Karst
The world's largest karst area is the Nullarbor Plain, part of the area of flat, almost treeless, dry country of southern Australia. It is on the Great Australian Bight coast with the Great Victoria Desert to its north. It is the world's largest single exposure of limestone bedrock, and occupies an area of about . At its widest point, it stretches about  from east to west across the border region between South Australia and Western Australia.