Early Miocene to Pleistocene fluctuations in ice-rafted debris at DSDP site 274

The initiation and growth of the antarctic ice cap has been studied directly using the deep-sea sedimentary record and indirectly using inferences from global changes in sea level, climate, and vegetation (Drewry 1975). Since the recovery of ice-rafted debris (IRD) off Antarctica during the H.M.S. Challenger expedition (Murray and Renard 1891), attempts have been made to distinguish IRD in deep-sea sediments from other terrigeneous components. IRD in deep-sea sediments commonly has been though of as poorly sorted angular grains consisting of quartz, feldspars, garnet, and rock fragments. DSDP site 274, located on the continental rise in the northwest Ross Sea, is ideally located to record the accumulation of sediment from the initiation and subsequent fluctuations of the west antarctic ice sheet. The early Miocene through Pleistocene record of site 274 can be correlated with paleoceanographic changes within the southern ocean.