| Rockdale Run Formation | |
| Type: | Formation |
| Age: | Lower Ordovician |
| Period: | Early Ordovician |
| Prilithology: | Limestone |
| Otherlithology: | dolomite, chert |
| Region: | Maryland, Pennsylvania, Virginia[1] and West Virginia |
| Country: | United States |
| Unitof: | Beekmantown Group |
| Underlies: | Pinesburg Station Dolomite |
| Overlies: | Stonehenge Limestone |
| Thickness: | 2450 ft |
The Rockdale Run Formation is a geologic formation in Maryland, Pennsylvania, Virginia and West Virginia.[2] It preserves fossils dating back to the Ordovician period.