| Au Train Formation | |
|---|---|
| Stratigraphic range: Early Ordovician | |
 Au Train Formation at Munising Falls (Pictured Rocks National Lakeshore) | |
| Type | Formation |
| Underlies | Black River Formation |
| Overlies | Munising Formation |
| Location | |
| Region |  Michigan |
| Country |  United States |
The Au Train Formation is a geologic formation in Michigan. It preserves fossils dating back to the Ordovician period.