Kotcho Formation

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Kotcho Formation
Stratigraphic range: Middle Famennian
Type Geological formation
Underlies Exshaw Formation
Overlies Tetcho Formation
Thickness up to 210.9 metres (690 ft)[1]
Primary Shale
Other Limestone
Coordinates 60°09′18″N 121°18′16″W / 60.15500°N 121.30444°W / 60.15500; -121.30444 (Kotcho Formation)Coordinates: 60°09′18″N 121°18′16″W / 60.15500°N 121.30444°W / 60.15500; -121.30444 (Kotcho Formation)
Region  British Columbia
 Northwest Territories
Country  Canada
Type section
Named for Kotcho Lake
Named by H.R. Belyea, D.J. McLaren, 1962

The Kotcho Formation is a stratigraphical unit of middle Famennian age in the Western Canadian Sedimentary Basin.

It takes the name from Kotcho Lake, and was first described in the Imperial Island River No. 1 by H.R. Belyea and D.J. McLaren in 1962.[2]


The Kotcho Formation is composed of green-grey shale, locally bituminous, with thin argillaceous limestone beds or lenses. [1]


The Kotcho Formation reaches a maximum thickness of 210.9 metres (690 ft).[1]It is up to 30 metres (100 ft) thick in the Fort Nelson area, and thins down southwards, disappearing completely on the northern flank of the Peace River Arch.

Relationship to other units[edit]

The Kotcho Formation is overlain by the Exshaw Formation and conformably overlays the Tetcho Formation.[1]

To the east, it grades into the upper Wabamun Group carbonate, and to the south-west into the Palliser Formation. To the east it is replaced by the Besa River Formation shale.


  1. ^ a b c d Lexicon of Canadian Geologic Units. "Kotcho Formation". Retrieved 2009-03-01. 
  2. ^ Belyea, H.R. and McLaren, D.J., 1962. Upper Devonian formations, southern pan of Northwest Territories, northeastern British Columbia and northwestern Alberta. Geological Survey of Canada, Paper 61-29.