SCIENCE 903PHYSICAL GEOLOGY

CONTENTS

I. EARTH STRUCTURES . . . . . . . . . . . . . . . . . 2

Shape . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Rocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Igneous Structures . . . . . . . . . . . . . . . . . . 9

Mountains . . . . . . . . . . . . . . . . . . . . . . . . . 13

II. EARTH CHANGES . . . . . . . . . . . . . . . . . . . . 17

Weathering . . . . . . . . . . . . . . . . . . . . . . . . 17

Erosion and Sedimentation . . . . . . . . . . . . 19

III. EARTH MOVEMENTS . . . . . . . . . . . . . . . . . 31

Isostasy . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Folding . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Plate Tectonics . . . . . . . . . . . . . . . . . . . . . 38

Author: Carl Sandberg, M.Ed.Editor-In-Chief: Richard W. Wheeler, M.A.Ed.Consulting Editor: Harold Wengert, Ed.D.Revision Editor: Alan Christopherson, M.S.

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“Surely there is a vein for the silver, and aplace for gold where they find it. Iron is takenout of the earth, and brass is molten out of thestone… .” (Job 28:1-2) “As for the earth, out ofit cometh bread; and under it is turned up as itwere fire. The stones of it are the places ofsapphires: and it hath dust of gold.” (Job 28:5-6). “My substance was not hid from thee, whenI was made in secret, and curiously wrought inthe lowest parts of the earth.” (Psalm 139:15)

The purpose of God in creating our planet isrevealed in Isaiah 45:18: “For thus saith theLord that created the heavens; God Himself thatformed the earth and made it; he hathestablished it, he created it not in vain, heformed it to be inhabited… .”

In fulfilling His intention to create aninhabited planet, God placed within and on theearth all things needed for human life: theminerals of which our bodies are made (Psalm139:15), which come from the ground byagriculture (Job 28:5).

God has put into the rocks of earth allminerals needed by organisms. He has alsotaken care that deadly poisons are not presentin soil in more than trace amounts. Asessential minerals are removed from the soil,rocks chemically disintegrate and make newsoil.

Heat, generated by radioactive elements,causes deeply buried elements to expand andcome to the surface where minerals needed forlife become available. Lowly worms andbacteria reprocess dead bodies of animals andplants into soil nutrients. Psalm 139:15 statesthat God formed the substance of our bodies

when the minerals were “in the lowest parts ofthe earth.”

Besides providing the necessities of life,God has put within the stones materialsnecessary for industry and commerce, as Jobsaid in chapter 28, verses 1–6. The earth’smagnetic field and its atmospheric electriccharges gave man information about the natureof atoms and the particles of which they aremade. This structure makes electroniccommunication possible. It reveals scientificprinciples by which to perform technologicalwonders. The marvelous ingenuity of man’smathematical systems and technical inventionsdemonstrate that the divine Creator made mana special creation like no other.

In space God is highly glorified by Hiscreation of billions of galaxies. The distancesbetween galaxies (measured in millions of lightyears) give man an understanding that God“inhabits eternity,” and that Jesus’ “goings-forth have been of old, from everlasting.”(Micah 5:2)

Since God is eternal, economy of timemeans nothing to Him, except within thehistorical framework of His plan of redemption.The time frame involves the generations ofpatriarchs and prophets preparing the way, theGospel age in which salvation is declared toevery tribe and nation, and Christ’s comingkingdom. Exactly how God created this planet,we are not told. In Genesis 1:1 the fact ofcreation is stated, and the account goes onfrom that point with the various parts of thesurface environment. This topic will be takenup in detail in this LIFEPAC®.

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PHYSICAL GEOLOGY

OBJECTIVES

Read these objectives. The objectives tell you what you will be able to do when you havesuccessfully completed this LIFEPAC.

When you have completed this LIFEPAC, you should be able to:

1. Glorify God by explaining how this world is designed as an environment for livingcreatures, including ourselves.

2. Trace the history of the concept of the earth’s shape.3. Name the three rock classes, to describe their origin, and name representatives of

each class.4. Describe the earth’s layers and the ways geologists have to investigate them.5. Name and describe igneous structures.6. List the types of mountain structures.

SECTION OBJECTIVES

Review these objectives. When you have completed this section, you should be able to:

1. Glorify God by explaining how this world is designed as an environment for livingcreatures, including ourselves.

2. Trace the history of the concept of the earth’s shape.3. Name the three rock classes, to describe their origin, and name representatives

of each class.4. Describe the earth’s layers and ways geologists have to investigate them.5. Name and describe igneous structures.6. List the types of mountain structures.

