Unit Name: Cunningham Formation
Unit Type: Lithostratigraphic
Usage: Currently in use
Age Interval: Late Proterozoic (900 - 542 ma)
Province/Territory: British Columbia
Originator: Holland, S.S., 1954; Sutherland-Brown, A., 1963; Campbell, R.B. et al., 1973.
Reference Section: Haggen Creek, northern Caribou Mountains (53 deg 28'N, 121 deg 13'W), British Columbia.
The Cunningham Formation is thickest near the reference section (550 m, 1,804 ft). It thins to about 240 m (787 ft) and becomes more dolomitic eastward near the southern Rocky Mountain trench north of Goat River, to 135 m (443 ft) at Holy Cross Mountain, east of the Trench, and reaches its depositional edge southeast of Morkill River. The section at Holy Cross Mountain may include shales equivalent to part of the Yankee Belle Formation in its upper part.
The Cunningham Formation consists of plaformal, bedded to massive, recrystallized grey limestone, with abundant pisolites, oolites, pellets, algal coated grains and intraclasts. Dolostone with minor quartz is present near the top. Sandstone and mudstone are minor constituents. The Cunningham is typified by nonskeletal particles formed in a shallow marine, platformal environment.
The Cunningham Formation abruptly, but apparently conformably overlies black phyllite and limestone of the Isaac Formation. It is conformably overlain by the Yankee Belle Formation in the western Cariboo Mountains. In the eastern Cariboos the basal sandstone of the Yankee Belle Formation locally truncates bedding in dolostone beds of the uppermost Cunningham Formation.
Originally only one limestone unit was recognized in the Cariboo Group, leading to grouping of the Cunningham and Mural formations into a single "limestone unit". These were separated into two formations by Campbell et al. (1973).
Campbell et al., 1973; Holland, 1954; Pell and Simony, 1987; Sutherland-Brown, 1963.
Source: CSPG Lexicon of Canadian Stratigraphy, Volume 4, western Canada, including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba; D.J. Glass (editor)
Contributor: M.R. McDonough
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 29 Apr 2003