University of Vermont researchers have discovered a 3 million-year-old ancient tundra landscape below the Greenland Ice Sheet.
University of Vermont geologist Paul Bierman said that organic soil was found frozen at the bottom of the ice sheet.
Bierman said that since its formation the ice-sheet has remained steady and not melted completely at any time, even during the warmest periods. This eventually buried the tundra landscape under ice through millions of years of global warming and cooling.
"The traditional knowledge about glaciers is that they are very powerful agents of erosion and can effectively strip a landscape clean," study co-author Lee Corbett, a UVM graduate student, said in a press release. "Instead, we demonstrate that the 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."
The researchers initially tested 17 ice samples, collected from the bottom of the 10,019-foot GISP2 ice core extracted from Summit, Greenland, in 1993. The researchers then examined the sample for isotope beryllium-10, this element produced by cosmic rays falls from the sky and sticks to rock and soil. The longer the soil is exposed at Earth's surface, the more beryllium-10 it gathers.
The sample contained higher amounts of beryllium isotope. It is a startling discovery, considering the residue had not been exposed to the sky for a long period of time. This concentration of beryllium is normally found in soils that have been developing over millions of years.
The researchers also examined nitrogen and carbon (left by plant material) levels in the core sample and discovered significant amounts of organic material, indicating that the soil must have been exposed at the surface somewhere between 200,000 and one million years before being covered by ice.
"Greenland really was green! However, it was millions of years ago," Dylan Rood a co-author on the new study from the Scottish Universities Environmental Research Centre and the University of California, Santa Barbara said, "Greenland looked like the green Alaskan tundra, before it was covered by the second largest body of ice on Earth."
The finding is published in the journal Science.
