COSMOGENIC CL-36 DATING OF THE FOOTHILLS ERRATICS TRAIN, ALBERTA, CANADA

The Foothills erratics train of Alberta was carried into place during coalescence between montane glaciers and the Laurentide ice sheet. Its age has been controversial: Late Wisconsinan and pre-Wisconsinan ages have been assigned to it. Cosmogenic Cl-36 exposure dating was carrie d out on erratics over a 130 km segment of the erratics train. Seven o f eight age determinations support emplacement during the late Wiscons inan glaciation. These ages eliminate the possibility of an ice-free c orridor during the last glacial maximum. They are also consistent with the hypothesis that the Laurentide ice sheet was the most extensive o f all Pleistocene continental ice sheets in western Canada.