ABSTRACT

The Permo-Carboniferous Rocky Mountain Group is divided into three formations. From the top down these are: the Ishbel formation of Permian age, the Kananaskis formation of early Middle Pennsylvanian age, and the Tunnel Mountain formation of mainly Lower Pennsylvanian age. The Ishbel formation attains maximum development in the west and consists of a widespread transgressive chert/sandstone member (the Upper Ishbel), a middle sandy carbonate member in westerly sections only (the Middle Ishbel), and a lower member consisting of silty carbonates, shaly siltstones, and black spicular phosphatic cherts (the Lower Ishbel). A distinctive, widespread, phosphatic chert conglomerate occurs in the following situations: 1. Between the Upper and Middle Ishbel. 2. Between the Upper and Lower Ishbel where the Middle Ishbel is eroded. 3. Between the Upper Ishbel and the Carboniferous where the Middle and Lower Ishbel are eroded (mainly north of the Clearwater River). 4. Alone in some easterly sections as the only representative of the Ishbel formation. The conglomerate contains Helicoprion, Orbiculoidea, Lingula, Conularia, bones and fish teeth.

The Kananaskis formation is represented by patchy occurrences of a thin white silicified carbonate with Plagioglypta and Bellerophon. It appears to be absent in the Jasper area. The Tunnel Mountain formation consists of thick dolomitic sandstones (with Spirifer occidus) in the west and thinner sandstones and carbonates in the east, due partly to facies change, although the upper beds may be eroded eastwards. The Tunnel Mountain sandstone facies is absent north of the North Saskatchewan River where beds of similar age in the Jasper area are in carbonate facies.

In some sections Permian rocks overlie the Carboniferous with apparent conformity (paraconformity) but in others topographic relief of up to three feet is seen on the Carboniferous surface.