Coastal paleogeography of the California–Oregon–Washington and Bering Sea continental shelves during the latest Pleistocene and Holocene: implications for the archaeological record

Abstract

Sea-level rise during the last deglaciation and through the Holocene was influenced by deformational, gravitational, and rotational effects (henceforth glacial isostatic adjustment, GIA) that led to regional departures from eustasy. Deglacial sea-level rise was particularly variable spatially in areas adjacent to the Cordilleran and Laurentide Ice Sheets. Such regional variability in sea level due to GIA is important to identify when investigating potential coastal migration pathways used by early Americans. An improved understanding of regional sea-level rise may also be used for predictive modeling of potential archaeological sites that are now submerged. Here we compute relative sea-level change across the California Oregon Washington and Bering Sea continental shelves since the Last Glacial Maximum using an ice-age sea-level theory that accurately incorporates time-varying shoreline geometry. The corresponding non-uniform sea-level rise across these continental shelves reveals significant departures from eustasy, which has important implications for improved understanding of potential coastal migration routes and predictive modeling of the location of now-submerged archaeological sites.