A SIGNIFICANT LATE PLEISTOCENE GLACIAL RE-ADVANCE DURING RETREAT OF THE CORDILLERAN ICE SHEET ON THE CENTRAL COAST OF BRITISH COLUMBIA

Descriptions of the dynamics of Cordilleran Ice Sheet (CIS) retreat after the Last Glacial Maximum (LGM) have often included short-lived re-advances occurring during the Older and Younger Dryas stadial periods and into the Holocene. Proposed causes of these re-advances have included changing bed conditions and climatological factors, although identification of these events has been limited to southwest and central British Columbia as well as northwest Washington State. We present evidence of a post-LGM re-advance of Cordilleran ice on Calvert Island on the central coast of British Columbia between Northern Vancouver Island and Haida Gwaii. Evidence is provided by sedimentological and palaeoecological information contained in an exposed glacial advance sequence combined with LiDAR-derived geomorphic mapping of glacial features in the region. Radiocarbon ages from the sequence suggest ice advanced to—and retreated from—the western edges of the island between 15086 and 13809 cal. yr BP, respectively. These data fill an important spatial and temporal gap in knowledge of fluctuations of the retreating ice sheet margin, and have implications for climate and sea-level reconstructions, past human migration patterns, and the paleoecology of an understudied area of the Pacific Northwest.