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Final Exam

Which of the following lithospheric plates is not included among the seven largest?


Earth's lithospheric plates are composed of crust and which of the following layers?

The outermost portion of the mantle.

Which of the following processes can be observed at the margins of lithospheric plates?


In studies of rock obtained from ocean basins all over Earth, the oldest ages obtained are approximately 200 million years before the present. Why have no older oceanic rocks been discovered?


Which of the following regions was not part of the large Southern Hemisphere continent of Gondwana?

North America

Which of the following techniques can be used to recreate the configuration of supercontinents that existed before Pangaea?

apparently wandering polar paths

During the breakup of Pangaea, volcanic island arc systems may have formed that no longer exist. What likely happened to these arcs?

They may have been accreted onto continents after their formation.

What geologic process initiated the breakup of Pangaea approximately 165 million years ago?

Continental rifting

Since the breakup of Pangaea approximately 165 million years ago, a new supercontinent cycle has begun with the collision of which of the following continents?

India and Asia

When oceanic and continental crust collide at a subduction zone, one plate is forced under the other. The angle at which the subducting plate descends is due to what?

The density of the plate being sub ducted and the age of the plate being subducted. Older crust subducts at a steeper angle because something about the plate changes over time.

As oceanic crust is subducted below continental crust, what factors most directly drives the melting that will fuel volcanoes at the surface?


When oceanic crust is sub ducted below continetal crust, partial melting can occur. Which of the following best explains why the resultant magma rises through the crust toward the surface?

The magma is less dense than the surrounding solid rock.

A volcanic arc is formed when which of the following conditions exists?

A piece of oceanic crust is subducted below continental crust.

What type of stress is most directly associated with convergent boundaries?

compressional stress

Although new crust is being formed at divergent boundaries, Earth remains the same size. What is the reason for this?

An equal volume of crust is being consumed at convergent boundaries.

As oceanic crust is subducted, it melts, forming a body of magma. When this magma rises and interacts with the overlying continetal crust, what change occurs in the composition of the magma?

The silica content of the magma increases.

The formation of the Himalaya and the Tibetan Plateau was caused by which of the following events?

There was a collision of two pieces of continental crust at a subduction zone.

What is convection?

a cycle of moving material formed by the rise of less-dense material and the sinking of denser material

What is the relationship between temperature and density?

In general, warmer materials are less dense, and colder materials are denser.

What is a plume?

a zone of upwelling material originating at the outer core-mantle boundary

What features at the surface provide evidence of plumes?

Hot spots

What is the relationship between the crust and the lithosphere?

All of the crust is contained within a larger layer called the lithosphere.

What is the relationship between the mantle and the lithosphere?

Some of the mantle is contained within a smaller layer called the lithosphere.

What is the relationship between the mantle and the asthenosphere?

All of the asthenosphere is contained within a larger layer called the mantle.

What surface feature provides evidence for the location of hot spots?

volcanoes within tectonic plates

When will a hot spot volcano become extinct?

when the volcano is carried away from the hot spot by the tectonic plate

What surface feature would you expect to form if both a hot spot and a tectonic plate are stationary?

a single volcano

Plates move apart at __________ boundaries, move together at __________ boundaries, and move side-by-side at __________ boundaries.


Which geologic features are associated with divergent boundaries?

mid-ocean ridges and continental rift valleys

Which geologic features are associated with convergent boundaries?

ocean trenches and volcanoes

Where is the youngest ocean floor found?

Along the crest of mid-ocean ridge

What would happen to Earth if ocean floor were created at divergent boundaries at a faster rate than it is destroyed at convergent boundaries?

The Earth would increase in volume.

What is a volcanic arc?

a row of volcanoes that forms on the overriding plate near a subduction zone

Which of the following mountain ranges are examples of continental arcs?

Andes and Cascades

What is a terrane?

a slice of lithosphere that has been added to the margin of a continent during plate collision

Where does most terrane accretion occur?

in association with a continental-oceanic subduction zone

Why are terranes added to continental margins, rather than subducting under them?

Terranes are too buoyant to subduct.

Which of the following statements about terranes is most accurate?

The margins of many continents have grown through the accretion of terranes.

Which feature would you expect to find at the mouth of a submarine canyon?

A deep sea fan

Which coast represents an active continental margin?

the west coast of South America.

Moving off the east coast of North America, identify the sequence of environments you would encounter as you move deeper into the Atlantic Ocean?

continental shelf, continental slope, continental rise, abyssal plain

Which statement best explains the formation of seamounts?

They represent volcanoes situated over mantle plumes that have since moved away from their source of magma and subsided

Which response best explains the absence of volcanoes and earthquakes at a passive continental margin?

