a long submarine canyon rising from the Bering Abyssal Plain on the floor of the Bering Sea southeast of the Pribilof Islands, Alaska. It runs across the edge of the continental slope and is 265 miles (426 km) long with walls 6,000 feet (1,800 m) high. The canyon is characterized by a V-shaped valley with steep and rocky walls, and its floor is covered by sands and gravels. It is believed to have been formed when large masses of sediments supplied by Alaskan and Siberian rivers slumped down the slope of the continental shelf, and the canyon was cut by streams flowing across the exposed continental shelf. Alluvial fans (broad sedimentary aprons) spread out from its mouth to cover the continental rise; these terminate in the Bering Abyssal Plain.