Bakken Formation  search
BTChronostratigraphic Units
 .Phanerozoic
 ..Paleozoic
 ...upper Paleozoic
 ....Bakken Formation
RTUpper Devonian
 Saskatchewan
 Montana
 North Dakota
 Manitoba
 Lower Mississippian
SNUpper Devonian? and Lower Mississippian. North Dakota, Montana, Manitoba and Saskatchewan. Indexed with ages as applicable. Added to Thesaurus in 1985.