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Ch9
Wegener’s continental drift hypothesis
stated that all the continents once joined
together to form ____.
• a.two major supercontinents
• b.two major supercontinents and three
smaller continents
• c.one major supercontinent
• d.three major supercontinents
Ch9
The supercontinent in the continental drift
hypothesis was called ____.
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a.Panthalassa
b.Pangaea
c.Mesosaurus
d.Africa
Ch9
What hypothesis states that the continents
were once joined to form a single
supercontinent?
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a.plate tectonics
c.continental drift
b.seafloor spreading
d.paleomagnetism
Ch9
In the plate tectonics theory, the lithosphere
is divided into ____.
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a.100 major plates
b.7 major plates and many smaller plates
c.many small plates, but no large plates
d.50 major plates and many smaller plates
Ch9
The lithospheric plates move an average of
____.
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a.5 inches per year
b.50 inches per year
c.5 centimeters per year
d.50 centimeters per year
Ch9
A tectonic plate consists of ____.
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a.the crust and uppermost mantle
b.the oceanic and continental crust only
c.the crust and entire mantle
d.the asthenosphere only
Ch9
Which of the following is a geographic
example of a transform fault boundary?
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a.the East African Rift valley
b.the San Andreas Fault
c.the Mid-Atlantic Ridge
d.the Andes Mountains
Ch9
New ocean crust is formed at ____.
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a.divergent boundaries
c.continental volcanic arcs
b.convergent boundaries
d.transform fault boundaries
Ch9
Which of the following results when
divergence occurs between two oceanic
plates?
• a.seafloor spreading
• b.a subduction zone
• c.an ocean trench
• d.a volcanic island arc
Ch9
What forms when one oceanic plate is
forced beneath another plate?
• a.an ocean basin
• b.an ocean ridge
• c.a subduction zone
• d.a rift valley
Ch9
Deep ocean trenches are associated with
____.
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a.ocean ridge systems
b.subduction zones
c.transform fault boundaries
d.rift zones
Ch9
• What type of plate boundary is illustrated in
Figure 9-1?
• a.transform fault boundary
• b.divergent boundary
• c.convergent oceanic-oceanic boundary
• d.convergent oceanic-continental boundary
Ch9
Volcanic island arcs are associated with
what type of plate boundary?
• a.divergent boundary
• b.convergent continental-continental
boundary
• c.convergent oceanic-continental
boundary
• d.convergent oceanic-oceanic boundary
Ch9
Continental volcanic arcs are associated
with what type of plate boundary?
• a.convergent continental-continental
boundary
• b.convergent oceanic-continental
boundary
• c.transform fault boundary
• d.convergent oceanic-oceanic boundary
Ch9
If a deep ocean trench is located adjacent to
a continent, active volcanoes would likely
be found ____.
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a.seaward from the trench
b.along the axis of the trench
c.at the ends of the trench
d.landward from the trench
Ch9
Why are subduction zones not commonly found at
convergent continental-continental boundaries?
• a.Continental lithosphere is too buoyant to be
forced down into the mantle.
• b.Subduction zones are never found at
convergent boundaries.
• c.Oceanic lithosphere is too buoyant to be
forced down into the mantle.
• d.Continental lithosphere is too dense to be
forced down into the mantle.
Ch9
Strips of alternating magnetic polarities
found in rocks in the ocean basins ____.
• a.conflict with the theory of plate tectonics
• b.provide evidence that Earth’s magnetic
field has never reversed polarity
• c.indicate changes in Earth’s gravitation
field
• d.provide evidence for seafloor spreading.
Ch9
What do the strips of low-intensity
magnetism represent on the ocean floor?
• a.areas where there is no magnetism
• b.areas where the rocks have a normal
polarity
• c.areas where the rocks have a reversed
polarity
• d.areas of different types of rock.
Ch9
What feature is labeled A in Figure 9-2?
• a.subduction zone
• b.trench
• c.volcanic island arc
• d.continental volcanic arc
Ch9
According to Figure 9-2, if the plate labeled H descends
into Earth’s interior, what will occur between the
positions labeled Y and X?
• a.The rock at X will be cooler than the rock at Y.
• b.Earthquake foci will be shallower at Y and increase in
depth at X.
• c.Earthquake foci will be deeper at Y and decrease in
depth at X.
• d.Rifting will begin to occur between Y and X.
Ch9
According to Figure 9-2, if the plate labeled H descends
into Earth’s interior, what will occur between the
positions labeled Y and X?
• a.The rock at X will be cooler than the rock at Y.
• b.Earthquake foci will be shallower at Y and increase in
depth at X.
• c.Earthquake foci will be deeper at Y and decrease in
depth at X.
• d.Rifting will begin to occur between Y and X.