Plate tectonics

5. what moves the crust
7. plates are moving towards one another.
10. occurs when two tectonic plates move away from each other.
13. the primary source of the movement of plates
14. plates are moving up and down each other
16. has a less density than oceanic crust
17. elevated areas of the sea floor characterized by high heat flow and volcanism
18. a hypothesis, first proposed in the 1960s by harry hess
19. a continues elevated zone on the floor of all the major ocean basins
20. made the hypothesis of the sea floor spreading

1. of irregular topography on the deep ocean floor
2. what is the oceanic crust made of
3. they are made by earthquakes
4. a narrow elongated depression of the sea floor
6. what does a convergent plates make
8. two oceanic plates converge
9. a chain of volcanic islands generally located a few hundred km from trench
11. mountains formed in part igneous activity associated with the subduction of oceanic lithosphere beneath a continent
12. has a greater density than continental crust
15. older,denser portions of oceanic lithosphere descends