Image

Peeling Back the Layers

May 14, 2007

Sediments accumulate over time in layers on the seafloor, and they typically contain fossil shells of surface-dwelling microscopic marine animals. These shells incorporate radiocarbon and other isotopes from seawater that were present when the animals lived, and hence provide a chronological record of past ocean conditions. (Photo by Tim Eglinton, Woods Hole Oceanographic Institution)