During much of the earth's history the climate was warm and relatively uniform. The change to the present glacial and interglacial periods did not proceed uniformly. These were marked by discrete and sudden coolings which are linked with changes in oceanic circulation. There was a prominent change about 38 million years ago, followed by subsequent coolings 14 million years ago, 6 million years ago, and 3 million years ago. These intervals are separated by times of much higher stability although fluctuations have been defined. Since the last proposal was submitted three years ago, a number of high quality hydraulic piston cored sedimentary sequences of late Oligocene through Neogene age from the Pacific have become available for detailed analysis, some of these sites were drilled during DSDP-IPOD Legs 90 and 89; they form a latitudinal transect of unprecedented quality extending from the equator to the subantarctic in the South Pacific. These sediment sections are of great paleoceanographic value. This project wants to further extend paleoceanographic studies of middle and late Cenozoic sedimentary sequences in middle and low latitudes and to correlate with events found elsewhere; the major objectives are: to continue time-series analysis of paleoceanographic history; to examine events during the terminal Miocene, the middle and late Pliocene; to define the main quantitative changes as they are preserved in planktonic/benthonic foraminifera.
