Greenland Mega Canyon, discovery, river v. glacier carved canyons, Grand Canyon:
“We started looking at the data, and once we put it all together, we realized there was this strange feature in the middle of Greenland,” he says. “And we started looking into it in a bit more detail.”
The picture that emerged was that of a canyon rivaling the one carved through the red rock in the American Southwest.
“It’s almost twice the length of the Grand Canyon, about half its depth and about twice its width in most places,” he says. And it looks like it was carved by rivers, back before Greenland was covered with ice, four million years ago.
“Nowhere does it look like a typical U-shaped valley,” which is what you would expect if it were carved by glaciers, he says. “At its northern limit, it looks pretty much like a river valley. It’s got relatively steep slopes, and it’s quite deep.”
“We think this was a major river system in Greenland before the ice sheet was there,” he says. “And it’s just survived the cover by the ice sheet.”