The center of Greenland's ice field. I watched this river create a massive gorge over a three day period. I photographed it from a Sikorsky helicopter hovering at 2,000 feet. The surface of the giant glacier is constantly changing during the 90 day period between July and September because the sun's energy melts the ice creating millions of gallons water. Rivers and lakes form on the surface in a matter of hours because the sun never sets during this period.