Unit Name: Kootenay Group
Unit Type: Lithostratigraphic
Usage: Currently in use
Age Interval: Late Jurassic - Late Cretaceous (161.2 - 65.5 ma)
Province/Territory: Alberta; British Columbia
Originator: Dawson, G.M., 1886; emended by Cairnes, D.D., 1908, Norris, D.K., and Gibson D.W, 1979
None designated; there are excellent exposures in the Highwood Pass-Mist Mountain and Mount Allan areas of Alberta (Gibson, 1979).
Occurs throughout the Rocky Mountain Foothills and parts of the eastern front ranges of southwestern Alberta and southeastern British Columbia, between the United States border and North Saskatchewan River. The group attains a composite maximum measured thickness of 1,335 m (4,379 ft), thinning to zero toward the east.
Comprises three formations which, in ascending order are: Morrissey - massive, cliff forming, predominantly sandstone; Mist Mountain - interbedded sandstone, siltstone, mudstone, shale and thin to thick seams of bituminous to semianthracite coal; Elk - interbedded sandstone, siltstone, mudstone, shale and locally thick beds of chert-pebble conglomerate and thin seams of high volatile bituminous coal. The Morrissey Formation comprises two members: a lower, Weary Ridge - orange-brown to brownish grey weathering, very fine- to coarse-grained sandstone; and Moose Mountain - well-indurated, cliff forming, medium grey weathering, fine- to coarse-grained sandstone, with rare mudstone and coal.
The Kootenay Group conformably overlies the Upper Jurassic Fernie Formation, and in most areas is disconformably overlain by Lower Cretaceous strata of the Blairmore Group. In some western areas it may possibly be overlain conformably by the Pocaterra Creek Member of the Blairmore Group (Gibson, 1979, 1985; Ricketts and Sweet, 1984). The Kootenay Group grades laterally into the Nikanassin Formation in the vicinity of the North Saskatchewan River. It may correlate with part of the upper Morrison Formation of the United States.
Originally named 'Kootanie Series' by Dawson (1886), later modified and renamed Kootenay Formation by Cairnes (1908, 1914) to include the stratigraphic interval between the Blairmore Group (Dakota Formation) and the Fernie Formation. Newmarch (1953) later recognized a three fold subdivision of the Kootenay in the Fernie area and defined an upper unit at the top of the Kootenay succession as the Elk Formation, while retaining the name Kootenay for the lower two units. In the Coleman-Blairmore area of Alberta Norris (1959) subdivided the Kootenay Formation into four members and assigned the type section to Grassy Mountain. Recently Gibson (1979, 1985) subdivided strata between the Jurassic Fernie Formation and the Lower Cretaceous Blairmore Group into 3 formations, a lower, Morrissey, a middle, Mist Mountain and an upper, Elk. Accordingly the Kootenay Formation was elevated to group status. The name Kootenay Formation was incorrectly applied by some early workers for coal-bearing strata now included within the Blairmore Group. The name Kootenai Formation of Montana is used for strata equivalent to the Blairmore Group.
Cairnes, 1908; Dawson, 1886; Gibson, 1979, 1985; Newmarch, 1953; Norris, 1959; Ricketts and Sweet, 1984.
Source: CSPG Lexicon of Canadian Stratigraphy, Volume 4, western Canada, including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba; D.J. Glass (editor)
Contributor: D.W. Gibson
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 30 Oct 2007