Using Geoarchaeology to Predict the Presence of Offshore Sites in Southern California (Invited)

During the late Pleistocene and early Holocene, the continental shelves off southern California were exposed and available for occupation by prehistoric peoples. Subsequent sealevel rise and marine transgression of the continental shelf resulted in both submergence and potentially reworking of site materials. A model has been developed and tested for continental shelf site locations, using geoarchaeological methods including seismic reflection imaging, coring, and invertebrate fossil identification. In this model, such factors as topography, rate of sea level rise, sediment thickness and context of deposition are all applied to the assessment of potential for site presence and preservation. The most desirable locations for site preservation are found in offshore valley floors and flanks, whereas adjacent uplands are prone to site erosion. Cultural materials from the La Jollan Complex were recovered from two separate offshore sites by large-scale dredging operations. Transgression at these sites occurred prior to about 8000 B.P.. The relation of these cultural materials to the offshore site location model will be discussed.