reached depths of less than 150km (about 90 miles) below the earth’s surface they were then in the zone where diamonds are no longer the stable form of carbon under the ambient temperature and pressure conditions. Consequently, if the magma ‘blobs’ moved too slowly up through the crust to the surface, and took too long to cool and harden there, then the contained diamonds would have been converted to graphite. These magmas would also have contained water and carbon dioxide gas, the water particularly enhancing the oxygen chemical reactivity of the ascending magma and potentially assisting the rapid oxidation and combustion of contained diamonds.Laboratory experiments, coupled with other mineralogical and textural features in kimberlites and lamproites, indicate an ascent rate for these molten ‘blobs’ of diamond–bearing magmas of between 10 and 30km (6–19

miles) per hour.9 In other words, if these magma ‘blobs’ began their journey surfacewards at depths of 250km (about 155 miles), picking up diamonds on the way up to 150km (about 90 miles) depth, then they would have needed to reach the earth’s surface in only 8–25 hours!Many people, of course, find it hard to conceive of a geological process like that occurring so rapidly, particularly as we have been constantly indoctrinated with the slow and gradual, uniformitarian philosophy. So how is it that these molten ‘blobs’ of magma made their way through solid rock from depths of around 250km (about 155 miles) or less to the earth’s surface in a day or less?The magmas had within them components that produced a driving force for their rapid ascent. First there was the carbon dioxide gas content which would have built up an explosive gas drive.10 Then there was the water content, which at the magma’s temperatures was present as superheated steam, and would have been responsible for hydraulic fracturing and wedging.11 Both the carbon dioxide and water in the magmas were confined under pressure, much like soda in a corked bottle, ready to explosively exploit any weaknesses in the rocks above them.It is hardly surprising then that most kimberlite and lamproite pipes occur at the intersections of major deep fracture systems. These fractures extend to within 2km (1.25 miles) of the surface, where they connect with the root zones of the pipes (see Figure 2 again). But why the change of mode at that depth? As the magmas rise along the fractures towards the earth’s surface the temperatures of the surrounding rocks and the confining pressures progressively fall. Because the magmas have travelled rapidly upwards they have had little time to cool.At the shallow depth of 2km (1.25 miles) the confining pressures on the magmas were greatly diminished, which allowed the superheated steam in the magmas to in effect boil. Concurrently, the magmas came in contact with circulating groundwater, which had also been brought rapidly to boiling point by the heat of the rising magmas. The net result was explosive releases of energy, which are estimated as equivalent to two or three times the energy released per kilogram of magma in the Mount St Helens blast of May 18, 1980.12 These decompression reactions which suddenly produced rapid expansion of the confined gases and steam explosively, like a cork being popped out of a soda bottle, or like a bomb detonating, ‘punched’ holes all the way up to the surface. This is how the chimney-like pipes were formed.The explosive eruptions were very localized and probably very short-lived, but resulted in ‘shattering’ of the then rapidly cooling magmas. Thus fragmented, they ended up filling the pipes as broken masses of coarse volcanic ash (or tuffs) whose grains and fragments were welded together to form hard masses (because of the heat still being released).13 The explosiveness and force involved is evident from the fragments of rocks, through which the pipes have been cut, that have also been included in the pipes. The diamond crystals themselves are thus carried rapidly from their place of formation deep in the earth into these pipes, where we find them today along with the shattered remains of the magmas that brought them up to the earth’s surface. Conclusions

This evidence for the rapid formation of diamond deposits confirms that there are extremely rapid and catastrophic geological processes which evolutionary geologists have been forced to concede do occur. Furthermore, the eyewitness testimony from the Australian Aborigines, distorted by verbal transmission and the ‘mists of time’, undoubtedly points to their having seen the explosive eruption that produced the Argyle diamond deposit, which places its formation therefore in the very recent post-Flood period. To these undoubtedly awe-struck Aboriginal observers such an eruption could well, in their technically unsophisticated understanding, look like a giant fish jumping out of water.Today’s diamond deposits at today’s land surface are in kimberlite and lamproite pipes that were intruded through strata most of which were undoubtedly deposited by the Flood. This means that the rapid ascent of molten kimberlites and lamproites and the explosive volcanism that resulted in the pipes must have occurred late in the Flood, soon after it, or sometime later (after Babel; in the case of the Argyle event seen by the Australian Aborigines. And of course the 8–25 hours it took the magmas to ascend and explosively form the pipes and craters is totally consistent with the young time framework in which the Flood occurred some 4500–5000 years ago.

