Scientists have Discovered an Ancient Lakebed Beneath Greenland’s Ice
upstart writes in with an IRC submission for Runaway1956:
Scientists Discovered An Ancient Lakebed Under Greenland's Ice:
Using radar and other ice-penetrating instruments, scientists have detected a "fossil lakebed" preserved beneath the Greenland ice sheet, in what is the first discovery of its kind.
Now a basin smothered by a gigantic sheet of ice, this former lake once measured 2,740 square miles (7,100 square kilometers) in size, which is an area comparable to Rhode Island and Delaware combined, according to a Columbia University press release. In some places it got as deep as 820 feet (250 meters), and it was fed by more than a dozen streams. Doesn't sound very Greenland-ish today, but this is how the island likely looked millions of years ago.
Eventually, however-and we're not entirely sure when-this lake got covered in ice, never to see daylight ever again. New research published in Earth and Planetary Science Letters shows the lakebed is now buried beneath 1.1 miles (1.8 kilometers) of ice. The water that once coursed through this ancient basin is probably long gone, smeared away by the encroaching ice sheet, but the lake's sediments have remained in place.
[...] The data used to make the discovery was gathered by NASA's Operation IceBridge, which involves low altitude surveys of Greenland's ice sheet using ice-penetrating radar and instruments capable of measuring gravity and magnetic anomalies. Radar allowed scientists to create a topographic map of the Earth's surface beneath the ice sheet, revealing the basin. Gravity measurements showed that material in the basin is less dense than what's found in the surrounding rock, which is hard and metamorphic. And because sediments are less magnetic than solid rock, the researchers were able to map the depth of the sediments lying in the basin.
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