A new study of ice samples taken from the Greenland Ice Sheet illustrates how the earth endured in the face of sometimes dramatic climate swings.

Glaciers, the research explains, are commonly thought to work like belt sanders, scraping off everything -- including vegetation, soil and even the top layer of bedrock -- as they slide over land.

Which is why scientists were astonished when they discovered evidence of ancient tundra preserved under the sheet, an estimated two miles thick.

"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, who worked on the study. He added the collected data offered evidence the Greenland Ice Sheet has persisted much longer than previously known, enduring through many past periods of global warming.

"The ancient soil under the Greenland ice sheet helps to unravel an important mystery surrounding climate change," said Dylan Rood, a co-author of the new study from the Scottish Universities Environmental Research Center and the University of California, Santa Barbara.

In particular, the latest data shows that even during the warmest periods since the ice sheet formed, the center of Greenland remained virtually unchanged.

Findings of the study were published April 17 in the journal Science.

It's likely, said Bierman, that glacier ice "did not fully melt at any time." Vermont's Bierman said. This allowed a tundra landscape to be locked away, unmodified, under ice through millions of years of global warming and cooling.

Even though glaciers are typically considered "very powerful agents of erosion and can effectively strip a landscape clean," said study co-author Lee Corbett, a Vermont graduate student who contributed to the ice analysis, the study demonstrates. "[T]he Greenland Ice Sheet is not acting as an agent of erosion; in fact, at its center, it has performed incredibly little erosion since its inception almost three million years ago."

Put another way, said Bierman, the ice sheet has served as an enormous "refrigerator that's preserved this antique landscape."

Scientists and policymakers alike have keen interest in Greenland, since the future stability of ice sheet -- which is approximately the size of Alaska -- is expected to significantly affect how fast and high global sea levels will rise from human-caused climate change.