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BTChronostratigraphic Units
 .Phanerozoic
 ..Mesozoic
 ...Cretaceous
 ....Colorado Group
RTNew Mexico
 Idaho
 Montana
 Iowa
 Colorado
 Nebraska
 North Dakota
 Kansas
 Belle Fourche Shale
 Cody Shale
 Graneros Shale
 Benton Formation
 Carlile Shale
 Greenhorn Limestone
 Blackleaf Formation
 Frontier Formation
 Mowry Shale
 Newcastle Sandstone
 Niobrara Formation
SNIncludes Thermopolis Shale, Mowry Shale, Warm Creek Shale, Graneros Shale, Greenhorn Limestone, Carlile Shale, Niobrara Formation, Belle Fourche Shale, Marias River Formation, Skull Creek Shale, Fall River Sandstone, Newcastle Sandstone, and Telegraph Sha