Scientists have discovered evidence of a massive ancient undersea landslide next to Australia’s Great Barrier Reef.
The Gloria Knolls Slide is at least 300,000 years old and 32 cubic km in volume, or 30 times the size of Uluru.
The landslide could also have triggered a large tsunami, said the international team behind the find.
The scientists said debris from the landslide, found as deep as 1,350m (4,430ft) below the sea, also provided clues about hidden marine life.
The team made the discovery while conducting three-dimensional mapping of ancient reefs in the Queensland Trough, a vast basin adjoining the Great Barrier Reef.
Dr Robin Beaman, from Australia’s James Cook University, said the researchers located a cluster of hills, or knolls, more than 1,100m beneath the surface.
“What we discovered was the smoking gun,” he told the BBC.
“It was quite clear that those knolls were the remains of a very large undersea landslide that had occurred some time ago.”
That time was at least 300,000 years ago, he said, because coral fossils collected from the knolls went back that far, and the landslide would have predated them.
He described it as “catastrophic collapse” because the knolls – as long as 3.6km (2.2 miles) – were found 30km from their original location.
Other evidence of the landslide would have been buried over time, he said.