The occurrence of the ammonite Discamphiceras cf. silberlingi Guex in a core 25 cm above the base of dark, bituminous shales of the lowermost Fernie Formation in the subsurface of northwestern Alberta establishes their middle to late Hettangian age. Associated coccoliths suggest a possible late Hettangian to early Sinemurian age, which is the oldest so far assigned to these shales and differs considerably from both the Sinemurian age of the type Nordegg Member of the outcrop belt and the Pliensbachian age of its supposed basinal equivalents (“Nordegg Member” of some recent authors).

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