GWU GEOL 1005 EXAM 3 NASSAR

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Masses of ice that move under their own weight, under the force
What is a glacier?
of gravity.
1. Precipitation
2. A higher rate of snowfall than melt each year. This allows the
glacier to grow over time.
What conditions are needed for glaciers to form?
3. Mountains: higher elevations ’ colder temperatures
4. Gentle slope: if the slope is > 30°, avalanches may form, clearing
the glacier away.
High latitudes and/or high altitudes as snow patches that survive
Where do glaciers typically form? the summer. This is favored on north-facing slopes, which receive
less direct sunlight.
What is firn? Compacted granular ice that forms where snow is deeply buried.
Formed as the firn is buried and further compacted and crystalized
How is glacial ice formed?
until it transforms.
the process can take decades or thousands of years (depending
on the rate of snowfall).

1. Initially, loose snow is 90% air.

2. As more snow is deposited on top of it, the snow becomes
Describe the transformation of a glacier? denser and more compacted as air is driven out, and turns into
firn (25% air);
3. Firn turns into a compact solid mass of interlocking ice crystals
called glacial ice (20% air).
4. Eventually, if there is a slope, gravity pulls the mass of ice
downslope, creating a glacier.
What are alpine glaciers? Called mountain or valley glaciers, more common
Larger and rarer called ice caps or ice sheets. A large glacier
covering extensive land areas and may be several km thick.
What are continental glaciers?
’ Greenland and Antarctica have the biggest
Rigid zone Upper part of a glacier in which there is no plastic flow.
begins at depths of 60 m where ice layers in the middle of the
glacier slip over themselves as the glacier becomes heavier. The
Plastic zone (middle region)
ice grains change shape very slowly as the glacier moves, and/or
new grains grow while old ones disappear.
At what depth is the boundary between the plastic and rigid
60 m at the brittle-plastic transition
zones?
lower part of a glacier
Part of a glacier where ice is lost (ablated) at the toe of the glacier
1. By melting
Zone of Ablation (wastage)
2. Sublimation (evaporation of ice into water vapor)
3. Calving (breaking of chunks of ice at the end of the glacier that
is flowing out over the water) forming icebergs
The part of a glacial system where snow and ice are accumulating
Zone of Accumulation
faster than they are melting away. Snowfall adds ice to a glacier
It moves downslope in response to its own weight and pressure
How does a glacier move
and the pull of gravity
The shape of a valley formed by the erosion of a glacier- glaciers
U-shaped valley
widen the sides and floor of the valley
Valleys eroded due to fast flowing water often found in upland
V-shaped valley
areas. Initially carved out by the stream
Bowl-shaped depression that develops on the side of the mountain
Cirque
at the head of a glacier. formed by glacial erosion.

Arete

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the wall of rock between two glaciers formed by alpine glaciers
flowing side by side. That is thinned to a sharp ridge by glacial
erosion.
a pointed mountain peak surrounded by at least three cirques
Horn
(Like the Matterhorn in Switzerland)
Glacial striations Scratches and grooves on bedrock caused by glaciers moving
Poorly sorted sediment transported by flowing ice and deposited
glacial till
beneath a glacier or at its toe
form on the sides or outer edges of the glacier as the glacier
lateral moraine
scrapes rocks off the sides of mountains as it moves past.
Where two valley glaciers merge, the debris in the two lateral
medial moraine moraines merge to become a medial moraine, which is often seen
as a stripe running down the composite glacier
The debris deposited by the furthest extent of glacial ice (ex: Cape
terminal moraine
Cod, Long Island)
Nearly every lake in Canada and the northern United States is
Where are some geographic areas within North America whose glacial in origin
landscapes have been influenced by glacial activity? (ex: Great Lakes, Rocky Mountains, Canada's Hudson Bay,
drainage of the Mississippi river)
glacial period a period of ice advance associated with falling temperatures
interglacial period The time between when glaciers retreat and advance
As temperatures rise, glaciers melt faster than they accumulate
What is the relationship between climate change, glacial activity,
new snow. As these ice sheets and glaciers melt, the water even-
and changes in global sea level?
tually runs into the ocean, causing sea level to rise
Look at the change in the shape of the Earth's orbit, tilt, and wobble
What are Milankovitch cycles?
of the Earth's axis over time
Dune- low mound or ridge made up of sand.

