| A | B |
|---|
| continental shelf | the gently sloping section of the continental margin located between the shoreline and the continental slope |
| continental slope | the steeply inclined section of the continental margin located between the continental rise and the continental shelf |
| continental rise | the gently sloping section of the continental slope and the abyssal plain |
| abyssal plain | a large, flat, almost level area of the deep-ocean basin |
| mid-ocean ridge | a long, undersea mountain chain that forms along the floor of the major oceans |
| rift valley | a long, narrow valley that forms as tectonic-plates separate |
| seamount | a submerged mountain on the ocean floor that is at least 1,000 m high and that has a volcanic origin |
| ocean trench | a steep, long depression in the deep-sea floor that runs parallel to a chain of volcanic islands or a continental margin |
| guyot | flat underwater mountain |
