Big Snowy Group
| 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 |
The Big Snowy Group is a stratigraphical unit of Chesterian age in the Williston Basin.
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.