TECTONIC PLATES

5. The outer layer of Earth.
7. At or near the middle.
8. Move apart.
9. A layer of molten iron and nickel that surrounds the inner core of Earth. (2 words)
11. The soft layer of the mantle on which the lithosphere floats.
12. Move together.
14. An undersea mountain chain where new ocean floor is produced. (3 words)
17. A large piece of land.
18. Under or below.
20. The study of physical Earth, the rocks of which it is composed and the process by which they change.

1. The point or line where one region ends and another begins.
2. The layer of hot solid material between Earth's crust and core.
3. A dense sphere of solid iron and nickel at the center of the Earth (2 words)
4. A rigid layer made up of the uppermost part of the crust.
6. The process by which the ocean floor sinks beneath a deep ocean trench and back into the mantle.
10. Continents moving over Earth's surface. (2 words)
13. The supercontinent that was pulled apart by continental drift.
15. Part of Earth's lithosphere that surfaces in ocean basins. (2 words)
16. The scientist who discovered continental drift.
19. A section of the lithosphere that slowly moves over the asthenosphere carrying pieces of continental and oceanic crust.