Chapter I Introduction to Geology

7/31/2019 Chapter I Introduction to Geology

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Introduction to GeologyChapters 1, 22


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The science of Geology

Geology is the science that pursues an

understanding of planet Earth

Physical geology - examines materials

composing Earth to understand processes

that operate beneath and on its surface


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Geology, people, and the environmentRelations exist between people and naturalenvironments

Problems and issues addressed by geology

What aspects of Geology affect people?


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Aspects of Geological Science that affect people

Natural Hazards

Floods

Earthquakes

Volcanic eruptions

Landslides

Natural Resources

Oil and Gas

Metals

Coal, Uranium

Gravel, Sand

Water


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earthquakesresources

floods volcanoes


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Oil Production - all of CO.

Water Use - Colorado River, Front RangeWater grabs, etc

Debris Flows - I-70 corridorBig earthquakes - San Luis Valley

Little earthquakes - Denver, Trinidad

Rock Quarries - Lyons, Eldorado Mtn

Big Thompson Flood - Loveland

Metals and Pollution - Climax mine, I-70

Tourism: Natl Parks, RMNP, CO Natl Mon.

What aspects of Geology affect us in Colorado?


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Geologic time

The magnitude of geologic time

Involves vast timebillions of years

An appreciation for the magnitude of geologic

time is important because many processes occur

intermittently (not at 80 yr lifespan of humans)

Recurrence of Geologic events greater than

usual human lifespans

What geologic events have happened in your lifetime?

Earthquakes, Volcanic eruptions, Floods


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Geologic Time Scale

First defined by

organisms (fossils)

Later given actual

numbers using

radioactive age dating

Gives us a historical

framework to place

events into

Memorize this later


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Scientific Inquiry

Science assumes the natural world is

consistent and predictable

Goal of science is to discover patterns in

nature and use the knowledge to make

predictions

Scientists collect facts through

observation and measurements.


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How would a Geologist make observations?

Geologic Mapping - walk around, look at rocks,

make maps

Satellite images, photos & other dataGlobal Positioning Satellites

Drillholes from oil exploration

Seismic Reflection Data

Topographic maps, radar and laser scanning


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Radar mapping of ground movements

& earthquakes with INSAR,

Interferometric Side Aperature Radar


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Satellite

Images,

photos &

spectral data

AthensOlympic

venues

Need Boulder Ikonos


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Laser scanning of topography

(Loveland CO)

Laser scanning of topography

(Loveland CO)


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What are objects on Image?A) Rocks

B) Trees

C) Houses

D) Lakes

E) All of above


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Seismic Reflection Profiles

Geological CAT scans


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Earth as a system

The Earth system is powered by the

Earths interiorHeat remaining from its formation and that

generated by radioactive decay powers the

internal processes that produce volcanoes,

cause earthquakes, and make mountain

belts.

Earth convects like a

boiling pot - exchangingheat from its interior to

the surface.


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Earth as a system

The size and composition of a planetaffects how quickly it sheds its internalheat budget

Earth still shedding lots of heat (drives plate tectonics byconvection of the mantle)

Smaller Mars already has lost much of its internal heat(probably never convected)


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The rock cycleSeries of processes by which rocks changes intoother types of rocks

Illustrates various processes and paths as earthmaterials change both on the surface and insidethe Earth

What are the

three main rock

types?

IgneousMetamorphic

Sedimentary


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Early evolution of Earth

Origin of planet Earth

Earth and the other planets formed at

essentially the same time from the sameprimordial material as the Sun

Nebular hypothesis

Layered structure developed by chemicalsegregation early in formation of Earth

Dense material moves to center of Earth,

lighter material remains at shallower levels.


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Nebular Hypothesis

Gas cloud -> Disc -> Solar system

Sun mostly Hydrogen and Helium

99.9% of mass in solar system

Universe is ~13 Billion years old

Solar system ~4.5 Billion years old

Heavier elements from older stars

Sun will eventually swell, fry inner

planets and then shut off


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Earths internal structure

Earths internal layers can be defined by

Chemical composition

Physical properties

Layers defined by composition

Crust

Mantle

Core


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Earths internal structureFour main layers of Earth are based onphysical properties and hence mechanical

strength Lithosphere (behaves like a brittle solid)

Asthenosphere (behaves like a plastic solid)

Lower Mantle

Core

Note the lithosphere is comprised of the crust anduppermost mantle


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How was the moon formed?

Facts:

Moon made up of same rocks as Earths

mantle

Moon is about the same age as Earth(timing of giant impacts in solar system)


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Formation of the Moon

- impact of a Mars sized

planet with an early Earth

Frames from a simulation

of this event

super computer analysis of planet collision (Jay Melosh UA)


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6.7 minutes0.0 minutes

13.4 minutes 20.1 minutes

super-computer analysis of planet collision (Jay Melosh-UA)


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26.7 minutes

33.4 minutes


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Early Moon & early Earth were hammered

by large impacts. Solar System eventually cleans

itself up and gets organized into planets withstable orbits.


