Unit Name: Ishbel Group
Unit Type: Lithostratigraphic
Rank: Group
Status: Formal
Usage: Currently in use
Age Interval: Permian (299 - 251 ma)
Age Justification: Scattered occurrences of brachiopods, fusulinaceans, corals, bryozoa, crinoids and Helicoprion (see Logan and McGugan, 1968) and conodonts (see Henderson and McGugan, 1986).
Province/Territory: Alberta; British Columbia

Originator: McGugan, A. and Rapson, J.E., 1961b, 1963b, p. 56.

Type Locality:
Type section of Ishbel Group not specified: Composite. See Belcourt, Johnston Canyon, Telford, Ross Creek, Ranger Canyon and Mowitch Formations. Type section of Ishbel Formation, as originally defined, on the west flank of Mount Ishbel (51 deg 16'N, 115 deg 47'W).

Distribution:
Maximum thickness of 427 m (1,401 ft) at Telford Creek Ridge, southeastern British Columbia. Minimum thickness 0.3 m (1 ft) or less in easternmost front range conglomeratic condensed feather-edge deposits. Widely distributed in all front range sections from the Flathead area in the south to the Peace River area in the north. Absent in the foothills subsurface except for the homotaxial Belloy Formation of the Peace River area.

Lithology:
Various lithologies representing Phosphoria Formation (northwestern U.S.A.) depositional conditions in western Canada. Comprises several formations, in ascending order: Belcourt Formation: Grey and brown silty dolomite with chert nodules; Wapiti Lake area of northeast British Columbia, north-central foothills; probably homotaxial with phosphatic shaly siltstone and silty fossiliferous limestone of informal Mount Greene beds to north in Pine Pass and Peace River area. Johnston Canyon Formation: Dark grey, rhythmic sequence of shaly phosphate siltstones, calcareous siltstones and silty carbonates in the southern Rockies. Telford Formation: Light grey cliff forming, fine- and coarse-grained sandy limestones and dolomites in southeastern British Columbia. Ross Creek Formation: Dark grey, recessive phosphatic, shaly siltstones, calcareous siltstones, silty carbonates, phosphatic coquinas in southeastern British Columbia. Ranger Canyon Formation: Dark chert complex with thin, phosphate basal conglomerate. Remnants of silicified sandstone, phosphatic siltstone and evaporites throughout the front ranges of the Rocky Mountains of Alberta and east-central British Columbia. Mowitch Formation: Coarse grey and brown sandstone with wind blown gypsum in north-central Rockies. Fantasque Formation: Rhythmically bedded, spicular chert, shale and siltstone, with a thin basal lag deposit of phosphate and chert nodules and pebbles in northeastern British Columbia. Belloy Formation: Carbonates and sandstones in the subsurface of west-central Alberta and northeastern British Columbia. Kindle Formation: Siltstone, shale and subordinate silty carbonates north of Pine Pass, in the northern Rocky Mountains and southern Mackenzie Fold Belt.

Relationship:
Unconformably overlies Lower Pennsylvanian Tunnel Mountain clastics in southern and western sections of the front ranges of the Rocky Mountains, and Middle Pennsylvanian Kananaskis silty dolomites in the Kananaskis, Spray and Sand areas (central front ranges). Disconformably overlies Upper Mississippian (and locally, perhaps Lower Pennsylvanian) rocks in the Jasper and Peace River areas. Overlain unconformably by the Triassic Spray River Group. Partly equivalent to the Phosphoria Formation of Montana and Idaho.

History:
McGugan and Rapson (1961b) proposed the name Ishbel Formation for the upper part of the Norquay Formation in the Banff area and divided the formation into upper (now Ranger Canyon Formation) and lower (now Johnston Canyon Formation) Ishbel. Subsequent work by these investigators in the Crowsnest area revealed the presence of Permian rocks younger than the lower Ishbel Formation. These were named the middle Ishbel Formation, (now Telford Formation) (McGugan and Rapson, 1962, p. 357), and the upper and lower Ishbel Formation in the Banff area were found to be separated by an unconformity. Later work in the Crowsnest area on Telford Creek Ridge (McGugan, 1963, p. 623) revealed a thick sequence of Permian rocks (subsequently named the Ross Creek Formation} overlying the middle Ishbel Formation and overlain by the upper Ishbel Formation. McGugan and Rapson (1963b) raised the Ishbel Formation to Group status and divided it into the Belcourt, Johnston Canyon, Telford, Ross Creek, Ranger Canyon and Mowitch formations.

Other Citations:
Henderson, 1989; Henderson et al., in press; Henderson and McGugan, 1983, 1985, 1986; Logan and McGugan, 1968; McGugan, 1961, 1963, 1983, 1984; McGugan and Rapson, 1961b, 1963a, 1963b, 1979; McGugan and Rapson-McGugan, 1971, 1972; McGugan et al., 1964; MacRae and McGugan, 1977; McGugan and Spratt, 1981.

Source: CSPG Lexicon of Canadian Stratigraphy, Volume 4, western Canada, including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba; D.J. Glass (editor)
Contributor: A. McGugan; C.M. Henderson
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 04 May 2004