Surficial geology, Hay River, Alberta

This 1:100 000 scale map represents a product of the Shallow Gas and Diamond Opportunities in Northern Alberta and British Columbia project (NRD 4450) conducted by the Geological Survey of Canada (Natural Resources Canada), Alberta Geological Survey (Alberta Energy and Utilities Board), and Resource Development and Geoscience Branch (British Columbia Ministry of Energy and Mines). Surficial geology maps covering the rest of the 1:250 000 (NTS) 84L map area are published by Plouffe et al. (2004) and Paulen et al. (2005a, b). Prior to commencement of field activities, black and white, 1:60 000 scale airphotos (Alberta Sustainable Resource Development, 1994) were scanned for the Hay River map area (NTS 84L/SW). Preliminary surficial geology interpretations were drawn on the airphotos, and then subsequently ground truthed in the field. Fieldwork was mainly conducted in summer 2003, with additional site surveys in summer and fall, 2004. Field activities included: 1) inspection, logging and characterization of surficial geology from truck, foot traverse and helicopter field surveys of exposures along cutbanks, borrow pits, gravel pits, seismic line trenching activities, as well as from hand-dug and augered holes, 2) sampling of till at a reconnaissance scale (1 sample per 25 km2) for geochemistry, particle-size, carbonate content, and kimberlite indicator minerals, 3) measurement of clast fabrics from tills and paleocurrent directions from fluvially deposited material. The Hay River map area is part of the Fort Nelson Lowlands physiographic region and is blanketed by Boreal forest (white and black spruce, aspen, lodgepole pine) and extensive bogs and fens. Soils are generally poorly drained, commonly with shallow water tables, reflecting the high clay content of the tills (10-40%) in which they have formed. In raised areas, where soil development is more advanced, gray luvisols predominate. Static and turbic cryosols are found in regions of sporadic discontinuous permafrost, and solonetzic soils are found in areas of thin drift overlying marine shale bedrock. Outcrops of Cretaceous Dunvegan Formation sandstone are found in the southern uplands (>600 m above sea level) of the map area, while outcrops of Cretaceous Fort St. John Group shales (Shaftesbury Formation) are found in the south-central region of the map area along cut-banks of former glacial meltwater canyons and channels. The Hay River flows east to west through a conspicuous glacial meltwater canyon (which incorporates Rainbow Lake) in the central part of the map area. This meltwater canyon is considered to have formed both sub-glacially and ice-marginally, and likely served as the outlet of glacial Lake Peace into the Fontas-Nelson River system to the west during the late Indian Creek stage of Mathews (1980).