| A | B |
|---|
| abyssal plain | very level area of the deep-ocean floor, usually lying at the foot of the continental rise |
| bathymetry | the measurement of ocean depths and the charting of the shape or topography of the ocean floor |
| biogenous sediment | seafloor sediment of biological origin, such as shells and skeletons of marine life |
| Calcerous ooze | thick, common biogenous sediment produced by dissolving calcium carbonate shells |
| continental margin | that portion of the seafloor adjacent to the continents; It may include the continental shelf, continental slope, and continental rise. |
| continental rise | the gently sloping surface at the base of the continental slope |
| continental shelf | the gently sloping submerged portion of the continental margin, extending from the shoreline to the continental slope |
| continental slope | the steep gradient that leads to the deep-ocean floor and marks the seaward edge of the continental shelf |
| gas hydrate | a gas, such as methane, trapped in a lattice-like structure of water molecules |
| hydrogenous sediment | seafloor sediment consisting of minerals that crystallize from seawater; An important example is manganese nodules. |
| manganese nodule | rounded lump of hydrogenous sediment scattered on the ocean floor, consisting mainly of manganese and iron and usually containing small amounts of copper, nickel, and cobalt |
| ocean basin floor | area of the deep-ocean floor between the continental margin and the oceanic ridge |
| oceanic ridge | a continuous elevated zone on the floor of all the major ocean basins and varying in width from 1000 to 4000 kilometers; The rifts at the crests of ridges represent divergent plate boundaries. |
| oceanography | the scientific study of the oceans and oceanic phenomena |
| seafloor spreading | the process by which plate tectonics produces new oceanic lithosphere at ocean ridges |
| seamounts | an isolated volcanic peak that rises at least 1000 meters above the deep-ocean floor |
| siliceous ooze | biogenous sediment composed of the silica-based shells of single-celled animals and algae |
| sonar | An electronic depth-sounding mechanism; Sonar is an acronym for sound navigation and ranging. Sonar calculates ocean depth by recording the time it takes for an energy pulse to reach the ocean floor and return. |
| submarine canyon | a seaward extension of a valley that was cut on the continental shelf during a time when sea level was lower; a canyon carved into the outer continental shelf, slope, and rise by turbidity currents |
| submersible | a small underwater craft used for deep-sea research |
| terrigenous sediment | seafloor sediment derived from eroded rocks on land |
| turbidity current | a downslope movement of dense, sediment-laden water created when sand and mud on the continental shelf and slope are dislodged and thrown into suspension |