What is a dune? How do they move? Move if there is a strong enough prevailing wind direction, its
particles get blown up the side of one shallower surface and slide
down the steep slip face creating crossbeds
1. Less than 20 in of rain
What are some ways in which deserts form naturally? 2. High surface temperatures
3. Topography
Rapid development of deserts (or expansion of existing deserts)
caused by the impact of human activities, often due to land-use
What is desertification and why is it a cause of environmental practices. Reduces the amount of arable land on which the world
concern? depends for food

Ex: Dust Bowl in the midwest

Why are there deserts at 30° north and south latitude of the Hot air from the equator rises, then cools, moisture is lost, and the
equator? dry air comes down at 30 degrees north and south
A patch of land that has been forced to become a desert because
mountain ranges blocked all plant-growing, rainy weather.

- On one side of the mountain it precipitates and on the other side

What is a rain shadow and where/how do they form? of the mountain—the rain shadow side—all that precipitation is
blocked.

Ex: Sierra Nevada mountains, CA, Cascade Range of the Pacific

NW, Himalaya mountains, Andes Mountains
Weather: short-term atmospheric conditions that can change in an
What is the difference between weather and climate? instant
Climate: weather averaged and fluctuates over time

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the warming of the atmosphere due to trapping of infrared rays by
What is the greenhouse effect?
greenhouse gases.
1. Water vapor: H2O (most abundant)
What are the major greenhouse gases? Of these, which are the 2. Carbon dioxide: CO2
most abundant greenhouse gases? 3. Methane: CH4
4. Nitrogen oxides: NOx
How do greenhouse gases contribute to global warming? trap infrared radiation (heat) and warm the lower atmosphere
The first to measure rising CO2 levels accurately at Mauna Loa
Who was Charles Keeling and what was his contribution to the
which proved that the Greenhouse Effect was real and Earth's
study of climate change?
temperatures are rising
A a graph that plots the ongoing change in concentration of carbon
What is the Keeling Curve?
dioxide in Earth's atmosphere since 1958.
Why are there fluctuations in the Keeling curve over the course of
a result of differing levels of photosynthesis based on the season.
a single year?
What ramifications will the loss of Arctic Sea ice have on global Less ice means less reflected heat, meaning more intense heat-
warming? waves worldwide
soil that remains permanently frozen below the surface
What is permafrost? year-round, seen in 20% of the land area in the world in cold
climates
1. surface meltwater cannot infiltrate the frozen ground below b/c
permafrost is marshy.

2. Affects the distribution of surface water and groundwater.

How does permafrost increase global warming?
3. Thawed permafrost releases more (formerly trapped) methane
gas into the atmosphere

- north coast of Alaska, melting permafrost and loss of protection

from waves has led to the collapse of coastal cliffs.
How do the oceans play a role in climate change and global
Oceans store and transport heat
warming?
Thermo: Heat
Haline: Salt
What is thermohaline circulation?
The movement of ocean currents due to differences in tempera-
ture and salinity in different regions of water.
where ocean currents act as conveyer belts of warm and cold
water, sending heat toward the polar regions and helping tropical
areas cool off
What is an "ocean conveyor" and how does it influence regional
Ex: Gulf Stream where warm surface water is transported E &
temperatures?
N to Greenland, where it cools from contact with cold Canadian
air. As the water cools, it increases in density and sinks to the
bottom, then flows S & E to the Pacific, where it warms up again
and upwelling occurs.
As winds blow offshore, warm surface water is pushed away from
the coast, and the deeper, cooler waters rises up toward the ocean
How does wind influence upwelling (rising of seawater) along a
surface. This water is nutrient-rich, and in many regions of the
coast, and what is its effect on local ecosystems?
world where upwelling occurs (e.g., the west coasts of North and
South America), diverse, aquatic ecosystems grow and thrive
How does El Nino disrupt this system along the western shore of A halt in upwelling where the fertile cold waters no longer rise up
South America? along the western South American coasts.
The oceans are capable of absorbing excess CO2 and thus help
How does rising CO2 in the atmosphere affect ocean acidity
slow the rate of global warming. But as CO2 levels build up in the
levels?
oceans, the oceans become more acidic

