SAGE Fall 2010

Session 3

Vagabonds Tramping Geology: Austin to Arctic Alaska

Carlsbad to the Rio Grande Rift

The impatient thrust for scholarship is the secret of youthfulness: the undying flame that lights the human spirit

Senior University Fall 2010

Session 3

Vagabonds Tramping Geology: Austin to Arctic Alaska

Carlsbad to the Rio Grande Rift

Rare earth metals are a collection of seventeen chemical elements in the periodic table, namely scandium, yttrium, and the fifteen lanthanides

Uses: hybrid cars, superconductors, television sets, welding, munitions, etc

Geology in the News

Geology in the News

Geology in the News

Large area of interior drainage due to glacier melting 12,000 years ago

Geology in the News

From the minute to the sublime

Putting It All Together

Last Glacial Maximum: 16,000 years ago

Geology in the News

Carriz

o San

dstone

outcro

p

Deposition and Burial before Uplift and Erosion

Younger CretaceousOlder Cretaceous

Carrizo Sandstone

Area forWater wells

Geology in the News

Car

rizo

San

dsto

ne o

utcr

op

Giddings290

Giddin

gs

Gas F

ield

s

Geology in the News USATerritorial waters

Putting It All Together

The Earth’s Amazing Living Crust

Living: it reproduces itself

Continental Crust: Periodically Renewed

Oceanic Crust: Continuously Recycled

Granites firstFoundation rocks of the continents

Basalts & Gabbros nextFoundation rocks below the deep oceans

AND below the continental crust.

After the atmosphere and oceans were formed:

4.8 billion years ago cooling of hot gases and dust created igneous rocks of the continents & oceanic crust

Then the oceans and the atmosphere

After the atmosphere and oceans were formed:

The granites at the surface of the continents were weathered and eroded into:

Clay and Sand

The clay & sand were carried by rivers to the oceans and deposited at the continental margins

Burial of the clay and sand produced sedimentary rocks of shale and sandstone

and

and

Mountain building along the continental margins melted the sedimentary rocks producing:

Metamorphic rocks (partially melted) and Igneous rocks (completely melted)

Rocky & Cordilleramountains

Deformed sedimentary rocksMetamorphic rocksIgneous granites and basalts

Deformation of Continents: Two Types

Rocky Mountains

Deformation of Continents: Two Types

1. Mountain building: collision of twoor more crustal plates

2. Continent warping creating major rivers that deposit erosional debris along the coast

The history of the Oceanic CrustResult: Major rivers concentrate erosional debris in the oceans at the continental marginsAnd plate collisions weld that debris back into the continent as mountains

Oceanic Crust: Basalt 5 miles thickContinuously Re-cycled

Oceanic crust ismelted as it is over-ridden by continental crust

New oceanic crust is created in oceanic ridges

Resulting in: Oceanic crust is 0 to 250 million years old Continental crust is 0 to 4.8 billion years old

The North American Pacific Example

Earth’s Crust: Plates

Earth’s Crust: PlatesPacific and North America

Earth’s Crust: Pacific and North American Plates

Back to our route to New Mexico

Pacific Plate

under North America

Recent Rocky MtDebris

From: Roadside Geology of TexasHow far did this river debris extend?

“Recent River debris from the rising Rocky Mountains on top of older rocks

A Closer Look on OurWay to New Mexico

Cretaceous Limestones

Gravels & Sands

Sands & Muds

Recent Erosional Debris in Texas from the Mountains of New Mexico

Rece

nt R

ising

Rock

y M

ount

ains

Recent Debris in New Mexico

Recent Debris in New Mexico

Mo

un

tain

s sh

edd

ing

deb

ris

east

war

d

Recent gravels& sands from rising Rocky Mts

Pecos River

Now the big picture in North America

Pacific Plate

under North America

Cordilleran &

Rocky M

ountains

Hypothesis: Yellow: recent debris from the rising mountains that might have provided the access to the Americas for early humans migrating out of Siberia

A quick look at the advent of humans

Melting Continental Glacier

Earth’s Crust: PlatesPacific and North America

HomoerectusHomo

Antecessor/mauritanicus

Homoergaster

The Current Geological Record on the Advent of Humans Focus on the

last 80,000 years

Homorhodesiensis

Homoneanderthalensis

Homo sapiens

Times of Continental Glaciation:Northern Hemisphere

Missing Link?

