Figure F9. Lithologic columns for Sites 1218, 1219, 1220 and 1221 showing where diatoms are common to abundant (>10% based on smear slide analysis). Diatoms are a significant constituent of sediments from all the southern sites during the RP15 radiolarian zone (upper middle Eocene). RP19 and 20 (basal Oligocene) is diatom rich, with the exception of Site 1219. At Site 1219, a pronounced peak in diatom abundance is found in upper Oligocene sediments. O/M = Oligocene/Miocene boundary, E/O = Eocene/Oligocene boundary, P/E = Paleocene/Eocene boundary.