Three Devonian rock units outcrop at Gypsum Cliffs comprising, in ascending sequence: gypsum of the Fort Vermilion Formation; limestone and dolomitic limestone, commonly brecciated, of the Slave Point Formation; and calcareous shale with thin intercalated limestone beds of the Peace Point Member of the Waterways Formation preserved in sinkholes and erosional cavities in the Slave Point Formation. The Fort Vermilion is unfossiliferous but occurs above the highest level of Stringocephalus in western Canada. The Slave Point contains a meagre megafauna characterized by Emanuella vernilis Crickmay in the lower part and Desquamatia (Independatrypa) sp. cf. D. (I.) independensis (Webster) in the upper beds. The latter megafauna is associated with a conoclont fauna of low diversity comprising Polygnathus brevilaminus Branson and Mehl, lcriodus subterminus Youngquist, and possibly Ozarkodina semialternans (Wirth), which is interpreted as a shallow water biofacies of the Schmidtognathus hermanni - Polygnathus cristatus Zone. The Peace Point beds contain a rich brachiopod fauna including Ladogioides pax McLaren, Platyterorhynchus russelli (McLaren), Tecnocyrtina billingsi (Meek) and Eleutherokomma impennis Crickmay as its more diagnostic forms. Associated conodonts are moderately abundant and belong to the Pandorinellina insita fauna which is probably assignable to the Lowermost Polygnathus asymmetricus Zone. The base of this zone has commonly been accepted as the base of the Upper Devonian in western Canada. New brachiopod taxa from the Peace Point Member comprise Platyterorhynchus russeli new form A, Desquamatia (Variatrypa) klukasi n. sp., and Pseudoatrypa devoniana boyeri n. ssp.