Three Forks Group
The Three Forks Group is a stratigraphical unit of Famennian age in the Williston Basin.
| Three Forks Group | |
|---|---|
| Stratigraphic range: | |
| Type | Geologic group |
| Sub-units | Bakken Formation, Lyleton Formation, Big Valley Formation, Torquay Formation |
| Underlies | Madison Group |
| Overlies | Saskatchewan Group |
| Thickness | 35 metres (110 ft) to 80 metres (260 ft) |
| Lithology | |
| Primary | Dolomite, mudstone, shale |
| Location | |
| Region | Western Canadian Sedimentary Basin, Williston Basin |
| Country | Canada United States |
| Type section | |
| Named for | Three Forks, Montana |
| Named by | A.C. Peale, 1893 |
It takes the name from the city of Three Forks, Montana, and was first described in outcrop near the city by A.C. Peale in 1893 (for the Three Forks Shale).
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