Unit Name: Pakowki Formation
Unit Type: Lithostratigraphic
Usage: Currently in use
Age Interval: Campanian (83.5 - 70.6 ma)
Province/Territory: Alberta; Saskatchewan
Originator: Dowling, 1916.
Near the mouth of Pakowki Coulee, southwestern Alberta, in Twp. 3, Rges 8 and 9W4M, and Twp. 2, Rges. 8 and 9W4M.
Maximum thickness is about 200 m (656 ft) in west-central Saskatchewan. Thins dramatically to the west and pinches out near the eastern edge of the foothills in southwestern Alberta. The Pakowki can be recognized wherever the underlying Milk River (or Eagle) Formation is present or where the distinctive subsurface marker, the Milk River (or Eagle) 'shoulder' is recognized on geophysical logs. This includes the plains of Alberta and Saskatchewan between 49 deg N and 53 deg N, 104 deg W and 113 deg W (see McLean, 1971, Fig. 17).
Dark grey mudstone is the predominant lithology. Lighter grey and olive-grey siltstone to very fine-grained sandstone is subordinate, but normally increases in number and thickness of beds upward. The base is usually marked by a thin pebble conglomerate bed.
Overlies the Milk River Formation abruptly and is overlain gradationally by the Judith River (or Foremost) Formation. It pinches out to the west into the Belly River Formation. To the east it becomes an undifferentiated part of the Riding Mountain Formation and, to the north, where the Milk River (Eagle) is not recognizable it is equivalent to the upper part of the Lea Park Formation.
Outcrops at the mouth of Pakowki Coulee were examined, although not formally named by Dawson (1884, p. 125c), but were mis-correlated with what is now the upper part of the Colorado Group. Hatcher and Stanton (1903) introduced the name Claggett to the Pakowki Coulee area, but the name was not adopted by Dowling (1916), who formally introduced the name Pakowki shales for the same sequence. The name Pakowki subsequently has been used by most authors, with intermittent attempts to reintroduce the name Claggett because it has precedence.
Dawson, G.M., 1884. Report on the region in the vicinity of Bow and Belly rivers, Northwest Territory. Geol. and Nat. Hist. Surv. and Museum Can., Rept. Progress 1882-8344, Part C, p. 1-169.
Dowling, D.B., 1916. Water Supply, Southeastern Alberta (Contains Geological Map 1604); Geological Survey of Canada, Summary Report 1915, pp. 102-110.
Hatcher, J.B. and Stanton, T.W., 1903. The stratigraphic position of the Judith River beds and their correlation with the Belly River beds. Science, no. 5, v. 18, p. 211-212.
McLean, J.R., 1971. Stratigraphy of the Judith River Formation in the Canadian Great Plains. Saskatchewan Res. Counc., Geol. Div., Rept. 11.
Ogunyomi, O. and Hills, L.V., 1977. Depositional environments, Foremost Formation (Late Cretaceous), Milk River area, southern Alberta. Bull. Can. Petrol. Geol., v. 25, no. 5, p. 929-968.
Russell, L.S., 1940. Stratigraphy and structure. In: Geology of the southern Alberta Plains, Russell, L.S. and Landes, R.W. (Eds.). Geological Survey of Canada, Memoir 221, pp. 1-12B.
Russell, Loris S., 1970. Correlation of the Upper Cretaceous Montana Group between southern Alberta and Montana; Canadian Journal of Earth Sciences = Journal Canadien des Sciences de la Terre, vol. 7, no. 4 (August), pp. 1099-1108.
Source: CSPG Lexicon of Canadian Stratigraphy, Volume 4, western Canada, including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba; D.J. Glass (editor)
Contributor: J.R. McLean; G.E. McCune
Entry Reviewed: No
Name Set: Lithostratigraphic Lexicon
LastChange: 08 Apr 2008