Search SEDIS
| Data sets | Publications | Expeditions | Thesaurus | 
| Spergen Formation  | |
|---|---|
| BT | Chronostratigraphic Units | 
| .Phanerozoic | |
| ..Paleozoic | |
| ...Carboniferous | |
| ....Mississippian | |
| .....Upper Mississippian | |
| ......Meramecian | |
| .......Spergen Formation | |
| RT | Iowa | 
| Kentucky | |
| Missouri | |
| Illinois | |
| Indiana | |
| SN | S Indiana, Illinois, E Iowa, W Kentucky and E Missouri. Added to Thesaurus in 1985. |