| Chugwater Formation (Group) | |
|---|---|
| Stratigraphic range: Triassic | |
 Outcrop of Chugwater Group near Thermopolis, Wyoming | |
| Type | sedimentary |
| Underlies | Nugget Sandstone, Morrison Formation |
| Overlies | Dinwoody Formation, Goose Egg Formation |
| Lithology | |
| Primary | sandstone |
| Other | shale, gypsum, limestone |
| Location | |
| Extent | Wyoming, Colorado, Montana |
| Type section | |
| Named for | Chugwater, Wyoming |
| Named by | N. H. Darton, 1904[1] |
The Chugwater Formation is a mapped bedrock unit consisting primarily of red sandstone, in the states of Wyoming, Montana, and Colorado in the United States. It is recognized as a geologic formation in Colorado and Montana, but as a Group (set of formations), the Chugwater Group, in Wyoming. Despite its presence below the highly studied Morrison Formation, the Chugwater receives little attention.