Abstract

Triassic rocks in the Rocky Mountain Foothills and Front Ranges comprise a westward thickening, shoaling upward sequence of marine siltstone, sandstone, limestone, dolostone, collapse breccia, and rare gypsum, ranging in age from Early Triassic Griesbachian to Late Triassic Norian. In the vicinity and north of the Pine River, in northeastern British Columbia, the succession comprises up to eight formations, which are, in ascending order: Grayling, Toad, Liard, Charlie Lake and its western equivalent Ludington, Baldonnel, Pardonet, and Bocock. This last formation is recognized only in the region between Williston Lake and the Pine River. South of Williston Lake the Baldonnel Formation is divided into two litho-facies, the lower of which is called the Ducette Member. Throughout the remainder of northeastern and southeastern British Columbia and western Alberta, only two formations are recognized, the Sulphur Mountain and White-horse. Each formation consists of several members, which in ascending order are: Phroso, Vega, Whistler, Llama (Sulphur Mountain), Starlight Evaporite, Brewster Limestone and Winnifred (Whitehorse). Correlation of western surface Triassic formations and members between the northern and southern Foothills and Front Ranges is established. However, correlation with some of the important subsurface hydrocarbon-bearing members and formations to the east remains speculative because of inadequate fossil control and because only limited cores and well samples have been examined.