Across
- 5. any trace of an ancient organism that has been preserved in rock
- 6. rift valleys where the crust has been stretched
- 7. plates move together
- 8. continents that move slowly on the Earth's surface
- 11. plates move apart
- 12. the last supercontinent on Earth about 300 million years ago
Down
- 1. plates slip past each other
- 2. deep underwater canyons
- 3. mid-ocean ridges continually add new material to the ocean floor
- 4. from long chains of mountains that rise up from the ocean floor
- 9. a large elongated depression with steep walls
- 10. ocean floor sinks beneath and deep ocean trench and back into the mantle again