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Disclaimer: These notes were taken by Marcus Pollard in Geology 1040 during the
Fall semester of 2004 and were not distributed nor approved by any Geology
professor directly.
Geology
8-30-04
1. Introduction
a. What is Geology?
i. It is the study of our planet (Earth) and its processes and changes
in the past, present and future.
1. It is unique to geology and time
2. Processes take 10s of millions of years
b. What do Geologists do?
i. Solid Earth:
1. Earthquakes
2. Volcanoes
3. Land-shaping Processes
4. Structure and Movement of Rocks
5. Structure/Processes of the Inner Earth
6. All Rocks and Minerals
7. Streams and Lakes
8. Soils
9. Earth Chemistry
ii. Resources:
1. Making Maps
2. Geothermal Energy
3. Ground Water
4. Mineral Resources
5. Petroleum (Oil & Natural Gas)
6. Coal
iii. Life History:
1. Fossils and earliest life (3.465 Ga)
2. Geoarchaeology
iv. Ocean and Climate History:
1. Glaciers
2. Ocean and Climate Dynamics (Global Warming)
v. Planetary History:
1. Formation of Earth
2. Formation/Structure of other planets (Mars exploration
rovers: There was once water on mars!)
3. Meteorites
c. What is Science?
i. A particular way of knowing about the world
ii. A disciplined way of asking questions and seeking answers
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iii. It’s an explanation of physical world limited to those based on
observations and experiments
iv. Questions that science can address:
1. How old is the earth?
2. How do birds fly?
3. Why is the sky blue?
v. Questions science can’t answer:
1. Is the Mona Lisa a great painting?
2. Is it ever ok to lie?
3. Is there an afterlife/reincarnation?
d. The Method of Science:
i. Recognize the problem
ii. Collect the data and facts
1. Facts: an observation that can be confirmed
iii. Propose a hypothesis
1. Hypothesis: A testable statement about the physical world
2. A possible explanation
iv. Test the hypothesis
1. The experiment will either reject or confirm the hypothesis
v. Theory: A time-tested well established explanation. It’s not a
guess or a hunch. It’s supported by an abundance of evidence.
They stand the test of time.
1. Atomic Theory: Over 100 years old
2. The sun is at the center of the universe
3. Biological Evolution: 150 years old
e. History of Geology:
i. Early Greek writing (Aristotle)
ii. Catastrophism: Earth’s landscapes are created suddenly by
catastrophes.
iii. Uniformitarianism: Same processes we see today were operating
throughout Earth’s history.
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The rates of processes have changed
James Hutton (late 1700’s): He wrote Theory of Earth
He recognized that geologic periods occur over very long time periods.
Uniformitarianism: This is the fundamental doctrine of geology. “Present is key to the
past”.
2. Cosmology: A branch of astronomy that deals specifically with the study of
large-scale structure of the universe, its origin, and evolution throughout time.
a. Our place in the Universe:
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i. Geocentric Universe (A Greek idea): Thought by Plato/Aristotle.
This claimed that the Earth is the center of the universe. Ptolemy
supported the idea by mathematical equations that he forced to fit
the problem.
ii. Heliocentric Universe: Proposed by Philolaus (500 B.C.). The sun
is the center of the universe. Copernicus in the 16th century
disproved Plato/Aristotle’s mathematics.
1. Galileo’s Evidence:
a. The moons of Jupiter
b. The phases of Venus
c. Sun spots
2. Kepler (late 1600’s): He showed that orbits weren’t
circular but are slightly elliptical.
b. What is known today?
i. The universe is 13.7 billion years old.
ii. The shape of the universe is geometrically flat.
iii. The make-up of the universe is 27% matter.
iv. Only 4% is ordinary matter (matter that can be seen).
v. 23% is dark matter that can’t be seen.
vi. 73% of the make-up of the universe is dark energy.
vii. The universe is currently expanding 71km per second.
c. Data by “MAP” Probe:
i. The Milky Way is 10-11 billion years old. It holds 100 billion
stars. It’s 100,000 light years across.
1. Light years travel 186,000 miles per second.
ii. There are about 100 billion galaxies.
iii. The most distant galaxies are about 13 billion light years away.
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d. Origin of the Universe (As presented by cosmologists)
i. Big Bang Theory (BBT)
1. Proposed in 1927 by George Lamaitre, a Frenchman.
2. He believed that all matter and energy seen today was
created suddenly.
3. The universe expanded from a hot, dense state to the
cooler, less dense state today.
a. This was predicted by Einstein
4. The BBT can’t explain anything before it.
ii. Evidence for the BBT
1. Red shift in lights from other galaxies
a. There is a shift in light toward longer wavelengths
and lower energy.
b. Doppler Effect: A change in sound wavelength as
source moves with respect to observer.
i. This is also the same with light wavelengths.
c. Edwin Hubble (1929):
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i. Galaxies in the Virgo cluster were all red
shifted.
ii. His interpretation was that galaxies were
moving away from the earth.
2. Cosmic Microwave Radiation (CMR)
a. CMR is believed to be remnants of the BBT.
b. It was first detected in the 1960’s.
c. It was found that radiation was the same in all
directions in the sky.
d. Due to the find, the BBT was widely accepted.
e. The wavelengths are 7cm.
e. What happened after the Big Bang?
i. Early universe was too hot to have matter, only energy (10 billion
degrees Fahrenheit).
ii. At 1 second the universe cooled enough to have fundamental
particles (protons, electrons, neutrons, quarks).
iii. At 3 minutes, cooled enough for atoms:
1. hydrogen
2. helium
3. lithium
iv. < 200 million years star and galaxy formation
1. Four hydrogen atoms squeezed together to make helium
and lots of energy which created first star generations.
v. Heavier elements formed in the cores of stars.
1. Dispersed throughout the universe through a supernova
2. There are 92 naturally occurring elements that originated
from stars.
f. Formation of the Star System
i. Began about 5 billion years ago
ii. Nebula hypothesis
1. Must explain the formation of the solar system, sun and
planets.
2. All planets revolve around the sun in the same direction
and the same plane (Ecliptic Plane) except for Pluto.
iii. Nebula (Gas and Dust) in Milky Way Galaxy begin to rotate.
Rotation is important because it concentrates mass in the center.
Rotation is induced by rotation of the Milky Way or a nearby
supernova.
iv. Gravity concentrates mass in the center of the nebula. This is
where the sun forms.
1. Nuclear fusion is required for stars.
v. Planetesimals: Condensed in eddies (little swirls) of nebula.
1. Leftover planetesimals (comets).
2. They crash into each other and get larger.
3. They get large enough that they form protoplanets.
vi. Solar Wind (from sun) blew lighter elements away from the sun
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1. Solar wind: A stream of cosmic particles.
