The characteristics of the Cayar Submarine Canyon off the coast of Senegal suggest that its evolution was controlled by submarine processes. This well-delineated, hitherto-unsurveyed canyon originates near the shoreline (10 to 20 m deep) on the upcurrent side of the Cape Verde peninsula and extends downslope to the oceanic basin. Its channel remains a prominent feature at 1800 fm (3294 m); its maximum width is 5 nautical miles (9 km).
The Cayar Canyon confirms the conditions which attend the development of canyons up-current from headlands: a supply of sediment available at the canyon head, a steep nearshore gradient, and a decrease in longshore current transport. The conspicuous absence of fluvial influence and the apparent lack of direct tectonic involvement in recent geologic time suggest that the canyon was developed by the movement of sediment downslope in response to a localized over-accumulation of continental detritus. This canyon is probably second only to the Congo Canyon in geologic importance around Africa.