Arikaree Group  search
BTChronostratigraphic Units
 .Phanerozoic
 ..Cenozoic
 ...Tertiary
 ....Arikaree Group
RTWyoming
 Montana
 Colorado
 lower Miocene
 upper Oligocene
 South Dakota
 White River Group
SNUpper Oligocene to lower Miocene. Previously considered Miocene. The Arikaree Formation has been considered Miocene. Comprises Sharps, Monroe Creek, and Harrison Formations. Colorado, S South Dakota, SE Montana, and SE Wyoming. Indexed with upper Oligocen