Giant Lake Mungo was 20 per cent bigger than we thought, say researchers

Results of an international study has revealed that the iconic Lake Mungo, 90 kilometres north-east of Mildura, was actually a mega-lake almost 20 per cent bigger than previously thought.

Bridie Smith 18 June 18 2015 - 4:15AM

Sand dunes near Lake Mungo: Blue markers are where stone tools were found, green markers where animal food remains were found. (Photo: La Trobe University)

The Aboriginal people who called the arid area around Lake Mungo home some 24,000 years ago were likely accomplished inland seafarers living in what is now desert country.

Results of an international study has revealed that the iconic Lake Mungo, 90 kilometres north-east of Mildura, was actually a mega-lake almost 20 per cent bigger than previously thought.

After dating the sediment layers found in the nearby sand dunes, researchers established that the lake's high water mark was five metres higher than realised.

Archaelogist Nicola Stern. (Photo: Simon O'Dwyer)

This created an island between Lake Mungo and Lake Leaghur to the north, on which archaeologists found stone tools and fireplaces – all evidence of human habitation.

"Traces of people's activities are actually embedded in sediment, so that tells us that people were relying on watercraft to get around to exploit what was on the island in terms of animals to hunt," said La Trobe University archaeologist Nicola Stern.

Located in the far south-west corner of NSW, Lake Mungo has been dry for the past 15,000 years.

Artefacts discovered at Lake Mungo. (Photo: Simon O'Dwyer)

The sand dunes to the east of Lake Mungo have provided the evidence, allowing researchers to map how the ancient landscape changed.

Dr Stern said when the lake level dropped, fine clay sediment from the freshly exposed lake floor was picked up by the wind and dumped on the dunes. This fine clay sediment landed on top of the coarser sand, which had travelled from the beach at the edge of the lake when the water levels were higher.

"When you've got sand, you know the lake was full and when you get clay you know that the lake was lower," Dr Stern said.

Modern technology such global positioning systems and luminescence dating techniques have allowed archaeologists to study a new line of beach gravel five metres above the main shoreline, which indicates the lake held 250 per cent more water than previously thought. However in geological terms, the high water level was short-lived – lasting about 1000 years.

"It tells us that climate change is not always smooth," Dr Stern said. "It happens in bursts."

Published in the journal PLOS ONE on Thursday, the findings provide a key insight into the history of human settlement and climate change at one of the country's most important archaeological sites.

Lake Mungo is internationally archaeologically significant. It is from where Mungo Man, the oldest human remains found in Australia, were found and also where Mungo Lady, the oldest human remains in the world to be ritually cremated, were uncovered.

Geologists Kathryn Fitzsimmons from Germany's Max Planck Institute for Evolutionary Anthropology and Colin Murray-Wallace from the University of Wollongong also took part in the research.