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 ____.

• a.Panthalassa

• b.Pangaea

• c.Mesosaurus

• d.Africa

Ch9

What hypothesis states that the continents were once joined to form a single supercontinent?

• a.plate tectonics

• c.continental drift

• b.seafloor spreading

• d.paleomagnetism

Ch9

In the plate tectonics theory, the lithosphere is divided into ____.

• 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 ____.

• 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 ____.

• 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?

• 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 ____.

• 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 ____.

• 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 ____.

• a.seaward from the trench• b.along the axis of the trench • c.at the ends of the trench• d.landward from the trench

Ch9Why 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.

Ch9Strips 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.

Ch9What 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.