Mist Mountain Formation
| Mist Mountain Formation Stratigraphic range: Late Jurassic to Early Cretaceous) |
|
|---|---|
| Type | Geological formation |
| Unit of | Kootenay Group |
| Underlies | Elk Formation |
| Overlies | Morrissey Formation |
| Thickness | maximum 665 metres (2,180 ft) |
| Lithology | |
| Primary | Sandstone, siltstone, mudstone |
| Other | Coal, conglomerate |
| Location | |
| Region |
 Alberta British Columbia
|
| Country |
 Canada
|
| Type section | |
| Named for | Mist Mountain, Alberta |
| Named by | D.W. Gibson, 1979 |
The Mist Mountain Formation is a latest Jurassic to earliest Cretaceous geologic formation in the Western Canada Sedimentary Basin of southeastern British Columbia and southwestern Alberta. It was named for outcrops along a western spur of Mist Mountain in the Canadian Rockies of Alberta. It contains economically important coal reserves that are mined in southeastern British Columbia.
The Mist Mountain Formation consists of interbedded light to dark grey siltstone, silty shale, mudstone, and sandstone, with localized occurrences of chert- and quartzite-pebble conglomerate and conglomeratic sandstone. It also contains a series of economically important coal seams.
The Mist Mountain Formation is part of the Kootenay Group, an eastward-thinning wedge of sediments 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 fluvial channel, floodplain, swamp, coastal plain and deltaic environments along the western edge of the Western Interior Seaway.
The Mist Mountain Formation is present in the front ranges and foothills of the Canadian Rockies in southeastern British Columbia and southwestern Alberta. It extends from the Canada–US border to north of the North Saskatchewan River. It thins eastward, ranging from 665 metres (2,180 ft) thick near Elkford, British Columbia, to less than 25 metres (80 ft) in the eastern foothills in Alberta. Farther to the east it was truncated by pre-Aptian erosion.
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