| Stonington Formation | |
|---|---|
| Stratigraphic range: Late Ordovician | |
| Type | Formation |
| Unit of | Richmond Group (geology) |
| Sub-units | Ogontz Member and Bay de Noc Member |
| Underlies | Big Hill Formation |
| Overlies | Bill's Creek Shale |
| Location | |
| Region |  Michigan |
| Country |  United States |
The Stonington Formation is a geologic formation in Michigan. It preserves fossils dating back to the Ordovician period.