'Imagine a lush tropical island slipping beneath the waves': Drowned island the size of Iceland found off Brazil

By Eos.org, Erin Martin-Jones published 2 days ago
An undersea volcanic plateau in the southwestern Atlantic was a tropical island 45 million years ago.



Scientists have found the remains of an island off the coast of Brazil. (Image credit: EduLeite via Getty Images)

In 2018, Brazilian and British scientists were exploring the seafloor around a volcanic plateau known as the Rio Grande Rise when they spotted rocks that looked like they belonged on dry land.

Watching video relayed from their remotely operated submersible 650 meters (2,100 feet) below the surface, unusual red clay layers caught their attention. "You just don't find red clay on the seabed," said Bramley Murton, a marine geologist from the National Oceanographic Centre in Southampton, U.K., who was on the expedition. "The deposits looked like tropical soils," he explained.

In a recent study, the team showed that the clay's distinctive mineral makeup could have formed only by open-air weathering in tropical heat and humidity. It's the latest in a string of discoveries hinting that this patch of ocean, 1,200 kilometers (750 miles) from Brazil's coast, was once an island.

Volcanic origins

"Imagine a lush tropical island slipping beneath the waves and lying frozen in time. That's what we've uncovered," said Murton, who coauthored the study. He and colleagues think the island would have been similar in size to Iceland (about a fifth of the Rio Grande Rise's total area).

More:
https://www.livescience.com/planet-earth/imagine-a-lush-tropical-island-slipping-beneath-the-waves-drowned-island-the-size-of-iceland-found-off-brazil