Plate Tectonics

4. a hypothesis, first proposed in the 1960s by Harry Hess
5. when the supercontinent began breaking into smaller continents to their present location
9. average amount of seafloor spreading that happens
10. occurs when igneous rocks melt over a temp range
15. a boundary which when two plates move together resulting in oceanic lithosphere being thrust beneath an overriding plates

1. deep canyon like structure
2. Volcanos grow up from the ______ instead upon a continental platfrom.
3. fixed geographic positions and were ancient
6. A boundary in which two plates move apart resulting in a upwelling of material from the mantle to create a new sea floor
7. supercontinent containing all of the existing continents
8. _____ were formed when India "rammed" into Asia
11. Heat is continuously flowing outward from Earth's interior, causing convection in the _____.
12. another name for the upwelling of material from the mantle to create new seafloor
13. a narrow, elongated depression of the seafloor
14. also equals low angle of descent