NASA discovers mega-canyon beneath Greenland’s ice

A NASA airborne mission to Greenland has revealed a huge and previously unknown canyon, that's been locked beneath the ice of the isolated island since before the rise of humanity. 

Resembling a river channel, NASA says the canyon is 460 miles long — longer than the Grand Canyon — and as deep as 2,600 feet in some places, making it one of the largest such geological features on the planet.

Read more from GlobalPost: Greenland ice melt hits rare levels 

"One might assume that the landscape of the Earth has been fully explored and mapped," said Jonathan Bamber, professor of physical geography at the University of Bristol in the United Kingdom, and lead author of the study, to NASA. "Our research shows there's still a lot left to discover."

Bamber and colleagues suspect the canyon may help route some of the meltwater Greenland's ice releases to the ocean, explaining why there are so few lakes under its interior ice sheet, writes LiveScience. 

"It probably doesn't have water flowing through all of it today, given the interference by the ice overburden. However, when ice-free, water would channel through all of it," study co-author Martin Siegert told LiveScience. 

The canyon was discovered during a NASA-supported scientific mission to help determine just how high world sea levels will get if Greenland's ice melts due to global warming, using airborne radar data to analyze the landscape lying beneath the thick layer of ice.