Seismic data correlated to lithologic and age control at DSDP/ODP drill sites show that glacial unconformities are located within lower Pliocene strata on the antarctic outer continental shelves. The glacial unconformities are significant because they provide direct evidence that the Antarctic Ice Sheets advanced across the continental shelves despite the generally warmer climates and elevated sea levels that characterized the majority of the early Pliocene. The magnitudes of the peak eustatic lowstands and 0-18 enrichments indicate that the ice volume on Antarctica probably exceeded today's ice volume which suggests that the ice-sheet grounding events on the shelves probably were associated with larger than present ice volumes on two to three occasions during the early Pliocene.