Continental Rise

Continental rise

The continental rise is a layer of sediment from the base of the slope that forms a dip between the foot of the continental slope and the deep ocean floor. At the base of many continental slopes, the ocean bottom flattens out to a mere gradient of one degree. This broad underwater plain of sediment is called the continental rise. Some of the ocean basin is the vast depression in the earth’s surface bordered on all sides by continents and filled with a continuous body of saltwater, the ocean. Present-day oceans have overflowed the basin and flooded the edge of the continents to a depth of about 200m. The ocean basin and associated submerged continental edges are not flat. They display numerous features varing from submerged mountain chains to deep trenches that extend several kilometers below the adjacent sea floor.

Locally, deep submarine canyons have been eroded into the shelf, slope and rise by turbidity currents, density currents of sediment laden water that flow rapidly down-slope under the force of gravity. Deposition of sediments at the mouth of the canyons may form enormous fan-shaped accumulations called submarine fans. Submarine fans form part of the continental rise.

Abyssal plain:

Outward from the continental rise is the abyssal plain, a relatively flat featureless area where sediments have buried most of the sea floor irregularities. Isolated hills may protrude through the sedimentary cover. They are called knolls if less than 100m high or seamounts if higher than 1000m. The number of knolls and seamounts increases towards the exposed oceanic ridge. They become the dominant feature in the abyssal hills because sedimentary is too thin to completely bury the flank of the oceanic ridge.

Last modified: Tuesday, 26 June 2012, 11:14 AM