| Alpena Formation | |
|---|---|
| Stratigraphic range: Middle Devonian | |
| Type | Formation |
| Unit of | Traverse Group |
| Sub-units | Four Mile Dam Member and Newton Creek Member |
| Underlies | Thunder Bay Limestone |
| Overlies | Long Lake Limestone |
| Location | |
| Region |  Michigan |
| Country |  United States |
The Alpena Formation is a geologic formation in Michigan. It preserves fossils dating back to the Devonian period.