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Terrestrial Planets: Planets closest to the sun, small, dense, and rocky. Major elements
for construction are Fe, Mg, Si, Al (Mercury, Venus, Earth, and Mars)
Jovian: Planets that are large, less dense, gaseous, and further from the sun. They are
made up of methane, ammonia (Jupiter, Uranus, Saturn, Neptune).
The earth formed 4.56 billion years ago.
The moon formed by a planetesimal impact on earth and the matter was captured by
earth’s gravitational pull. It is suspected to be 4.54 billion years old.
Meteorite bombardment lasted until 3.85 Ga.
Ga: Geologist shorthand for “billion years ago”.
Today there are now 120 planets recognized outside our solar system.
3. Earth’s Interior Structure:
a. Formation of Earth’s Layers:
i. Early earth has a homogenous composition (this is known from
meteorites).
ii. Early earth was very hot (gravitational compaction, meteor
impacts, and radioactivity).
iii. Differentiation of materials by density (dense material sank to the
center of the earth, lighter material rose).
b. Three layers:
i. Crust: Thin, rocky outer layer (less dense than the mantle).
P=2.8glcm3.
1. Continental:
a. 25-70km thick.
b. 40% of earth’s crust.
c. Rock Type: granite (P=2.8glcm3)
2. Oceanic:
a. 7-10 km thick
b. 60% of earth’s crust
c. Rock Type: basalt (P=2.9glcm3)
3. Moho: The base of the crust
ii. Mantle: Middle layer of rock (less dense than the core).
1. 82% of earth’s volume is in the core
2. Rock Type: Peridotite (P=4.5glcm3)
iii. Core
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1. Outer Core: Molten iron.
a. The movement of the iron generates the magnetic
field on earth.
2. Inner Core: Solid iron and nickel.
a. P=10.7glcm3)
b. Pressure: 50 million PSI
c. Physical Layers of the Earth
i. How do layers behave? Strong vs. Weak.
1280°C: Where mantle begins to melt.
1. Lithosphere: Outermost zone of cooler, stronger rock (60250 km thick). It includes all crust and part of the upper
mantle.
a. It is stronger than the asthenosphere because it is
cooler.
b. Temperature wins!
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2. Asthenosphere: The hotter, weak mantle rock that flows
like salt water taffy.
General boundary between the two: 1280°C. This is the temperature at which peridotite
begins to melt.
3. Mesosphere: Hot, strong mantle rock.
a. The pressure keeps the mantle rock strong.
b. Pressure wins!
c. An increase in pressure increases the melting
temperature.
4. The Earth’s Surface:
a. Continents and Oceans:
i. Continents:
1. 0.8 km above Sea Level
2. Composed of granite which is low density (2.8glcm3)
3. Granite is usually 40 km thick
4. The combined low density and thickness is somewhat a
buoyancy factor.
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ii. Features of Continents:
1. Mountain Belts
2. Craton: Interior of continent (stable greater than 600 Ma)
Ma: Million years
iii. Ocean:
1. 2.4 km below Sea Level
2. Composed of Basalt which is more dense than granite
(2.9glcm3).
3. Basalt is usually 8 km thick
iv. Features of Oceans:
1. Continental Shelf: An extension greater than 1 km of the
continent under sea level.
2. Abyssal Plain: Flat seafloor, deep ocean (2-2.5 km deep).
3. Trench: Deep, linear depression (greater than 11 km deep).
4. Mid-Ocean Trenches: Linear mountain belts (total 70,000
km in length).
a. Mid-Atlantic Ridge
i. Iceland
5. Volcanic Island Arcs: Chain of oceanic islands next to
trenches.
a. Aleutian Islands
b. Alaska
6. Seamounts: Submarine volcanoes that may form islands.
5. Continental Drift & Seafloor Spreading:
a. Continental Drift (Proposed in 1915 by Alfred Wegener)
i. Slow, lateral movements of continents across earth’s surface.
ii. Wegener claimed that during the Permian Period all continents
merged into a super continent.
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6. Jurassic Pangea breaks apart; Continents drifted away
a. Wegener’s Evidence:
i. Fit of the contincents; matching shorelines (South America/Africa)
ii. Distribution of different types of deposits
1. Glacial features found in deserts
2. Coal beds/deposits
3. Ancient deserts (old sand dunes)
4. Fossils with the same land animal on different continents
(mesosaur: a freshwater, fish-eating reptile)
iii. Matching of mountain ranges (Appalachians/Calenides)
b. Wegener’s fate:
i. 1926 the New York Meeting discounted Wegener’s hypothesis “no
visible mechanics for the break up of the continents”.
ii. New Observations (1930’s-1960’s):
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1. Marine trenches (troughs) 11 km deep.
2. Distribution of earthquakes: location isn’t random (occur
in zones)
iii. Seafloor Spreading Hypothesis (HESS 1962)
1. lateral movement at oceanic crust away from mid-ocean
ridge.
2. Oceanic crust created at mid-ocean ridge.
3. Moves laterally and returns to mantle at trench.
4. Continents move passively with oceanic crust
a. Mechanism for continental drift.
iv. Evidence for sea-floor spreading:
1. Magnetic reversals in oceanic crust.
a. Magnetite: Magnetic minerals in basalt.
Earth’s Magnetic field changes polarity. Today, minerals point to North magnetic pole.
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2. Age of oceanic basalt
3. Sediment thickness
a. It increases away from mid-ocean ridge
4. GPS measures the rate of sea-floor spreading
a. New York and London are moving apart 2 cm/year
v. Plate Tectonics: The Unifying Theory:
1. Lithosphere is broken into a series of rigid pieces (plates)
that can move over the earth’s surface
a. Earth’s Surface
i. 7 major, 7 intermediate, 12 small plates.
ii. Explains distribution of earthquakes,
volcanoes, mountains, ocean, basins,
continents.
2. The Details:
a. Plates move over the weaker asthenosphere.
b. Oceanic and continental crusts move passively with
plates.
c. Plates move because of:
i. Variations in temperature in mantle
ii. Variations in plate’s density
d. Plate:
i. Oceanic crust only (Pacific Plate)
ii. Continental crust only (Iranian Plate)
iii. Combination of both (North American
Plate)
3. The Process:
a. Oceanic crust (lithosphere) at mid-ocean ridge.
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b. Subducts (sinks in mantle) at trenches
c. Crust created = crust subducted
d. Oceanic crust subducts, continental crust never
subducts.
4. Plate Boundaries:Earthquake belts are defined on
boundaries
a. Divergent (mid-ocean ridge): How the lithosphere
forms as basaltic magma rises from asthenosphere
and coals.
