plate tectonics

4. what type of rock is found farther away from a ridge
5. where dose sea floor spreading begin
6. where pieces of earths crust diverge on land, a deep valley forms
8. what type of belt does seafloor spreading and subduction make when working together
9. what is created when along a mid ocean ridge and is destroyed at a deep ocean trench
11. what boundary slips past each other
13. the theory that earths plate slow constant motion is called
15. what boundary colloid together
17. what did scientist really find at the bottom of the ocean
18. what is the thickest layer of the earth
19. when the ocean floor sinks beneath the deep ocean trench is called
20. when two continental plates colloid what do they make

1. when two plates move away from each other is called
2. when the oceanic crust bends downward is called
3. who thought of continental drift
7. what did scientist use to find things at the bottom of the ocean
10. when it adds more material is called
12. what pulls the older,denser oceanic crust down beneath the trench and back into the mantle
14. what idea did wegner come up with
16. super continent 300 million years ago