The Beaufort Shelf
The Beaufort continental shelf
The Beaufort Shelf is a well-studied feature of the Beaufort Sea. This shelf is only about 110 kilometres wide and reaches a maximum depth of about 500 metres. It is the only shelf to have a large number of underwater pingos. Pingos are typically terrestrial formations associated with permafrost. They are oval-shaped hills of frozen sediment and bedrock that have a solid ice core. Pingos are ordinarily formed when surrounding permafrost traps water, which then freezes. This newly frozen ice forces the surrounding permafrost into a large hill, filling its core with solid ice. The similarity of the underwater pingos to their terrestrial counterpart indicates they probably share the same origin. The submarine pingos on the Beaufort Shelf average 400 metres in diameter and are about 30 metres high! Since their first discovery, several hundred pingos have been found and it is likely that more have yet to be charted. These hills present a hazard to ships in the western Arctic Ocean.