An Extensive River Network Discovered Beneath The Greenland Ice Sheet

Scientists discovered the first evidence of an extensive river network in the landscape underneath the Jakobshavn Isbrae, which is the largest outlet glacier in West Greenland.

The study was published in the Geophysical Research Letters. It was led by researchers from School of Geographical Sciences, University of Bristol, Bristol in the United Kingdom and Grantham Institute for Climate Change, Imperial College London, London.

The researchers stated that the river network covers an area equivalent in size to the Ohio River Basin. It exists before the formation of the ice sheet about 3.5 million years ago. According to the team, the size of the drainage basin is approximately 450,000 square kilometers and this accounts for about 20 percent of the total land area of Greenland.

They used the digital model generated from ice-penetrating radar data and corrected for the weight of the modern ice sheet. These reveal a dendritic network of valleys radiating inland from the Jakobshavn Glacier.

In the analysis of the researchers, it shows that the watershed is mostly smooth and low in height. On the other hand, it also has a mountainous terrain on its eastern edge with an elevation of 3,382 meters. They also discovered very large channels up to 1400 meters deep and 12 kilometers wide. These exceed the north Greenland "mega-canyon."

The researchers assess that it would take about 2.3 million years to carve the observed channels. They also noticed an abrupt break in slope at the confluence of three ancient channels. This matches with the location where the surface flows the Jakobshavn Glacier quickly accelerates.

Jacobshavn Glacier is situated close to the Greenlandic town of Ilulissat, which is a town in western Greenland and ends at the sea in the Ilulissat Icefjord, which is a fjord or a narrow inlet with steep sides or cliffs in western Greenland. The glacier depletes about 6.5 percent of the Greenland ice sheet and creates around 10 percent of all Greenland icebergs. The Jakobshavn Glacier has abetted in making the researchers understand the climate change and icecap glaciology.