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Dating corals

MIT/WHOI Joint Program Student Andrea Burke of the Geology & Geophysics department cuts pieces of a deep-sea coral (Desmophyllum dianthus) collected from about 1000 meters depth in the Drake Passage. Burke is using coral samples to reconstruct past ocean circulation through the last deglaciation. Pieces of coral are cut off and chemically cleaned to remove the ferromanganese crust (brownish coating on the coral) and other surface contaminates. Then the radiocarbon in the carbonate is measured at the National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS). The sample is also dated by using uranium, thorium and protactinium isotopes. Pairing the two measurements allows researchers to examine changes in circulation and carbon cycle processes through time. (Photo by Tom Kleindinst, Woods Hole Oceanographic Institution)