U.S. Geologists Discover Preglacial Terrain Supporting Evidence for Greenland’s Past
A preglacial tundra landscape preserved for 2.7 million years far below Greenland glaciers has been discovered by U. S. geologists. The findings have been released on analyzing 17 samples extracted from the ice sheet in 1993 from Summit, Greenland.
On analyzing pollen and plant DNA buried in the seafloor offshore Greenland also suggested that the island once used to have tundra and patchy forest similar to that of today's high Arctic. Preglacial tundra is the region buried thousands of feet under the Greenland Summit, highest point on Greenland's ice sheet, and is an area born before humans ever walked on earth.
The results seem to be surprising as they found preglacial tundra in perfect condition at depth of two miles below ice covering.
Generally, glaciers vanish of everything from any plot to top layer bedrock. Paul Bierman, University of Vermont geologist, said the findings supports the fact that ice sheets have survived numerous global warming episodes.
Paul added that the ice covering acts as refrigerator for the preglacial tundra and thus preserved the landscape by being frozen.
Bierman and his colleagues collected samples of sediment locked in the frozen ice and applied geochemical technique, called beryllium-10 dating, to gain insight into history of sediments. Counting number of beryllium-10 isotopes helps researchers measure age of landscapes because the isotopes only form in rocks and soil exposed at the surface.
The ice sheets did not caused modification through millions of years of changing temperatures and sealed the tundra landscape. The findings hold strong evidence that the center of Greenland was stable and did not melt fully even during the warmest periods of ice sheet's life.