Scientists discover Antarctica’s lost river 34 million years later

Scientists have discovered that a river comparable in size to the Rio Grande once dominated West Antarctica, offering a rare glimpse of the continent’s land covered in ice today.

It is believed that the 900-mile-long waterway flowed about 44 to 34 million years ago, shortly before the continent’s immensely thick ice sheets began to build up.

At that time, after the dinosaurs and long before human life, Antarctica had a mild climate and may have been home to giant penguins, noted study author Cornelia Spiegel of Germany’s University of Bremen. The discovery also implies that West Antarctica was above sea level at the time.

“We found that, before West Antarctica became covered by ice, it was dominated by a large river system, had a temperate climate (the water temperature at the surface of the river in summer was about 19°C) and a swampy environment.” she said Newsweek via email.

“The river probably meandered through an extensive coastal plain with swampy marshland along the banks.”

An international team of scientists discovered this river after analyzing samples of the sandstone rock beneath the Amundsen Sea Embayment, where the West Antarctic Ice Sheet meets the ocean. In this rock, which dates to the Eocene – a geological period that lasted about 56 million to 34 million years ago – they found evidence of sediments that originated in the Transantarctic Mountains, implying that they were washed all the way there by an ancient river .

The researchers also found traces of organic chemicals associated with freshwater bacteria, further supporting the presence of a large river delta in the region. It stretched between the Transantarctic Mountains and the West Antarctic Ice Sheet and drained into the Amundsen Sea, according to the paper in the magazine Scientific progress.

“Our research also shows that West Antarctica was largely above sea level (today, most rocks under the ice are below sea level), but at the same time was quite flat. Because of that missing topography, West Antarctica likely remained free of large glaciers, while the mountainous areas of East Antarctica began to freeze about 34 million years ago,” Spiegel said.

The researchers hope that the discovery of this river will help them better understand the history of Antarctica’s geography, and how it became the frozen continent that it is today.

“The Great Antarctic Ice Age began during the transition between the Eocene and the Oligocene [when the planet is known to have undergone a period of intense cooling] 34 million years ago, marking one of the most pronounced climate transitions of the Phanerozoic [from 538.8 million years ago to the present],” the researchers wrote.

They added that the reconstruction of conditions in Antarctica before this transition “provides important framework conditions for understanding subsequent cooling and the onset of glaciation, with major implications for ice sheet modeling.”

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