No earthquake or volcanoe can occur due to the distance from any active boundaries

Which one of the following is an important fundamental assumption underlying the plate tectonic theory?

Earth's diameter has been essentially constant overtime

The continental drift hypothesis was rejected primarily because Alfred Wegener could not __________.

Identify a mechanism capable of moving continents.

Deep-focus earthquakes are associated with ________ plate boundaries.

Convergent (subducting)

A transform plate boundary is characterized by _____________.

a deep, vertical fault along which two plates slide past one another in opposite directions

Which one of the following would most likely be covered with thick turbidite layers?

Deep-sea fan at the base of a continental slope

Deep ocean trenches are surficial evidence for ____________.

Sinking of oceanic lithosphere into the mantle at a subduction zone

"Black smokers" are associated with ____________.

a. oceanic ridge b. mineral-rich waters c. hot water d. all of these (ALL OF THESE)

______ marks the edge of a continent.

The lowest part of the continental slope

All of the following are layers that comprise oceanic crust except for?


Which of the following best characterizes the tectonic development of fault-block Mountains?

Normal faults; crustal stretching and brittle failure of the upper crust

Oceanic ridges are elevated compared to the surrounding ocean floor because ________.

Newly formed lithosphere is hotter and therefore less dense than the surrounding rocks

Which of the following best describes the geology of the Pacific coastal regions of western North America including Alaska?

Geologically different, micro continent-sized fragments and terranes, formed elsewhere, were tectonically accreted to North America.

The ________ are a geologically old mountain range folded and deformed during the Paleozoic.

Appalachians in the eastern United States

Folded limestone's that occur high in the Himalayas were originally deposited as sediments in a ________.

Marine basin between India and Eurasia

Volcanism along a continental arc is dominated by the eruption of ________.

Andesitic lavas and pyroclastic materials

Which one of the following operates primarily in areas of permafrost?


Of the following, which one would most likely be triggered by an earthquake?

Rock avalanche

All of the following are factors affecting mass wasting except for ________.

geologic age

Why was the Alaskan pipeline built above ground and insulated?

To protect the pipeline against damage due to thawing ground and to keep the crude oil hot and fluid

Which of the following statements concerning mudflows is not true?
a. Mudflows may be caused by heavy rains or melting snow.
b. In hilly areas, mudflows move down the canyons and stream valleys.
c. Mudflows deposit talus slopes.
d. Mudflows can move and carry very large boulders and other coarse debris.

c. Mudflows deposit talus slopes.

As an erosional process, how is mass wasting unique from wind, water, and ice?

Mass wasting does not require a transporting medium.

Most dry lands lie between ________ degrees north and south of the equator.

20 and 30

In which area would surface water most effectively infiltrate into the local groundwater system?
A. a stream in a steep-sided, bedrock canyon in the mountains
B. streams flowing in the numerous channels of an alluvia fan
C. a playa lake with a thick mud bottom
D. all of these would promote infiltration.

B. streams flowing in the numerous channels of an alluvia fan

Which one of the following statements about sand dunes is correct?
A. A dune migrates in the direction of inclination of the slip face.
B. the more gently sloping surface is the leeward slope of the dune.
C. sand is blown up the slip face and rolls down the more gently sloping flank of the dune.
D. in a sand dune, the more gently inclined strata lie parallel to the slip face.

A. A dune migrates in the direction of inclination of the slip face.

Which one of the following will effectively limit further deflation in a given area?

desert pavement

Which of the following is determined by the angle of repose for dry sand?

Inclination angle of a dunce slip face

Which of the following responses are examples of how water can promote mass wasting? B,D,E

A. Water can infiltrate sediment, partially filling the pore spaces between grains and reducing slope integrity.
B. Waves and streams can undercut banks and cliffs, causing them to fail.
C. Water enhances the ability of vegetation to grow on weathered particles.
D. When water is added to weathered particles, the mass of the sediment is increased, which can promote mass wasting.
E. Water can saturate sediment, reducing the integrity of the slope and allowing it to move.

When dry sediment accumulates, the angle of repose represents what property of the deposit?

The steepest angle at which those sediments can accumulate and remain stable.

When sediment accumulates, the angle of repose can be increased by changing which of the following conditions? D

A. undercutting by waves and streams
B. removing all the moisture from the sediment (drying)
C. removal of vegetation
D. slight addition of water to the sediment
E. earthquake activity

Of the following types of mass wasting, which tends to be the fastest moving and most destructive?


Which of the following examples of mass wasting is characterized by a crescent-shaped scarp or cliff at its head?


Which of the following types of mass wasting is extremely slow and occurs when saturated soil flows downslope?


During the eruption of Mount St. Helens on May 18, 1980, snow and glacial ice on the mountain melted and rushed down the Toutle River. What is the name given to this specific type of mass wasting?