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5. Divergent Margin:
a. Example: Mid-Atlantic Ridge
6. Convergent (trenches, subduction zone):
a. 2 plates moving towards each other.
b. Oceanic lithosphere is subducted at the trench.
c. When the two come together the older oceanic
lithosphere will subduct.
d. Trenches are locations of deep earthquakes up to
about 700 km. Deep.
e. Adjacent to trenches you find volcanic island arcs.
i. Volcanic Island Arcs: The melting of a
subductive plate that produces magma
(amdesite) that erupts on the surface.
f. Continental Volcanic Arc: Develops on continental
crust.
7. Transform:
a. 2 plates moving/sliding past each other along a
strike-slip fault.
b. Link-segments of Mid-Ocean Ridge
i. Example: San Andreas Fault (Greater than
1,000 km long)
8. What drives the movement of tectonic plates?
a. Subduction due to unequal distribution of heat in
the earth.
i. Hottest: Mid-Ocean Ridge
ii. Coolest: Trench (as it becomes cool it gets
more dense)
7. Minerals
Mineral: A naturally occurring, inorganic chemical solid that is crystalline.
Crystalline: An orderly atomic arrangement.
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Rock: A cohesive solid that is composed of one or more minerals.
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a. Characteristics of minerals:
i. 4,000 minerals on earth
ii. Only 20 are common in crust
iii. Identified by chemical composition
iv. Physical Features:
1. Crystal Form: The shape of the mineral if allowed to grow
unrestrictedly.External extrusion of crystallinity
2. Physical Property
b. Silicate Minerals (SiO4 : A complex silicate anion): Most rocks of crust
and mantle.
Concentration of crust in the mantle:
1. Oxygen
45%
2. Silicon
27%
3. Aluminum
8%
Silicate Tetrahedron: Building block for all silicate minerals:
Blue: 1 Silicon
Orange: 4 Oxygen
ii. Silicate Structures:
1. How do tetrahedral link together?:
a. Single chain (Augite); linked by oxygen atoms
b. Double chain (Hornblende)
c. Sheet (Mica)
d. 3-D Network (Feldspar, Quartz)
c. Carbonate Minerals: Has a carbonate anion (CO3)2i. Calcite: Chemical formula of CaCO3
d. Mineral Formation:
i. Solidification from molten rock
ii. Precipitate the mineral from water
8. Igneous Rocks
 Form from cooled lava (molten material on earth surface) or magma (within
earth)
 Earth’s crust composed mostly of igneous rocks
 First rocks to form on earth
a. Fate of Magma
 Magma is buoyant (less dense); wants to migrate to surface
i. Igneous Intrusion:
1. Dike: Cuts across layering
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2. Sill: Parallel to layering
3. Pluton: Irregular blob
4. Batholith: Large pluton (100’s of km3)
a. Sierra Nevada
ii. Igneous Extrusion: Lava flows, eruption of ash from volcanoes.
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b. Classification of Igneous Rock
i. Texture: Coarse vs. fine
ii. Composition: Light vs. dark
 Intrusive (plutonic): coarse grained; cooled slowly
 Extrusive (volcanic): fine grained; cooled slowly
 Pyroclastic: Rock fragments and ash ejected from volcano
c. Types of Igneous Rocks:
i. Plutonic (Coarse):
1. Granite
Continental Crust
2. Diority
Continental Crust
Darker in color
Less SiO2
3. Gabbro
Oceanic Crust
4. Peridotite
Mantle
ii. Volcanic (Fine)
1. Rhyolite
Continental Crust
Darker in color
Less SiO2
2. Andesite
Continental Crust
3. Basalt
Oceanic Crust
9. Magma & Volcanoes
 50 Volcanic eruptions each year
 Volcanoes concentrated along plate boundaries
a. Magma
 Melt (Mostly SiO2)
 Solids (Silicate)
 Gas (H20 Vapor, CO2, SO2)
i. Composition:
1. Basaltic:
a. Most common type
b. 50% SiO2
c. Example: Mt. Edna, Italy
2. Andesitic
a. 60% SiO2
b. Example: Mt. St. Helen’s, Washington
3. Rhyolitic
a. 70% SiO2
b. Example: Yellowstone National Park, Wyoming
ii. Temperature:
1. 750°C (Rhyolitic) - 1200°C (Basaltic)
iii. Viscocity: Resistance to flow
1. At higher temperature, magma is less viscous
2. High SiO2 = More viscosity
b. Origin of Magma:
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
Divergent and convergent margins
i. Heat 100km (1200°C - 1400°C) Pressure
ii. Pressure: Reduce pressure, rock will melt (decompression
melting). This occurs on mid-ocean ridges. Along the mid-ocean
ridge the peridotite flows up to lower pressure.
iii. Volatiles: Water and other gases. Subduction zones add water to
rocks
Dry
Wet
850°C
650°C
c. How Magmas Evolve
i. Basaltic magma
ii. Bowen’s Reaction Series: Minerals crystallize systematically
based on melting temperature (Figure 4.23)
iii. Partial Melting and Magma Formation:
1. Incomplete melting of a rock (1-2% Volume)
a. Produces most magma
2. Minerals with the lowest melting temperatures melt first.
PM
Basalt
Andesite
Intrusion
Basalt
Rhyolite/Granite
Cont. Crust
d. Eruption of Magma
i. Basaltic Magma
1. Non-violent volcanic eruptions
2. Gases have escaped
ii. Andesitic/Rhyolitic:
1. Violent eruption
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e. Volcano Ejecta
i. Lava Flows: Pahoehoe (Ropey); aa (sharp, jagged)
ii. Pyroclastic Debris: Broken rock material (large to small to tuff)
iii. Gas
f. Volcano Types
Volcano: A vent in the earth that erupts lava, pyroclastic debris and gas.
i. Shield: Low, broad profile; over 100km in diameter. (Hawaii)
ii. Cinder Cone: Less than 1km in diameter. It ejects loose material
at high pressure; can occur on shield volcanoes.
iii. Stratovolcanoes (Composite): Interlayered lavaflows and
pyroclastic flows. Larger then cinder cones. There are about 15
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active ones in the Pacific NW in the Cascade Mountains. These
produce violent eruptions due to it consisting of Andesitic Magma.
iv. Hot-spot Volcanoes: Isolated volcanoes within plates. Mt.
Monokeia: Biggest mountain on earth (9km, Hawaii). The mantle
plume is solid peridotite. There are 40 around the world.
g. Other Volcanic Features:
i. Caldera: A large, bowl-shaped depression in a volcano (collapsed
magma chamber).
ii. Thermal Springs and Geysers: Groundwater is heated by magma.
iii. Fissure Eruptions and Flood Basalts: Basalt erupts along a deep
narrow crack.
