Elk Formation
| Elk Formation Stratigraphic range: Late Jurassic to Early Cretaceous |
|
|---|---|
| Type | Geological formation |
| Unit of | Kootenay Group |
| Underlies | Cadomin Formation |
| Overlies | Mist Mountain Formation |
| Thickness | Maximum 590 metres (1,940 ft) |
| Lithology | |
| Primary | Sandstone, conglomerate |
| Other | Siltstone, mudstone, coal |
| Location | |
| Region |
 British Columbia Alberta
|
| Country |
 Canada
|
| Type section | |
| Named for | Elk River coal mine east of Fernie, British Columbia |
| Named by | C.B. Newmarch, 1953 |
The Elk Formation is a stratigraphic unit of the Western Canada Sedimentary Basin that is present in southeastern British Columbia and southwestern Alberta. It is probably of Early Cretaceous age, but in some areas its strata could be as old as Late Jurassic. It includes minor thin coal beds and was named for outcrops near the now-abandoned Elk River coal mine east of Fernie, British Columbia.
The Elk Formation is a sequence of interbedded sandstone, siltstone, mudstone, shale, and chert-pebble or cobble conglomerate. Thin coal seams are present in some areas. Thick-bedded, cliff-forming sandstones and conglomerates are the most conspicuous lithologies. Most of the Elk Formation coals are of high-volatile bituminous rank and most seams are less than 60 centimetres (20 in) thick. An unusual type of coal, referred to as "needle coal" occurs in very thin beds in the upper third of the formation. It consists of compacted masses of rod-like "needles" and has been shown to be of algal origin. "Needles" of vitreous coal are also found in some of the siltstones associated with the needle coals.
The Elk Formation is an eastward-thinning wedge of clastic sediments that were derived from mountains to the west, transported eastward by river systems, and deposited in alluvial plain environments. These include river channel, crevasse splay, overbank, and marsh environments. Conglomeratic units may represent alluvial fan and braided river deposits.
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