Which of the following statements about deserts is true? C

A. Deserts are dominated by sand dunes.
B. Deserts are lifeless.
C. Water is the most significant agent of erosion in deserts.
D. Deserts are always hot.

Which of the following statements characterizes ephemeral streams? E

A. Ephemeral streams generally depend on groundwater in the desert to flow year round.
B. Ephemeral streams flow all the time in the desert.
C. Ephemeral streams are streams that flow through deserts, but have their origins outside of the desert.
D. Ephemeral streams don't have any life in them.
E. Ephemeral streams flow only at certain times of the year.

In the desert environment, how are ventifacts created?

Ventifacts are produced on the surface of a rock by the continued impact of very small particles carried by the wind.

When desert pavement is produced in a desert, why do the larger particles accumulate on the surface? A

A. The wind can move particles of only a very specific size and it takes away these small particles, concentrating the larger ones.
B. Particles are cemented together as water evaporates.
C. Running water carries away all the smaller material.
D. Large particles fall from the nearby slopes due to mass wasting.
E. Wind is capable of moving the large particles to a site where they are deposited.

Which of the following statements is the best explanation for the occurrence of the Great Basin Desert in the western United States? E

A. Snow in the mountains surrounding the Great Basin melts very slowly.
B. The Great Basin Desert exists because descending high-pressure air masses do not contain any moisture.
C. Water is removed from the Colorado River before it gets to the Great Basin, causing it to be dry.
D. Storms from the east rarely make it to the Great Basin while they still have moisture in them.
E. The Great Basin Desert exists because it is a rain shadow desert

With the noted increases in global temperature, what changes will be associated with Earth's climatic regions?

Deserts will expand into steppe and humid regions of the globe.

Which of the following provides the best explanation for the abundance of desert areas in the low latitudes?

? In these regions, air is cooled and compressed, which precludes the transport of water in the atmosphere.

Fan-shaped cones deposited at the mouth of a canyon in a desert are known as _____________.

Alluvial fan

Which of the following terms best describes long, sinuous bed forms that develop perpendicular to the prevailing wind direction in desert environments? E

A. Star dunes
B. barchan dunes
C. Parabolic dunes
D. Longitudinal dunes
E. Transverse dunes

The majority of the loess deposits on the Great Plains owe their accumulation to which of the following explanations?

Loess in the Great Plains accumulated as fine sediments blown from outwash deposits adjacent to the retreating continental ice sheet.

What are cross beds?

Inclined layers in sediment or sedimentary rocks that reveal the direction of wave or wind transport

What do cross beds represent?

The moving front of a ripple or dune

What is the relationship between water currents and cross beds?

Cross beds sit at an angle to current direction

Why do desert dunes migrate?

Wind erodes material on the back side of the dune and deposits it on the front side of the dune.

How do pieces of rock move under the influence of wind?

Rolling, sliding, bouncing, suspension

What property of a piece of material will most directly determine how it is carried by wind?


What is dust?

The particles carried in suspension by wind

Which of the following features would you expect to find on the outside bank of a stream meander loop? A: a cut bank

a yazoo tributary
an oxbow lake
a cut bank
a very gentle slope
a point bar

When the local gradient of a stream changes as it goes from a mountainous area to a large flat-lying area, which of the following features could form?

A alluvial fan

In a delta, sedimentary layers deposited under circumstances that appear to violate the Principle of Original Horizontality are found in which of the following circumstances?

Forrest beds

Which of the following choices does not directly affect stream velocity?

location of the drainage divide

The amount of meandering that occurs in a stream influences the gradient is which of the following ways?

With more Meanders, the stream gradient decreases.

While working on a stream in your field study area, you find that the channel with is 20 meters, the channel depth is 2 meters, and the velocity is 1.2 meters/ sec. What is the discharge of the stream?


What is a floodplain?

A flat surface next to a river channel

What is a natural levee?

a ridge of flood deposits next to a river channel

How does the formation of a natural levee impact flooding?

Natural levees raise the height of the stream channel, reducing the amount of flooding that will occur on the floodplain.

How can pieces of rock in contact with a stream bed move?

Rolling, sliding, bouncing

Complete this analogy: Bouncing is to sand as suspension is to_____________.


which are part of the bed load?

Sand, gravel

What are the three types of loads carried by streams?

dissolved load, suspended load, and bed loads

What is suspended load?

the fine-grained particles that travel in the water column above the stream bed

What is the dominant fluvial process in a clear, sediment-poor stream moving down a steep slope?


Where do deposition and erosion of material occur along a meander

Deposition occurs on the inside of the meander, whereas erosion occurs on the outside

How are oxbow lakes formed?

