| Group or Formation |
Period |
Notes |
| Almond Formation | Cretaceous | |
| Almy Formation | Paleogene | |
| Amsden Formation | Carboniferous | |
| Arikaree Formation | Neogene | |
| Ash Hollow Formation | Neogene | |
| Aspen Shale | Cretaceous | |
| Aycross Formation | Paleogene | |
| Beartooth Butte Formation | Devonian | |
| Bell Springs Formation | Triassic | |
| Belle Fourche Formation | Cretaceous | |
| Benton Formation | Cretaceous | |
| Bighorn Formation | Ordovician | |
| Bridger Formation | Paleogene | |
| Brule Formation | Paleogene | |
| Brule Formation | Paleogene | |
| Carlile Shale | Cretaceous | |
| Casper Formation | Permian, Carboniferous | |
| Chadron Formation | Paleogene | |
| Chugwater Group/Alcova Limestone | Triassic | |
| Chugwater Group/Crow Mountain Formation | Triassic | |
| Chugwater Group/Popo Agie Formation | Triassic | |
| Chugwater Group/Red Peak Formation | Triassic | |
| Cloverly Formation | Cretaceous | |
| Cody Shale | Cretaceous | |
| Colorado Formation | Cretaceous | |
| Colorado Group/Graneros Shale | Cretaceous | |
| Colorado Group/Mowry Shale | Cretaceous | |
| Colter Formation | Neogene | |
| Dakota Formation | Cretaceous | |
| Deadwood Formation | Ordovician, Cambrian | |
| Dinwoody Formation | Triassic | |
| Dry Creek Shale | Cambrian | |
| DuNoir Formation | Cambrian | |
| DuNoir Limestone | Cambrian | |
| Eagle Formation | Cretaceous | |
| Evanston Formation | Paleogene | |
| Fall River Sandstone | Cretaceous | |
| Ferris Formation | Paleogene, Cretaceous | |
| Fort Union Formation | Paleogene | |
| Fowkes Formation | Paleogene | |
| Frontier Formation | Cretaceous | |
| Gallatin Formation | Cambrian | |
| Gartra Formation | Triassic | |
| Gering Formation | Paleogene | |
| Goose Egg Formation | Permian | |
| Green River Formation | Paleogene | |
| Gros Ventre Formation | Cambrian | |
| Gypsum Spring Formation | Jurassic | |
| Gypsum Springs Formation | Jurassic | |
| Hailey Shale | Cretaceous | |
| Hanna Formation | Paleogene | |
| Harebell Formation | Cretaceous | |
| Harrison Formation | Miocene | |
| Hoback Formation | Paleogene | |
| Iles Formation | Cretaceous | |
| Indian Meadows Formation | Paleogene | |
| Jelm Formation | Triassic | |
| Lamar River Formation | Paleogene | |
| Lance Formation | Cretaceous | |
| Lance Formation | Cretaceous | |
| Laramie Formation | Cretaceous | |
| Lebo Formation | Paleogene | |
| Madison Group/Lodgepole Formation and Mission Canyon Formation | Devonian | |
| Mancos Shale | Cretaceous | |
| Marsland Beds Formation | Neogene | |
| Medicine Bow Formation | Cretaceous | |
| Mesaverde Formation | Cretaceous | |
| Mesaverde Formation | Cretaceous | |
| Mesaverde Formation | Cretaceous | |
| Mesaverde Group/Almond Formation | Cretaceous | |
| Meteetse Formation | Cretaceous | |
| Middle Variegated Sequence Formation | Paleogene | |
| Minnekahta Formation | Permian | |
| Monroe Creek Formation | Paleogene | |
| Montana Group/Fox Hills Formation | Cretaceous | |
| Montana Group/Pierre Shale | Cretaceous | |
| Morrison Formation | Jurassic | |
| Mowry Shale | Cretaceous | |
| Newcastle Sandstone | Cretaceous | |
| Niobrara Formation | Cretaceous | |
| North Park Formation | Neogene | |
| Ogallala Formation | Neogene | |
| Open Door Formation | Cambrian | |
| Open Door Limestone | Cambrian | |
| Park City Formation | Permian | |
| Park Shale | Cambrian | |
| Pass Peak Formation | Paleogene | |
| Phosphoria Formation | Permian | |
| Pierre Shale | Cretaceous | |
| Pinyon Conglomerate Formation | Cretaceous | |
| Polecat Bench Formation | Paleogene | |
| Puerco Formation | Paleogene | |
| Rock Springs Formation | Cretaceous | |
| Satanka Formation | Permian | |
| Sepulcher Formation | Paleogene | |
| Shedhorn Formation | Permian | |
| Shooting Iron Formation | Pliocene | |
| Snowy Range Formation | Cambrian | |
| Split Rock Formation | Neogene | |
| Sundance Formation | Jurassic | |
| Tatman Formation | Paleogene | |
| Teewinot Formation | Neogene | |
| Telegraph Creek Formation | Cretaceous | |
| Tepee Trail Formation | Paleogene | |
| Thaynes Formation | Triassic | |
| Thomas Fork Formation | Cretaceous | |
| Twin Creek Formation | Jurassic | |
| Twin Creek Limestone | Jurassic | |
| Wagon Bed Formation | Paleogene | |
| Wapiti Formation | Paleogene | |
| Wasatch Formation | Paleogene | |
| Washakie Formation | Paleogene | |
| White River Formation | Paleogene | |
| Wiggins Formation | Paleogene | |
| Willwood Formation | Paleogene | |
| Wind River Formation | Paleogene | |
| Woodside Formation | Triassic | |
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