1. Example: Columbia Plateau of OR and WA; 1km thick of
basalt.
iv. Volcanic Neck: Igneous rock solidified in throat of volcano. Over
time the flanks will erode away leaving the neck which is more
resistant.
1. Example: Devil’s Tower, WY
h. Plate Tectonics and Igneous Activity:
Plate boundaries: Example: “Ring of Fire”
Plate Tectonics allows for melting of mantle rock
i. Convergent: Addition of volatiles produce magma
1. Volcanic Arcs
ii. Divergent: Decompression melting
iii. Intraplate Activity: Hot spot volcanoes (Hawaii, Yellowstone)
i. Volcanoes and Earth Climate:
i. Large stratovolcanoes erupt lots of ash
ii. Ash can reflect sunlight, reducing ground temperature
1. Example: 1815 in Mt. Tambora, Indonesia reduced
temperature around the world by 2-3 degrees.
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10. Weathering:
 Chemical alteration and physical breakdown of rock during exposure
to air, water and organic matter
o It is an external process powered by the sun.
 Weathering converts solid rock to sediment (loose rock and minerals),
new minerals and ions.
o Stone, concrete and metals are also affected
a. Physical Weathering: Break-up of solid rock into fragments.
i. Jointing: Fracturing of rock. Very common in crustal rock.
ii. Crystal Growth: Precipitation from water of salt in joints.
1. Example:
a. Halite (NaCl) : >100 pounds per square inch.
i. This is a problem in the Northeast where
they have to salt the roads.
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iii. Frost Wedging: Water freezes in joint, expanding joint; >100
pounds per square inch. This is most important in temperate
climates
iv. Plant Roots: Roots grow in joints plus they produce organic acids
b. Chemical Weathering:
 Decomposition of rock by chemical reaction
 Most minerals are unstable at the earth’s surface (Quartz is very
stable)
 Carbonic acid is the principle agent
o Formed in air or soil (H2O + CO2)
 Other acids:
o SO2 (Sulfuric Acid)
o NO2 (Nitric Acid)
i. Oxidation: “Rusting” in iron minerals in rock
1. Iron Oxides:
a. Hematite (red mineral)
b. Limonite (yellow)
ii. Dissolution: Minerals dissolve in water creating NaCl + H20
yields Na+ + Cliii. Hydrolysis: H+ in water replaces cation in mineral.
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c. Enhancement of physical and chemical weathering
i. Both processes operate together
ii. More physical weathering leads to enhanced chemical weathering
and decomposition of rock minerals.
d. Factors affecting weathering
i. Rock type: Rocks with quartz are more stable
ii. Climate:
1. Chemical weathering is greater in warm, moist climates.
2. Physical weathering is greater in cooler climates (freezethaw)
iii. Time: More time = more weathering
11. Soils: Weathering Products; a layer of weathered rock and organic material that
can support plants.
a. Soil Types:
i. Regolith?: Any loose material over bedrock.
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ii. Diagram of horizons:
iii. Soil Profile:
1. Organic: Known as the “O” Horizon. Black In color;
consists of leaf litter and animal remains
2. Humus: Known as the “A” Horizon. Decaying plant and
animal materials and minerals.
3. Known as the “B” Horizon. Iron and Aluminum
Oenides??; lots of clay
4. Known as the “C” Horizon. Yellow/Brown
5. Parent Rock
b. Soil Types affected by:
i. Parent material: granite vs. limestone
ii. Climate: wet or dry, long-term precipitation and temperature
trends
iii. Soil organisms: 1 gm = up to 1 trillion microbes.
iv. Topography
v. Time
Ultisol: Subtropical climate soil; heavily weathered (leached), unfertile.
vi.
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Soil Erosion (Removal by wind and water)
 Human activities have accelerated erosion
 7% of earth’s soils are lost every 10 years
 Poor farming practices, overgrazing, deforestation, urban sprawl
 U.S. Midwest erosion is 14 times faster than rate of soil production
12. Sedimentary Rocks:
 75% of earth’s surface is covered by sedimentary rocks
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a. Types of sedimentary rocks:
i. Detrital (clastic): Rocks formed by the cementing together of
weathered rock fragments (Quartz, feldspar, clay).
1. How clastic rocks form:
a. Form sediment
b. Transport by wind, water, ice
c. Deposit in new location
d. Lithofication (transformation into rock)
i. Compaction from weight overlying sediment
ii. Cementation by dissolved minerals in
ground water between grains. (quartz,
calcite, hematite)
ii. Chemical: Direct precipitation from water. Inorganic origing
1. Evaporites: Formed by evaporation of saline water
a. Closed basins and salt flats (Death Valley)
b. Halite, gypsum
2. Travertine: calcize ground of springs and caves
iii. Biochemical: Form from remains of plants and animals
1. Calcite, silica (Coquina)
2. Limestone (CaCO3, chert and silica)
iv. Organic: Carbon-rich material (land-plants); coal
1. Coal forms from peat (only plants)
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13. Sedimentary Depositional Environments
 Sediments deposited by wind, water and ice
 Sediment size decreases from source area
o Gravel-sand-silt-clay
 How to infer past depositional environments:
o Rock type
o Sedimentary structures
o Fossils
a. Different Basic Types of Depositional Environments
i. Continental Environment:
 Water dominates erosion and deposition
 Ice at higher latitudes
 Wind in arid regions
1. Stream: Gravel and sand. Crossbeds and ripples.
a. During flooding: Floodplains receive sediment
i. Silt, clay and organic
b. Alluvial fans form at the base of the mountain
2. Eolian: Dunes with large crossbeds and ripples
3. Lake: Layers of sand, silt, and clay
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a. Playalake: Arid regions between mountains.
Evaporites
4. Glacial: Chaotic mix of sediment (Boulder and clay till)
ii. Marine Environments (There are 2 types)
1. Shallow: <200 meters in depth; from the coast to the edge
of the continental shelf.
