Bighorn Dolomite  search
BTChronostratigraphic Units
 .Phanerozoic
 ..Paleozoic
 ...Ordovician
 ....Upper Ordovician
 .....Bighorn Dolomite
UFBig Horn Dolomite
RTIdaho
 Wyoming
 Montana
 North Dakota
 South Dakota
 Red River Formation
 Williston Basin
SNCentral N United States. Extends into Saskatchewan. Added to Thesaurus in 1995.