AN ARCHAEOLOGICAL CHRONOLOGY FOR HOLOCENE DUNE BUILDING ON SAN MIGUEL ISLAND, CALIFORNIA

San Miguel Island, located approximately 40 km off the southern California Coast, has a long history of dune building and human occupation. Hundreds of archaeological shell middens, now known to span at least the past 12,000 calendar years, are built in paleosols formed in the extensive dunes that cover much of the island. By radiocarbon dating scores of these shell middens, we have built a chronology of human occupation that also provides a chronological record of dune building for the past 10,000 calendar years. In this paper, we describe the dunes and eolianites of San Miguel Island, and discuss the timing and general extent of dune building during the Holocene. Although sea level rise may have submerged older dunes, archaeological evidence from terrestrial sites suggests that dune building began in some areas of San Miguel Island by about 10,000 years ago. Dune building was much more widespread and extensive during the Middle Holocene, with thick vertical sections of sand accumulating on many coastal terraces. By the Late Holocene many large longitudinal or parabolic dunes had climbed high on the island topography, some of them extending from northwest to southeast completely across portions of the island. The vast dune fields of San Miguel Island ultimately were badly destabilized by the introduction of sheep and other grazing animals by Euroamerican entrepeneurs during the mid-1800s. Devegetation and dune deflation severely damaged both the terrestrial ecology and archaeology of the island. With the removal of exotic grazers, however, San Miguel is revegetating and its dunes are again stabilizing. The extensive remnants of archaeological sites found in these dunes contain priceless ecological records of more than 10,000 years of human interaction with the marine and terrestrial environments of the California islands.