2. Deep: >200 meters in depth; Edge of the continental shelf
into abyssal plain silt and clay
Differences: Climate and Clastic Input (Sediment)
3. Transitional Environment:
a. Beach: Sand/gravel with ripples
b. Tidal Flats: Intertidal zone (Silt, clay and
mudcracks)
c. Delta: Deposit of sand, silt, clay at mouth of
river/stream.
b. Sedimentary Structure:
i. Bedding: Layering of sediment
ii. Crossbeds: By wind or water
iii. Ripples: Small waves of sand or silt that typically from on the
bedding surface. Formed by water or wind.
iv. Mudcracks: Drying mud (clay) in a hexagon shape.
v. Fossils: Only found in sedimentary rocks
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14. Metamorphic Rocks and Metamorphism
 Undergone change in mineral composition and texture due to:
o Increase in temperature (100°-800°C)
o Changes in pressure
o Presence of fluids
 Protolith (parent rock): Rock from which a metamorphic rock forms
o Any rock class can be metamorphic
a. Metamorphism occurs in the solid state…no melting; does not include
weathering; occurs to achieve equilibrium with environment (temperature,
pressure, fluid).
i. Agents of metamorphism:
1. Heat: Provides energy for chemical reactions and
recrystalization
a. ????? →Heat → Muscovite
b. Limestone → Heat → Marble
c. Quartz SS → Heat → Quartzite
d. Sources of heat: Convergent margins; plutons;
geothermal gradient (~25°C 1km)
Page 18
2. Pressure: Increases density of rock (burial?, convergent
margins)
a. Confining Pressure: Equal in all directions
(hydrostatic pressure)
b. Differential Stress: Unequal pressure (greater in
one direction)
3. Fluids: Volatiles (mostly H20): Facilitate recrystalization
by moving ions within/outside of a mineral
a. Magma’s, sedimentary rock, hydrated minerals
(clay, micas, hornblende)
ii. Metamorphic Texture:
1. Foliation: Plainer??? arrangement of platy minerals in a
rock (clay, micas, hornblende)
a. Results from differential stress
b. Not all metamorphic rocks have foliation
c. Equidimensional rocks (QEZ) do not give good
foliation
d. Slaty cleavage: Foliation from fine-grained
minerals
2. Non-foliated: Protoliths contain equidimension minerals
10-13-04
iii. Classification of Metamorphic Rocks:
1. Foliated Rocks
a. Slates: Fine (Clay 1/256mm in size) grained with
slaty cleavage.
b. Schist: Medium grained with obvious minerals
(Muscovite/Biotite)
i. Garnet (Fluids)
c. Gneiss: Medium to coarse grained rock. Displays
compositional bonding
Shale → 300°C → Slate → 500°C → Schist → 700°C → Gneiss
Granite/Rhyolite → 700° → Gneiss
2. Non-foliated Rock:
a. Marble: Coarse grained (due to recrystalization and
heat) with interlocking calcite crystals.
i. Limestone → 300-500°C → Marble
b. Quartzite: Coarse grained with interlocking quartz
crystal
i. Quartz S.S → Quartzite
iv. Metamorphic Environments:
1. Contact/Thermal Metamorphism
a. Occurs adjacent to igneous intrusion
Page 19
b. Local phenomenon
c. Produced non-foliated metamorphic rocks
2. Regional Metamorphism:
a. Affects large volumes of crust
b. Associated with convergent plate margins and
mountain building
i. Foliated rock
1. Example: Blue Ridge Mtns TN/NC
v. Metamorphism and Plate Tectonics:
1. Convergent margins
2. Regional and thermal metamorphism together
3. Divergent margins: “Hydrothermal metamorphism”
a. Basalt goes through changes and becomes
serpentinite (a metamorphic rock)
15. The Rock Cycle:
 All rocks (igneous, sedimentary, metamorphic) are subject to change
a. Cycle powered by:
i. Sun (generates weather)
ii. Earth’s internal heat
iii. Gravity
b. Cycle began with the 1st Igneous rocks
i. Figures given for examples:
1. Fig. 8.19
2. Fig. 8.21
3. Fig. 8.24***Exam Material
4. Fig. 8.28
5. Fig. 1.21
10-15-04
16. Geologic Time: The interval of time since Earth’s formation
Page 20


It’s the time frame that geologists use to describe features (rocks, fossils,
landscapes, mountains).
Geologic Column
o Relative Age: Age of one feature to another.
 Is A older than B?
o Numerical Age: Associate age in years.
 A is 100 Ma.
a. Principles of Relative Age
i. Principles of uniformitatianism: Same processes have been
happening over time. Present is key to past.
ii. Principle of superposition: In sedimentary rocks the oldest layer is
on the bottom.
iii. Principle of original horizontally.
iv. Principle of lateral continuity.
v. Principle of cross cutting relations
 Geologic History: Uses relative ages to piece together
history.
10-20-04
b. Uncomformity: A surface that represents a period of erosion/nondeposition
i. Hiatus: A time gap (interval of time missing)
1. How do you figure it out?
2. Look for the fossils right above and right below the
uncomformity.
ii. There are 1000’s of uncomformities around the
world.
iii. The presence of an uncomformity signifies that earth’s processes
have been working over a very long period of time.
iv. Uncomformities in rock records signify that plate tectonics,
erosion and sedimentation have occurred throughout Earth’s
history.
c. Rock Correlation: Defining rock ages between different geographic areas.
i. Two Types:
1. Lithologic Correlation: Matching rock units
2. Fossil Correlation: Matching fossils
Page 21
ii. Fossil: A trace or remnant of a living organism. This occurs in
sedimentary rock/sediments due to rapid burial which preserves the
hard parts of an organism such as bones and teeth.
1. Fossil record is biased
iii. Principle of Fossil Succession:
1. Fossils succeed one another in a definite/determinable
order.
10-22-04
MISSING
10-25-04
17. Beta Emission:
a. Radioactive Decay half-lives are constant
i. They are unaffected by geologic and human processes or position
(crust vs. mantle)
ii. The proportion of parent/daughter is used to date material.
b. What is really being dated?
i. Rocks are dated by their minerals that make up their composition
ii. Igneous rocks contain lots of radioactive elements (Zircon)
iii. Sedimentary/metamorphic rocks
c. Numerical Age and Geologic Column
i. ***Josh Martin has the illustration that needs to be added here***
ii. Radiometric Dating (For the figure above)
1. Basalt1 = 100 ma
2. Basalt2 = 50 ma
3. Tuff1 = 200 ma
4. Tuff2 = 175 ma
iii. Strat Column:
1. Basalt2 50 ma
2. SS2
3. Basalt1 100 ma
4. LS1
5. Tuff2 175 ma
6. SH1
7. Tuff1 200 ma
8. SS1
iv. The Age of Earth:
1. Acasta Gneiss: The oldest rock on earth was found in
Canada and dated at 4.1 Ga
2. Moon Rocks: 4.55 Ga
3. Meteorites: 4.55 Ga and contain uranium 238 & 235
10-27-04
Page 22
18. Geologic Structure, Faults and Folds: Features in rocks caused by deformation
(change in volume, shape, position). This is caused by movement of tectonic
plates.
a. Stress and deformation: Action and reaction
i. Differential stress deforms rock
ii. Three types of stress
1. Compression (Squeezing)
2. Tension (Stretching)
3. Shear (Smearing)
b. Types of geologic structures:
i. Brittle: Forms when rock cracks and breaks (faults, joints, veins)
ii. Ductile: Forms when rock changes shape without breaking (folds,
foliation)
iii. Temperature and pressure influence behavior of rock during
deformation.
