Unit Name: Bison Creek Formation
Unit Type: Lithostratigraphic
Usage: Currently in use
Age Interval: Late Cambrian (499 - 488.3 ma)
Age Justification: The rich trilobite fauna of the Bison Creek contains all of the faunal zones of the Franconian Stage, and representatives of the Saukia Zone present in the top of the formation suggest that the Trempealeauan Stage is also present.
Originator: Greggs, 1962; Aitken and Greggs, 1967
On Mount Murchison, above and west of the north branch of Bison Creek, in Alberta, on the slopes above the prominent cliffs of the Lyell Formation.
The Bison Creek Formation is 192 m (629 ft) thick at the type section, and 203 m (664 ft) thick at Mount Whiterose to the west. The formation merges to the north into the upper Lynx Group. In eastern exposures, in the Sawback and Bourgeau ranges the unit is slightly over 61 m (200 ft) thick.
Thickness(m): Minimum 61, Maximum 203, Typical 192.
Interbedded calcareous grey and green shales, with somewhat thicker beds of argillaceous shaly limestones; silty interbeds are present near the base. Large, well developed stromatolites (Collenia) are a consistent feature, and limestone pebble conglomerates occur near the top of the formation.
The Bison Creek overlies the massive carbonates of the Lyell Formation with very sharp contact. The contact with the overlying Mistaya Formation is gradational, from shaly carbonates into increasingly thicker, more massive carbonates.
Beds constituting the Bison Creek Formation (and the overlying Mistaya) were occasionally included by Walcott in his Mons Formation. In later years the term Sabine Formation was used for the Bison Creek sequence. On the basis of similarity of trilobite faunas Walcott often correlated part of his Mons with the Sabine Formation.
Aitken, J.D. and Greggs, R.G., 1967. Upper Cambrian formations, southern Rocky Mountains of Alberta, an interm report; Geological Survey of Canada, Paper 66-49, 91 p.
Greggs, R.G., 1962. Upper Cambrian biostratigraphy of the southern Rocky Mountains, Alberta; University of British Columbia, Vancouver, BC, Canada, Ph.D. thesis, 256 p.
Source: CSPG Lexicon of Canadian Stratigraphy, Volume 4, western Canada, including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba; D.J. Glass (editor)
Contributor: R.G. Greggs
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 28 Mar 2014