To understand the timing of deglaciation of the northernmost marine-terminating glaciers of the Cordilleran Ice Sheet (CIS), we obtained 26 10Be surface-exposure ages from glacially scoured bedrock surfaces in Prince William Sound (PWS), Alaska. We sampled six elevation transects between sea level and 620 m and spanning a distance of 14 to 70 km along ice flow paths. Most transect age–elevation patterns could not be explained by a simple model of thinning ice; the patterns provide evidence for lingering ice cover and possible inheritance. A reliable set of 20 ages ranges between 17.4 ± 2.0 and 11.6 ± 2.8 ka and indicates ice receded from northwestern PWS around 14.3 ± 1.6 ka, thinned at a rate of ~120–160 m/ka, and retreated from sea-level sites at 12.9 ± 1.1 ka at a rate of 20 m/yr. The retreat rate likely slowed as glaciers retreated into northern PWS. These results are consistent with the growing body of reported deglacial constraints on collapse of ice sheets along the Alaska margin indicating collapse of the CIS soon after 17 ka. These data are consistent with paleotemperature data indicating that a warming North Pacific Ocean caused catastrophic collapse of this part of the CIS.
Bibliographical noteFunding Information:
Thanks to Kara and Katie Haeussler for help in sample collection and to Keith Labay for help with drafting of some of the figures. Thanks to editor Derek Booth, associate editor Yeong Bae Seong, two anonymous reviewers, and John Jaeger for exceptionally constructive journal reviews; Adrian Bender, Sue Karl, Marti Miller, and Janet Slate for their reviews; and Jason Addison for additional input. Fieldwork was funded by the U.S. Geological Survey; the Hebrew University Jerusalem funded analysis of samples. Any use of trade, firm, or product names is for descriptive purposes only does not imply endorsement by the U.S. government.
Copyright © University of Washington. Published by Cambridge University Press, 2021
- Be exposure ages
- Cordilleran Ice Sheet
- Prince William Sound
- Retreat rate
- Thinning rate
- Be-10 exposure ages