Amsden Formation  search
BTChronostratigraphic Units
 .Phanerozoic
 ..Paleozoic
 ...Carboniferous
 ....Amsden Formation
RTMississippian
 Pennsylvanian
 Wyoming
 Montana
 North Dakota
SNIn Montchauve Group. Montana, Wyoming and North Dakota. Added to Thesaurus in 1985.