plate tectonics trinity tran

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