Australia: The Land Where Time Began

A biography of the Australian continent 

Lake Dieri

The processes that led to the formation of Lake Eyre began about 200 million years ago when a large band of land between the Gulf of Carpentaria and the area of the South Australian salt lakes began to sink. About 100 million years ago the whole area was inundated by the sea. 20-30 million years later the sea receded leaving only several large rivers that are thought to have flowed to the southern coast. About 1 million years ago the land to the south of the salt lakes was tiled up, the faulting blocking the flow of the rivers to the coast. The result was a huge lake, Lake Dieri, named after one of the Aboriginal tribes living east of Lake Eyre.

35,000 years ago Lake Dieri was 3 times the size of the present Lake Eyre and had a depth of at least 17 m. At that time lush vegetation surrounded the lake. From 20,000 years on the climate changed so much that the rivers that fed the lakes diminished and then stopped flowing, apart from the occasional flood, and the area became as arid as it is today, the lakes shrinking until only salt lakes remained. Most of the salt delivered to the lakes was leached from the ancient marine sediments that underlie the catchment. 

Satellite imaging has allowed the outline of Lake Dieri to be seen in its entirety for the first time. From space it can been seen that Lake Dieri once covered an area of about 110.000 sq km. It once encompassed all of Lakes Callabonna, Blanche, Frome, Gregory and Eyre, plus some. In satellite images it can be seen that many large salt pans, including these lakes, form a series of arcs that appear like tide lines roughly parallel to the  and eastern shorelines of lakes Frome, Callabonna, Blanche, Gregory and Eyre. It seems the lakes of the present are probably all that is left of the one mighty lake, more like an inland sea in extent, that gradually dried up.

Sources & Further reading

1. Penny Van Oosterzee, The Centre, the Natural History of Australia's Desert Regions, Reed, 1993
2. Mary E White, Running Down, Water in a Changing Land, Kangaroo Press, 2000

Links

The Dieri