Growing Opals—Australian Style

by Dr. Andrew A. Snelling on December 1, 1989 Originally published in Creation 12, no 1 (December 1989): 10-15. In a dusty old wooden shed on a side street in Lightning Ridge, New South Wales, Australia, a bush scientist trying to discover the origin of opal has been able to ‘grow’ opal which is virtually indistinguishable from the mined precious stone.

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Len Cram’s shed has to be one of the oddest, out-of-the-way research laboratories anywhere in the world. On the walls are shelves with row upon row of bottles, peanut butter jars, and other containers. Each is covered with a plastic lid and rubber band with data scrawled over it.The jars and bottles are filled with a milky-coloured liquid, and at the bottom of each lies a few centimetres of residue. On closer examination, it has the unmistakable colour and flash of the most beautiful precious opal one could imagine. Yes, man-made opal, grown in the laboratory, over a short period of time—not millions of years!Len’s opals have fooled old miners who have lived in Lightning Ridge all their lives. So skilled has Len become that he can have them believing his opals are from any one of the various opal fields around the town.Far from boasting about his extraordinary discoveries, Len is usually reluctant to talk about them. In a town where people’s livelihoods depend on the real stuff coming from the ground, there is much suspicion about his work. But Len’s main object is not to manufacture opal. Rather, his is purely a quest to find how opal forms. Other theories upset

His experiments have turned traditional theories about opal upside-down, even challenging accepted ideas of evolutionary geology and its alleged millions of years for the formation and age of opals. But Len is not a sophisticated scientist—just ‘10 per cent inspiration and 90 per cent perspiration’!Few people know more about opal than Len does. Even scientists who refuse to acknowledge his work admit he is a world authority on the subject.Len left school when he was 15. Self-taught, with a very analytical and inquiring mind, his formal training came only after he had completed most of his opal-growing research. This includes an earned Ph.D. (for a thesis on his opal research)—academic credentials he says he needed so that his work would be accepted in scientific circles!Len started his association with opal in Queensland in the 1950s. Even then, he wondered if he could grow opal, and so began his first experiments, using of all things honey and sulphuric acid. Eventually, in 1962, he moved to Lightning Ridge, in New South Wales, where he began in earnest to pursue his dream of making opal.Thus began an ongoing scientific adventure. He studied every scientific paper on silica he could lay his hands on. He went through years of experiments—trial after trial, failure after failure. Each experiment was carefully recorded. Results were documented. Often discouraged, but still hopeful, he carried on. CSIRO research At the same time Len was doing his work in the bush, others—including Australia’s CSIRO (Commonwealth Scientific and Industrial Research Organisation)—were also doing research on opal. A research team headed by Dr John Sanders of CSIRO’s Material Science Division in Melbourne made some major breakthroughs in explaining the colour and

construction of opal.1Using an electron microscope, Dr Sanders found that opal was made up of millions of tiny silica balls in a regularly arranged pattern. In between each of these balls were found even smaller holes or interstices, through which light is diffracted, that is, when white light or ordinary sunlight shines through the holes, it is split into colours. In opal where the balls were small, the colours produced were the darker colours of the rainbow—violet, indigo and blue. When the balls were large, yellow, orange and red colours were produced. Precious opal is found when the balls are in a regularly arranged pattern. In potch or common opal there is no set pattern.Dr Sanders and his team produced an artificial material in 1968 that was comparable to natural opal. They took out patents in England and the United States. However, like Len Cram, they realized the potential dangers of their work (e.g. if opal could be cheaply produced artificially it would completely undermine the value of natural opal and thus bring economic ruin to the opal mining industry). They thus tried to keep a lid on their breakthrough.Meanwhile, Len was eventually able to use the CSIRO research for his own work. He did more and more experiments, all of which failed to produce results—‘successful failures’. On the wall of his laboratory he has pinned two sayings around which his work is based: ‘In this laboratory, success is never guaranteed and failure is never permanent’, and ‘Fear of the Lord is the beginning of all wisdom.’ Success at last

It was not until 1975 that Len had his first success. He poured a bit of ‘this’ and a bit of ‘that’ into a bottle. He gave it a shake, put it on the shelf, and forgot about it. Sometime later he and a friend were in the shed-laboratory doing something else when his friend noticed the bottle. On the bottom was a three millimetre (one-eighth inch) growth of precious opal! Len built on this success. Having now unlocked the door, he could grow the most natural-looking opal anyone could imagine. On his shelves are Andamooka blue/greens; Coober Pedy whites and ‘crystals’; Mexican oranges, and Lightning Ridge blacks—all grown in his shed. The opal is so natural-looking that there are different colour bars with different patterns, and lines of potch between them. Len’s opal looks real, simply because it is real. His process apparently is a mimicking of the process which formed opal in nature. And Len’s opal grows at normal room temperature without any pressure or mechanical assistance. Furthermore, Len’s latest opal looks identical to natural opal even under the electron microscope. Other attempts at manufacturing opal, including those of CSIRO, look noticeably different.He is a creationist and claims his experiments discredit uniformitarian geology theories of slow-and-gradual opal formation (evolution) over thousands and millions of years. While developing his system for growing opals, he learned a great deal about how opal is formed. Len believes it took only a few months within suitable portions of the voluminous sediment layers laid down catastrophically by the Great Flood—and he says he can prove it. Evolutionary theory wrong