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Impacts have higher

momentum produced by

high velocity of projectile

Magnum bullet

analogue


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What evidence for large impacts exists

In our Solar System?

A) CratersB) High concentrations of Iridium

C) Spin axis of some planets (Uranus sideways spin,

Mercury spun completely around)

D) Broken & melted rocks

E) All of above

Clicker Question


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Craters on Moon

C t M


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Craters on Mercury


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Craters on Mars

Very recent example Older crater with

fluidized ejecta


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Comparison of Earth and Mars

Both are terrestrial planets

Mars is smaller

Mars lost heat early in history, mantle never convected

(no plate tectonics, heat lost through one place, Tharsis

Mars lost its magnetic field and atmosphere

(less erosion on Mars, especially late in its history)


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A. Oceans on Earth keep it cooler making it less prone to

volcanic eruptions

B. Earths core is made of of different materials than on Mars

C. Convection of Earths mantle (produces plate motions)

D. A smaller core on Mars causes its magnetic field to shut on

and off

Given the difference in size of Earth and Mars, and their

cooling histories, what fundamental process occurs deep inthe Earth that controls many geologic processes such asearthquakes and volcanism?

Clicker Question


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Are geologic processes the same on Mars as Earth?

Olympus Mons: huge volcano on Mars (70 miles tall!)


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Olympus Mons: huge volcano on Mars (70 miles tall!)


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Sand Dunes on Mars, dark spots are melting carbon dioxide ice

Ch l d d b fl i t i th t MCh l t th i t f t t i ll i th t


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Channels eroded by flowing water in the past - MarsChannels suggest the existence of past water, especially in the past

L d di t d it d i b i b i d d b i dO t f d d di t


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Layered sediments deposited in basin, now being eroded by windOutcrops of eroded sediments


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Mars Exploration Rovers - a current geologicalinvestigation of the surface of another planet

See: http://marsrovers.jpl.nasa.gov/home/

What is a MER?

How do the Rovers work?

What do the Rovers do?

What have the Rovers discovered (so far)?


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Question: Why does NASA want to go to Mars?

A) Search for water

B) Search for life (LGM?)

C) Spend tax dollars

D) Keep bored scientists busy

E) Develop new technology

Where should we go?

Someplace with possible record of past life


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Mars factoidsMars had a solid/liquid Ni/Fe core 4 Billion yrs ago

Core solidified, shut off planetary magnetic field

Solar wind blew atmosphere/water out into space

Water still exists, but now mostly buried icePolar icecaps are CO2 ice

Atmosphere is very thin, 1% of Earths


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How do we go to Mars?

Once every two years due to Earth/Mars orbits

With a Delta Rocket, takes about 6 months

How do we land on Mars?

With a supersonic parachute, backshell rockets,

kevlar airbags (2 of 3 missions fails)

Where can we land on Mars?

At low elevations due to 1% atmosphere

Someplace where the rover can maneuver

Someplace that is geologically interesting

Show Mission Movie:

http://marsrovers.jpl.nasa.gov/gallery/video/animation.html
http://marsrovers.jpl.nasa.gov/gallery/video/animation.htmlhttp://marsrovers.jpl.nasa.gov/gallery/video/animation.html


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How are tools used by rover different from a geologist on Earth?

Rover GeologistCost = 400M$ 80K per year

Moves 30 m/day Moves ~ 5-10 km/day

Works in extreme environments Limited to terrestrial environments

Onboard chemical analyzers -> samples back to lab, same results

Limited to onboard tools -> samples for other analyses (rx age)

Uses images from orbiting spacecraft Uses images from orbiting spacecraft

Doesnt drink beer Access to other databases, GPS,

seismographs, etc


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Landing Ellipse in Gusev Crater

Wind causes variation in landing

Spacecraft is not steerable


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Spirit Landing Site

On Meridiani Planum


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Dust Devil


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360 degree panorama 20X

What do you see in this image?


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Map of landing site on Meridiani


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Rover Opportunity landed on Meridiani Planum

Descended directly into a small crater

First discovery of rock outcrops (earlier

missions examined rocks that had been

carried into landing sites during floods)


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Stone Mountain Context

Outcrops of sedimentary rocks in crater

Closeup


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Stone Mountain - Meridiani

p

What features


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What features

would a geologist

observe and note

in this image?


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Spherules in soil

Spherules in rock

Different comp-

osition of spherules

relative to encasing

rock

Layering in rock

Wind deposits


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How did

the different

size particlesend up as

loose

sediment?

A) Wind?

B) Impacts?

C) Groundwater?

D) Combination?