1. High temperature and pressure favor ductile structures and
weak rocks such as shale and slate.
c. Faults: Fracture with movement
i. Normal Fault: Hanging wall block moves down with respect to
foot wall block (Nevada, S.W. Arizona)
ii. Reverse Fault: Hanging wall block moves up with respect to foot
wall block (Eastern TN)
1. Thrust Fault: A type of Reverse Fault that has a shallow
fault surface (Great Smoky Thrust)
iii. Strike-slip fault: Horizontal movement parallel to vertical fault
plane (San Andreas Fault)
d. Folds: A bend in the rock layer
i. Anticline: The oldest rocks are in the center. A bend upwards.
ii. Syncline: The youngest rocks are in the center. A bend
downwards.
iii. Dome: Like an anticline but overhead? a cereal bowl. (Nashville
Dome)
iv. Basin: Like a syncline but also a cereal bowl.
e. Relationships between faults and folds:
i. They occur together
ii. They are active and former plate margins
1. Example: Eastern TN
f. Joints:
i. A fracture without movement
ii. It is the most common structure
iii. Vein: A joint filled with a mineral
1. It’s filled with calcite and quartz
19. Earthquakes: Vibrations in earth that result from sudden movement along faults.
 They generally occur at plate margins
 Hundreds of thousands earthquakes occur every year.
a. Origin of EQ’s (Elastic Rebound Model):
Page 23
i. Stress within the Earth is stored in rocks as elastic deformation
(non-permanent)
ii. Faults release elastic deformation slowly (creep) or suddenly
which generates an earthquake.
iii. “Locked Fault”; too much frictional resistance.
b.
c.
d.
e.
f.
10-27-04
Foreshocks and Aftershocks
Seismology: The study of earthquakes
i. Seismograph: A tool used to measure EQ’s. It makes horizontal
and vertical motion.
ii. Seismogram: Record of the EQ
Seismic Waves:
i. After EQ, elastic energy radiates outward from focus in all
directions.
ii. Buoy waves: Travel through the earth
1. P: Primary compressional wave “sound wave”
a. Fastest waves (6-7km/s) largest volume.
2. S: Secondary: Changes rock shape. Shear waves cannot
move through liquid. The waves move about 3.5 km/s
iii. Surface waves: Travel close to earth’s surface at about 3 km/s.
They move like ocean waves and cause the most damage.
EQ Belts: Concentration of EQ along plate margins
i. Circum-pacific belt: Japan, Alaska, Phillipines, Chile
ii. Most EQ’s (90%) occur in upper 100 km of surface.
1. Subduction zones have deeper EQ’s (10-700 km) in
subducted plates.
2. Mid-Ocean Ridge
Measure EQ
i. Richter scale (1935): Describes the amount of energy released in
an EQ (Grump shake).
1. Determined by max. P, S, surface wave on seismogram.
2. Logarithmic Scale
ii. Mercalli Scale (1902)
1. Describes the intensity of EQ
2. It’s a better measure of human impact.
3. Scale: 1-XII
Seismic Risk and Damage
i. Seismic Risk Maps:
ii. Damage from EQ’s vary:
1. Magnitude
2. Duration
3. Local Geology
4. Construction Geology
iii. EQ Hazards:
1. Ground Shaking
Page 24
2. Fire
3. Landslide
4. Tsunami wave-large water waves (not tidal waves)
20. Formation of Ocean Basins:
 Oceans are born when continents (and super continents) break apart.
o Examples:
 Atlantic Ocean
 Indian Ocean
 Continental Rifting: The first step in the formation of an ocean basin.
o Characteristics:
 Continental crust is stretched and thinned
 Extension (tension)
 Normal faults
 High heat flow
a. Rift Evolution:
b. Mechanisms of Continental Rifting
i. Mantle plumes and hot spots
1. The mantle supplies heat to weaken the continent
lithosphere.
2. Slab pull and slab suction
c. The Supercontinent Cycle:
i. 2.5 Ga (Plate tectonics as known today)
Page 25
ii. Before Pangea (250 Ma) there was Rodinia
iii. Ocean basins will form and be destroyed
11-12-04
21. The Formation of Mountains
 American Cordicera??? (Cape Horn, South America-Alaska)
o Includes the Andes and the Rockies
 Alpine-Himalaya (Mediterranean-Iran-India)
 Arcs of the Circum-Pacific Belt (Japan, Philippines, Indonesia)
 Appalachian – Calaponians
 Uracs (Central Russia)
a. Convergent Margins
i. Island Arcs:
1. Volcanic rocks (Andesite, Basalt)
a. Aleutians Islands, AK
2. Andean Type Margin
a. Continental volcanic mountains (Cascade
Mountains)
i. Rhyolite and Andesite
ii. Sierra Nevada- Granite
b. Continental Collisions (Compression)
i. Horizontal Shortening and Vertical Thickness
1. 40 km (up to 70 km thick)
ii. Fold thrust belt
iii. Deep marine sediments thrust up above sea level
c. Fault (Bedrock Mountains???)
i. Continental rifting
ii. Mountains are bound by normal faults
iii. Example: Basin and Ridge Divide? (Began 30 Ma)
11-15-04
d. What limits mountain elevation?
i. As crust rises, erosion increases (glaciers)
ii. Gravity affects mountain: crustal root is only so strong
1. Gravitational Collapse: hot, lower crust spreads laterally.
The upper crust is brittle and normal faults form.
2. If horizontal compression is greater than the effect of
gravity, mountains will stay high.
e. Origin of Continents
i. 4.0 Ga Earth cooled enough for stable continental crust.
1. Resembled island arcs.
ii. Island arcs combined to form protocontinents.
Page 26
iii. By 2.5 Ga, 80% of continental crust was already formed.
iv. North America: Assembled piecemeal over 2 billion years.
