Greenland's mega canyon
In August 2013 NASA announced a “mega canyon” lying under Greenland’s ice sheet.
Data from the first three years of NASA’s six-year IceBridge mission was coupled with existing data from Germany and the U.K., to reveal the geographic feature which has never been seen by humans.
Radar was used to map Greenland’s geographic features under the ice. At certain wavelengths the radar waves penetrate through the ice and bounce back off the bedrock beneath. A longer time interval means the bedrock is further away. In this way an accurate 3D map of Greenland’s geography was able to be constructed.
The canyon is at least 750 km long and in some places reaches 800 m deep. This length makes it longer than the Grand Canyon in the U.S., and the depth is on par with some sections of the Grand Canyon.
The canyon extends from near the centre of Greenland all the way to the northern coast and ends at the Petermann Glacier fjord. Evidence suggests it predates Greenland’s ice sheet, and was likely once a major river system.
It is now thought to play a major role in the transportation of Greenland’s meltwater into the Arctic Ocean.
Given that climate change (climate crisis?) is a thing, stick around a few more years, and we may be able to see the canyon for the first time.