Current scientific theory, based on the geologists’ uniformitarian belief in slow and gradual processes over millions of years, states that opal formation was a sedimentary process.2 Silica gel (a warm water solution supersaturated with silica) was deposited over millions of years, layer after layer, filling in cracks and spaces in a parent rock, which is often a friable sandstone, locally (i.e. in the opal mines) called opal dirt. Over millions of years more the gel supposedly slowly dried out to become hard. It has been suggested that it took around five million years for about a centimetre (a little more than a third of an inch) of opal to develop, perhaps through rain washing the silica gel into the opal dirt.But Len has proved that the opal formation process is probably very different to this. In his jars, the first touch of colour appears within 15 minutes! In three months he gets more than one centimetre (half an inch) of vertical growth. Len says the longest part is the drying-out process, as the water contained within the developing opal structure is expelled over subsequent months and years. The actual formation of the opal takes only a very short time (only a matter of weeks). The accepted evolutionary theory, however, says that the water evaporated and the opal formed as the silica gel dried out. This is untrue according to Len. Natural opal, he says, was not formed by flows of silica gel, but went hard (indurated) under water.Len says that he has succeeded because he was prepared to look at the scientific problem completely unshackled by evolutionary and uniformitarian assumptions—an attitude different from that of other scientists.Although some of the scientific theories of CSIRO’s Dr Sanders are in conflict with Len Cram’s, Dr Sanders has described Len’s work as remarkable. ‘He has shown incredible dedication in trying to find how and why opal was formed. The Japanese have made opal but it is nowhere near the same as those produced by Len’, Dr Sanders says.3 No one else has managed to capture the fire of the precious opal, or the natural look that Len’s opal has. The recipe

There is no doubt that Len has demonstrated that opal can form quite quickly. All it takes is an electrolyte (a chemical solution that is electrically charged), a source of silica and water, and some alumina and feldspar. The basic ingredient in this recipe for making opal is a chemical called tetraethylorthosilicate, or TEOS for short, which is an organic molecule containing silica. The amount of alumina which turns to aluminium oxide determines the hardness of the opal.The opal-forming process is one of ion exchange, a chemical process that involves building the opal structure ion by ion (an ion is an electrically charged atom, or group of atoms (molecule)). A reasonable analogy would be that of the growth of a crystal within a chemical solution. When the proper chemical mix is present, a tiny crystal forms in the liquid. Then the crystal grows larger and larger until the chemicals needed to make it are used up from the solution. Opal is not a crystal, but Len has shown that it grows in much the same way. The ion exchange process starts at some point and spreads until all the critical ingredients, in this case the electrolyte, are used up. This initial formation process takes place quickly, in a matter of months, in Len’s laboratory.After the initial formation in a matter of weeks, the opal has beautiful colour patterns, but it still has a lot of water in it. Slowly over months, further chemical changes take place which consolidate the silica gel. These changes create varying patterns of colour and ‘squeeze’ the water out. It is not the initial forming that takes time; rather, it is this restructuring. Only after the opal has restructured is it stable and useful as a gemstone. Rapid formation in nature

So now we have a new explanation of how opal is probably formed in nature. At some point in the host rock, the correct mixture of electrolyte and other ingredients is present. The chemical process starts and expands outward. It transforms the host sandstone or opal dirt into precious opal through the ion exchange process. As it does, it uses up the electrolyte. When it is all used up, the process stops and no more precious opal forms. After this initial formation, the silica gel naturally restructures, becoming more compact, ‘squeezing’ out water as it does.This simple experimentally verified process can explain how opal formed in so many different ways. The so-called nobbies (round nodules of opal) of Lightning Ridge (and probably the ‘crystal blobs’ in Andamooka) are thus the result of a small pool of electrolyte in which the opal formation process started. As the opal grew from the centre out, a concretion or roundish shape was created. The size of the nobby or nodule was probably determined by how much electrolyte was available.One wonders how a nobby, or a spot of opal in Mexican rhyolite (a volcanic lava rock), could have been formed under the sedimentation processes of standard evolutionary/uniformitarian theory. Where did the gel come from? How did it travel into the space it supposedly filled? There are usually no cracks to provide access. Len Cram’s explanation solves this problem. With the necessary ingredients already part of the lava rock, the process started from the inside out, transforming the matrix into precious opal as it proceeded

