Read About It! Plate Tectonics & Earth's Surface

What causes tectonic plates to move?

• The movement of ocean water

• Convection currents in the mantle

• Pressure from the outer core

• Gravity pulling plates apart

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How do convection currents work in the mantle?

• Hot rock at the bottom rises, and cooler rock near the crust sinks, creating a circular motion.

• Mantle materials move in straight lines due to gravity.

• Heat causes the outer core to spin, moving the mantle.

• Mantle rock moves toward the crust and stays there permanently.

What are the three types of plate boundaries?

• Divergent, convergent, and transitional

• Convergent, divergent, and transform

• Transform, parallel, and subduction

• Divergent, overlapping, and convergent

How do mountains form at convergent boundaries?

• Two oceanic plates collide and create underwater peaks.

• One plate slides under the other, creating a trench that pushes up the land.

• Two continental plates collide, pushing the crust upward.

• Plates move apart, and magma forms mountains.

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What is seafloor spreading and how does it affect ocean basins?

• Magma rises at transform boundaries, causing ocean basins to shrink.

• At convergent boundaries, new crust forms, shrinking the ocean basins.

• Plates move apart at divergent boundaries, forming new crust and enlarging the ocean basins.

• Ocean basins grow smaller as dense plates sink into the mantle.

How does subduction create ocean trenches?

• When two plates move apart, molten rock forms valleys underwater.

• When one dense plate sinks beneath a less dense plate, it melts and forms a trench.

• Ocean trenches form when two continental plates push downward.

• Ocean trenches are formed by mid-ocean ridges growing taller.

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