chapter i introduction to geology
TRANSCRIPT
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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
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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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p p y y , j ,
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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Lets assume you are a geo-astronaut at Meridiani landing site.
What are the immediate implications of these early findings?
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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Lets assume you are a geo-astronaut at Meridiani landing site.
What are the immediate implications of these early findings?
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.
2) Rock outcrops or soil may contain insitu hematite - helping
to explain its origin (related to standing water, or
groundwater)
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Lets assume you are a geo-astronaut at Meridiani landing site.
What are the immediate implications of these early findings?
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.
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?