Unit Name: Snake Indian Formation
Unit Type: Lithostratigraphic
Rank: Formation
Status: Formal
Usage: Currently in use
Age Interval: Middle Cambrian (513 - 499 ma)
Age Justification: The Snake Indian Formation yields fossils assigned to the Middle Cambrian Plagiura-Poliella, Albertella, Glossopleura and Bathyuriscus-Elrathina zones (Mountjoy and Aitken, 1978).
Province/Territory: Alberta; British Columbia
Originator: Mountjoy, E.W. and Aitken, J.D., 1978.
Type Locality:
Chetamon Mountain, 21 km (13 mi) north of Jasper, Alberta. A reference section at Whitecap Mountain, 8 km (5 mi) along strike to the northwest was also designated.
Distribution:
The Snake Indian thins depositionally from 433 m (1,420 ft) at the type section to 152 to 244 m (499 to 800 ft) in the Miette thrust sheet in eastern Jasper Park. It thickens westward to 671 m (2,201 ft) in the Snaring thrust sheet west of the type section. It may be recognizable northwestward as far as Pine Pass (Slind and Perkins, 1966). The Snake Indian Formation passes southeastward along strike into the equivalent Mount Whyte-Cathedral-Stephen succession of the Bow Valley at a line "passing a little to the north of Mount Athabasca and Beauty Creek" (Aitken, 1997).
Locality Data:
Thickness(m): Minimum 152, Maximum 671, Typical 433.
Lithology:
The Snake Indian Formation "... can be divided into nine informal members: a basal red member and a green quartz siltstone member, followed by four shale units - first second, third and fourth recessive members, separated by three resistant limestone units - lower, middle and upper limestones" (Mountjoy and Aitken, 1978).
Relationship:
The type section of the Snake Indian Formation includes at its base a thin, partly red unit of limestone, dolomite and mudstone that is equivalent to the Peyto Formation (Aitken, 1997). Where the Peyto or equivalent Hota Formation are mapped apart from the Snake Indian the basal contact is a sub-Middle Cambrian unconformity (Rasetti, 1951; Aitken, 1997). The Snake Indian is overlain conformably and gradationally by Eldon/Titkana) Formation. The Snake Indian Formation was erected because the equivalent Mount Whyte-Cathedral-Stephen succession of the Bow Valley becomes unrecognizable northward, largely through the thickening of two shaly tongues (members) in the Cathedral Formation.
History:
Mountjoy (1962, 1964) was unable to recognize the classical Middle Cambrian succession of the Bow Valley along the Athabasca River transect of the Rocky Mountains. Accordingly he mapped the strata between the top of the Gog Group sandstones and the base of the Eldon (Titkana) Formation as map-unit 3. The Snake Indian Formation was erected to formalize map-unit 3 and provide a basis for its full description and discussion.
Other Citations:
Aitken, in press; Mountjoy, 1962, 1964; Mountjoy and Aitken, 1978; Rasetti, 1951; Slind and Perkins, 1967.
References:
Aitken, J.D., 1997. Stratigraphy of the Middle Cambrian platformal succession, southern Rocky Mountains; Geological Survey of Canada, Bulletin 398, 322 p.
Mountjoy, E.W. and Aitken, J.D., 1978. Middle Cambrian Snake Indian Formation (new), Jasper region, Alberta; Canadian Society of Petroleum Geologists (CSPG), Bulletin of Canadian Petroleum Geology, vol. 26, no. 3 (September), pp. 343-361.
Mountjoy, E.W., 1962. Mount Robson map-area (southeast), Rocky Mountains of Alberta and British Columbia; Geological Survey of Canada, Paper 61-31.
Mountjoy, E.W., 1964. Mount Robson (southeast quarter, 83E5E); Geological Survey of Canada, Map 47-1963.
Rasetti, F., 1951. Middle Cambrian stratigraphy and faunas of the Canadian Rocky Mountains. Smithsonian Inst., Misc. Coll., v. 116, no. 5.
Slind, O.L. and Perkins, G.D., 1966. Lower Paleozoic and Proterozoic sediments of the Rocky Mountains between Jasper, Alberta and Pine River, British Columbia; Canadian Society of Petroleum Geologists (CSPG), Bulletin of Canadian Petroleum Geology, vol. 14, no. 4 (December), pp. 442-468.
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.D. Aitken
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 14 Apr 2009