The Sassenach Formation is a stratigraphic unit of

Late Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, wher ...

(early Famennian) age. It is present on the western edge of the

Western Canada Sedimentary Basin The Western Canadian Sedimentary Basin (WCSB) underlies of Western Canada including southwestern Manitoba, southern Saskatchewan, Alberta, northeastern British Columbia and the southwest corner of the Northwest Territories. This vast sedimentary ...

in the Rocky Mountains and foothills of Alberta. It consists primarily of

mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology. ...

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, p ...

, 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.Geldsetzer, H.H.J., Goodfellow, W.D., McLaren, D.J. and Orchard, M.J. 1987. Sulfur-isotope anomaly associated with the Frasnian-Famennian extinction, Medicine Lake, Alberta. Geology, vol. 15, no. 5, p. 393-396. It includes fossil conodonts.Wang, K. and Geldsetzer, H.H.J. 1995. Late Devonian conodonts define the precise horizon of the Frasnian-Famennian boundary at Cinquefoil Mountain, Jasper, Alberta. Canadian Journal of Earth Sciences, vol. 31, p. 1825-1834.

Lithology and thickness

The Sassenach Formation was deposited below wave base in an off- reef marine setting. It consists of silty to sandy mudstone and siltstone, with argillaceous to silty and sandy limestone and

dolomite Dolomite may refer to: *Dolomite (mineral), a carbonate mineral *Dolomite (rock), also known as dolostone, a sedimentary carbonate rock *Dolomite, Alabama, United States, an unincorporated community *Dolomite, California, United States, an unincor ...

. It has a maximum thickness of about .

Distribution and relationship to other units

The Sassenach Formation is present in the Rocky Mountains and foothills of Alberta, extending from northern Jasper National Park to the North Saskatchewan River, and it has also been tentatively recognized in some areas farther south. It overlies the Southesk Formation or the Mount Hawk Formation, depending on the location. It is overlain by the Palliser Formation, and is laterally equivalent to the upper beds of the

Alexo Formation The Alexo Formation a stratigraphic unit of Late Devonian (late Frasnian to early Famennian) age. It is present on the western edge of the Western Canada Sedimentary Basin in the central Rocky Mountains and foothills of Alberta. The formation cons ...

References

{{Western Canadian Sedimentary Basin, Canadian Rockies=yes Geologic formations of Alberta Western Canadian Sedimentary Basin Devonian Alberta Fossiliferous stratigraphic units of North America Paleontology in Alberta