The succession at Highwood Pass was previously misinterpreted. The "Storm Creek formation" is directly overlain by Norquay beds containing early Middle Pennsylvanian fossils, and is underlain by clastic rocks bearing Morrowan fossils. It is equivalent to the type Tunnel Mountain formation. The "Norquay formation" is not equivalent to the type Norquay but corresponds to the Todhunter member of the Tunnel Mountain clastic rocks. The Tunnel Mountain formation" is not equivalent to the type Tunnel Mountain, but is typical of carbonate rocks of the Etherington formation with a high Chesteran fauna. Thus the "Stenopora zone" is not Permian in age but Lower Pennsylvanian, and the "Plagioglypta canna zone" as shown by fusulinids is early Middle Pennsylvanian in age, not Permian. The Rocky Mountain group is divided into 3 formations. From the top down these are: the Ishbel formation (new name) of Permian age, the Kananaskis formation (new name) of early Middle Pennsylvanian age, and the Tunnel Mountain formation (restricted) of Lower Pennsylvanian age, which includes Tunnel Mountain clastic rocks only.

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