Type Locality:

Redoubt Mountains northeast of Lake Louise, Banff National Park, Alberta.

Distribution:

818 m (2663 ft) at the type section (Walcott 1912, p. 131). This must have been an estimate, because Palonen (1976) measured only about 510 m (1,673 ft). Walcott's views (1928) on the distribution seem confused because he gave no criterion for separating the Fort Mountain from the overlying St. Piran in the absence of the Lake Louise Shale, and acknowledged that the shale was missing (or unrecognizable) at Fort Mountain. Walcott recognized the Fort Mountain in the Mount Assiniboine area (160.3 m, 526 ft), at Castle Mountain and at Mount Sedgwick above Siffleur River.

Lithology:

"Massive-bedded, cliff-forming, purplish, hard, fine grained quartzitic sandstones, with bands of siliceous and finely arenaceous shale in lower portion. An arenaceous, quartzitic basal conglomerate occurs in some localities" (Walcott, 1928).

Relationship:

The Fort Mountain Formation, as amended by Aitken (1969) rests unconformably on the type Hector Formation and is overlain by the Lake Louise Shale where that unit can be recognized. Walcott's criterion for separating Fort Mountain and St. Piran in the absence of Lake Louise Shale was never stated. Walcott (1928) suggested that the McNaughton Formation of the Jasper-Robson region "may represent the Fort Mountain in that area" Subsequent workers have found that division of the later-named Gog Group into Walcott's three formations is unworkable. The Fort Mountain Formation is a lower part of the Gog Group, which contains Lower Cambrian body fossils in its upper parts. Trace fossils attributed to trilobites occur almost to the base of the Gog (Palonen, 1976), which is widely accepted as being entirely Lower Cambrian.

History:

The revised name Fort Mountain was applied by Walcott (1912) to the unit originally established as Fairview Formation (Walcott, 1908) because the latter had been pre-empted. The type section was also changed from Fairview Mountain to Redoubt (Fort) Mountain. In the latter section Walcott (and Deiss, 1939) included within the lower Fort Mountain Formation 110 m (361 ft) of "arenaceous, quartzitic basal Conglomerate since recognized as part of the upper Proterozoic Hector Formation (Aitken, 1969; Arnott and Hein, 1986) and removed from the Fort Mountain/Gog. Deiss (1940) found that, in the Mount Assiniboine area division of the lower Cambrian quartzite-dominated succession was impracticable and/or improper (see "Lake Louise Shale"), and accordingly erected the Gog Formation, the term which, as Gog Group has been widely applied since.

Other Citations:

Aitken, 1969; Arnott and Hein, 1986; Deiss, 1939, 1940; Palonen, 1976; Walcott, 1908, 1912, 1928.