PLEISTOCENE STRATIGRAPHY, PALEOPEDOLOGY, AND PALEOECOLOGY OF A MULTIPLE TILL SEQUENCE EXPOSED ON THE LITTLE-BEAR RIVER, WESTERN DISTRICT OFMACKENZIE, NWT, CANADA

The Little Bear River section lies in a transition zone between Macken zie Lowland and Canyon Ranges of Mackenzic Mountains. Within the trans ition zone, the maximum extent of the Laurentide ice sheet overlaps th e former extent of montane glaciers that emanated from the higher part s of Canyon Ranges or from the still higher Backbone Ranges to the sou thwest. Five montane tills, each with a paleosol developed in its uppe r part. indicate five separate glaciations during each of which a vall ey glacier emanating from the headwaters of Little Bear River extended eastward into the transition zone. The uppermost of the montane tills is overlain by boulder gravel containing rocks of Canadian Shield ori gin deposited by the Laurentide ice sheet. Solum and B horizon depths, red colours, and lack of leaching and cryoturbation indicate that alt hough each successive interglacial interval was cooler than the preced ing one, even the last of the intervals was warmer than the Holocene. Climatic conditions during one of the intervals inferred from the pale obotanic data, particularly spruce forest development, are consistent with conditions inferred from the associated paleosol. The uppermost o f the montane tills is thought to correlate with till of Reid (Illinoi an) age in central Yukon. The paleosol developed on that till is, acco rdingly, thought to correlate with the Diversion Creek paleosol develo ped on drift of Reid age. The Laurentide boulder gravel is assigned to a stade of Hungry Creek Glaciation of Late Wisconsinan age. The Laure ntide ice sheet reached its apparent all-time western limit during the Hungry Creek Glaciation maximum.