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| Ionia Formation | |
|---|---|
| Stratigraphic range: Jurassic | |
| Type | Formation |
| Underlies | Glacial drift |
| Overlies | Grand River Formation |
| Location | |
| Region |  Michigan |
| Country |  United States |
The Ionia Formation is a geologic formation in Michigan. It preserves fossils dating back to the Jurassic period.
