Greenland Ice Sheet (image) University of Vermont Caption Scientists were greatly surprised to discover an ancient tundra landscape preserved under the center of the Greenland Ice Sheet, below two miles of ice. "We found organic soil that has been frozen to the bottom of the ice sheet for 2.7 million years," said University of Vermont geologist Paul Bierman -- providing strong evidence that the Greenland Ice Sheet has persisted much longer than previously known, enduring through many past periods of global warming. Bierman led an international team of scientists that reported their discovery on April 17 in the journal Science. Credit Joshua Brown, 2012 Usage Restrictions With associated story. Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.