Coastal exposure: Tracking retreat of the Cordilleran Ice Sheet in western Canada

Earth Surface Science Institute seminar. Dr. Christopher Darvill, University of Manchester.



Reconstructing the demise of the former Cordilleran Ice Sheet in western North America helps us to appreciate changes in past climate and when routes were first open for the colonisation of the Americas. In this talk, I will outline ongoing work from remote islands on the central coast of British Columbia, western Canada. We are able to track the retreat of the ice sheet by dating the time at which ice exposed the landscape to the build-up of rare, cosmogenic nuclides. Our new data show that ice retreat was complex but that the central coast was ice-free earlier than previously thought. Critically, the coastal margin was exposed at the time that people are first thought to have migrated southwards into the continent. Our exposure data constrain the nature and timing of Cordilleran Ice Sheet retreat in relation to global climate change as well as rates of postglacial landscape change.

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