Geologists use rocks to interpret the

past history of a particular place, &

to infer past environments


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TES: Thermal Emission Spectrometer


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How an obscure mineral provided a vital clue to Martian water


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These images, taken by cameras on the Mars rover Opportunity, show a close-up of the rock

outcrop dubbed "El Capitan," located in the rover's landing site, a crater at Meridiani Planum.

Inset, a detail of the rock showing one of the tiny spherules, nicknamed "blueberries." NASA/JPL

By Blaine P. Friedlander Jr.

PASADENA, Calif. -- On the southeastern coast of Spain, the Sierra Almagrera range provides a bounty

for geologists. One area, in particular, the Jaroso ravine, has yielded a huge catalog of unusual minerals.

Among them is one that will be forever tied to Martian history. In 1852 a German mineralogist

discovered an unusual amber-yellow-brown mineral made of potassium iron sulfate hydroxide in Jaroso.

He named the mineral jarosite. Since then the world has had little use for jarosite. Until now.

On Tuesday, March 2, Cornell's Steven Squyres, principal investigator on the twin-rover Mars mission,

told a press briefing at NASA headquarters in Washington, D.C., that his team had found jarosite on

Mars. Since the mineral only forms in dilute sulfuric acid in ground water, the discovery was a clear

indication that water once abounded in the area around the rover Opportunity's landing site in a crater on

a vast plain called Meridiani Planum.

This modern voyage of discovery started in NASA's Jet Propulsion Laboratory (JPL) on Jan. 25, the day

following the rover Opportunity's landing, when Jim Bell, Cornell associate professor of astronomy and

the scientist in charge of the two rovers' panoramic cameras, received the rover's first color image of the

crater in which it had landed. When the image appeared on television monitors in JPL's von Karman

auditorium at 2 a.m., Squyres reacted by saying, "This is the first outcrop ever found on Mars."

Bedrock outcrops, he pointed out, usually provide strong clues to geologic history. Squyres wasprophetic. Beneath the dusty veneer and the rocky crust, jarosite awaited. For the next few weeks,


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Opportunity cruised around the crater while JPL scientists tested the rover's platoon of geologic tools.

By Feb. 20, or Martian day (sol) 27, the rover examined the outcrop, now dubbed El Capitan, with its

panoramic cameras, miniature thermal emission spectrometer (Mini-TES) and microscopic imager.

The following day Opportunity placed its Mssbauer spectrometer and its alpha particle X-rayspectrometer (APXS) on the rock surface to assess mineral presence. Opportunity performed its first

rock abrasion tool (RAT) operation on Feb. 24 on a rock target known as McKittrick Middle Rat at El

Capitan. The tool shaved the rock over a period of two hours, grinding into a total depth of about 4

millimeters (.16 inches). After the abrasion tool retracted, the scientists took microscopic images of the

hole, and the APXS was later pointed inside the rock. "Finding evidence of water hasn't been an 'Aha!'

moment," said Bell. "It's been a series of data sets building in our minds. The measurements trickle in

and we wait for data. Then we interpret the data, throw ideas around, reach a consensus and we get asnapshot of the consensus."

On sol 32 on Feb. 26, the Mossbauer continued to examine the hole for spectral signatures of iron-

bearing minerals. This led the science team to discover gray spheres, dubbed "blueberries," which had

likely been solidified from a water source. When all the data was in, the APXS had detected large

amounts of sulfur and the Mssbauer had detected jarosite, a finding that the late Roger Burns, a

geologist at the Massachusetts Institute of Technology, had predicted several years ago.

The last piece in this early stage Martian water puzzle fit, Squyres realized, when the last Mssbauer

data returned Friday, Feb. 27. Immediately NASA officials began working with him to organize the

March 2 press conference. "Most of the scientists went into this mission armed with hopes and

prejudices," said Squyres. "It's been fun over the past few weeks to watch the puzzle come together right

before my eyes."


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Hematite in banded

iron formation (bif)

Archean of Wyoming

Lets assume you are a geo astronaut at Meridiani landing site


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Lets assume you are a geo-astronaut at Meridiani landing site.

What are the immediate implications of these early findings?


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1) Bedrock is exposed in shallow craters, suggesting that this

part of Mars is covered by only a very thin layer of

windblown deposits -and it may be relatively easy to observe

and analyze underlying rocks.


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2) Rock outcrops or soil may contain insitu hematite - helping

to explain its origin (related to standing water, or

groundwater)


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2) Rock outcrops or soil may contain insitu hematite -helping to

explain its origin

3) Evidence for hematite in volcanic or hot-spring deposits

may be a great place to look for evidence of past life (e.g.

fossils).


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Clicker question

A) Large channels that were cut by water

B) Deposits of sedimentary rocks in craters

C) Minerals like Hematite that were precipitated from water

D) Layered sediments that could only form in streams or lakes

E) All of the above

What evidence for water on Mars has been discoveredin the past few years by NASA spacecraft?

Documents

Chapter I Introduction to Geology