plate tectonics
Across
- 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
Down
- 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