Rosebud Formation

The Rosebud Formation is a geologic formation of cemented pink silt in Nebraska and South Dakota, dating to the early middle Miocene epoch of the Neogene period. Possibly named for its color, no type location has been set for this unit, but it is associated with the Valentine Formation along the Niobrara River. The fine silt of the formation forms an aquitard beneath the Ogallala Aquifer carried by the Valentine Formation. Many springs from the Valentine sands flow down the Rosebud outcrop into the Niobrara River.