Huge canyon discovered under Greenland ice

Zachariah Torres.Greenland canyonOne of the biggest canyons in the world has been found beneath the ice sheet that smothers most of Greenland. The canyon – which is 800km long and up to 800m deep – was carved out by a great river more than four million years ago, before the ice arrived.

Source:  BBC News: Roger Harrabin, Environment analyst