The Stony Mountain Formation is a stratigraphic unit of Ashgill age in the Western Canadian Sedimentary Basin.
It takes the name from the community Stony Mountain, Manitoba, and was first described in the town quarry by D.B. Dowling in 1900.Dowling, D.B., 1900. Report on the Geology of the West Shore and Islands of Lake Winnipeg; Geological Survey of Canada, Annual Report 1898, Volume XI, Part F, with Map 664.
Lithology
Subdivisions
The Stony Mountain Formation is divided into the following sub-units: South (Williston Basin) Penitentiary Member: argillaceous dolomite Gunn Member: interbedded calcareous shale and fossiliferous limestone North Gunton Member: crystalline dolomite Lower Stony Mountain: argillaceous dolomite
Distribution The Stony Mountain Formation occurs throughout the Williston Basin. It reaches a maximum thickness of in the sub-surface at the Canada/United States border, and thins out towards the east, north and west. In Manitoba, where it is exposed at the surface in the erosion belt, it has a thickness of .
Relationship to other units
The Stony Mountain Formation is slightly unconformably overlain by the Stonewall Formation and sharply overlays the Red River Formation or the Herald Formation.
References