Mowry Shale  search
BTChronostratigraphic Units
 .Phanerozoic
 ..Mesozoic
 ...Cretaceous
 ....Lower Cretaceous
 .....Mowry Shale
RTUpper Cretaceous
 Wyoming
 Montana
 South Dakota
 Colorado Group
SNIn Colorado Group. Consists of hard lighter-gray shales and thin bedded sandstones that weather light gray and form ridges. Montana, W South Dakota, and Wyoming. Indexed with states as applicable.