| Garrard Siltstone | |
| Type: | Formation |
| Age: | Ordovician |
| Period: | Ordovician |
| Region: | Southeastern United States |
| Country: | United States |
| Underlies: | Calloway Creek Formation |
| Overlies: | Clays Ferry Formation |
| Extent: | Kentucky |
The Garrard Siltstone is a geologic formation in Kentucky. It dates back to the Ordovician period .