Big Snowy Group
The Big Snowy Group is a stratigraphical unit of Chesterian age in the Williston Basin.
| Big Snowy Group | |
|---|---|
| Stratigraphic range: | |
| Type | Geological group |
| Sub-units | Heath, Otter & Kibbey Formations |
| Underlies | Tyler Formation Watrous Formation |
| Overlies | Madison Group |
| Area | 51,800 square kilometres (20,000 sq mi) |
| Thickness | up to 135 metres (440 ft) |
| Lithology | |
| Primary | Shale, limestone, sandstone |
| Location | |
| Region | Williston Basin WCSB |
| Country | United States Canada |
| Type section | |
| Named for | Big Snowy Mountains |
| Named by | H.W. Smith |
| Year defined | 1935 |
It takes the name from Big Snowy Mountains in Montana, and was first described on the north slopes of the mountain by H.W. Smith in 1935.
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