Bulletin 799 Plate 2A Harpers Schist photomicrograph

The Harpers Formation is a geologic formation in Maryland, Pennsylvania, Virginia, and West Virginia, consisting of schist, phyllite, and

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especial ...

. It dates back to the early

Cambrian The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...

period. It is considered part of the

Chilhowee Group The Chilhowee Group is a sedimentary body composed of early Cambrian siliciclastic sedimentary rocks which crop out along the eastern margin of the Blue Ridge province in Alabama, Maryland, Tennessee, North Carolina, Virginia, and West Virginia. ...

Notable exposures

The type section is in gorges of the Potomac River and the

Shenandoah River The Shenandoah River is the principal tributary of the Potomac River, long with two forks approximately long each,U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed August 15, 2011 in t ...

at Harpers Ferry, West Virginia. The Harpers Formation overlies the

Ledger Formation The Ledger Formation or Ledger Dolomite is a geologic formation in Pennsylvania, United States. The Ledger is described as light-gray, locally mottled, massive, pure, coarsely crystalline dolomite. It may be siliceous in the middle part. Typ ...

(

dolomite Dolomite may refer to: *Dolomite (mineral), a carbonate mineral *Dolomite (rock), also known as dolostone, a sedimentary carbonate rock *Dolomite, Alabama, United States, an unincorporated community *Dolomite, California, United States, an unincor ...

) due to a thrust fault in small roadside quarry (currently overgrown) on Pottery Hill, southwest of York, Pennsylvania. A. J. Stose and G. W. Stose, 1944. ''Geology of the Hanover-York district'', U. S. Geological Survey Professional paper 204.

Gallery

File:Quartzite (Harpers Formation, Lower Cambrian; Verona, Virginia, USA).jpg, Quartzite sample of Harpers Formation from near

Verona, Virginia Verona is a census-designated place (CDP) in Augusta County, Virginia, United States. The population was 4,239 at the 2010 census. It is part of the Staunton– Waynesboro Micropolitan Statistical Area. History Mount Airy and Verona School ...

File:Jefferson Rock, Harpers Ferry, WV - area view.jpg, Harpers Shale by

Jefferson Rock Jefferson Rock is a rock formation on the Appalachian Trail in Harpers Ferry, West Virginia. It consists of several large masses of Harpers shale, piled one upon the other, that overlook the Shenandoah River just prior to its confluence with the P ...

in Harpers Ferry, West Virginia Harpers Phyllite Pottery Hill outcrop 2022.jpg, Sample of phyllite from the outcrop at Pottery Hill, southwest of York

References

Cambrian West Virginia {{Cambrian-stub