Giant Canyon Discovered Under Greenland Ice Sheet [1]

Summer meltwater has drained through a snow-covered channel in Greenland. Scientists say that the Greenland Ice Sheet sits atop a canyon twice as long as the Grand Canyon. Photograph by James Balog, National Geographic

 

Imagine if you could pick up the Greenland Ice Sheet [2] and see what lies beneath. Surely 1.7 million square kilometers of slowly thawing ice must rest on a massive pool of melted water, right?

Not necessarily, according to a study released today in the journal Science [3]. Unlike the ice sheet covering Antarctica that sits atop numerous lakes, the Greenland Ice Sheet blankets a giant subglacial canyon nearly twice as long as the Grand Canyon located in Arizona. (Read: "Changing Greenland [4]" in National Geographic magazine.)