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7. Explain the effects of weathering, erosion, and sedimentation.8. Name the agents of weathering.9. Describe evidence of movements in the earth’s crust.

10. Explain the current theory that explains the origin of volcanoes, earthquakes,mid-ocean ridges, ocean trenches, and mountain ranges.

Survey the LIFEPAC. Ask yourself some questions about this study. Write yourquestions here.

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I. EARTH STRUCTURES

Section I presents evidence from ancientwritings that people have known the earth to bea sphere for thousands of years. The sphere ismade up of several layers of differingcompositions. The top layer—the earth’s

surface—consists of three classes of rock. Twoof the classes are derived from the originaligneous rock. The surface has experiencedmovements that have produced a variety oflandforms.

VOCABULARY

Study these words to enhance your learning success in this section.asthenosphere (as then’ u sfir). A plastic, semi-liquid region of the earth’s mantle directly

beneath the crust.crust (krust). The solid outer layer of the earth.mantle (man’ tul). The part of the earth beneath the crust and above the outer core.

Note: All vocabulary words in this LIFEPAC appear in boldface print the first time theyare used. If you are unsure of the meaning when you are reading, study the definitionsgiven.

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Pronunciation Key: hat, a-ge, cãre, fär; let, e- qual, te.rm; it, i

-ce; hot, o-pen, ôrder; oil; out;

cup, pu. t, rüle; child; long; thin; /T-H/ for then; /zh/ for measure; /u/ represents /a/ in about,/e/ in taken, /i/ in pencil, /o/ in lemon, and /u/ in circus.

Ancient Asiatic Indians are said to havethought the earth was flat and supported bypillars. It is said they thought the pillars weremoral principles, such as truth and justice.Actually, however, they knew the earth was asphere and used the diameter of the earth asthe base of a triangle to calculate the distanceto the moon. They concluded that this distanceis thirty times greater than the diameter of ourglobe.

Eratosthenes, a Greek scientist who lived inEgypt, is usually credited as the first tocalculate the circumference of the earth. Atnoon on the first day of summer, he measuredthe angle of the sun’s rays at Alexandria and atSyene (Aswan), both in Egypt. Since thedifference in angle was almost one-fiftieth of acircle, the earth’s circumference was fifty timesthe distance between the towns. Eratosthenesmight have been merely confirming aconclusion that Egyptian surveyors had madelong before.

Aristotle, the Greek philosopher honoredand studied in the Later Middle Ages, said thatthe earth was a globe because the earth’sshadow (seen crossing the moon during aneclipse) is always round. The only shape thatgives a round shadow from every direction is asphere.

Saint Augustine of Hippo wrote, “It hasbeen scientifically proven that the earth is asphere,” although he doubted that people wereliving on the opposite side of the globe.

Astronomy taught in the Middle Ages wasthe teaching of the first-century Greek-Egyptianauthor, Ptolemy. Ptolemy was incorrect thatthe sun and other planets circled the earth. He

was correct when he described the earth as asphere with an equator, North Pole, and SouthPole.

From the fourth to the fourteenth centuries,kings in Europe held a globe to represent theworld in their hand during their coronationceremony. Countless incidental remarkspreserved in historical chronicles and poeticalworks confirm that the reading public allthrough the Middle Ages took for granted thatthe earth is a sphere. Textbooks used inmonastery and cathedral schools, as well as inlater medieval universities, are unanimous insaying that the earth is a sphere.

Sir Isaac Newton reasoned that the earthbulges slightly at the equator, and that theearth is flattened at the poles. Measurementsshow that his reasoning was true. The bulge isless than one-sixth of 1 percent of the diameter,and the flattening at the pole is about as large.One of Newton’s friends, William Whiston, reada manuscript of an ancient Greek author,Aqatharcides. This author was told by anEgyptian priest and college professor that thegreatest pyramid near Cairo was designed to beone-eighth of a minute of latitude in width, orone-480th of a degree of latitude on each side.When sand was dug away from the base of thepyramid, its width was found to be within a fewinches of that size. Possibly, ancient Egyptiansurveyors knew about the spherical shape ofthe earth, had measured it, and had passed ontheir knowledge to Greeks who traveled or livedin Egypt. Therefore, Egyptians of the pyramidage should more properly be given credit forfirst calculating the circumference of the earth.

