Three Forks Group
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The Three Forks Group is a stratigraphical unit of Famennian age in the Williston Basin.
Quick Facts Type, Sub-units ...
Three Forks Group | |
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Stratigraphic range: Famennian to Tournaisian | |
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)[1] |
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 |
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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).[2]