• Researchers say a vast population once lived on a now-submerged continental shelf off of Australia.
  • The land was submerged at the end of the last ice age, about 18,000 years ago. 
  • Researchers point to mounting evidence of human habitation there, before the waters rose.

A vast, now-submerged landmass off of Australia's coast may once have been capable of supporting up to half a million people, a new study suggests.

The area, in Australia's northwest, is about one and a half times the size of New Zealand, and likely played host to between 50,000 and 500,000 people at different times, archaeologists at Griffith University in Brisbane said.

But sea level rises at the end of the last ice age — about 18,000 years ago — caused the supercontinent known as Sahul to be split into modern-day New Guinea and Australia, placing the continental shelf underwater.

Analyses by the Griffith University team, led by Kashih Norman, revealed that the area would have included an inland sea, a freshwater lake, and river channels, all of which would have helped support thriving populations.

It would have been, they claim, unlike any other area on the present-day continent.

The study's authors said they made their findings by projecting historic sea levels onto high-resolution maps of the ocean floor. This revealed an archipelago that could have been used for people to migrate from Indonesia to Australia, they said.

Various rock art and stone ax findings around the areas of the now-submerged continental shelf. Foto: Kasih Norman et al/Griffith University

Many underwater coastal landmasses have been shown to have once supported ancient people. But in this case, researchers didn't previously think the formerly exposed land would have been productive enough for early Australians.

Ultimately, rising sea levels likely pushed resident populations off of the landmass, the authors said.

The oral histories of coastal First Nations Australians, thought to date back over 10,000 years, often tell of rising waters and drowned land, they added.

In a release published in The Conversation, Norman's team also reflected on present-day climate change and called for greater uptake of Indigenous-led environmental management.

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