Harpers Formation
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.
| 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] |
Photomicrograph of Harpers Schist
Notable exposures
The type section is in gorges of the Potomac River and the Shenandoah River at Harpers Ferry, West Virginia.
The Harpers Formation overlies the Ledger Formation (dolomite) due to a thrust fault in small roadside quarry (currently overgrown) on Pottery Hill, southwest of York, Pennsylvania.[3]
Gallery
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Quartzite sample of Harpers Formation from near Verona, Virginia
Harpers Shale by Jefferson Rock in Harpers Ferry, West Virginia
Sample of phyllite from the outcrop at Pottery Hill, southwest of York
References
- 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.
- A. J. Stose and G. W. Stose, 1944. Geology of the Hanover-York district, U. S. Geological Survey Professional paper 204.
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