Unit Name: Ottertail Formation
Unit Type: Lithostratigraphic
Rank: Formation
Status: Formal
Usage: Currently in use
Age Interval: Late Cambrian (499 - 488.3 ma)
Province/Territory: British Columbia

Originator: Allan, 1912a; formally defined by Allan, 1914b

Type Locality:
Not expressly stated, but implied by the following quotation: "(The Ottertail)... forms prominent escarpments wherever it outcrops. This cliff-forming feature is especially well developed along the northeast side of the Ottertail Mountains from Mount Hurd southeast to ... south of the Washmawapta Glacier, a distance of almost 20 miles" (Allan, 1914b, p. 84). The formation was named from the Ottertail Range, British Columbia.

Distribution:
470 to 500 m (1,542 to 1,640 ft) thick in the type area; locally may reach 750 m (2,460 ft) (Allan, 1914). The name Ottertail is applied only in the region west of the shale-out of most of the Cambrian carbonate formations - the Ottertail is the westward continuation of the Lyell Formation of the main and front ranges of the Rocky Mountains and extends to the Rocky Mountain Trench. Along the Trench it extends from north of Blaeberry River southward as far as White River.

Locality Data:
Thickness(m): Maximum 750.

Lithology:
Mainly thin-bedded lime mudstone, with some shaly limestone. Thin layers of chert and dolomitic limestone are common.

Relationship:
In the type area the Ottertail lies conformably between the Chancellor Formation below and the McKay Group or Goodsir Group (abandoned) above. The carbonate unit may be equivalent to the Jubilee Formation in the Stanford and other ranges immediately east of the Rocky Mountain Trench.

References:
Allan, J.A., 1912. Geology of Field map-area, Yoho Park, British Columbia; Geological Survey of Canada, Summary Report 1911, pp. 175-187.
Allan, J.A., 1914b. Geology of Field map-area, British Columbia and Alberta; Geological Survey of Canada, Memoir 55, 312 p. + Map 142A (Field, Kootenay District, British Columbia, Scale: 1 in. to 2 miles, 1915).

Source: CSPG Lexicon of Canadian Stratigraphy, Volume 4, western Canada, including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba; D.J. Glass (editor)
Contributor: L.V. Hills; J.D. Aitken
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 14 Mar 2014