We examined 75 samples from Unit I, Hole 1149A for diatoms. Fifty samples ranging from early Pliocene to late Pleistocene in age contained 139 diatom species and were attributable to the Neodenticula kamtschatica through Neodenticula seminae zones of the North Pacific diatom zonation and to the Nitzschia jouseae through Pseudoeunotia doliolus zones of the equatorial Pacific diatom zonation. Patterns of diatom abundance in Unit I correlate well with the diatom events of Barron. The data seem to show Barron's Events C and D and increases in diatom sedimentation in the late Pleistocene not specifically named by Barron but shown in his data. Inconsistencies of species ranges compared to published data suggest either extensive reworking or biogeographic control of first and last occurrences for some zonal indicator species. The presence of displaced Miocene, neritic, and benthic taxa strongly suggests aqueous or eolian transport of materials from coastal environments and/or land-based outcrops.