Increased acidity levels weaken or dissolve the limestone shells of

marine invertebrates
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What implications does rising CO2 in the atmosphere affect lime-
stone reefs (recall what concentrated acids do to limestone) and
photosynthetic marine microorganisms?
O16 will evaporate from an equatorial sea more readily than O18.
How are 018(heavier, rarer isotope) & O16 (most common isotope
Conversely, O18 will precipitate out more readily than O16 when
of oxygen) levels used as a proxy for measuring ancient climates?
returning as rain or snow back to the Earth.
the O18 / O16 ratio would be larger during ice ages because ocean
Why are O18 and O16 found in ice cores, and how do their levels
water would be enriched in O18 and O16 would be trapped in ice
change with global warming and cooling trends?
caps.
How far back do glacial ice-core records date? 800,000 years
What is albedo? the reflectivity of a surface
What substances have high albedo and why? Glacial ice and white clouds have a high albedo
The more glaciers retreat, the lower the albedo, the more quickly
How does albedo influence climate change?
the Earth warms up.
positive feedback the warming trend of Earth reinforces itself
the warming induces changes that encourage the opposite (in this
negative feedback
case, cooling)
Soil: all unconsolidated material containing organic matter that can
sustain life
What is the difference between soil and regolith?
Regolith: encompasses all unconsolidated material at the surface
Mechanical (physical): anything that breaks up a rock without
altering its composition; (ice, wind, water). This type of weathering
breaks larger chunks of rock into smaller ones.
What is the difference between mechanical (aka physical) and
chemical weathering? Chemical: breakdown of minerals either
1. by chemical reaction with water
2. with other chemicals dissolved in the water
3. with gases in the air
weathering is the breakdown of rocks at the Earth's surface, Ero-
How does weathering differ from erosion? sion is the transport of Earth materials from one place to another
via gravity, flowing water, wind and glaciers.
TOP:
1. O horizon "organic layer": consists of organic matter.
2. Topsoil (O & A horizon): the fertile portion of soil that farmers till
A horizon of soil for planting crops.
3. E horizon: The O, A, and E horizon form the zone of leaching
because rainwater percolates through this initial layer, dissolves
soluble minerals, and carries them away.
MIDDLE:
Lies in the zone of accumulation where ions, clay minerals, and
B horizon of soil
iron oxides accumulate. Organic matter from the surface is largely
absent from this layer.
BASE:
C horizon of soil Consists of material from the underlying bedrock that has under-
gone some weathering. It consists of mostly broken-up bedrock.
when soluble minerals dissolve into water that is carried down into
What does it mean to say that a soil is leached?
the soil
What is loam? a mixture of sand, silt, and clay

Moderately leached:
in more humid (wetter) regions, more leached, leaving the B
pedalfer soil horizon more enriched in aluminum and iron minerals, are usually
acidic.

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EX: In North America, these soils are found in higher-rainfall areas:
eastern US, NW US, most of Canada
Less leached:
developed in drier regions w/ less rainfall, soluble minerals like
calcium carbonate remain in the B horizon, usually less acidic due
pedocal soil to the presence of calcium carbonate.

EX: In North America, these soils are found in the southwestern

US.
heavily leached, very oxidized (hence red in color), an extreme
What is a lateritic soil? pedalfer. develop in tropical climates with high temperatures and
heavy rainfall
In what regions are lateritic soils found? rainforests
Reserve: mineral deposits that are profitable to extract
What is the difference between a mineral reserve and a mineral
Resource: any useful economic commodity, one that also changes
resource?
with time or context
What is an ore? A rock which contains a metal that's economically worth mining
The concentration necessary for profitable mining

