TECTONIC PLATES

3. At or near the middle.
4. The outer layer of Earth.
5. A layer of molten iron and nickel that surrounds the inner core of Earth. (2 words)
7. The soft layer of the mantle on which the lithosphere floats.
10. Continents moving over Earth's surface. (2 words)
13. Move apart.
16. The process by which the ocean floor sinks beneath a deep ocean trench and back into the mantle.
18. The scientist who discovered continental drift.
19. Under or below.

1. A dense sphere of solid iron and nickel at the center of the Earth (2 words)
2. The supercontinent that was pulled apart by continental drift.
3. An undersea mountain chain where new ocean floor is produced. (3 words)
6. Move together.
8. A section of the lithosphere that slowly moves over the asthenosphere carrying pieces of continental and oceanic crust.
9. The layer of hot solid material between Earth's crust and core.
11. Part of Earth's lithosphere that surfaces in ocean basins. (2 words)
12. A rigid layer made up of the uppermost part of the crust.
14. The study of physical Earth, the rocks of which it is composed and the process by which they change.
15. A large piece of land.
17. The point or line where one region ends and another begins.