Fort Union Formation  search
RTUpper Cretaceous
 Paleocene
 Wyoming
 Montana
 Colorado
 North Dakota
 South Dakota
 K-T boundary
 Bullion Creek Formation
 Lebo Member
 Ludlow Member
 Sentinel Butte Formation
 Tongue River Member
 Tullock Member
SNIncludes Lebo Shale Member, Tongue River Member, Tullock Member, Ludlow Member, Sentinel Butte Member. NW Colorado, Montana, North Dakota, NW South Dakota, and Wyoming. Indexed with ages as applicable.