# Luscar Group

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The **Luscar Group** is a geologic unit of [Early Cretaceous](/source/Early_Cretaceous) age in the [Western Canada Sedimentary Basin](/source/Western_Canadian_Sedimentary_Basin) that is present in the foothills of southwestern [Alberta](/source/Alberta).[1][2] It is subdivided into a series of [formations](/source/Formation_(stratigraphy)), some of which contain economically significant [coal](/source/Coal) deposits that have been mined near [Cadomin](/source/Cadomin) and [Luscar](/source/Luscar,_Alberta).[3] Coal mining in those areas began in the early 1900s[4] and continues near Luscar as of 2016.

## Lithology

The Luscar Group includes the [conglomerate](/source/Conglomerate_(geology)) and [quartzose](/source/Quartz) [sandstones](/source/Sandstone) of the [Cadomin Formation](/source/Cadomin_Formation) at the base, and the overlying formations consist of variable amounts of [sandstone](/source/Sandstone), [siltstone](/source/Siltstone) and [mudstone](/source/Mudstone). There are major coal seams in the [Gates Formation](/source/Gates_Formation), and minor coal, [argillaceous](/source/Argillaceous_minerals) [limestone](/source/Limestone) and [calcareous](/source/Calcite) [shale](/source/Shale) in the [Gladstone Formation](/source/Gladstone_Formation). The [Moosebar Formation](/source/Moosebar_Formation) consists primarily of mudstone and shale.[1][5]

## Stratigraphy

The strata encompassed by the Luscar Group were originally included in the [Blairmore Group](/source/Blairmore_Group). However, the Blairmore Group strata in the mountains and foothills of southwestern Alberta are of primarily nonmarine origin and are not coal-bearing, while those in the central and northern foothills include thick coal seams and a marine shale unit. Those strata were therefore reassigned to the Luscar Group. [1][5]

The [type section](/source/Type_locality_(geology)) for the Luscar Group consists of [outcrops](/source/Outcrop) along the railroad tracks near the town of Cadomin.[1]

Luscar Group is subdivided into the following formations from top to base:

Formation Age Lithology Max Thickness Reference Gates Formation early Albian sandstone, siltstone, mudstone, coal; minor conglomerate 345 m (1,130 ft) [5][6] Moosebar Formation early Albian grey mudstone; minor siltstone 60 m (200 ft) [5][6] Gladstone Formation Aptian to Albian fine-grained sandstone, siltstone mudstone; minor limestone and coal 115 m (380 ft) [5][6] Cadomin Formation Aptian conglomerate, sandstone 45 m (150 ft) [5][6]

## Distribution and thickness

The name Luscar Group is applicable in the northern and north-central foothills of southwestern Alberta, from the [Clearwater River](/source/Clearwater_River_(Alberta)) north to the [Kakwa River](/source/Kakwa_River) near the Alberta-[British Columbia](/source/British_Columbia) boundary. Its thickness is difficult to determine accurately due to [folding](/source/Fold_(geology)) and [faulting](/source/Fault_(geology)) that characterize the Alberta foothills, but is estimated to be about 145 m (480 ft) in the [type area](/source/Type_locality_(geology)).[1]

## Relationship to other units

The Luscar Group is correlative with the [Blairmore Group](/source/Blairmore_Group) of the southwestern Alberta foothills; with the [Bullhead Group](/source/Bullhead_Group) and the lower part of the [Fort St. John Group](/source/Fort_St._John_Group) of northeastern British Columbia; and with the [Mannville Group](/source/Mannville_Group) of the Alberta plains.[1][2] It [disconformably](/source/Unconformity) overlies either the [Nikanassin Formation](/source/Nikanassin_Formation) or the [Minnes Group](/source/Minnes_Group), and is disconformably overlain by either the [Shaftesbury Formation](/source/Shaftesbury_Formation) or [Blackstone Formation](/source/Blackstone_Formation,_Canada), depending on the location.[1]

## Environment of deposition and paleontology

The Luscar Group is an eastward-thinning wedge of [clastic](/source/Clastic_rock) [sediments](/source/Sediment) derived from the erosion of newly uplifted mountains to the west. The sediments were transported eastward by river systems and deposited in a variety of [braided stream](/source/Braided_stream), [river channel](/source/Channel_(geography)), [floodplain](/source/Floodplain), [swamp](/source/Swamp), [coastal plain](/source/Coastal_plain), marginal marine and shallow marine environments along the western edge of the [Western Interior Seaway](/source/Western_Interior_Seaway).[2][5] Its formations include a variety of [plant fossils](/source/Paleobotany), [trace fossils](/source/Trace_fossil), [bivalves](/source/Bivalvia), and [foraminifera](/source/Foraminifera).[5]

## References

1. Langenberg, C.W. and McMechan, M.E. 1985. Lower Cretaceous Luscar Group (revised) of the northern and north-central foothills of Alberta. Bulletin of Canadian Petroleum Geology, vol. 33, p. 1-11.

1. Mossop, G.D. and Shetsen, I. (compilers), Canadian Society of Petroleum Geologists and Alberta Geological Survey (1994). ["The Geological Atlas of the Western Canada Sedimentary Basin, Chapter 19: Cretaceous Mannville Group of the Western Canada Sedimentary Basin"](http://ags.aer.ca/reports/atlas-of-the-western-canada-sedimentary-basin.htm). Retrieved 2016-06-20.

1. Mossop, G.D. and Shetsen, I. (compilers), Canadian Society of Petroleum Geologists (1994). ["The Geological Atlas of the Western Canada Sedimentary Basin, Chapter 33: Coal Resources of the Western Canada Sedimentary Basin"](http://ags.aer.ca/reports/atlas-of-the-western-canada-sedimentary-basin.htm). Retrieved 2016-06-20.

1. Ross, Toni (1999). [*Oh! The Coal Branch*](https://archive.org/details/ohcoalbranchc00ross). Calgary, Alberta: D.W. Friesen and Sons Ltd., 240 p. ISBN 0-919212-51-4.

1. Langenberg, C.W. 1984. Structural and sedimentological framework of the Lower Cretaceous coal-bearing rocks of the Grande Cache area, Alberta. In: The Mesozoic of Middle North America, Canadian Society of Petroleum Geologists Memoir 9, p. 533-540.

1. 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. ISBN 0-920230-23-7.

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Adapted from the Wikipedia article [Luscar Group](https://en.wikipedia.org/wiki/Luscar_Group) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Luscar_Group?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.