The Gorman Creek Formation is a geologic formation of

Early Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Pro ...

( Valanginian) age in the

Western Canada Sedimentary Basin The Western Canadian Sedimentary Basin (WCSB) underlies of Western Canada including southwestern Manitoba, southern Saskatchewan, Alberta, northeastern British Columbia and the southwest corner of the Northwest Territories. This vast sedimentary ...

that consists primarily of nonmarine sediments. It is present in the northern foothills of the

Canadian Rockies The Canadian Rockies (french: Rocheuses canadiennes) or Canadian Rocky Mountains, comprising both the Alberta Rockies and the British Columbian Rockies, is the Canadian segment of the North American Rocky Mountains. It is the easternmost part ...

and the adjacent plains in northeastern British Columbia. Plant fossils and dinosaur tracks have been described from its strata.Stott, D.F. 1998. Fernie Formation and Minnes Group (Jurassic and lowermost Cretaceous), northern Rocky Mountain foothills, Alberta and British Columbia. Geological Survey of Canada, Bulletin 516.Glass, D.J. (editor) 1997. Lexicon of Canadian Stratigraphy, vol. 4, Western Canada including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba. Canadian Society of Petroleum Geologists, Calgary, 1423 p. on CD-ROM. .

Lithology

The Gorman Creek Formation consists of repetitive successions of argillaceous sandstone,

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, p ...

, coaly

mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology. ...

, and coal beds. Beds of conglomeratic sandstone are present in some areas, particularly in the upper part of the formation .

Depositional environment

The Gorman Creek Formation was deposited in primarily nonmarine environments adjacent to the Western Interior Seaway. Depositional settings include deltaic, coastal plain, floodplain, and

swamp A swamp is a forested wetland.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Swamps are considered to be transition zones because both land and water play a role in ...

environments.

Fossil content

A variety of plant fossils, palynomorph and microfossils have been described from the Gorman Creek Formation, and dinosaur track-ways are present on bedding surfaces near the Narraway River:

"More than 200 fossil footprints are preserved in at least 8 trackways... The majority of the footprints were made by small theropods, but the most dramatic track-way was made by a large biped whose feet were more than a half meter in length."Currie, P.J. 1991. Dinosaur footprints of western Canada. In: ''Dinosaur tracks and traces'', D.D. Gillette and M. Lockley (eds.), p. 294. Cambridge University Press, , 476 p.

Thickness and distribution

The Gorman Creek Formation is present in the foothills of the

and the adjacent plains from the Sukunka River in northeastern British Columbia to the Berland River in west-central Alberta. It attains a maximum thickness of roughly in the foothills near the

Kakwa River The Kakwa River is a tributary of the Smoky River in western Alberta, Canada. The river is named for ''Kakwa'', the Cree language, Cree word for porcupine. Porcupines are abundant in Kakwa Provincial Park and Protected Area. Tourism along the ri ...

in Alberta, and it thins to zero beyond the eastern edge of the foothills where it was removed by erosion prior to the deposition of the Cadomin Formation.

Relationship to other units

The Gorman Creek Formation forms the upper part of the Minnes Group. It conformably overlies the

Monteith Formation The Monteith Formation is a geologic formation of Early Cretaceous ( Valanginian) age in the Western Canada Sedimentary Basin that consists primarily of sandstone. It is present in the northern foothills of the Canadian Rockies and the adjacent ...

and is unconformably overlain by the Cadomin Formation. To the north it grades into the Beattie Peaks, Monach and Bickford Formations which comprise the upper part of the Minnes Group in that area.

References