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Discovery of an ancient river system under the ice in Antarctica

Discovery of an ancient river system under the ice in Antarctica

Beneath Antarctica’s thick ice sheets, a group of researchers has discovered an ancient landscape, carved thousands of years ago by a river. The valleys date back to a period when the continent was still part of Gondwana (a supercontinent that existed more than 200 million years ago) and had a climate similar to that of Patagonia, in southern South America.

The discovery was recently published in the journal Nature CommunicationsIt was prepared by mapping the topographic features of the soil beneath the East Antarctic ice sheets. For this purpose, ice-penetrating radar and satellites were used, with the aim of assessing how these platforms change the terrain of Antarctica.

The structure is located in the Aurora-Schmidt Basins (Credit: Jamieson et al., Nature Communications, 2023)

The ancient landscape is found in the Aurora-Schmidt basins, within the Denman and Totten glaciers, about 350 kilometers inside the ice shelf and under more than 2,000 meters of the ice surface. It consists of three blocks carved into the side of the river, about 40 kilometers wide. These structures are also filled with carved ridges and small valleys, perhaps from faults that appeared during the breakup of Gondwana.

We could see that there was something like a ghost scene under the ice. At some point in the past there were rivers flowing over it, which automatically means it predates the growth of the ice sheet.

In response, Stuart Jamieson, a researcher involved in topographic mapping Live sciences

The area extends over about 32,000 square kilometers, and may have been home to trees, forests and animals before it froze.

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Landscape shaping and climate change

The topography of the research area consists of three blocks covered by highlands and valleys, separated by two wide depressions. (Jamieson et al., Nature Communications, 2023)

Because of the well-preserved landscape, researchers believe the area froze rapidly 14 million years ago. Since then, temperature fluctuations have not been enough for the ice to retreat to the area and expose it to other erosion factors, unlike other areas of the continent.

  • The ice sheets in Antarctica began forming about 34 million years ago;
  • Before that, between 60 and 34 million years ago, a river would have flowed from the center of the continent to the coast;
  • The newly discovered area was probably covered by ice then, in a process that lasted about 14 million years, and is now stable.
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However, despite being preserved for millions of years, this may not last long. With climate change and the resulting increase in temperature, the Antarctic ice shelf may end up melting and the region being exposed to erosion processes.

In the future, if this area survives intact, researchers hope to go to the site and collect sediment and rock samples from the sub-glacial landscape, to understand what the region’s biodiversity was like before the continent froze. Moreover, researchers believe that other similar regions may exist.

Given this discovery of ancient landscapes hidden in plain sight, and others, we suggest that there will be other similar ancient landscapes, yet to be discovered, beneath Western Australia.

Excerpt from the article