A project that reconstructed sea surface temperatures 18 000 years before present (BP). The temperature information was derived from properties of deep-ocean sediments sampled by means of corers, and provided strong support for the role of Milankovitch variations as a pacemaker for climate fluctuations. The primary attributes used were the species composition of planktonic organisms found in the sediments, and the oxygen isotopic composition of foraminiferan skeletons.