The data revealed through examination of these Leg 178 sites add another facet to our expanding knowledge of Antarctic diatoms. The upper Quaternary sections of all three sites contained a noncontinuous record of an often sparse, fragmented diatom assemblage with many reworked species. This trend is consistent with other cores taken from around the Antarctic Continent (O'Brien, Cooper, Richter, et al., 2001). Even though the assemblage in this upper portion of the time column is often sparse, an interpretive biostratigraphic signal is present. The Pliocene-Pleistocene diatom biostratigraphic record is composed of a sequence of LO datums, with a few FOs and species acmes. Whereas upcore reworking and drilling make it more difficult to use LO datums, the presence of a rich assemblage of species that have been previously observed to co-occur adds reliability to such datums. The biostratigraphy developed from cores taken in the open ocean is applicable, with some regional differences, to these Antarctic margin sediments. Abundance and preservation, in general, was better in the Miocene and Pliocene intervals with an increased number of samples with well-preserved and diverse assemblages. Barren intervals in all three sites are readily identified in the diatom abundance data tables (Tables T3, T5, T6, T7, T9). These are to be expected with the glacially controlled nature of sedimentation.