Type Locality:

Mount Dalhousie, northern spur, Jasper National Park, Alberta, immediately south of the junction of the Southesk and Cairn rivers; and on the southeast side of the mountain immediately west of that junction. Located 63 km (39 mi) west-northwest of Nordegg townsite (52 deg 38'N, 116 deg 58'W).

Distribution:

The Southesk Formation forms the upper parts of carbonate buildups of the Fairholme Group. Where fully developed within carbonate buildups it is between 150 and 260 m (492 and 853 ft) thick. In the Flathead area of southeastern British Columbia the formation may be as thick as 300 m (1,000 ft). The Southesk Formation occurs discontinuously in the Fairholme Group in the front and main range of the Rocky Mountains, from northern Jasper National Park to the Flathead area in the south, a distance of over 600 km (372 mi). In the subsurface southern Alberta carbonate shelf the Southesk is present south of approximately Twp. 30 and also east of a line between Vermillion and Drumheller, where it may reach 150 m (500 ft) in thickness.

Locality Data:

Thickness(m): Minimum 150, Maximum 300.

Lithology:

The Southesk Formation consists of light grey weathering lime sands and dolomites that are thick- to massively bedded and frequently cliff forming, except for the more recessive and darker Grotto Member.

Relationship:

The Southesk Formation is a carbonate facies of the Fairholme Group restricted to the southern Alberta shelf and the isolated carbonate buildups of the Rocky Mountains. The Southesk Formation generally conformably overlies the Cairn Formation in the Crowsnest Pass area it conformably overlies the Borsato Formation. At buildup margins the formation may interfinger with the Perdrix and the Mount Hawk formations (see individual member descriptions). The base of the Southesk Formation has been the subject of controversy (see Taylor, 1957, 1958b; Belyea and McLaren, 1957b). The Cairn-Southesk boundary is often gradational over 5 to 30 m (16 to 98 ft) and placement of the change from mainly dark biostromal dolomites below to predominantly light lime sands above can be somewhat arbitrary. In the mountains the Southesk is unconformably overlain by either the Sassenach Formation or the equivalent Alexo Formation, or, rarely, the Palliser Formation. The Southesk is overlain by the Crowfoot Formation in the southern Alberta subsurface. It is lithostratigraphically equivalent to the upper Leduc and Nisku formations of subsurface central Alberta and is homotaxial with the upper Duperow and the Birdbear formations in southeastern Alberta.

History:

McLaren (1955) raised the Fairholme Formation of Beach (1943) to group status and named the former upper member the Southesk Formation. McLaren designated a new type section on Mount Dalhousie, within the Southesk-Cairn carbonate buildup. The Southesk Formation has since been split into four members, in ascending order the Peechee, Grotto, Arcs and Ronde, which are discussed separately in this Lexicon.

References:

Beach, H.H., 1943. Moose Mountain and Morley map-areas, Alberta; Geological Survey of Canada, Memoir 236, 74 p.

Belyea, H.R. and McLaren, D.J., 1957b. Revision of Devonian nomenclature in the Rocky Mountains, a discussion; Alberta Society of Petroleum Geologists, Journal of the Alberta Society of Petroleum Geologists, vol. 5, no. 11 (December), pp. 269-276.

McLaren, D.J., 1955. Devonian formations in the Alberta Rocky Mountains between Bow and Athabasca rivers; Geological Survey of Canada, Bulletin 35.

Taylor, P. W., 1957. Revision of Devonian nomenclature in the Rocky Mountains; Journal of the Alberta Society of Petroleum Geologists, vol. 5, no. 8, pp. 183-193.

Taylor, Peter W., 1958b. Further data on Devonian correlations; Journal of the Alberta Society of Petroleum Geologists, vol. 6, no. 7, pp. 13-19.