Unit Name: McKay Group
Unit Type: Lithostratigraphic
Rank: Group
Status: Formal
Usage: Currently in use
Age Interval: Late Cambrian - early Middle Ordovician (499 - 466.3 ma)
Province/Territory: British Columbia

Originator: Evans, 1933.

Type Locality:
John McKay Creek, Brisco Range, about 7 km (4.4 mi) east of Radium, British Columbia (50 deg 40'N, 116 deg 01'W).

Distribution:
Evans (1933, p. 126) estimated the unit to be 1,200 m (3,940 ft) thick at the type section. Complexly folded and faulted McKay Group slates outcrop widely in the western main ranges, western ranges and Rocky Mountain Trench, from the mouth of Bush River (Wheeler, 1963a) to Tanglefoot Creek in the Hughes Ranges (about Latitude 49 deg 40'N).

Lithology:
Mostly medium green-grey slate (as a microscopically penetrative structural fabric, in most places parallel to the axial surfaces of folds), with thin- to thick-beds of microcrystalline limestone, oolitic limestone, bioclastic limestone, and some limestone intraclast ("flat-pebble conglomerate") beds.

Relationship:
The McKay Group conformably rests on Ottertail Formation limestones (Upper Cambrian). At the type section the McKay Group is overlain by Middle Ordovician (?) Mount Wilson Formation quartz sandstones. In the Beaverfoot Range McKay Group shaly limestones are overlain by Middle Ordovician Glenogle Formation black shales. In the southern Brisco Range the upper pan of the McKay Group is Middle Ordovician and coeval with the lower part of the Glenogle Formation. The McKay Group is equivalent to the Bison Creek-Mistaya-Survey Peak-Outram succession of formations in the eastern main ranges; it replaces the now abandoned name Goodsir Formation (Allan, 1912), used at one time in parts of the main ranges (Aitken and Norford, 1967. p. 160).

History:
Evans (1933) applied the name McKay Group to slates in the western ranges and Rocky Mountain Trench that he suspected (but could not prove) were correlative with the Goodsir Formation of the western main ranges. Subsequently the name McKay Group was used widely in mapping (Leech, 1954; Wheeler, 1963a). North and Henderson (1954) suggested that the names McKay Group and Goodsir Formation applied to the same succession of rocks. With completion of regional mapping and elucidation of Upper Cambrian and Lower Ordovician stratigraphy Aitken and Norford (1967) suggested the name Goodsir Formation be abandoned and the name McKay Group be applied for the Upper Cambrian-Lower Ordovician (and locally lower Middle Cambrian) slate-dominated succession in the western main ranges, western ranges and Rocky Mountain Trench.

References:
Aitken, J.D. and Norford, B.S., 1967. Lower Ordovician Survey Peak and Outram formations, southern Rocky Mountains of Alberta; Canadian Society of Petroleum Geologists, Bulletin of Canadian Petroleum Geology, vol. 15, no. 2 (June), pp. 150-207.
Allan, J.A., 1912. Geology of Field map-area, Yoho Park, British Columbia; Geological Survey of Canada, Summary Report 1911, pp. 175-187.
Evans, C.S., 1933. Brisco-Dogtooth Map-area, British Columbia (with Map 295A); Geological Survey of Canada, Summary Report 1932, Part A, II, pp. 106-176.
Leech, G.B., 1954. Canal Flat, British Columbia; Geological Survey of Canada, Paper 54-7.
North, F.K. and Henderson, G.G.L., 1954. Summary of the geology of the southern Rocky Mountains of Canada. In: Alberta Soc. Petrol. Geol., 4th Ann. Field Conf. Guidebook, p. 15-81.
Wheeler, J.O., 1963a. Rogers Pass map-area, British Columbia and Alberta, (82N W½) (Report and Map 43-1962); Geological Survey of Canada, Paper 62-32, 32 p. + Preliminary Map 43-1962, Geology, Rogers Pass (Golden, West Half), British Columbia-Alberta, NTS 82 N (West Half), Scale: One Inch to Four Miles = 1:253 440.

Source: CSPG Lexicon of Canadian Stratigraphy, Volume 4, western Canada, including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba; D.J. Glass (editor)
Contributor: H.R. Balkwill
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 29 Dec 2008