Continental Drift

5. What theory states that the continents were once a single landmass?
8. What is the process where the ocean floor sinks below the deep ocean trench and back into the mantle?
9. A supercontinent that existed 250 million years ago.
10. What scientist proposed the theory of continental drift?
12. What theory states that the Earth's crust is made up of several pieces?
16. The downward portion of a rock fold.

1. When two plates move towards each other.
2. The Sierra Nevada's are an example of this type of mountain range.
3. The uplifted portion of a rock fold.
4. These are deep scratches left in bedrock across continents.
6. Mountain chain that rises from the ocean floor.
7. When two plates move apart from each other.
11. This tall, woody, seed-bearing plant fossil was found on several continents.
13. A deep valley on the ocean floor.
14. The mountain is growing at a rate of 1 cm per year.
15. When two plates slide past each other.