1. 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

2. Ch9
The supercontinent in the continental drift hypothesis was called ____.
a.Panthalassa
b.Pangaea
c.Mesosaurus
d.Africa

3. 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

4. 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

5. 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

6. 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

7. 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

8. Ch9 New ocean crust is formed at ____. a.divergent boundaries
c.continental volcanic arcs
b.convergent boundaries
d.transform fault boundaries

9. 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

10. 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

11. Ch9 Deep ocean trenches are associated with ____.
a.ocean ridge systems
b.subduction zones
c.transform fault boundaries
d.rift zones

12. 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

13. 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

14. 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

15. 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

16. 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.

17. 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.

18. 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.

19. Ch9 What feature is labeled A in Figure 9-2? a.subduction zone
b.trench
c.volcanic island arc
d.continental volcanic arc

20. 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.

21. 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.