Type Locality:

Southwest corner of Storelk Mountain southeastern British Columbia, near the head of Elk River, in narrow canyon 1.6 km (1 mi) E32 deg N from the mouth of Tobermory Creek. (50 deg 31.5'N, 114 deg 59.7W). Directly above the type section of the Storelk Formation.

Distribution:

In the type section (Elk Mountains) the unit is 66.4 m (218 ft) thick, and reaches a maximum of 101.5 m (333 ft) south of Crowsnest Pass (Flathead Range). From these areas the formation thins in all directions. It is 7.6 to 30 m (25 to 98 ft) thick in the Livingstone and Highwood ranges, 1 to 2 m (3 to 7 ft) at Mount Elpoca near Highwood Pass, and very thin north of Bow Valley.

Locality Data:

Thickness(m): Minimum 0, Maximum 101.5, Typical 66.4.

Lithology:

Composed dominantly of very fine- to fine-grained, bioturbated, light grey, quartzitic and dolomitic, well-sorted quartz-chert shallow marine sandstone. Medium and coarse chert sand occurs mainly as accessory grains in many beds and become abundant south of Crowsnest Pass, where thin beds of coarse-grained sandstone occur. Sorting also decreases toward the south and southeast. The quartz/dolomite cement alternates in zones ranging from thin laminae up to beds several metres thick. The sandstones are well stratified and cross-stratification is not characteristic, except locally. A few dolomite beds 0.3 to 4 m (1 to 13 ft) thick account for a small part of most sections; they are grey, sandy, microcrystalline and resemble those in the Kananaskis Formation. Some beds are composed of equal amounts of dolomite and sand, indicating that one lithology probably grades laterally into the other. Chert nodules are abundant in some beds. A few distinctive white, partially to completely silicified pelecypod coquinas from 2 cm to 1 m (0.8 in to 3 ft) thick occur at a few localities. One distinctive and unique accessory component in the sand is black, rounded detrital clasts of phosphorite resembling chert, ranging from sand through small pebble size. These occur in abundance at Mount Hosmer, British Columbia. In some areas the basal bed is a sandy dolomite and locally a thin bed of dolomite, sandstone, chert or phosphorite pebble conglomerate is present.

Relationship:

The lower contact is an unconformity, interpreted by Scott to be a regional angular unconformity that truncates increasingly older units towards the east and northeast such that, in the Livingstone and Highwood ranges the Tobermory rests unconformably on the Etherington Formation. The upper contact is conformable and locally transitional, between the High Rock Range and Highwood-Livingstone Range areas the formation thins in the Highwood Pass area at the Mount Elpoca to 2 m (7 ft) of white, spicular chert which rests unconformably on the Storelk Formation. In the Highwood-Livingstone ranges the Rocky Mountain Supergroup is less than 33 m (108 ft) thick and contains white chert, resting unconformably on the Etherington Formation, and is interpreted to be equivalent to the Tobermory Formation. The Tobermory is composed of similar lithologies to those in the Kananaskis Formation but they occur in different proportions. The two are believed to be, in part lateral facies equivalents.

History:

Tobermory is the name given to a unit originally contained within the Rocky Mountain Formation, Tunnel Mountain Member (Warren, 1947, 1956), later known as the Rocky Mountain Group, Tunnel Mountain Formation. The formation lies between two distinctive units, the Storelk Formation below and Kananaskis Formation above, and within the Tunnel Mountain Formation (restricted) of McGugan & Rapson (1961b).

Other Citations:

Henderson, 1989; McGugan and Rapson, 1961b; Scott, 1964a, 1964b; Warren, 1947, 1956.

References:

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.

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.

Warren, P.S., 1947. Age and subdivisions of the Rocky Mountain Formation at Banff, Albenta Bull. Geol. Soc. Amer., Abst., v. 58, p. 1238.

Warren, P.S., 1956. Age and subdivisions of the Rocky Mountain Formation in the Canadian Rockies. J. Alberta Soc. Petrol. Geol., v. 4, p. 243-248.