Fort Union Formation  search
RTBullion Creek Formation
 Colorado
 K-T boundary
 Lebo Member
 Ludlow Member
 Montana
 North Dakota
 Paleocene
 Sentinel Butte Formation
 South Dakota
 Tongue River Member
 Tullock Member
 Upper Cretaceous
 Wyoming
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.