Vast stretch of underwater Ice Age sand dunes preserved as stone

A vast stretch of submerged ancient sand dunes, found off the east coast of Australia, have scientists scratching their heads. The dunes are remarkably preserved, despite being drowned by rising seas.

Scientists think this is because they turned to stone before disappearing under the waves 12,000 years ago.

And they are like an ancient version of the World Heritage-listed Fraser Island sand dunes nearby.

"The site would have been an island exactly like Fraser Island, surrounded by water but 40 kilometres away from the current shoreline," said Tiago Passos, a PhD student at the University of Sydney who was part of a team that made the discovery.

The 70km stretch of dunes, discovered on the sea floor between Fraser and Moreton islands, has stumped scientists, who say such ancient structures should have been destroyed by rising water.

"I think the intriguing thing is what mechanism enabled them to be so well preserved," said Mr Passos, whose study on the dunes has been accepted for publication in the Australian Journal of Earth Sciences.

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