continental shelf summary

Written and fact-checked by The Editors of Encyclopaedia Britannica

Below is the article summary. For the full article, see continental shelf.

The broad, gentle pitch of the continental shelf gives way to the relatively steep continental slope. The more gradual transition to the abyssal plain is a sediment-filled region called the continental rise. The continental shelf, slope, and rise are collectively called the continental margin. Depth is exaggerated here for effect.

continental shelf, Broad, relatively shallow submarine platform that forms a border to a continent, typically extending from the coast to depths of 330–660 ft (100–200 m). Continental shelves average about 40 mi (65 km) in width. Almost everywhere they are simply a continuation of the continental landmass: narrow, rough, and steep off mountainous coasts but broad and comparatively level offshore from plains. Continental shelves are usually covered with a layer of sand, silts, and silty muds. Their surfaces feature small hills and ridges that alternate with shallow depressions and valley-like troughs. In a few cases, steep-walled V-shaped submarine canyons cut deeply into both the shelf and the slope below.