This project was performed to investigate the evolution of Western ice sheet (WIS) in the Eastern Basin (Ross Sea), Antarctica. The Ross Sea is part of the West Antarctic Rift System that has three main depocenters as the Eastern Basin, the Central Basin and the Victoria Land Basin. The Eastern Basin contains a thick sedimentary sequence that tells about the WIS advance and retreat. DSDP cores were drilled in this area (Hayes and Frakes, 1975) gives knowledge about the stratigraphy and the depositional environment of the area from Upper Miocene to Pleistocene (Hayes and Frakes, 1975). Large erosional hiatuses and poor interpretations of DSDP cores, do not let to construct of the Eastern Basin depositional history and the evolution of the WIS (Hayes and Frakes, 1975; Denton et al., 1991). On the other hand, multichannel seismic studies in the Ross Sea gives more knowledge about the sedimentary sequences and unconformities (ANTOSTRAT, 1995). These studies show that Lower Pliocene is identified by a marked erosion surface, called RSU2 (De Santis et al., 1995; Brancolini et al., 1997), and is correlated with a large hiatus in DSDP 273 which is dated from 10.5 to 4 ma (Savage and Ciesielski, 1983). Horizon RSU2 corresponds to a sharp change in the structure and lithology of sediments, which may be interpreted as a major increase of the glacial influence. Thus, it is clear that RSU2 identifies a major, unique event in the depositional history at the Ross Sea. The explanation of this event is today largely hypothetical, based on progressive climatic cooling occurred during Pliocene and the consequent grow of the Antarctic ice sheet. For setting up reliable paleo-climatic models, however, we have to define precisely the extension and features of the ice sheet: thus, we proposed to carry out a detailed geophysical study in a specific area of the Ross Sea, for reconstructing dimensions and dynamics of the Eastern ice sheet during Pliocene, a period of large changes at a global level, anda also the most debated one for the history of the Antarctic ice sheet.