Continental Slope

continental slope

Seaward border of a continental shelf. The world's combined continental slope is about 200,000 mi (300,000 km) long and descends at an average angle of about 4° from the edge of the continental shelf to the beginning of the ocean basins at depths of 330–10,500 ft (100–3,200 m). The slope is most gradual off stable coasts without major rivers and is steepest off coasts with young mountain ranges and narrow continental shelves. Slopes off mountainous coastlines and narrow shelves commonly have outcrops of rock. The dominant sediments of continental slopes are muds; there are smaller amounts of sediments of sand or gravel.

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continental slope [¦känt·ən¦ent·əl ′slōp]

(geology)

The part of the continental margin consisting of the declivity from the edge of the continental shelf extending down to the continental rise.

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Continental Slope 

one of the principal elements of the continental margin; it is located between the shelf and the continental rise. The continental slope has a steeper gradient than do the shelf and the ocean floor (an average of about 4°, but often 15°-20° and as much as 40°) and very rugged relief. Typical forms of rugged relief are terraces parallel to the lip and base of the slope and transverse hollows, or submarine canyons that usually begin on the shelf and extend to the base of the slope or the continental rise.

Through seismic research, dredging, and deep-water drilling it has been established that in terms of geological structure the continental slope is a direct continuation of the structures developed in adjacent areas of the continent. Because of the steepness of its surface the processes taking place in the upper part of the continental slope result in the movement of large masses of sedimentary material that take the form of subaqueous slumping and turbidity currents. Accumulation processes are more typical for the lower part of the continental slope. The types of deposits on the continental slopes include terrigenous sediments that are usually of silt composition, carbonaceous biogenic silts in the warm seas, and iceberg deposits and diatomaceous silts in the antarctic zone of the world ocean. The continental slope is a zone that is highly productive of organic matter and is singled out as a special bathyal zone.

O. K. LEONT’EV