Quaternary Stratigraphy and Surficial Geology Peace River-Winagami Region, Alberta; Year Two Report For The End Fiscal Year 1994-95

The surficial geology and glacial stratigraphy of the Peace River region (NTS 84C/w half) indicate the area was affected by one major ice advance. The surficial morainal deposits, flutes, and morainal ridges which are generally situated in the uplands of the Clear and Whitemud Hills, are evidence of an unobstructed southerly flowing Laurentide Ice Sheet. Deglaciation is marked in the uplands by deposition from stagnant ice and erosion by meltwater channels flowing down slope. In the lowlands, deglaciation caused the formation of glacial lakes which inundated the Peace River valley including the towns of Manning and Peace River. Glacial stratigraphy in the study area is recorded by one glacial till. The composition and texture of this unit are both laterally and vertically variable due to deposition that took place from basal, englacial, and superglacial positions within the glacier. Terrace formation along the major rivers followed deglaciation. Processes active at present include slumping of surficial and bedrock material as the rivers cut laterally, and the accumulation of organic sediments in bogs, swamps and other areas of poor drainage.

The Quaternary geology and stratigraphy of the Winagami region (NTS 83N/W half) are consistent with at lease one glaciation. Distribution of the surface units and ice directional landforms suggest two major ice movement directions, a strong south to southwest movement, and a weaker, topographically controlled southeasterly one. Most surficial deposits are associated with either ice stagnation and deglaciation, or are really extensive. Colluvium and alluvium exist among the flank of and infill most drainage valleys. Stratigraphic correlation of the Upper Quaternary units between boreholes and large well exposed sections, supports a single glaciation event. The lowermost diamict is a dark grey, massive, silt-clay, englacial to basal till of Laurentide origin. Upper diamicts represent facies changes in the one major till. The thickness of the Quaternary deposits vary, ranging from a few metres near Reno to over 75 m in the buried paleochannels. Bedrock topography is irregular, due to several large paleochannels and their tributaries.