Geoarchaeology of Late Pleistocene to Early Holocene Occupation at the EL Peregrino and Colina Castor Sites on Cedros Island, Baja California, Mexico

Abstract

This study presents the geoarchaeological and chronometric analysis of two Late Pleistocene to Early Holocene archaeological sites: El Peregrino (PAIC-88) and Colina Castor (PAIC-91), located on Cedros Island, Baja California, Mexico. Both sites are situated at the base of fossil spring localities above modern sea level and contain stratified cultural materials associated with now-extinct freshwater sources that likely played a critical role in supporting early human occupation within an otherwise arid coastal setting. Bayesian chronological modelling, predicated on > 40 new radiocarbon measurements, places the onset of occupation at El Peregrino and Colina Castor during the Younger Dryas, with El Peregrino dating from 12,905 to 12,050 cal BP and Colina Castor from 12,780 to 12,105 cal BP. Stratigraphic and sedimentological data indicate site formation through a combination of alluvial fan deposition, aeolian input, and localised floralturbation around spring margins. Marine shell and lithic artifacts were transported inland as far as 15 km from the paleo-coastline during periods of lower sea level. These findings expand the known spatial and temporal range of Late Pleistocene coastal foragers in North America and highlight the importance of freshwater availability in structuring early human mobility and site selection along the Pacific coast. The Cedros Island record provides a rare inland perspective on early maritime adaptations during the transition from the Pleistocene to the Holocene.