A comprehensive survey of the literature, combined with preliminary study of a pyritized fauna from Jasper Park, was undertaken with a view to interpreting the depositional history and age of the Exshaw Formation of Western Canada.

Although the lower contact is sharp, the literature survey reveals that disagreement over the upper contact makes much of the data virtually useless.

Euxinic depositional environment is commonly postulated for black pyritiferous shales. While the Exshaw does not seem to have had a simple history, the final sedimentary process appears to have been controlled by a transgressing epicontinental sea, probably the same as that responsible for other black shales of comparable age found throughout the continental interior.

Pyritized siltstone from Jasper Park has yielded goiatites (Imitoceras sp. aff. I. discoidale (Smith), etc.), pelecypods (Parallelodon sulcatus (Weller), etc.), conodonts (Siphinidella duplicata Branson & Mehl, etc.), brachiopods (Ambocoelia minuta White, Schuchertella louisianenses Williams, etc.), annelids, foraminifera, and several specimens of unknown affinities.

Although these determinations do not conclusively establish the age, they suggest that in Jasper Park the Exshaw is lower Mississippian.

Further work may justify these conclusions.

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