Well-preserved fossils deposited in the sediments of an Antarctic lake about 14 million years ago pin down when a large part of the now-icy continent most recently dipped below freezing. The new findings chronicle the changing climate of the region and answer long-standing questions about when and how quickly Antarctica cooled.
ANCIENT LAKE DWELLER This fossilized tiny crustacean, an ostracod, lived among mosses in a freshwater lake in Antarctica about 14 million years ago, when climate across a large part of the now-icy continent dipped below freezing. | M. Williams
Antarctica holds about 90 percent of the world’s ice, which blankets the continent at an average depth of about 1.6 kilometers. Yet small regions, including the McMurdoDryValleys along the eastern side of the TransantarcticMountains, are bare, says David R. Marchant, a geologist at BostonUniversity.