Huge canyon lies beneath ice sheet


A huge canyon twice the size of the longest river in Britain and as deep as the Grand Canyon lies beneath the ice sheet in Greenland, scientists said Thursday.

Prior to the establishment of the ice sheet 4 million years ago, the canyon is believed to have been a major pathway for water from the interior of the land mass to the coast. Even today, the deep river channel — which originates in the center of Greenland and terminates at its northern coast — transports subglacial meltwater to the edge of the ice sheet and then into the ocean.

Scientists found the canyon using airborne radar data, much of which came from a NASA mission that used radio waves that traveled through the ice to measure the depth of the bedrock. The study was published in the U.S. journal Science.