Uniquely human characteristics?1. Reason

2. Conscience (right & wrong)3. Adapt to any climate

Time of WrittenWorld History

Now, a look at the human migration route

Last ice age

Rift ValleysLocation of earliest human fossils

Nile River

Possible Migration Route of Humans

It’s a 15,000 mile walk from

Kenya to Austin, Texas!!!Back to our journey to New Mexico

App

alac

hian

Mou

ntai

ns

Rocks of Central & West TexasPermian Rocks 260 million years old

Permian rocks at the surface

Thick PermianReef LimestonesCretaceous

L

imestones

The big Permian picture

Thickness Map: Permian Period

Permian Basin

P B King; The Evolution of North America, 1959

A Cross Section of the Permian Basin

Reefs

The oil fields of the Permian Basin

Permian Reef at the surface

The oil fields of the Permian Basin

Delaw

are

Basin Perm

ian BasinM

idlan

d

Basin

Central B

asin

Platform

Now, into New Mexico

Two drainage systems

Natural Resources

Only copper and coal no tin or iron

Little farming land

But the geology is fantastic!

Rio

Gra

nd

eR

ift

(tre

nch

)R

ock

y M

ou

nta

in

Arc

h

Present daysurface

Continental

Crust

Continental CrustContinental Crust

Mantle rock (hot!)

A cross section of the Rio Grande Rift

HorstHorst

RiftGrabenTrench

Arch

From Roadside Geology of New Mexico, Chronic, Halka, 1987

The Rio Grande Rift (graben)

Graben partially filled with debris from bounding horsts

Western Horst Eastern Horst

Rio

Gra

nd

e G

rab

en

Eas

tern

Ho

rst

Wes

tern

Ho

rst

Focus: Eastern HorstCarlsbad to Roswell to Alamogordo

Rio

Gra

nde

Rift

Geologic Map: Southeast, NM

Mountains on the East HorstOrange= non volcanic red = volcanic

Rio

Gra

nde

Rift

Rio

Gra

nde

Rift

Sierra BlancaIgneous Mountains

Sierra BlancaIgneous Mountains

Igneous Rocks and Rifts

Present daysurface

Continental

Crust

Continental CrustContinental Crust

Mantle rock (hot!)

HorstHorstGraben

Sierra BlancaIgneous Mountains

Sierra Blanca Mountains Volcanic Igneous rocks: Tertiary Age

Cloudcroft

Geologic Map: Sacramento Mountains

Alamagordo Sacram

ento

Mountains

Cloudcroft

Alam

ogor

doR

ec

ent

Rif

t V

alle

y f

ill d

eb

ris

Do

wn

Rocks at the surfacePermianPennsylvanianLower PaleozoicPre-Cambrian

Geologic Map: Sacramento Mountains

Up

How thick are these pre-Permian Rocks?

Recen

t Mounta

in

deb

ris

Perm

ian a

ge ro

cks

Pennsylvanian age rocks

Lower Paleozo

ic age rocks

Pre-Cambrian continental foundation rocks

Recent fill

Now, going west across the Rio Grande Rift

Cross Section of Eastern Horst

Rio

Gra

nde

Rift

Road Map: New Mexico

Crossing the Rio Grande Rift

White Sands

White Sands

Modified Space Photo

White Sands National Monument

Crossing the Rio Grande Rift

San Andres Mountains

San Andres Mountains

White Sands

http://en.wikipedia.org/wiki/San_Andres_Mountains

San Andres M

ountains

San Andres Mountains

Complex Up-thrown Fault Block in middle of Rio Grande RiftInvolves Permian & Tertiary sedimentary rocks Contains rhyolites & granites (continental crust melted)

Present daysurface

Continental

Crust

Continental Crust

Mantle rock (hot!)

HorstHorstGraben

Continental Crust

Crossing the Rio Grande Rift The Western Horst

San Andres Mountains

Plains of St. Augustine

Datil-MogollonVolcanichighlands

Rio

Gra

nd

e R

ift

Wes

tern

Ho

rst

What is a Caldera? Answer: A “granitic”** volcano that has blown off its top

**Granitic = melted continental crust

Caldera

Explosion!!!!

Collapse !!

Volcanic Explosions: Mt. St. HelensTambora in Indonesia

Tambora36 cubic milesof ash!!!!

Mt. St. Helens.25 cubic milesof ash!!!

Largest knownVolcanic explosionIn human history!!

Earth

Volcano

Volcanic Ash

Indonesia, Island of Sumbawa

Indonesia

Indonesia Sumbawa Island Tambora Volcano

SumbawaIsland

Tambora Volcano, IndonesiaLargest in Human History

Tambora36 cubic Miles!

Mt St Helens.25 cubic Miles

Two of Three Volcanic Explosionsat Yellowstone

HuckleberryRidgeVolcanicExplosion600 cubic milesof ash!!!!!

Lava CreekVolcanicExplosion

Yellowstone Volcanic Explosion Calderas!!!

Tambora36 cubic miles

Lava Creek & HuckleberryRidge, 600 cubic miles!!!

Mt. St. Helens

Yellowstone’sThree Explosion Calderas!!!

YellowstoneExplosion Calderas!!!

Arizona and California

Next Week

Rio

Gra

nd

eR

ift

Ro

cky

Mo

un

tain

A

rch

ColoradoPlateau