Plate tectonics

1. A soft layer of the mantle on which the lithosphere floats
3. Thickest layer of the Earth; it consists of two layers - the lithosphere and the asthenosphere
6. Dense ball of solid material at the center of he Earth
7. A layer of molten iron and nickel that surrounds the inner core of the Earth
9. The process by which oceanic crust sinks beneath a deep-ocean trench and back into the mantle at a convergent plate boundary
11. A plate boundary where two plates move away from each other
13. A deep valley where two plates move apart
15. The undersea mountain chain where the new ocean floor is produced; a divergent plate boundary
17. A deep canyon on the ocean floor
18. A rigid layer made up of the uppermost part of the mantle and the crust
19. The process by which molten material adds new oceanic crust to the ocean floor

1. German Scientist who developed the Theory of the Continental Drift in 1912.
2. alfred Wegener's hypothesis that the continents were once one huge land mass but have since then drifted apart
4. A plate boundary where two plates move toward each other
5. The layer of rock that forms the Earth's outer surface
8. A plate boundary where two plates grind against each other, moving it different directions
10. Cause the plates to move; between the lithosphere and the asthenosphere
12. Theory that pieces of the Earth's lithosphere are in motion,driven by convection currents in the mantle
14. The name of the single landmass that broke apart about 225 million years ago
16. A break or crack in the Earth's lithosphere along which rocks move