Plate Tectonics

1. A layer of molten iron and nickel that surrounds the inner core of the earth
5. break or crack in the Earth's lithosphere along which rocks move
6. Alfred Wegener's hypothesis that the continents were once one huge land mass but have since then drifted apart
8. A plate boundary where two plates move toward each other
9. A deep canyon on the ocean floor
10. A soft layer of the mantle on which floats the lithosphere
12. dense ball of solid material at the center of the earth
13. The name of a single landmass that broke apart 225 million years ago
14. thickest layer of the earth; consists of two layers-the lithosphere and the asthenosphere

2. A deep valley where two plates move apart
3. The layer of rock that forms the Earth's outer surface
4. The process by which the oceanic crust sinks beneath a deep-ocean trench back into the mantle at a convergent plate boundary
7. cause the plates to move; between the lithosphere and the asthenosphere
11. A rigid layer made up of the uppermost part of the mantle and the crust