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Shells in the Sands of Time

January 26, 2011

In sediments beneath the Sargasso Sea, WHOI geologist Lloyd Keigwin found a 17,500-year-old clamshell and a mystery: Why was this South Atlantic species living in deep water near Bermuda at that time? In fact, previous research has shown that water from the Southern Ocean water once flowed into the North Atlantic. This suggests the Atlantic’s heat-distributing “conveyor belt” had slowed or stopped, chilling northern climates and allowing deep water from the far south flow into the deep North Atlantic, carrying with it, among other things, clam larvae. (Photo by Lloyd Keigwin, Woods Hole Oceanographic Institution)