Unit Name: Charles Formation
Unit Type: Lithostratigraphic
Rank: Formation
Status: Formal
Usage: Currently in use
Age Interval: Mississippian (359.2 - 318.1 ma)
Province/Territory: Saskatchewan; Montana

Originator: Seager, O.A., 1942.

Type Locality:
Arro-California Charles 4 well, in Sec. 21, Twp. 15 N., Rge. 30E, Garfield Country, Montana.

Distribution:
The Charles Formation is 184.4 m (605 ft) thick at the type section in central Montana and increases in thickness to more than 243.8 m (800 ft) in the central Williston Basin area (Nordquist, 1953). Because of pre-Jurassic truncation the Charles decreases in thickness northward toward its erosional limit in southern Saskatchewan.

Relationship:
The Charles Formation is conformably underlain by the Mission Canyon Formation. In Montana the Charles is overlain conformably by the Chesteran Big Snowy Group; in southern Saskatchewan the upper boundary represents a major unconformity covered by Triassic-Jurassic redbeds. The Charles is represented by the Mount Head formation in southwestern Alberta and the Midale, Ratcliffe and Poplar beds in southern Saskatchewan (Sask. Geol. Soc., 1956). Brindle (1960, p. 11) showed the "Charles facies" to extend downward from the Poplar beds to the base of the Kisbey sandstone in the middle of the Frobisher-Alida beds.

History:
Seager's (1942) description of the Charles in the type well did not define a depth interval but did define a stratigraphic position, as he placed it in the Big Snowy Group. Perry and Sloss (1943) established the Charles as Iying between the depths of 929.6 and 1161.3 m (3050 and 3810 ft) in the type well. Nordquist (1953) showed that the depth of 929.6 m actually represented the top of the "Kibbey limestone" and revised both the top and bottom of the type Charles to 973.8 m and 1158.2 m (3195 and 3800 ft). Sloss (1952) removed the Charles from the Big Snowy Group and included it in the Madison. Sando (1978) strongly recommended that the term be restricted to the subsurface of the Williston Basin.

Other Citations:
Brindle, 1960; Edie, 1958; Fuzesy, 1960; Haidl, 1978; Nordquist, 1953; Perry and Sloss, 1943; Sando, 1978; Sask. Geol. Soc., 1956; Sloss, 1952.

Source: CSPG Lexicon of Canadian Stratigraphy, Volume 4, western Canada, including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba; D.J. Glass (editor)
Contributor: D.M. Kent
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 11 May 2004