plate tectonics

4. A string of volcanoes that form as the result of subduction of one oceanic plate beneath another.
7. A deep depression in the ocean floor caused by subduction.
8. Wegener's hypothesis that continents slowly move across Earth's surface.
9. The rigid outer part of the earth, consisting of the crust and upper mantle.
10. The semi-fluid layer of the mantle that tectonic plates move on.
12. A plate boundary where two plates move away from each other.
14. A deep valley that forms where two continental plates move apart.
16. An area where magma from deep within the mantle melts through the crust above it (e.g., Hawaii).
17. Molten rock that reaches the Earth's surface.
19. The name of the supercontinent that existed 250 million years ago

1. An underwater mountain range formed by plate tectonics.
2. Molten rock beneath the Earth's surface.
3. The process of one plate sinking beneath another into the mantle.
5. A plate boundary where two plates move toward each other.
6. The point on Earth's surface directly above an earthquake's focus.
8. The transfer of heat by the movement of fluid (driving force of plate motion).
11. The process that creates new oceanic crust at mid-ocean ridges.
13. A plate boundary where two plates slide past each other horizontally.
15. Large ocean waves often triggered by underwater earthquakes.
18. A break in the Earth's crust where rocks have slipped past each other.