NASA scientists have recently discovered a canyon underneath Greenland’s ice sheet by using radar data. The canyon is 400 miles long and half a mile deep (for comparison, the Grand Canyon is 277 miles long and a little over a mile deep). This canyon was believed to have been formed before the glacier over Greenland formed.
Radar uses electromagnetic waves to penetrate through the ice. In much the same way that shining a flashlight through a window to a wall will case light to reflect off of the wall back to the person holding the flashlight outside, the longer radio waves used with radar reflect off of the earth’s surface.
It is definitely interesting to learn about this canyon, but the importance of the discovery is beyond being a neat fact. Water flowing beneath the glaciers actually contributes to a complex relationship with glacial movement and melting, and the transport of glacial melt water from inland portions of the glacier to the ocean is pertinent to this topic.