Subdivisions
- Montana-Wyoming-Manitoba
The following formations are recognized in Montana, Wyoming and Manitoba, from top to base:
| Sub-unit | Age | Lithology | Max. Thickness |
Reference |
|---|---|---|---|---|
| Charles Formation | Mississippian | dolomitic limestone | 244 m (800 ft) | |
| Mission Canyon Formation | Osagian | white bioclastic limestone, oolitic calcarenite, occasionally dolomitized; anhydrite in the Williston Basin | 183 m (600 ft) | |
| Lodgepole Formation | Kinderhookian | lime mudstones, shale, chert, contains bitumen | 245 m (800 ft) |
- Saskatchewan
The following subdivisions (of formation rank) are recognized in Saskatchewan, from top to base:
| Sub-unit | Age | Lithology | Max. Thickness |
Reference |
|---|---|---|---|---|
| Poplar Beds | Meramecian | limestone, argillaceous dolomite, evaporite | 152 m (500 ft) | |
| Ratcliffe Beds | Osagian | dense dolomites, mudstone with three anhydrite beds | 80 m (260 ft) | |
| Midale Beds | Osagian | oolitic to pisolitic and skeletal grainstone to packstone with vuggy porosity, dolomite, porous wackestone | 45 m (150 ft) | |
| Foirbisher Evaporite | Osagian | supratidal anhydrite | 9 m (30 ft) | |
| Kisbey Sandstone | Osagian | porous silty dolomite and calcareous sandstone | 10 m (30 ft) | |
| Alida Beds | Osagian | oolitic to pisolitic grainstone and packstone, silty and dolomitic limestone, crinoidal limestones | 63 m (210 ft) | |
| Tilston Beds | Kinderhookian | oolitic, pisolitic and crinoidal grainstone and packstone; cherty or dolomitic crystalline limestone, silty limestone, anhydrite | 80 m (260 ft) | |
| Souris Valley Beds | Kinderhookian | argillaceous limestone, calcareous shale, chert | 176 m (580 ft) |
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