The Sassenach Formation is a stratigraphic unit of Late Devonian (early Famennian) age. It is present on the western edge of the Western Canada Sedimentary Basin in the Rocky Mountains and foothills of Alberta. It consists primarily of mudstone, siltstone, and silty carbonate rocks, and was named for Mount Sassenach in Jasper National Park by D. J. McLaren and E. W. Mountjoy in 1962. The Sassenach Formation was deposited near the beginning of the Fammenian stage of the Devonian, following the Frasnian–Fammenian extinction event. It includes fossil conodonts.