Oxbow lakes form when one meander erodes into another, cutting off water to part of the stream channel.

Which of the following zones is the location of the most biological activity?

the zone of soil moisture

In terms of freshwater storage, groundwater is second only to which of the following sources?


The majority of ground water is stored within which of the following zones?

the zone of saturation

During a summer with little rainfall, your house on a hill slope experiences an interval during you well runs dry. You have to borrow water from your neighbor who lives downslope from you. Why does you neighbor have water when you don't?

as the water table drops due to the lack of precipitation, it goes below the base of your well.

The quantity of groundwater that can be stored within sedimentary material is most directly controlled by which of the following parameters?

the porosity of the material

The permeability of a material is directly related to which of the following parameters?

the grain size of the material

Rock, such as shale or clay, or other unlithified sediment can produce layers that are well sorted, but do not allow water to move through them. Which of the following terms is most accurate for this type of layer?

an aquitard

An agricultural company purchased a large tract of land adjacent to your property and built a group of large commercial greenhouses on it. This company uses a lot of water to keep the plants green and healthy. During a particularly dry summer, the amount of water available to your well starts to decrease. Since you are utilizing the same aquifer, what has this company done to the water supply?

The company has compromised the aquifer and is essentially mining the water from it.

As a hydrogeologist looking for a source of water for a housing development, which of the following attributes would you look for in a layer of sediment or sedimentary rock?

High porosity, high permeability, extent over a large geographic area

How would the water table be affected if Earth were made up of uniform, permeable material?

The water table would not exist.

Why does groundwater discharge to Earth's surface?

Earth's surface is irregular, and permeability decreases with depth within Earth.

Which of the following would produce a lower water table?

an increase in the amount of discharge to surface water, a decrease in the amount of recharged to ground water

How does the use of water by humans affect the water table

use of water by humans increases discharge, resulting in lowered water table

Which of the following statements characterize the activity of glaciers and their impact on the landscape? Glacial activity can change the position of sea level relative to present conditions, glaciers are capable of oversteepening slopes, glaciers are capable of moving large amounts of sediment, glaciers can disrupt the hydrologic cycle

All answers are relevant

Compared with the amount of ice that existed during the last glacial maximum, how much exists today?


You are working in a field area that you think at one time contained valley glaciers. What evidence would you look for to determine this?

You would look for rounded, U shaped valleys

Which is the best definition of glacial snow line

the line dividing zones of accumulation and melting of ice at the surface of a glacier

Under what conditions will the front of a glacier remain stationary?

Glacial fronts remain stationary when melting and snow accumulation are equal.

Which way does ice flow in a glacier retreating uphill?


How would a snow line on a glacier move as a glacial front is advancing?

The snow line would move downslope

How would you expect the front of a glacier to move if it undergoes a period of net accumulation, followed by net wastage, and finally a period of net accumulation?

The glacier's front would move forward, backward, and then forward again.

Which one of the following statements is correct? A

A: Sea level drops when water is stored in expanding ice sheets and continental glaciers.
B. Sea level rises when water is added to the oceans through increased rainfall and increased inflow from rivers.
C. Sea level drops when evaporation rates increase over the oceans and when this extra, atmospheric moisture falls on land as rain.
D. Sea level rises when water is stored in expanding ice sheets and continental glaciers.

In the absence of cutoff, how does a river meander loop behave over time?

The gradient is lowered as the channel lengthens and migrates toward the cut or outer bank of the loop.

________ are components of the hydrologic cycle that release water vapor directly to the atmosphere.

Evaporation and transpiration

Which of the following features characterize wide streams and valleys

Natural levees; broad

________ are characteristics of down cutting streams and a youthful stage of valley evolution.

Rapids and lots of whitewater

Which one of the following statements is true concerning natural levees?

mostly fine sand and silt that build up during floods

The water table is ________.

a boundary between saturated rock below and unsaturated rock above

________ controls the ease (or difficulty) of groundwater transmission through a porous material.


An aquifer is ________.

a saturated, porous, and permeable layer or stratum

Which one of the following applies to a valley glacier that lengthens (extends its terminus down slope) over a period of many years?

Accumulation exceeds wastage.

________ account for the largest usage of groundwater in the United States.

Agriculture and irrigation

________ is the volume of voids or open space in a rock or unconsolidated material.


________ are erosional features produced by valley/alpine glaciers.


A(n) ________ represents a former meltwater channel or tunnel in glacial ice that was filled with sand and gravel.


A drumlin is a ________.

smooth, tapering ridge of till; formed and shaped beneath a continental ice sheet

Which eon translates to "visible life" from the Greek?


Which is the shortest interval of geologic time?


The subdivisions of the Geologic Time Scale were based on which criteria or characteristics?

types of fossils within the units

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