11-17-04
22. The Earth System
 As semblance and interaction of Earth’s parts
 Earth is a closed system (Exchange of energy with surroundings, but not
matter)
 All systems on earth are open systems
a. The Earth’s Spheres:
i. Atmosphere: Mixture of gas that surrounds the earth.
ii. Hydrosphere: Liquid, gas, ice
iii. Biosphere: All organisms and biomass
iv. Geosphere: Solid earth and regolith
b. Interaction Between Spheres:
i. Erosion: Physical, chemical weathering, transport
1. Water: Hydrosphere
2. Sediment: Geosphere
3. Wind: Atmosphere
4. Root Wedging: Biosphere
ii. Hydrosphere
iii. Biosphere
iv. Atmosphere
v. Geosphere
1. Rock Cycle
2. Tectonic Cycle
3. Hydrologic Cycle
23. Surface Water:
a. Hydrologic Cycle (Water Cycle)
i. Transfer of water from reservoir to reservoir:
Page 27
1. Oceans: 97.2%
2. Glaciers/Ice Sheets 2.15%
3. Groundwater .62%
4. Surface Water
Combined .03%
5. Atmosphere
6. Soils/Plants/Animals
ii. The water cycle is powered by the sun; cycle circulates more than
100 million ???? gallons/year
iii. 4.4 Ga: The first liquid water
iv. Water is the main erosive agent
b. Running Water:
i. Sheet flow---Collects in low-lying areas---stream ( a body of water
that flows into a channel)
ii. Streams: Carry sediment and dissolved substances
iii. Load: All material carried by a stream
iv. Discharge: Volume of water in a channel passing a point each
second (cubed feet per second) (Q=VA)
1. Q= Discharge
2. V=Velocity
3. A=cross sectional area of stream
c. Stream Architecture:
i. Cross Channel Profile
1. As Discharge rates increase the shape transforms from a
“V” shape to more of a “U” shape and then to a “bowl”
shape.
11-19-04
d. Stream Patterns
 As water moves through a stream it erodes the sides and bottom and
this is known as downcutting
 Downcutting is most rapid in high-velocity streams (soft bedrock and
regolith)
i. Meandering streams: A stream that contains meanders (loop-like
bends in the channel)
1. Fine-grained sediments and gentle gradients
2. Low downcutting
3. Over time, oxbow lakes form which leaves meander scars.
4. Cutbank: The curve in a stream (Erosion-deep)
5. Pointbar: The inside of a curve in a stream (Depositionshallow)
ii. Braided Stream: A stream that contains many small streams
separated by bars/islands.
1. Sediment supply exceeds capacity of stream.
Page 28
e. Stream Action:
i. Erosion:
1. Potholes: Creates eddies (bath tub drain)
ii. Transport:
1. Bed load: Sediment that moves along the stream bottom
2. Suspended load: Sediment carried by stream; largest
component/load
3. Dissolved load: Ion in solution (Ca+, Na+, K+, HCO-23)
a. A lot of the dissolved load comes from groundwater
iii. Deposition: Occurs when stream velocity decreases.
1. bars/islands
2. point bar
3. flood plain: Covered with water during a flood
4. Alluvial fans
Page 29
5. Delta
iv. Drainage systems:
1. Drainage Basins (Watersheds): Total area of Earth’s
surface that contributes water to a stream
2. Divides (Uplands/Mtns.)
v. Drainage Patterns:
11-22-04
f. Flooding:



Most costly natural disaster in the U.S.
The volume of water exceeds the capacity of streams
Flooding is a natural event but human activities can increase
the severity of flooding
i. Human contribution to flooding:
1. Urban Sprawl: Construction materials are impermeable
and reduce infiltration rates into the ground.
2. Deforestation and draining of wetlands
a. Vegetation reduces sheetflow and volumes of water.
ii. Flood Mitigation:
1. Flow control dam: Allows humans to control discharge
a. Destroys aquatic habitat
2. Artificial Levees: Allows discharge
3. Channelization: Straightens streams that meanders
4. Preserve wetland and zoning: Don’t build on floodplains
24. Groundwater:
 3% of earth’s water is fresh
o 85% Ice
o 14% Groundwater
o 1% Surface water
 More than 50% of the U.S. population relies on groundwater for domestic use.
a. Water Table:
i. Groundwater: Water contained in a fracture or void in rocks or
sediments
Headward Erosion: Eroding back into the divide
Page 30
11-24-04
b. Groundwater Movement
 Groundwater moves from high to low elevation and high to low
pressure
 Groundwater moves through void space in rocks/sediment.
o Exceptions:
 Caves
i. Porosity: Volume of void space in rock/sediment
1. Clay: 45-55%
2. Sand: 30-50%
3. Gravel: 25-40%
ii. Permeability: The ease that fluids move through rocks/sediments
1. Clay: Less than .01 meters per day
2. Sand: Between .01 and 10 meters per day
3. Gravel: Between 1,000 and 10,000 meters per day
 Sedimentary rocks have a higher porosity and
permeability than other rock types.
KA (h1-h2)
 Darcy’s Law:
Q = -------------d
o K = Permeability
o A = Cross sectional area of aquifer
o D = Distance?
iii. Recharge and Discharge
iv. Aquifiers: Body of permeable rock or sediment
1. Unconfined aquifer: No impermeable layer above
2. Confined aquifer: An impermeable layer above exists
v. Groundwater Withdrawal
1. Falling Water Table: When withdrawal exceeds the
recharge rate.
2. Land subsidence: Sinking of land surface
a. Example:
i. Las Vegas
ii. Phoenix
iii. New Orleans
iv. Venice, Italy
vi. Groundwater Qualities:
1. Groundwater chemistry is a function of rock/sediment type
a. Ca+ + Mg+ + Limestone = hard water
b. Groundwater pollution: air, water, soil may pollute
i. Landfills
ii. Farmlands
iii. Filling stations
iv. Houses
vii. Groundwater Activity:
1. Dissolution: Acidic groundwater dissolves rock
2. Cementation: Groundwater precipitates calcite and quartz
Page 31
3. Caves: Limestone or evaporates.
11-29-04
c. Caves: Form from dissolution of bedrock, best developed in warm, humid
climates.
i. Formation of Caves:
1. Dissolution of bedrock is enhanced at cracks and crevasses
in bedrock
a. Bedrock needs to be below the water table in the
saturated zone
2. Development of large groundwater condivits (caves)
3. Deposition of travertine (Calcite) in caves in unsaturated
zones.
a. Cave formations:
i. Speleothem travertine deposits in
unsaturated zone
1. Requires air to form
2. Uses CO2 combined with
groundwater to keep pH of
groundwater low (acidic) thus
keeping the calcite in liquid form as
groundwater trickles into the
crevasses the CO2 is lost and the
groundwater becomes more basic
(pH rises) and calcite becomes able
to precipitate and makes cave
formation.
Stalactite
Column
Stalagmite
Soda Straws
Flow Stone
4. Sinkholes: Circular depression formed by the dissolution
of groundwater through bedrock
a. Gradual Sinkhole: Occurs gradually
b. Collapsing Sinkhole: Occurs due to lack of support
considering a cave is/was underneath the sinkhole.
