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As the earth’s climate changes, one tool for understanding its environmental impacts is the study of past climate changes, revealed by layers of sediment scientists take from the sea floor. At the Lamont-Doherty Earth Observatory in Palisades, New York, frozen samples of those sediments are housed in a facility called the Core Repository. Time capsule Lamont research professor Maureen Raymo, the director of the Core Repository, slides open a long, narrow drawer from the cabinet. Like thousands of others here, the drawer contains a long, thin cylinder of layered sediment. It’s a sample extracted from the ocean floor and below. According to Raymo, the cylinder’s distinctive stripes of varied colors and widths are a unique visual record, a sort of vertical time capsule. “Imagine you are out on a boat, and you could see right through the four kilometers of water that is between you and the bottom. And on the bottom all the little fossils, all the little plankton that die over the years in the water column, their remains settled to the sea floor, just gently settled to the bottom," Raymo says. "And they accumulate, layer by layer by layer, over millions of years. So imagine you just came along and just stuck a big piston tube into the sediment, or took a straw and stuck it into the sediment and pushed it 20 meters down and extracted it, you would have a long core that would essentially be a record of sedimentation going back in time. For geologists, it’s the equivalent of a tape recorder.” | 
