Across
- 1. ridge The undersea mountain mountain chain where new ocean floor is produced; a divergent plate boundary
- 4. boundary A plate boundary where two plates grind against each other, moving it in different directions
- 6. boundary A plate boundary where two plates move away from each other
- 8. A soft layer of the mantle on which the lithosphere floats
- 11. zone The process by which oceanic crust sinks beneath a deep-ocean trench and back into the mantle at a convergent plate boundary
- 12. A break or crack in the Earth's lithosphere along which rocks move
- 14. A rigid layer made up of the uppermost part of the mantle and the crust
- 15. boundary A plate boundary where two plates move toward each other
- 17. Thickest layer of the Earth; it consists of two layers - the lithosphere and the asthenosphere
- 19. spreading The process by which molten material adds new oceanic crust to the ocean floor
- 20. The layer of rock that forms the Earth's outer surface
Down
- 2. currents Cause the plates to move; between the lithosphere and the asthenosphere
- 3. Wegener German Scientist who developed the Theory of the Continental Drift in 1912.
- 5. core Dense ball of solid material at the center of he Earth
- 7. The name of the single landmass that broke apart about 225 million years ago
- 9. valley A deep valley where two plates move apart
- 10. Drift Alfred Wegener's hypothesis that the continents were once one huge land mass but have since then drifted apart
- 13. A deep canyon on the ocean floor
- 16. core A layer of molten iron and nickel that surrounds the inner core of the Earth
- 18. of Plate Tectonics Theory that pieces of the Earth's lithosphere are in motion,driven by convection currents in the mantle