Greenland's 'grand canyon' was part of a large river system before an ice sheet covered it millions of years ago, a new study says. Now it appears to be a vital part of the island's plumbing.
Running from deep within the island's interior north to Greenland's northwest coast, the canyon measures at least 470 miles long, six miles across at its widest, and as many as 2,600 feet deep – reaching its widest and deepest points near the coast. The Grand Canyon, by comparison, is 277 miles long, 18 miles wide, and 6,000 feet deep.
The portrait points to how little scientists know about what lies beneath the world's great ice sheets. It also could help researchers understand how the ice sheet and melt water are working together to feed outlet glaciers along a coast where glaciers have been thinning at an increasing pace within the past decade.
Mapping Greenland's hidden landscape is important "so we can understand how the ice sheet is presently routing mass out toward its edges and how the ice sheet and water underneath the ice will interact," says Mark Fahnsetock, a geophysicist at the University of Alaska at Fairbanks.