earth science HW 8 – Flashcards
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Which is not one of the three broad zones describing the ocean floor?
continental slope
mid-oceanic ridge
continental margin
deep-ocean basin
answer
continental slope
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Which feature would you expect to find at the mouth of a submarine canyon?
alluvial fan
a deep sea fan
beach
delta
talus slope
answer
a deep sea fan
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Which coast represents an active continental margin?
answer
the west coast of South America
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Moving off the east coast of North America, identify the sequence of environments you would encounter as you move deeper into the Atlantic Ocean.
answer
continental shelf, continental slope, continental rise, abyssal plain
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Which statement best explains the formation of seamounts?
answer
They represent volcanoes situated over mantle plumes that have since moved away from their source of magma and subsided.
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Which response best explains the absence of volcanoes and earthquakes at a passive continental margin?
answer
Earthquakes and volcanoes are rare due to the distance from any active boundaries.
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Where are most modern divergent plate boundaries found?
answer
at mid-ocean ridges
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Where do most divergent boundaries originate?
answer
within continents
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Which type of faulting is associated with the development of new ocean floor?
answer
normal faulting
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What causes melting of material under divergent plate boundaries?
answer
decompression of rock
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When do new oceans form?
answer
when a continent is broken apart by a divergent boundary
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At a convergent boundary, what is the relative motion of plates on each side of the boundary?
answer
The plates move toward each other.
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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 which of the following factors?
CHOOSE ALL THAT APPLY.
the density of the plate being subducted
the amount of water in the plate being subducted
the depth of the water over the plate being subducted
the composition of the plate being subducted
the age of the plate being subducted
answer
the age of the plate being subducted
AND
the density of the plate being subducted
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As oceanic crust is subducted below continental crust, which of the following factors most directly drives the melting that will fuel volcanoes at the surface?
answer
water
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When oceanic crust is subducted beneath continental crust, partial melting can occur. Which of the following best explains why the resultant magma rises through the crust toward the surface?
answer
The magma is less dense than the surrounding solid rock.
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A continental volcanic arc is formed when which of the following conditions exists?
answer
A piece of oceanic crust is subducted below continental crust.
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Although new crust is being formed at divergent boundaries, Earth remains the same size. Which of the following statements provides the best reason for this?
answer
An equal volume of crust is being consumed at convergent boundaries.
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As oceanic crust is subducted, it melts, forming a body of magma. When this magma rises and interacts with the overlying continental crust, what change occurs in the composition of the magma?
answer
The silica content of the magma increases.
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The formation of the Himalaya and the Tibetan Plateau was caused by which of the following events?
answer
There was a collision of two pieces of continental crust at a subduction zone.
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Which mountainous range is not the result of continental collision?
answer
Cascades
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The Ural Mountains were formed by the collision of which continents?
answer
Europe and Asia
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Which mountain range, formed via continental convergence, developed just before the Appalachians of North America?
answer
Caledonian Mountains
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Which feature would you expect to find associated with continental collisions?
answer
reverse faults
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What type of tectonic activity led to the formation and uplift of the Andes on the western margin of the South American Plate?
answer
formation of a volcanic arc
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Which of the following are classifications describing how rock and other material move downslope?
answer
fall, slide, slump, creep, flow
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What is mass movement?
answer
movement of material under the influence of gravity alone
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How is a fall different from creep?
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Falls occur rapidly and in areas with high slope, whereas creep occurs slowly in areas with low slope.
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How are slumps and slides related?
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Slumps are a type of slide in the special case where the rupture surface is curved.
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How are debris avalanches and flows related?
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Debris avalanches are large, rapid flows of rock.
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Which type of mass movement event requires the addition of water?
answer
flow