5. Karst Terrain/Topography
a. Characterized by:
i. Caves
ii. Sinks
iii. Disappearing streams
Page 32
iv. Solution Valleys
v. Linked sinkholes
25. Glaciers and Glaciations (80% of freshwater is in ice)
 Ice covers 10% of continental land surface
o Glacial features cover 75% of that 10%
 Glacier: A mass of ice that persists year round and flows
o Occur at high latitudes and/or high altitudes (Rockies, Alps, Andes,
Himalayas)
a. Types of Glaciers:
i. Alpine: Confined to mountains. Small (100 km. long). They flow
down mountain valley.
ii. Continental (Ice Sheets): Large (Greater than 50,000 km. area, 2-4
km. thick)
1. They form at high latitudes called central highlands.
iii. Ice Shelf: Ice over water (North Pole)
b. Glacier Formation:
i. Glaciers form above the snowline (Limit of perennial snow)
ii. They form over years (100’s-1000’s years) snow compacts and
converts to glacial ice.
iii. Critical Mass is needed for flow
c. Glacial Movement:
i. Internal Flow: Ice crystals slip past one another
ii. Basal Sliding: Movement along the base
Crevasses
1. Water provides buoyancy
Brittle
12-1-04
d. The Glacial Budget (Accumulation or loss of ice)
i. Advance of Glacier: Accumulation exceeds ablation
ii. Retreat of Glacier: Ablation exceeds accumulation
e. Erosion Features of Glaciers:
 Glaciers can erode and transport sediment/rock very effectively
 Sediment becomes embedded in ice and gives the sandpaper effect as
it grinds rock into rock flour
i. Glacial Striations/Grooves/Flutes
1. Scratches in bedrock
ii. Glacial Valleys:
1. Mountains
2. U-shaped valley: Steep sides with rounded floor
a. V-shpaed streams
iii. Cirque: A bowl-shaped depression formed at the head of alpine
glacier.
Page 33
1. Plucking: Glaciers pulling craters into rock as it passes
over tarn lake in cirque.
2. Urete: Steep ridge between cirques
3. Fjord: Glacial valley invaded by seawater
f. Depositional Features of Glaciers:
 Glaciers transport a wide range of particle sizes (clay-boulder)
i. Till: Sediment deposited directly from melting ice.
ii. Outwash: Deposit from melted water of ice glacier; braided
streams. Too much sediment and not enough water.
iii. Loess: Wind transported silt/clay from outwash plain
12-3-04
iv. Erratics: Ice-transported boulders
1. 100km transports are possible
v. Depositional landforms:
1. End Moraine: Till at the toe of glacier
2. Drumlin: Elongate mound of till
g. Ice Ages:
 A period of time when continental glaciers cover large areas of land
 There have been 5 ice ages in the past billion years
 During an ice age, glaciers advance and retreat (interglacial period)
i. Indirect effects of glaciations:
1. Lower sea level (~300 ft.)
2. Extinction of plants and animals
3. Subsidence and rebound of land surface
4. Pluvial lakes- freshwater lakes
12-6-04
ii. Evidence for Pleistocene Glaciations:
1. O18/O16 variations in marine sediments
2. O18 is heavier than O16. O16 is evaporated preferably and
incorporated in glaciers. Thus oceans are enriched in O18.
3. High O18/O16 ratio indicates large ice volumes, which
indicates glaciations which indicates cooler global
temperatures.
h. Causes of Ice Ages:
 Tillite: Loose sediment that has formed into rock. Older ice ages
i. Movement of tectonic plates: Movement to polar regions
Page 34
ii. Concentration of CO2 in atmosphere: CO2 traps heat. More CO2
equals a warmer temperature. Low CO2 equals a lower
temperature.
1. Air bubbles trapped in ice record CO2 levels
a. An increase in CO2: Volcanoes; erosion
b. Decrease in CO2: Formation of coal; limestone
iii. Changes in ocean circulation (plate movements)
i. Why do glaciers advance/retreat during an ice age?
 Variations in solar energy coming from the sun (short-term variations)
i. Precision: The wobble of the earth’s axis (25,000 year cycle)
ii. Tilt of earth’s axis: 23.5° (41,000 year cycle)
iii. Eccentricity of orbit (100,000 year cycle)
iv. Milankovitch cycles: Short term variations in solar radiaton.
12-8-04
26. Deserts and Winds:
a. Atmosphere: A mixed layer of gas that surrounds our planet.
i. Water vapor, CO2, SO2 (Early Atmosphere)
ii. Photosynthesis produces oxygen
iii. Currently the atmosphere is compromised of:
1. Oxygen
21%
2. Nitrogen
78%
3. CO2 + CH6 1%
b. Wind: Movement of Air
i. Can transport sediment (silt and clay)
ii. Global circulation: Air pressure moves air
1. Changes in pressure are due to changes in temperature.
a. Surface temperature varies with latitude
b. At the equator warm air rises and moves
North/South towards the poles.
c. Air cools and sinks; little moisture
c. Deserts: Regions receiving less than 10 inches of precipitation per year.
Deserts cover 30% of earth’s surface.
i. Deserts aren’t necessarily hot
1. Low latitude deserts: 20-30° N/S Latitude
a. These are earth’s largest deserts
2. Mid-latitude deserts: Form in continental interiors
3. Rain Shadow Desert: Down wind of a mountain range
12-10-04
27. Energy Resources:
 85% of the world’s energy comes from fossil fuels
a. Fossil fuels (coal, oil, natural gas): Remains of plants/animals trapped in
sedimentary rocks that can be used as fuel.
Page 35
i. Coal (~22% energy for U.S.)
1. Remains of plants
2. Most abundant fossil fuel
3. Formation:
a. Plant material accumulates in oxygen poor wetlands
(slows decomposition)
4. During compaction of plant materials, H2O vapor, CO2,
CH6 escape, leaving carbon, burial composition.
Peat
Lignite
Bituminous
Anthracite
Graphite
(Very hard black coal)
ii. Oil and Natural Gas (62% of U.S. Energy)
1. Natural Gas: C1-C4
2. Gasoline: C5-C10
3. Formation of Petroleum:
a. Marine plankton consume energy for life
b. Plankton die and settle to the floor of ocean/lake
i. Oxygen poor environment inhibits
decomposition
ii. Incorporated into sediment
c. Sediment lithifies into a rock (Black organic rock)
“Source Rock”
d. At higher temperature 80-160°, organic material
converts to oil
i. Greater than 160° natural gas forms
e. Oil and natural gas rise from source rock
i. Reservoir rocks hold hydrocarbons
ii. “Seal” rock: an impermeable rock that traps
oil