Pre‐Younger Dryas resurgence of the southwestern margin of the Cordilleran ice sheet, British Columbia, Canada

Abstract

Clague, J. J., Mathewes, R. W., Guilbault, J.‐P., Hutchinson, I. & Ricketts, B. D. 1997 (September): Pre‐Younger Dryas resurgence of the southwestern margin of the Cordilleran ice sheet, British Columbia, Canada. Boreas, Vol. 26, pp. 261–278. Oslo. ISSN 0300–9483.A lobe of the Cordilleran ice sheet readvanced into the central Fvaser Lowland, southwestern British Columbia, Canada, on at least two occasions near the end of the last glaciation. This ice also flowed into the previously deglaciated, lower reaches of mountain valleys adjacent to the Fraser Lowland and into Washington state. The first of these advances occurred before about 11900 BP and ended with glacier retreat and the establishment of lodgepole pine forest on newly deglaciated terrain. Parts of this forest were overridden by ice during a second advance, shortly after 11300 BP. The younger advance is most likely older than the Younger Dryas Chronozone (11000–10000 BP) and may correlate with an intra‐Allerad cooling event (the Killarney‐Gerzensee oscillation). The older advance may have occurred during the Oldest Dryas or Older Dryas cold period. Non‐climatic factors could also be involved, as emergence of the Fraser Lowland before the older advance greatly reduced or eliminated calving at the glacier margin and thus altered the mass balance of the ice lobe.