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| Scales Shale | |
|---|---|
| Stratigraphic range: Ordovician | |
| Type | Formation |
| Unit of | Maquoketa Group |
| Underlies | Fort Atkinson Limestone |
| Overlies | Trenton Limestone |
| Location | |
| Region | Illinois, Indiana |
| Country | United States |
The Scales Shale is a geologic formation in Illinois. It preserves fossils dating back to the Ordovician period.