plate tectonics

2. what type of rock is found farther away from a ridge
8. what idea did wegner come up with
10. what is created when along a mid ocean ridge and is destroyed at a deep ocean trench
11. who thought of continental drift
12. the theory that earths plate slow constant motion is called
15. when the ocean floor sinks beneath the deep ocean trench is called
16. when it adds more material is called
18. what did scientist really find at the bottom of the ocean
19. when the oceanic crust bends downward is called
20. where pieces of earths crust diverge on land, a deep valley forms

1. what pulls the older,denser oceanic crust down beneath the trench and back into the mantle
3. what type of belt does seafloor spreading and subduction make when working together
4. when two continental plates colloid what do they make
5. when two plates move away from each other is called
6. what boundary colloid together
7. where dose sea floor spreading begin
9. super continent 300 million years ago
13. what boundary slips past each other
14. what is the thickest layer of the earth
17. what did scientist use to find things at the bottom of the ocean