It has been established that pollen deposited in marine sediments on continental margins provides terrestrial vegetation and climate records that are directly correlated with global chronostratigraphic events (Dupont, 1992; Heusser and van de Geer, 1994; Van Campo et al., 1982). Interpretations of past vegetation and climate of western North America from pollen deposited offshore are based on comparisons of downcore pollen spectra with modern marine and terrestrial pollen spectra (e.g., pollen assemblages from marine and terrestrial sediment traps and surface samples), vegetation, and climate (Heusser and Balsam, 1977; Heusser, 1988). Previous studies showed that Milankovitch-scale variations in vegetation of coastal Washington and Southern California reconstructed from pollen deposited in the northeast Pacific Ocean during the last glacial cycle were similar to those inferred from onshore pollen data ascribed to the same time (Heusser and Florer, 1973; Heusser, 1995). To extend these studies in space and time, we present preliminary results from pollen analyses of sediments deposited off Northern California during the last ~500 k.y.
Pollen from piston cores taken on the continental margin of western North America between 32°N and 43°N also showed systematically related short-term changes superposed on Milankovitch-scale oscillations of the past 60 k.y. During oxygen isotope Stage 3, for example, brief warming events in California and Oregon appear correlative with interstadial events in waters offshore (Heusser, 1998). Here we extend high-resolution pollen analyses of sediments deposited on the northern California margin over the last ~140 k.y.