| Cummingsville Formation | |
| Type: | Formation |
| Age: | Ordovician |
| Period: | Ordovician |
| Country: | United States |
| Overlies: | Decorah Shale |
| Extent: | Iowa and Minnesota |
The Cummingsville Formation is a geologic formation in Iowa and Minnesota. It preserves fossils dating back to the Ordovician period.