Late Wisconsinan Laurentide glacial limits of northwestern Canada: the Tutsieta Lake and Kelly Lake phases

Extensive segments of well preserved moraine and other ice-marginal features have been recognized within the all-time limit of the northwestern part of the Laurentide ice sheet. Many of the segments can be linked ta define the margin of the ice sheet at the culmination of a Late Wisconsinan advance, here called the Tutsieta Lake Phase. Others can be linked ta define the limit of a later advance, here called the Kelly Lake Phase. Still other moraine segments cannot be referred readily ta either phase. Radiocarbon dating indicates that the advance of the Laurentide ice sheet ta its all-time limit during Hungry Creek Glaciation culminated about 30 000 years ago, and dates for causally related inundation of Old Crow and Bluefish basins support that timing. Interpretations placed on "old" dates on marine shells from the Mackenzie Delta area, however, are incompatible with a Late Wisconsinan age for the maximum Laurentide advance, posing a major chronological problem. Radiocarbon dates indicate an age of about 13 000 years or somewhat aider for culmination of the Tutsieta Lake Phase, and some time before 10 600 years aga for the Kelly Lake Phase. The correlation suggested here implies that during the Late Wisconsinan Tutsieta Lake Phase, westerly moving ice in Amundsen Gulf impinged against the northwest flank of Brock Upland ta a level of 455 m and extended westward beyond Parry Peninsula. In contrast, other workers have suggested that during the Late Wisconsinan, an ice lobe in Amundsen Gulf barely reached the eastern margin of the study area. This difference in interpretation indicates a need for field checking of the photo-interpretive correlations offered herein.