What is a concentration factor used for and how is it determined? 5G5R 5P5\5[5P5R5[5a5_5N5a5V5\5[ 5\5S 5a5R 5Z5R5a5N5
-----------------------------------------------------
5G5R 5N5c5R5_5N5T5R 5P5\5[5P5R5[5a5_5N5a5V5\5[ 5\5S
What are the US's predominant mineral resources (and are they
Iron & aluminium
metal-based)?
commonly found along plate boundaries (areas with extensive
What are some tectonic conditions for ore repositories to form?
magmatic activity)
rare, unusually coarse-grained igneous intrusions, that in rare
What are pegmatites? cases produce single crystals over 10 m (30') long, reflecting a
very slow growth rate of the crystal
What mineral is commonly found in pegmatites feldspars
What is a kimberlite? For what mineral is it known? the igneous rock that diamonds are mined from
when fluids that seep into the cracks of surrounding rocks cool
How are hydrothermal deposits formed? What type of metals do down and deposit their minerals
they produce?
Produce copper, lead, zinc, gold, silver, platinum, and uranium
ancient deposits consisting of alternating layers of sedimentary
rock and extremely rich in iron oxides
What are banded iron deposits and why are they a valuable
economic resource?
EX: responsible for fueling the rise of the iron industry in cities like
Pittsburg, PA and Baltimore, MD
Formed when a body of seawater becomes trapped in a shallow
What are evaporite deposits? basin, dries up and evaporates, and leaves salt and any associ-
ated minerals carried by the sea water
formed by flowing water where as the water velocity slows down,
(e.g., at a meander in a stream) minerals such as diamond and
What are placer deposits?
gold may, over time, settle out and accumulate in the sand and
gravel in these regions.
Of the nonmetallic metals, which are economically (or environ-
Sulfur and halite
mentally) significant?
Are minerals renewable resources? No
surface mining technique of extracting rock or minerals from the
open pit mining & quarries (surface mine)
earth by their removal from an open pit or borrow.

involves the removal of the Earth's surface all the way down to the
strip mining
level of the mineral seam.

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- commonly used to extract coal, but also limestone and other
materials.
What are spoil banks? the waste rock and soil were simply dumped back on top
where cyanide solutions percolate through the tailing piles to
What is heap-leaching?
dissolve out gold
Abandoned mining operations can leach iron and other chemicals
How does mining contribute to pollution?
such as copper, lead and mercury into nearby waterbodies
extracts the metal by using heat which historically produces sul-
What is the environmental concern regarding smelting?
furic acid as a waste product gas, contributing to acid rain
What are some examples of fossil fuels? coal, oil, natural gas
They come from decomposition of organic material 100-500 mil-
Why are they called fossil fuels?
lion years ago
What two elements are fossil fuels predominantly composed of? Carbon and Hydrogen
What % of our nation's energy supply comes from fossil fuels vs
79% fossil fuel, 13% renewable, 8% nuclear
hydropower/nuclear power?
Are fossil fuels a renewable resource? No
Petroleum: crude oil
What is the difference between petroleum, oil, and natural gas? Oil: petroleum in the liquid phase
Natural gas phase: petroleum in the gas phase
What is the chemical make-up of natural gas? Methane (CH4)
1. A large supply of organic matter (rich in carbon and hydrogen)
Environmental conditions needed to create fossil fuels? 2. Rapid burial, to protect it from being broken down by oxygen in
the atmosphere which preserves and concentrates it
Under what temperatures do fossils fuels ideally form? 60-120°C (140-250°F)
Source rock: fine-grained clastic sedimentary rocks where oil
gradually and naturally seeps out of its source rock and migrates
What is the difference between source rock and reservoir rock? elsewhere.

Reservoir rock: porous rock

What is cap rock? the impermeable rocks that cap a large quantity of oil/gas
porous, permeable reservoir rocks from which they can readily
In what type of geological environments does oil get trapped?
flow out once a well is drilled.
What is the minimum estimated burial time needed to produce oil
1-2 million yrs
and gas to form?
How many gallons are in a barrel of oil? 42
Roughly, what is the number of global oil reserves? ~1.73 trillion barrels
Roughly, what is the number of proven US reserves? About how
long would they be expected to last if no new reserves were 35.8 billion barrels, roughly a 5-year supply
found?
How many billions of barrels of oil does the US consume per year,
7.22 billion barrels/year only supplying 35% of our total needs
and how much overall energy does it supply to our total needs?
Canada: Half
Mexico: 10%
About how much oil (%) do we import, and what are the primary
Saudi Arabia: 7%
countries from whom we import oil?
Iraq: 4%
Columbia: 3%
Where is the biggest oil field in the US? Prudhoe Bay field on the North Slope of Alaska
NPRA: National Petroleum Reserve-Alaska
NPRA and ANWR
ANWR: Arctic National Wildlife Refuge
How is oil transported from the Alaskan North Slope to the south-
Trans-Alaskan Pipeline system
ern part of the state?

