Scientists detect signs that mammoth rivers flowed in Antarctica 80 million years ago

Scientists have discovered carvings left by ancient rivers millions of years ago under the Antarctic Ice Sheet. As these rivers eroded, large, flat surfaces were formed beneath the ice in East Antarctica between 80 million and 34 million years ago. The research was published on July 11 in the journal Nature Geoscience. Experts are now trying to understand what led to the creation of these features under the ice, as this could help make more accurate predictions about future ice loss. Neil Ross, a geophysicist at Newcastle University in the UK, said in a statement, "We've long been intrigued and puzzled about fragments of evidence for 'flat' landscapes beneath the Antarctic ice sheets." The researchers added that this reveals "how these ancient surfaces formed, their role in determining the present-day flow of the ice, and their possible influence on how the East Antarctic Ice Sheet will evolve in a warming world."

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East Antarctic Ice Sheet at risk of collapse

Climate change risks that global sea levels to rise by several feet in the coming decades. The East Antarctic Ice Sheet could also melt, triggering sea levels to rise by 160 feet. Scientists say that accurately predicting how much the ice sheet might melt in the coming years requires an understanding of past behaviour and the conditions at its base. Radar data from four previous surveys were used in the study to map the shape of the bedrock beneath the ice. "When we were examining the radar images of the sub-ice topography in this region, these remarkably flat surfaces started to pop out almost everywhere we looked," study co-author Guy Paxman, a polar geophysicist at Durham University in the UK, said in the statement. "The flat surfaces we have found have managed to survive relatively intact for over 30 million years, indicating that parts of the ice sheet have preserved rather than eroded the landscape." Also Read: Dinosaurs survived a freezing dark land in Australia-Antarctica 120 million years ago

Rivers under Antarctic ice

The discovery includes a 3,500 kilometre section of the East Antarctic coastline, comprising flat expanses and deep troughs in some places. The troughs supposedly formed when meltwater dipped as the East Antarctic Ice Sheet expanded. Talking about the timing of the formation of the carvings, they are believed to have formed before the East Antarctic coastline existed, but some time after the supercontinent of Gondwana broke apart. This puts the timeline somewhere between 80 million and 34 million years ago. Ice also moves at different speeds in the two regions. Over the flat surfaces, it moves more slowly, while in the troughs between them, the ice flows much faster. Scientists say that retrieving rock samples from under the ice and analysing them will help with predictions about how much ice loss could occur in the future, triggering a rise in sea level.