Sahul Shelf

Continental shelf of Western Australia
the paleocontinent

Geologically, the Sahul Shelf (/s//ə/'/h//uː//l/) is a part of the continental shelf of the Australian continent, lying off the northwest coast of mainland Australia.

The name "Sahull" or "Sahoel" appeared on 17th century Dutch maps applied to a submerged sandbank between Australia and Timor. On his 1803 map, Matthew Flinders noted the "Great Sahul Shoal" where Malays came from Makassar to fish for trepang (sea cucumber). The name Sahul Shelf (Sahoel plat) was coined in 1919 by G. A. F. Molengraaff, an authority on the geology of the then Dutch East Indies. In the 1970s, biogeographers coined "Sundaland" and "Sahul" as contrastive names for the continental regions extending from the adjacent shelves.

When sea levels fell during the Pleistocene ice age, including the Last Glacial Maximum about 18,000 years ago, the Sahul Shelf was exposed as dry land. Evidence of the shoreline of this time has been identified in locations which now lie 100 to 140 metres below sea level. A Flash based interactive timeline of sea level changes was developed by Monash University in the 2000s.

The Arafura Shelf formed a land bridge between Australia, New Guinea, and the Aru Islands, and these lands share many Marsupial mammals, land birds, and freshwater fish as a result. Lydekker's Line, a biogeographical line, runs along the northwestern edge of the Sahul Shelf where it drops off into the deep waters of the Wallacea biogeographical area. Wallacea sits in a gap between the Sahul Shelf and the Sunda Shelf, part of the continental shelf of Southeast Asia. The land bridge enabled early human migrations to Australia.