| Dubuque Formation | |
| Type: | Formation |
| Age: | Ordovician |
| Period: | Ordovician |
| Region: | Illinois, Minnesota |
| Underlies: | Maquoketa Formation |
| Overlies: | Galena Group |
The Dubuque Formation is a geologic formation in Illinois, Iowa, Wisconsin and Minnesota. It preserves fossils dating back to the Ordovician period.