| Harpers Formation | |
|---|---|
| Stratigraphic range: Cambrian | |
 Harpers Schist. Shows older folded schistosity parallel to bedding cut by younger cleavage inclined to bedding. | |
| Type | Metamorphic |
| Unit of | Chilhowee Group |
| Sub-units | Snowden Member (VA), Montalto Quartzite Member (PA) |
| Underlies | Antietam Formation |
| Overlies | Weverton Formation |
| Lithology | |
| Primary | Schist |
| Other | Phyllite, shale |
| Location | |
| Region | Appalachia, Mid-Atlantic United States, and Southeastern United States |
| Country | United States |
| Extent | Maryland, Pennsylvania, Virginia,[1] West Virginia |
| Type section | |
| Named for | Harpers Ferry, West Virginia |
| Named by | Arthur Keith (1894)[2] |
The Harpers Formation is a geologic formation in Maryland, Pennsylvania, Virginia, and West Virginia, consisting of schist, phyllite, and shale. It dates back to the early Cambrian period. It is considered part of the Chilhowee Group.
- ^ Paleozoic Sedimentary Successions of the Virginia Valley & Ridge and Plateau
- ^ Arthur Keith, 1894. Harpers Ferry folio, Virginia, Maryland, West Virginia. United States Geological Survey Geologic atlas of the U.S. Folio 10. Field edition. Washington D.C., engraved and printed by the US Geological Survey. 5p., 5 maps. folio.