Ocean Topo IAN 2

8.  midocean ridge-undersea mountain range, the longest mountain range on Earth!

9. rift valley-deep valley in the midocean ridge formed where the sea floor is being pulled apart by plate tectonics, caused by divergent boundaries.

10. deep-sea trench-very steep sided cut (valley) in the ocean floor, deepest part of the ocean, can be more than 11,000 meters, caused by convergent boundaries.

11.  Mariana Trench-deepest part of the ocean, over 36,000 feet deep.  Water pressure is over 8 tons per square inch!!!