Plate Tectonics

4. How scientists study the inside of Earth since we can’t drill down that far
6. When plates move away from each other
8. When oceanic crust sinks beneath a deep-ocean trench and back into the mantle
10. Measure of how much mass there is in an object
11. When plates come together
12. A break in Earth’s crust where rocks slipped past each other
14. When molten material is added to make new oceanic crust
16. Theory of how the continents spread away from each other
19. The theory that Earth’s plates are in a slow, constant motion
20. The remains of a prehistoric organism

1. Scientist that came up with the theory of continental drift
2. What scientists use to explore the ocean floor
3. Valley along the ocean floor where oceanic crust sinks into the mantle
5. Where seafloor spreading begins
7. When pieces of Earth’s crust diverges on land
9. When plates slip past each other
13. Causes the plates to move
15. 3rd layer of Earth that is very hot, yet solid where convection currents are
17. Supercontinent that existed around 300 million years ago
18. Produced when 2 continental plates collide