Watch: Giant, Subterranean Lake the Size of Delaware and Rhode Island Discovered in Greenland
A giant prehistoric lake has been discovered in Greenland — more than a mile underneath the ice.
The lake, which was formed when the area was ice-free, stretches around 2,700 square miles and is the first of its type to be found anywhere in the world.
It was discovered by a team of US scientists who mapped its area by analysing data from low flying NASA aircraft fitted with geophysical instruments that penetrate the ice.
In recent years, scientists have found existing subglacial lakes in both Greenland and Antarctica, containing liquid water sandwiched in the ice or between the bedrock, but this ‘fossil’ lake bed is different, with no evidence there is still water there today.
The images they produced show a network of at least 18 one time streams carved into the adjoining rock in a sloping escarpment to the north that fed the lake. There is another outlet stream to the south.
The researchers calculated the water depth ranged from about 50m to 250 m (164ft to 820ft).
Their research, published in the scientific journal Earth and Planetary Science Letters, suggests that the lake bed is believed to contain an archive of fossils and chemical signals that could shed some light on events in the areas history.
Lead author Dr Guy Paxman, of Columbia University, New York, said: “This could be an important repository of information, in a landscape that right now is totally concealed and inaccessible.
“We are working to try and understand how the Greenland ice sheet has behaved in the past. It is important if we want to understand how it will behave in future decades.”
Dr Paxman said the basin may have formed along a now-dormant fault line, where the bedrock stretched out and formed a low spot.
“Alternatively, but less likely, previous glaciations may have carved out the depression, leaving it to fill with water when the ice receded,” he said.
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According to the researchers, material washed out from the edges of the ice sheet have been found to contain the remains of pollen and other materials, suggesting Greenland may have undergone warm periods during the last million years.
Dr Paxman said the area could have been repeatedly covered and uncovered as ice melted extensively on some occasions, advancing and retreating over Greenland at various points.
“If we could get at those sediments, they could tell us when the ice was present or absent,” he added.
The researchers assembled a detailed picture of the lake basin and its surroundings by analysing radar, gravity and magnetic data gathered by NASA.
Using ice-penetrating radar, they revealed the outlines of the smooth, low-lying basin, nestled among higher-elevation rocks, underneath the ice.
Dr Paxman said: “The basin may be an important site for future sub-ice drilling and the recovery of sediment records that may yield valuable insights into the glacial, climatological and environmental history of the region.
“With the top of the sediments lying 1.8 km (1.2 miles) below the current ice surface, such drilling would be daunting, but not impossible.”
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