Across
- 3. / any trace of an ancient organism that has been preserved in a rock
- 5. trenches / the name of the canyons that the ocean floor plunges into deep underwater
- 6. / the process by which the ocean floor sinks beneath a deep-ocean trench and back into the mantle
- 8. boundary / a plate boundary where two plates move toward each other
- 10. spreading / the process of mid-ocean ridges continually adding new material to the ocean floor
- 12. / the continents were joined all together creating a supercontinent about 300 million years ago
- 13. valley / a deep valley that forms where two plates move apart
Down
- 1. ridge / an underwater mountain system formed by plate tectonics
- 2. / breaks in earth's crust along which rocks move
- 4. drift / the gradual movement of the continents across the earth's surface through geological time
- 7. boundary / a plate boundary where two plates move away from each other
- 9. boundary a plate boundary where two plates move past each other in opposite directions
- 11. tectonics / the theory that pieces of earth's lithosphere are in constant motion, driven by currents in the mantle