The Finke River in central Australia is one of the oldest rivers in the world and salt lakes of the Yilgarn region in Western Australia are the remnants of a drainage pattern which was active before continental drift separated Australia from Antarctica.Australia began its journey across the surface of the Earth as an isolated continent between about 55 and 10 million years ago, and continues to move north by about seven centimetres each year.Much of the centre of Australia is flat, but there are numerous ranges such as the Mac Donnell and Musgrave Ranges, as well as some individual structures, of which the best known is Uluru.Faulting and folding in the areas took place long ago, and the current topography is the result of millions of years of erosion and redistribution of sediments removed from high areas and filled-in depressions in this largely internal drainage system.Recently, scientists have been able to obtain a much clearer picture of Australia's geological past through deep seismic surveys, which has provided new information about how the continent was formed, particularly around Broken Hill, Mount Isa, .Although the shape of Australia is due largely to tectonic Earth movements and long term changes in sea level, most of its topography is a result of prolonged erosion by wind and water.
The Eastern Highlands are made up of a series of mountains in the south topped by Mount Kosciuszko and volcanic plugs, ash domes and flow remnants further north.
The past few million years were notable for the Quaternary ice age which resulted in various glacial and interglacial periods.
The last glacial period was at its most intense about 20 000 years ago, and by around 11 700 years ago the ice had retreated and rising sea levels separated mainland Australia from Tasmania and New Guinea.
Australia's present topography is the result of a long landscape history, which, fundamentally, started in the Permian Period when Australia was very near the South Pole, and much of the continent was glaciated by large ice caps.
After the ice melted, parts of the continent subsided and formed sedimentary basins such as the Eromanga Basin in South Australia.