Topic 4: Plate Tectonics

3. The force that acts on rock to change its shape or volume.
5. Magma that reaches Earth’s surface.
8. An instrument used to record the motion of the ground during an earthquake.
10. Squeezes rock until it bends or breaks.
11. A wave or series of waves produced by an earthquake or landslide.
14. A single number geologists use to assign to an earthquake based on the earthquake’s size.
15. An undersea valley that is the deepest part of the ocean.
16. A dead volcano that poses very little threat of eruption.
17. A molten mixture of rock-forming substances, gasses, and water from the mantle.

1. A structure that forms in Earth’s crust when molten material, or magma, reaches Earth’s surface.
2. The shaking or trembling that results from plate movement.
4. The sinking movement of ocean floor back into the mantle.
6. Pulls on Earth’s crust, stretching the rock to make it thinner.
7. A sleeping volcano that poses little threat but could reawaken someday.
9. A volcano that is currently erupting or erupted recently.
12. When rock is being pushed in two opposite directions, to the point where it bends or breaks.
13. A break in the rock of Earth’s crust or mantle.