Plate Tectonics

5. The crust is ________ dense farther from the mid- ocean ridge.
6. What landform is made when two continental plates collide?
8. ________ theorized the continents moved.
10. These are created when magma cools immediately once erupted from the ridge.
11. The ocean floor is brand new every 200 _____ years.
14. Subduction and seafloor spreading act like a ______.
15. This boundary divides.
17. The supercontinent that formed about 200 million years ago.
18. This boundary slides.
20. ______ dense materials rise.

1. Stitched looking mountain ranges on the seafloor.
2. Movement in a gas or liquid in which the warmer parts move up and the cooler parts move down.
3. What did scientists use to map out the sea floor?
4. The remains or impression of a prehistoric organism preserved in petrified form or as a mold or cast in rock.
7. Where does oceanic crust bend downward in the ocean floor?
9. A break in the Earth's crust.
12. This part of the Earth contains our crust and the upper part of the mantle.
13. Energy caused by the sudden breaking of rock within the earth or an explosion.
16. Changes in what affect the ocean floor?
19. The _______ has convection currents which cause continental drift.