Lithostratigraphy
Carboniferous
Not placed in stage
Gilmore City formation (Mississippian)
Silurian
| Ludfordian | Racine dolomite (Homerian – Ludfordian) |
| Gorstian | Racine dolomite (Homerian – Ludfordian) |
| Homerian | Racine dolomite (Homerian – Ludfordian) |
Ordovician
| Katian | Dunleith formation Maquoketa formation Scales formation |
| Sandbian | Platteville limestone |
| Darriwilian | Winneshiek shale |
Cambrian
| Cambrian stage 10 | Jordan formation St. Lawrence formation (Jiangshanian – Cambrian stage 10) |
| Jiangshanian | St. Lawrence formation (Jiangshanian – Cambrian stage 10) |