The other study in Nature — led by Joerg Schaefer of Lamont - Doherty Earth Observatory and Columbia University, and colleagues — looked
at a small sample of bedrock from one
location beneath the middle of the existing ice sheet and came to what appears to be a
different conclusion: Greenland was nearly ice - free for
at least 280,000 years during the middle Pleistocene — about 1.1 million years
ago.