SHAPE

Complete these sentences.

1.1 The Greek scientist usually credited as the first to calculate the earth’scircumference was __________________________________________________________ .

1.2 The first century Greek-Egyptian whose explanation of astronomy was taughtin Europe and the Middle East was ________________________________________________ .

1.3 Textbooks used in monastery and cathedral schools, and in medievaluniversities, taught that the earth is a ____________________________________________ .

Answer these questions.

1.4 What evidence did Aristotle present for a spherical earth?_______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

1.5 According to an ancient Egyptian priest, a pyramid near Cairo was built with acertain basal dimension. What was the dimension?________________________________________________________________________________________________________________________

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The three main categories of rock in theearth’s crust are igneous, sedimentary, andmetamorphic. Igneous rocks were originallymolten; then they were crystallized by cooling.Sedimentary rocks were laid in place by movingwater, ice, or wind. Metamorphic rocks arerocks that were under enough pressure, or heatcombined with pressure, to twist the crystalswithout melting the rock.

Igneous rocks. Igneous rock that flowedout on the surface is lava; lava blown out of avolcano in explosive eruptions is volcanic ash,or tuff. Igneous rock beneath the surface ismagma. Igneous rock that contains separatecrystals of quartz (silicon dioxide), feldspar,and mica is granite. Igneous rock with thesame minerals as granite, but in microscopiccrystals, is rhyolite. A type of igneous rockwhich has more magnesium than aluminum isbasalt, whether it hardened above the groundas lava, below the ground and frozen into rowsof pillars, or under water where it makes pilesof “pillow lava.”

Sedimentary rocks. Sedimentary rockmade mostly of sand is sandstone. Pieces ofrock larger than sand are called gravel,pebbles, cobbles, or boulders, depending onhow large they are. Seashells and other forms

of calcium carbonate are cemented together inlimestone. Any sedimentary rock that containsrounded stones and sand is calledconglomerate. Rock containing broken piecesof rocks that have not been rounded is calledbreccia. Sedimentary rock made from mud iscalled siltstone, and rock made from clay iscalled shale.

Metamorphic rocks. Metamorphic rocksdiffer according to what kind of rock they aremade from, and according to the degree towhich they have been changed by heat andpressure. Shale can be mildly metamorphosedinto slate or further changed into schist.Limestone can be changed by pressure intomarble. Sandstone can be metamorphosedinto quartzite.

When high heat and pressure distort thecrystal structure of previously formed rockswithout melting them, the result is ametamorphic rock. Some metamorphic rocksare changed a small amount from their originalconditions. Bituminous (tar-containing) coal,for example, can be slightly metamorphosedinto anthracite (hard coal, used forsteelmaking). Greater pressure can causefurther stages of metamorphism, turninganthracite into graphite, the material fromwhich pencil “lead” is made.

ROCKS

Complete these sentences.

1.9 Rocks that originated from the liquid phase are classified as _______________ .1.10 Igneous rock that flowed out on the surface of the ground is called

_______________ .1.11 Igneous rock beneath the surface of the ground is called ______________ .1.12 Lava blown out of a volcano in explosive eruptions is called a. _______________ ,

or b. _______________ .1.13 Granite is composed of crystals of a. _______________ and the minerals

b._______________ and c. _______________ .1.14 A type of igneous rock with more magnesium than aluminum is _______________ .

Complete these activities.

1.15 Explain how the three categories of rock are formed.a. igneous___________________________________________________________________________________________________________________________________________________________________________b. sedimentary______________________________________________________________________________________________________________________________________________________________________c. metamorphic ____________________________________________________________________________________________________________________________________________________________________

1.16 Complete the chart of sedimentary rocks.

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Teacher check ___________________________________________________________________Initial Date

1.17 Complete the chart of metamorphic rock.

Pieces

sandrounded stonesangular rocksmud or clay

a. ____________________________b. ____________________________c. ____________________________d. ____________________________

Rock

Sedimentary Rock

shalelimestonesandstone

a. ____________________________b. ____________________________c. ____________________________

Metamorphic Rock

Write true or false.

1.6 __________ The equivalent of granite with crystals too small to be seen is rhyolite.1.7 __________ Metamorphic rock originated under conditions of high heat and pressure.1.8 __________ A characteristic that helps identify granite is crystal size.