Several species of freshwater mollusc, with radiocarbon dates of 10 900 – 9050 years BP, have been recovered from supraglacial and intraglacial lacustrine sediments in the Cooking Lake moraine region of south-central Alberta, Canada. The organisms indicate the onset of a warming trend in the region that lasted at least 2000 years, marking the final stages of melting in the continental Wisconsin ice sheet.This period of climatic amelioration correlates with a similar trend in southwestern Alberta during the time interval 13 000 – 9000 years BP based also on the evidence of late and early postglacial molluscan communities.

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