Scientists say that soil buried under Greenland's ice sheet is some 2.7 million years old and theorize that the island had tundra and a forest before being encased in ice.
"There was a really stable landscape on Greenland before the ice sheet came," said researcher Paul Bierman, a geomorphologist at the University of Vermont, as quoted by Live Science. "This landscape has been preserved from beyond the dawn of humankind."
Bierman and the other team members extracted silt buried in Greenland ice and analyzed it with a geochemical technique called beryllium-10 dating, which measures the amount of beryllium-10 isotopes in rock or soil.
The ice came from a 1993 deep-drilling project and is archived at the National Ice Core Laboratory in Denver, Colo. The study marks the first time scientists examined the silt in the bottom of the 10,019-foot-long drill hole.
The findings, which were published Thursday in the journal Science, indicate that the tundra buried under Summit, the highest point in the Greenland ice sheet, was open land for 200,000 to 1 million years before the ice came.
The researchers also found that the ice sheet has likely never melted even during the time of climate warming said to have heated up the Earth 130,000 years ago.
"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."
Other studies have shown that ice can preserve land forms from hundreds of thousands of years ago. Bierman's next project with colleagues is to find ancient landscapes under the ice in Antarctica.
"The bottom of an ice sheet can preserve some really old landscapes," Bierman said.