| Arikaree Formation | |
| Type: | Formation / Group |
| Age: | late Oligocene to early |
| Period: | Miocene |
| Prilithology: | Siltstone, Sandstone |
| Otherlithology: | Carbonate rock |
| Namedfor: | Arikara Indians |
| Namedby: | N. H. Darton |
| Region: | central High Plains |
| Country: | United States |
| Underlies: | unconsolidated sediment |
| Overlies: | Chadron Formation or Brule Formation |
| Thickness: | up to 426.5feet |
The Arikaree Formation, also Arikaree Group or Arikaree Sandstone is a geological unit in the central High Plains of the western United States. It preserves fossils dating to the late Oligocene to early Miocene.[1]