| Antietam Formation | |
| Type: | Formation |
| Age: | Cambrian |
| Period: | Cambrian |
| Prilithology: | Sandstone, quartzite |
| Otherlithology: | Schist |
| Namedfor: | Antietam Creek |
| Region: | Appalachia, Eastern United States, and Southeastern United States |
| Country: | United States |
| Unitof: | Chilhowee Group |
| Underlies: | Tomstown Dolomite |
| Overlies: | Harpers Formation |
| Thickness: | 550 ft |
| Extent: | Maryland, Pennsylvania, Virginia,[1] and West Virginia |
The Antietam Formation or Antietam Sandstone is a geologic formation in Pennsylvania, Maryland and West Virginia.[2] [3] [4] It is largely quartz sandstone with some quartzite and quartz schist. It preserves Skolithos trace fossils dating back to the Cambrian Period.[5]