Versace Belt Lion Head
The ice does flow, but it deforms like glass or warm plastic above a base that is stuck to the ground.
In the GISP2 ice core, the bottom 30 to 50 feet is frozen to bedrock, and the ice above is a whirl of folded, deformed layers, Bierman said.
Bierman and his colleagues are now searching for ancient landscapes in Antarctica, though the researchers must reach back further in time because the continent froze earlier than Greenland.
new findings hint that at Summit, the tundra landscape was open to the sky for 200,000 years to 1 million years before ice covered it. "This landscape has been preserved from beyond the dawn of humankind."
Counting the number of beryllium 10 isotopes gives an estimate of how much time a rock or soil spent at the surface, bombarded by Gucci Belt Red And Blue
Ancient Landscape Found Under 2 Miles Of Greenland's Ice
"Now we know that it's unlikely the ice sheet has disappeared for significant periods of time in the last 3 million years, at least at this one pinprick on this big island," Bierman told Live Science. "Now human activity may spell the end of it."
Bierman said he was stunned by the sky high levels of beryllium 10 in the soil from the GISP2 ice core.
New look at old iceThe ancient soil was pulled from beneath the Greenland Ice Sheet in 1993, during the GISP2 deep drilling project to reach the bedrock beneath Summit. The 10,019 foot long GISP2 ice core records more than 100,000 years of past climate history, but until now, no one had examined the dirt in the ice at the bottom of the drill hole. (The ice is archived at the National Ice Core Laboratory in Denver, Colo.)
Previous work by Bierman's students found that some Greenland glaciers protect the land like armor, preserving landscapes that were 800,000 years old.
Pollen and plant DNA buried in the seafloor offshore of Greenland also suggest the island once had tundra and patchy forest, similar to today's high Arctic. The Gucci Belt Replica White
The new results also mean the Greenland Ice Sheet gets a nod for endurance. Gucci Belt New Season
Only the interiors of Africa and Australia contain older landscapes, having escaped the erosive power of the Earth's recent ice ages. Soils in these hot continental interiors are many millions of years old.
Buried thousands of feet under Summit, the Versace Belt Lion Head highest point on Greenland's ice sheet, is a soil born before humans ever walked on Earth. The 2.7 million year old silt is a remnant of the verdant tundra that covered Greenland before it was entombed in ice, researchers reported April 17 in the journal Science.
"The bottom of an ice sheet can preserve some really old landscapes," Bierman said. Original article at Live Science's Our Amazing Planet.
"Our eyes just lit up. It was completely unexpected and one of the few times I've been totally surprised in my career," Bierman said.
Persistence of landOf course, that begs the question of why Greenland's glaciers didn't grind away the ancient soil. The answer: Mounting evidence suggests many ice sheets are frozen to their beds.
"I was asking a really different question than people who look at ice cores," Bierman said. "I was looking for a history of landscapes in ancient Greenland, and that mindset wasn't there 20 years ago. It's the evolution of science you're always coming up with new hypotheses to test," he said.
The frozen soil contains millions of beryllium 10 atoms, at a level comparable to other long lived Arctic landscapes, such as tundra soil in Alaska, the researchers said.
Beryllium 10 is a radioactive isotope produced by cosmic rays (high energy particles that rain down on Earth from space). The beryllium 10 isotopes help researchers gauge the age of landscapes, because the isotopes only form in rocks and soil exposed at the surface; cosmic rays can't penetrate thick ice or deeply buried rocks.
If the soil under Summit has been buried for 2.7 million years, then the discovery implies the ice sheet has never fully melted, even when the Earth went through an incredible natural warming swing 130,000 years ago one as warm as this century's predicted climate change.
These deforming ice sheets are called cold based glaciers, while those that erode their rocky bottoms with water and ice are known as warm based glaciers. [The Power of Ice: Photos of Glacier Erosion]
Versace Belt Lion Head
Lv Leather Belts