Plate Tectonic

3. A sudden and violent shaking of the ground caused by movement of Earth's plates.
8. A supercontinent that existed about 300 million years ago and eventually broke apart.
10. Plate A rigid segment of the Earth's crust that moves independently across the surface.
11. Valley A deep valley that forms where two plates move apart.
13. The rigid outer layer of Earth, including the crust and upper mantle.
14. Tectonics The theory that Earth's outer shell is divided into several plates that glide over the mantle.
15. Boundary A boundary where two plates slide past one another horizontally.
16. A mountain that forms when magma reaches the surface.
18. A crack in Earth's crust where movement has occurred.
20. Molten rock beneath the Earth’s surface.

1. Boundary A tectonic plate boundary where two plates move apart.
2. A process where one tectonic plate sinks beneath another into the mantle.
4. Drift The gradual movement of continents across Earth’s surface over time.
5. The layer of Earth between the crust and the core, where convection occurs.
6. of Fire A major area in the Pacific Ocean where many earthquakes and volcanic eruptions occur.
7. Ridge An underwater mountain range formed by divergent plates.
9. Spreading The process by which new oceanic crust forms at mid-ocean ridges.
12. The outermost layer of the Earth.
17. Boundary A tectonic plate boundary where two plates move toward each other.
19. Magma that reaches Earth’s surface.