Scientists have discovered ancient lake bed under Greenland ice

Using radar and other ice penetrating instruments, scientists have detected a preserved “fossil lake bottom” beneath the Greenland ice sheet, in what is the first such find.

Now a basin choked by a gigantic sheet of ice, this former lake once measured 7,100 square kilometers, which is an area comparable to that of Rhode Island and Delaware combined, according to a Columbia University. Press release. In some places, it was up to 250 meters deep and was fed by more than a dozen streams. It doesn’t sound very Greenlandic today, but this is what the island probably looked like millions of years ago.

Eventually, however – and we don’t really know when – this lake became covered in ice, never to see the light of day again. New research published in Earth and Planetary Science Letters shows that the bottom of the lake is now buried under 1.8 km of ice. The water that once flowed through this ancient basin is probably long gone, smeared by the invading ice cap, but the lake sediment has remained in place.

Scientists have already discovered subglacial lakes, in both Greenland and Antarctic. The difference here is that the recently discovered fossil lake bed does not contain liquid water and is located on the rocky surface of Greenland. Such a thing has never been discovered before, according to the press release.

The data used to make the discovery was collected by NASA’s Operation IceBridge, which involves low altitude. Greenland ice sheet surveys using ice-penetrating radar and instruments capable of measuring gravity and magnetic anomalies. Radar enabled scientists to create a topographic map of the Earth’s surface below the ice cap, revealing the basin. Gravity measurements have shown that the material in the basin is less dense than this found in the surrounding rock, which is hard and metamorphic. And because sediments are less magnetic than solid rocks, the researchers were able to map the depth of the sediments in the basin.

Tthe data revealsed that the old lake bed, located in northwest Greenland, once had water depths of between 164 and 820 feet (50 to 250 meters). The sediment layer was found 0.75 miles (1.2 km) thick, a considerable depth of filling which probably accumulated over hundreds of thousands of years –and maybe millions of years –before the Greenland Ice Age. Topographic features allowed the team to identify at least 18 ancient stream beds that once flowed into the lake along its northern shore. A possible stream has also been spotted to the south.

In the press release, Guy Paxman, postdoctoral researcher at the Lamont-Doherty Earth Observatory at Columbia University who led the study, said his team are still unable to date the lake, but if “we could get to these sediments they could tell us when ice was present or not.” Indeed, these scientists, and probably others, would very much like to get their hands on this ancient sediment, which they would do by drilling through the ice cap.

IIn addition to dating the lake and indicating when ice was and was not present, samples of sediment could show signs of old life in the form of plant spores or other organic material. If detected, these biosignatures would strengthen theories about Greenland’s climatic history and how it once presented vast forests. As the authors write, “the subglacial landscape predates extensive glaciation in Greenland” and, therefore, “the basin may contain important records of regional glacial history and paleoclimate”.

That said, some of that will be difficult to prove, as underground material has been carried all over the place by ebb and flow of glaciers.

Drilling this deep in the ice is not without precedent. In the 1990s, researchers drawn a 2-mile long (3.2 kilometers long) Ice core from the Greenland ice cap, capturing 110,000 years of history. Scientists have also had similar Success core drilling in Antarctic ice. And now, thanks to this new discovery, we have a tantalizing new target in Northwest Greenland. Let’s do the drilling!

Oh I would be remiss if I didn’t mention this incredible buried impact crater found in Greenland two years ago. Also found by ground-penetrating radar, the crater measures around 30 kms) through, making it one of the largest asteroid craters on Earth. Cool things lurk under gigantic ice caps – just watch.