Chapter 9 Review

Wegener's idea that forces might cause continental drift was shown to be impossible when it was

shown that the tidal forces needed to move continents would stop the Earth's rotation

What mechanism of plate motion is illustrated in figure 9-2

slab-pull

The main source of downward convection flow in the mantle is called

slab-push

According to whole-mantle convection

slabs of cold oceanic lithosphere move down into the mantle

What process is illustrated by the area labeled G in figure 9-1

subduction

What kind of plate boundary occurs where two plates grind past each other without destroying of producing lithosphere?

transform fault boundary

What feature is labeled B in figure 9-1

trench

What feature is labeled A in figure 9-2

volcanic island arc

What type of boundary is illustrated in figure 9-2

covergent oceanic-oceanic boundary

How did opponents of continental drift account for the exercise of similar fossil on widely separated continents?

migration across land bridges

The lithospheric plates move an average of

5 centimeters per year

How does the age of the seafloor sediments change with increasing distance from the ocean ridge?

Age increases

Why are subduction zones not commonly found at convergent continental-continental boundaries?

Continental lithosphere is too buyout to be forced down into the mantle

What type of plate boundary is illustrated in Figure 9-1

Convergent oceanic-continental boundary

According to figure 9-2 if the plate labeled H descends into the Earth's interior, what will occur between the position labeled Y and X

Earthquake foci will be shallower at Y and increase the depth

Where are most transform faults found?

Joining two segments of a mid-ocean ridge

At a transform fault boundary

Lithosphere is neither destroyed nor produced

Which of the following does not occur at a subduction zone

The leading edge of both plates are bent upward

What do the strips of low-intensity magnetism represent on the ocean floor

area where the rocks have reversed polarity

The Red Sea is theorized to be the site recently formed

divergent boundary

Evidence about ancient climates indicates that

glacial ice once covered much of what is now India and Australia

The downward sliding characteristic of ridge-push is the result of

gravity

If a deep ocean trench is located adjacent to a continent, active volcanoes would likely be found

landward from the trench

What layer of the Earth is labeled C in figure 9-1

oceanic crust

The age of the rock that makes up the ocean floor was determined by

radiometric dating