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An abyssal plain is a relatively flat area of the ocean basin floor which slope less than one part in 1000. These were formed by turbidity currents which covered the preexisting topography. Most abyssal plains are located between the base of the continental rise andabyssal hills. The remainder are trench abyssal plains that lie in the bottom of deep-sea trenches. This latter type traps all sediment from turbidity currents and prevents abyssal plains from forming further seaward, e.g. much of the Pacific Ocean floor.
The official International Hydrographic Organization definition for this undersea feature name is “an extensive, flat, gently sloping or nearly level region at abyssal depths.”
- Physical Oceanography Index
- Rhodes W. Fairbridge, editor. The Encyclopedia of Oceanography. Van Nostrand Reinhold Co., 1966