Pleistocene Glacial Lake Sequences in the Foothills, Southwestern Alberta, Canada

Abstract

Three separate advances of Laurentide ice during the preWisconsin and Early Wisconsin led to the formation of proglacial lakes in the Foothills of southwestern Alberta. Lakes formed in both the advance and recessional stages, the most extensive occurring during the latter. Evidence of lakes formed by the first advance is fragmentary, but for the later advances, the occurrence of extensive glaciolacustrine deposits and related features attests to the presence of former large bodies of water. Two lakes (Glacial Lakes Oldman and Westrup) resulted from the second advance of Laurentide ice into the Foothills. Damming of Cordilleran meltwaters by the third (Early Wisconsin) Laurentide ice sheet to affect the area, led to the formation of Glacial Lake Caldwell and the development of complex flights of valley train terraces along the Oldman and Crowsnest River valleys.The relationship of the proglacial lakes to the ice fronts substantiates the stratigraphic evidence that the Cordilleran and Laurentide ice-maxima during each advance were not synchronous and that the valley glaciers had receded considerably before the Continental ice sheet advanced into the Foothills of southwestern Alberta.