| A | B |
|---|
| continental margin | region of the sea that contains the shelf and the slope |
| continental shelf | part of the continent that is underwater |
| continental slope | where water deepens abruptly and the edge of the continental land mass drops off |
| ocean basin floor | begins where the slope ends, region made up of mountains, ridges, trenches, valleys, rifts, guyots, abyssal plains, and canyon plateau |
| abyssal plain | vast, smooth area on floor |
| trenches | cracks on the Earth's crust, deepest part of the ocean |
| guyots | flat topped, volcanic mountains |
| rift | a valley that runs along the center of the ridge |
| seamount | isolated mountain that rises more than 3,000 feet above the seafloor |
| mid-ocean ridge | great undersea mountain ranges characterized by frequent earthquakes and volcanoes |
| island | seamount that rises above the surface of the water |
| earth's water percentage | 75% |
