stable structural shelf or platform of the ocean floor, extending from the northern coast of Australia to the island of New Guinea. A continental shelf, it was once above sea level, and its surface still bears erosional features formed when streams crossed it to the oceans. The shelf was slowly warped downward by crustal forces; overall it has subsided, as indicated by drowned atolls along its margin, which extend to depths of 2,000 feet (600 metres). The shelf's main divisions are the shallow 360,000-square-mile (930,000-square-km Arafura Shelf, covered by the Arafura Sea and Gulf of Carpentaria; the Sahul Shelf (120,000 square miles 【310,800 square km】) under the Timor Sea; and the Rowley Shelf (120,000 square miles 【310,800 square km】) underlying a part of the northwest Indian Ocean extending to North West Cape, Western Australia. To the north lie the deeper Timor Trough and the volcanic Lesser Sunda Islands, separating the Sahul from the Sunda Shelf. The shelf's existence was suggested as early as 1845 by G.W. Earl.