| Cretaceous - Manson Gp. Impact Structure (Kmt) |
| Cretaceous - Manson Gp. Moat (Kmm) |
| Cretaceous - Manson Gp. Central Peak (Kmc) |
| Cretaceous - Niobrara Fm. (Kn) |
| Cretaceous - Fort Benton Gp. (Kf) |
| Cretaceous - Dakota, Windrow (Kd) |
| Jurassic - Fort Dodge Fm. (Jf) |
| Pennsylvanian - Waubonsee Gp. (Pw) |
| Pennsylvanian - Shawnee Gp. (Ps) |
| Pennsylvanian - Douglas Gp. (Pd) |
| Pennsylvanian - Lansing Gp. (Pl) |
| Pennsylvanian - Kansas City Gp. (Pk) |
| Pennsylvanian - Bronson Gp. (Pb) |
| Pennsylvanian - Marmaton Gp. (Pm) |
| Pennsylvanian - U. Cherokee Gp. (Pcu) |
| Pennsylvanian - L. Cherokee Gp. (Pcl) |
| Mississippian - Pella, St. Louis Fm. (Ms) |
| Mississippian - Augusta Fm. (Ma) |
| Mississippian - Gilmore City Fm. (Mg) |
| Mississippian - Kinderhookian (Mk) |
| Devonian - Fammenian (Df) |
| Devonian - Lime Creek Fm. (Dl) |
| Devonian - Cedar Valley Gp. (Dc) |
| Devonian - Wapsipinicon Gp. (Dw) |
| Silurian - LaPorte City Fm. (Sl) |
| Silurian - Gower Fm. (Sg) |
| Silurian - Scotch Grove Fm. (Ss) |
| Silurian - Hopkinton, etc. (Sh) |
| Silurian - Waucoma Fm. (Sw) |
| Ordovician - Maquoketa (Om) |
| Ordovician - Galena, Platteville (Og) |
| Ordovician - St. Peter, Prairie du Chien (Op) |
| Cambrian - Jordan, St. Lawrence, Lone Rock (Cj) |
| Cambrian - Wonewoc Frm. (Cw) |
| Cambrian - Eau Claire Fm. (Ce) |
| Cambrian - Mt. Simon Fm. (Cm) |
| Precambrian - Sioux Quartzite Fm. (Xs) |