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sedimentary rocks that contain a thick, semisolid, tar-like petrole-
What are oil sands (also called "tar sands")? What is the name of um called bitumen. The sand must be mined, crushed, or heated to
the petroleum product that they produce? extract the petroleum, and then the bitumen is refined into various
fuels.
What country possesses most of the world's oil sand reserves and
Alberta, Canada in the Athabasca oil sands
where is it located?
What is shale gas, and what is the method by which it is mined? extracted through fracking
Primary: when the first ½ of oil in a deposit in the ground comes
out either on its own or pressure as a gusher

Primary, secondary, and enhanced recovery of oil and gas Secondary: when the oil in the ground is pumped out with water

Enhanced: involves extracting the remaining oil in the ground (ex:

fracking)
Coal forms from the remains of land plants that died in swampy
What is coal and how does it form? environments, often hundreds of millions of years ago, under
anaerobic conditions (lacking oxygen)
How does the chemical composition of coal differ from that of oil
molecules in coal tend to be larger than those in oil and natural
and gas; and how does the origin of coal differ from that of oil and
gas
gas?
From low-grade to high-grade they are:
0. Peat: formed at the earth's surface. burial, more heat, pressure,
and time, causes peat to gradually dehydrate and form
1. Lignite: soft, low carbon content, high moisture content, low heat
What are the main grades of coal and how are they defined? content- i.e., does not release so much heat when burned
2. Subbituminous
3. Bituminous
4. Anthracite: hard, high carbon content, low moisture content,
high heat content
What is the estimated reserve supply of coal in the US? 250 billion tons
Benefits:
- has reserves to supply the nation's energy needs for the next 330
years
What are some of the benefits/drawbacks to using coal?
Drawbacks:
- Not as versatile as oil/gas
- It's polluting
How does the CO2 emission output of coal compare to that of oil
The burning of coal produces it much faster
and gas?
Why is sulfur content significant regarding coal? A contributor to acid rain
used to remove poisonous gases from industrial emissions before
What are "scrubbers"?
they are released into the atmosphere
What are some of the environmental impacts of coal mining? underground fires, natural gas explosions
What is done with the waste product of coal mining, ash? goes into landfills or containment ponds
On the wording of the 1977 Surface Mining Control and Reclama-
What are some of the challenges involved in land reclamation tion Act
once the mining operation is completed? - To what extent is the original mountaintop expected to be re-
stored, and at what cost?
What is fission? the splitting of a nucleus into smaller fragments
What isotope of what element is used in the production of nuclear Uranium- 235
energy? 92 protons and 143 neutrons
1. firing a free neutron into the nucleus of one U-235 atom.
2. When the neutron strikes the U-235 nucleus, the uranium nucle-
In general, what happens in a nuclear fission chain reaction?
us splits into two smaller nuclei and produces subatomic particles,
free neutrons, and heat.
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3. Each released neutron then strikes another U-235 atom, re-
leasing more neutrons, and so on
How is plutonium-239 created? transformed through the chain reaction
1. Reactors needs a water source for cooling purposes
2. The further away the reactor is from a city, the higher the
What are some risks associated with fission nuclear reactors? transmission costs:
3. reactors shouldn't be placed along fault lines, near flood zones,
or regions subject to tsunamis
What are some risks associated with spent fuel and nuclear waste Radioactive material remains radioactive, Lack of permanent
handling? long-term storage
Pros:
- Low operating costs
- account for about 9% of US energy
What are some of the pros and cons of nuclear energy? - No CO2 emissions.

Con:
- Risky
a way to produce electricity using sunlight.
In general, how to photovoltaic cells work?
The cells consist of two layers of semiconductor material oriented
to produce an electric current when struck by the sun's rays
Limitations:
1. Cost: expensive
2. Efficiency: designed to only make use of a small fraction of sun's
rays
Limitations of relying on solar cells as an alternative energy 3. Scale: a large commitment of both land and the mineral re-
source? sources from which the collectors are
made (some of which are toxic, others of which the US would need
to import)
4. Storage: the ability to store solar electricity is not practical
beyond the homeowner stage
The heat from the earth. This heat is used for bathing, to heat
What is geothermal energy? How do we make use of it?
buildings, and to generate electricity.
For large-scale use, where do we find an appropriate heat source? The Geysers in CA
Highly leached soils of tropical and subtropical climates, which
What are oxisols soils?
often have indistinct horizons
What are spodosols? Soils common under conifer forests in humid regions
Ultisols Moderately leached soils of temperate, humid climate
Vertisols clay-rich soils which swell or shrink with moisture
a farming technique in which trees are cut down and burned to
slash and burn agriculture
clear and quickly fertilize the land

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