Unit Name: Tunnel Mountain Formation
Unit Type: Lithostratigraphic
Rank: Formation
Status: Formal
Usage: Restricted
Age Interval: Bashkirian - early Moscovian (318.1 - 307.2 ma)
Age Justification: Scattered occurrences of brachiopods and endothyrid foraminifera in carbonate beds (Scott, 1964a; Norris, 1965b, p. 7, 8; McGugan and May, 1965).
Province/Territory: Alberta

Originator: Beales, F.W., 1950, p. 6.

Type Locality:
South end of Tunnel Mountain, Banff, approximately Sec. 33, Twp. 25, Rge. 12W5M.

Distribution:
91 m (300 ft) at the type section. Present in the front ranges of the Rocky Mountains. Thickens to over 610 m (2,000 ft) in some westerly sections, e.g., Connor lakes (Cummings Creek-Forsyth Creek, Norris, 1965) west of the Elk River (Sec. 28, McGugan et al., 1964; Sec. 5, Scott, 1964b). Recognized from the Flathead Valley in the south to Windy Point on the David Thompson Highway (Sec. 93, McGugan et al., 1964). Thins to 15 to 61 m (49 to 200 ft) in the Highwood and Livingstone ranges (Secs. 12, 28, 34, Scott, 1964); 152 m (500 ft) in the Misty Range (Sec. 32, Scott, 1964b). Absent in the foothills subsurface.

Locality Data:
Thickness(m): Minimum 0, Maximum 610, Typical 91.

Lithology:
The Tunnel Mountain Formation (restricted, McGugan and Rapson, 1961b) consists mainly of sandstone, with subordinate dolomite and dolomitic sandstone in the lower part two beds of quartzite occur in the upper part.

Relationship:
Conformably overlies the Mississippian Etherington Formation throughout its area of occurrence. Concordantly overlain by Kananaskis Formation wherever that formation occurs. In westerly sections, where the Kananaskis Formation is not recognized it is unconformably overlain by the Permian Ishbel Group, with a basal conglomerate.

History:
H.H. Beach, in a 1947 presentation to the A.S.P.G. used the term Tunnel Mountain Formation for the uppermost part of the Mississippian Rundle Formation. Warren (1947) recognized two unnamed members comprising the Rocky Mountain Formation. Beales (1950, p. 6) referred to an upper Norquay Mountain Member and a lower Tunnel Mountain Member in the Rocky Mountain Formation, attributing theses names to Warren (1947). Douglas (1953b, p. 68) also attributed these names to Warren (1947). McGugan and Rapson (1961b) divided the Rocky Mountain Group into three formations, in ascending order the Tunnel Mountain, Kananaskis and Ishbel. They restricted the Tunnel Mountain to exclude the basal carbonates, which were referred to the Etherington Formation of the Rundle Group. Scott (1964a, b) studied Lower Pennsylvanian clastics of the Tunnel Mountain and recognized four members within that formation, in ascending order the Todhunter, Tyrwhitt, Storelk and Tobermory. In some sections these units cannot be differentiated and therefore the name Tunnel Mountain Formation is most appropriate. Norris (1965b, p. 14, 41) referred the Lower Pennsylvanian clastics to the Misty Formation and equated the top and bottom of the formation to the section of Beales (1950, p. 43, 44).

Other Citations:
Allan, 1913; Beales, 1950; Douglas, 1953; Dowling, 1907; Henderson ,1989; McGugan, 1987; McGugan et al., 1964; McGugan and May, 1965; McGugan and Rapson, 1961b; McGugan and Spratt, 1981; Nelson, 1961; Nelson and Rudy, 1961; Norris 1955, 1965; Richards et al., in press; Scott, 1964a, 1964b; Shimer, 1926; Warren 1927, 1947.

References:
Beach, H.H., 1947. Mississippian and later Paleozoic stratigraphy of the Rocky Mountain Front Ranges Unpub. paper presented before the Alberta Society of Petroleum Geologists.
Beales, F.W., 1950. The Late Paleozoic formations of southwestern Alberta; Geological Survey of Canada, Paper 50-27 p. 58-64.
Douglas, R.J.W., 1953b. Carboniferous stratigraphy in the southern Foothills of Alberta; Alberta Soc. Petrol. Geol., 3rd Ann. Field Conf. Guidebook, p. 66-88.
McGugan, A. Roessingh, H.K., and Danner, W.R., 1964. Permian. In: Geological history of western Canada; McCrossan, R.G. and Glaister, R.P. (Eds.). Alberta Soc. Petrol. Geol., p. 103-112.
McGugan, A. and May, R., 1965. Biometry of Anthracospirifer curvilateralis (Easton) from the Carboniferous of southeast British Columbia, Canada; The Paleontological Society, Journal of Paleontology, vol. 39, no. 1 (January), pp. 31-40.
McGugan, A. and Rapson, J.E., 1961b. Stratigraphy of the Rocky Mountain Group (Permo-Carboniferous) Banff area, Alberta; J. Alberta Soc. Petrol. Geol., vol. 9, pp. 73-106.
Norris, D.K., 1965b. The stratigraphy of the Rocky Mountain Group in the southeastern Cordillera of Canada; Geological Survey of Canada, Bulletin 125.
Scott, D.L., 1964a. Stratigraphy of the lower Rocky Mountain Supergroup in the southern Canadian Rocky Mountains; University of British Columbia, Vancouver, BC, Ph.D. thesis, 271 p.
Scott, D.L., 1964b. Pennsylvanian stratigraphy, in, Flathead Valley, Fourteenth annual field conference, Fernie, B.C. (August 28, 1964); Canadian Society of Petroleum Geologists (CSPG), Bulletin of Canadian Petroleum Geology, vol. 12 (August), Special Guidebook Issue, pp. 460-493.
Warren, P.S., 1947. Age and subdivisions of the Rocky Mountain Formation at Banff, Albenta Bull. Geol. Soc. Amer., Abst., v. 58, p. 1238.

Source: CSPG Lexicon of Canadian Stratigraphy, Volume 4, western Canada, including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba; D.J. Glass (editor)
Contributor: C.M. Henderson; A. McGugan
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 02 Mar 2009