Seams (or layers) of opal also can be explained in this way. The electrolyte initiates the ion exchange and the process takes the path of least resistance, that is, along the layering in the host rock. Transformed into opal

Len has a bottle where he has put opal dirt from Lightning Ridge in the bottom and his solution on top. The layer of opal formed on top of the opal dirt, but then, strangely, a pocket of precious opal began to grow in the dirt. The opal dirt (or sandy grit) was literally being chemically transformed into precious opal. In another of his bottles, precious opal has grown in horizontal layers or seams in the opal dirt, one above the other. Each seam has varying qualities, colour bases and patterns. Thus seam opal is not necessarily a sedimentary deposit in previously existing cracks in the opal dirt. Rather the chemical reaction which creates the opal has made the seam where no crack or seam previously existed.There are other problems with the so-called sedimentation theory which make Len’s experimental explanation far more believable. In some opal fields there are often several large seams of opal deposits, sometimes six or nine metres (about 20 or 30 feet) across, lying one on top of the other with little space between them. If these opal seams had originally been open cracks in the host clay, how could this soft clay have stayed suspended for millions of years with large long cracks within it without collapsing while waiting to be filled with opal? No wonder geologists have difficulty in explaining opal formation in such occurrences!There is also a lot of natural opal that is impregnated with ‘opal dirt’ which has a lower specific gravity than does silica in solution. This opal dirt should thus have floated to the top of the gel if the sedimentation theory were correct, rather than being caught up in the middle of the opal as is so often the case.Both these observable details completely discount the evolutionary theory of silica gel sedimentation over millions of years.Potential confirmation of the comparability of Len Cram’s experiments with natural opal formation comes from an experienced Northern Territory opal miner. He recently recounted how after discovering some high grade colourful opal underground, he was dismayed to find that after only short exposure to sunlight, the opal lost its colourful patterns.4 This suggests that some mined opal is not yet stabilized, pointing to recent formation.This fascinating scientific story is not yet complete. The usual explanation for differences in base colour in opals is the presence of impurities. Len’s research has shown that this is not how the base colour is formed. He has shown that the chemical composition of black opal is identical to that of white or other types. Rather, it is the structure of the opal which creates the base colour. Vital creationist research

This again is a revolutionary idea, but as before Len has the proof in the bottles in his laboratory. He has opal growing where he initially mixed various dyes to make the solutions black. Sure enough, there sits a black liquid on top of a growing layer of pure clear opal. But in another jar the liquid is clear and the opal is black. Len maintains that every black opal in Lightning Ridge (and 98 per cent of the world’s black opal comes from Lightning Ridge) was originally white—he has seen white opals turn black in his bottles. So much for the old theory that the colours are produced by impurities!All this sounds exciting but, as always, there is a catch. Len has proved that good stable natural opal hardens while still underwater, because his opal is slowly doing the same. But he hasn’t so far waited the few years or decade necessary for completion of the process to be able to pour the water off his opal and cut it. Instead, he has siphoned the water off through a small hole in the plastic top over his jar and allowed the opal to slowly dry out over a number of months. And here is the ‘catch’. The forced drying caused the opal to crack. Len is working on this problem but has not solved it yet.Len’s opal is not yet ready to replace natural opal. He doesn’t intend it to. However, what Len’s experiments have done is provide a whole new explanation of how opal is formed, in only a matter of years. His short time-frame explanation, consistent with the young age framework, can readily account for the field observations of natural opal in its host rocks. Furthermore, the most likely explanation of the opalization of fossil bones is now therefore the same replacement (ion exchange) process that Len has demonstrated in his laboratory. The evolutionary ‘textbook’ story of opal formation slowly over millions of years is going to have to be rewritten.Research based on creationist presuppositions is thus not only true and proper research, but continues to contribute to true scientific endeavour.However, there are also practical applications. Len Cram’s creationist research into rapid opal formation has now provided a new model and exploration target in the search for more opal in existing opal fields and, more importantly, for the discovery of new opal fields.If most of the host sediments were catastrophically deposited recently in the Flood and opal formed rapidly, why should the uniformitarian geological time-scale, with its millions of years, limit exploration targets for new opal deposits to so-called Cretaceous sandstones? All sandstone strata that resemble the host rocks of known opal fields such as Coober Pedy (South Australia) and Lightning Ridge (New South Wales)—‘Cretaceous’—or Mintabie, South Australia (‘Ordovician’) should be regarded as prospective, regardless of their inferred uniformitarian geological age.