Wills Creek Formation

The Silurian Wills Creek Formation (Swc) is a mapped bedrock unit in Pennsylvania, Maryland and West Virginia. It forms the bedrock of the valley around and to the east of Lewistown, Pennsylvania. [cite map|url=http://www.dcnr.state.pa.us/topogeo/openfile/lewistown.pdf|format=pfd|title=Bedrock Geologic Map of the Lewistown Quadrangle, Mifflin and Juniata Counties, Pennsylvania| author = McElroy, Thomas A.| year = 2004 | publisher = Pennsylvania Geological Survey]

Description

The Wills Creek is defined as a moderately well bedded greenish-gray shale containing local limestone and sandstone zones, or more specifically as an olive to yellowish-gray, thin-bedded sandstone, calcareous shale, dolostone, argillaceous limestone, and sandstone. Red shale and siltstone occur in the lower part of the formation. The formation has a thickness between 450 feet and 600 feet in Maryland and 445 to 620 feet in Pennsylvania. [cite web | url = http://www.geosc.psu.edu/news/features/gold/Final%20report%20%20Gold%20&%20Doden/Final%20Tables/Table%201%20Strat%20section.pdf| title = Table 1. Paleozoic Stratigraphic Section in Central Pennsylvania | work = Geological Report On The Skytop Road Cuts| publisher = Pennsylvania State University Department of Geosciences | year = 2004]

Fossils

The Wills Creek Limestone contain fossils from the Pridoli to the Ludlow epoch, or 422.9 to 418.1 Ma.cite web |url=http://paleodb.org/cgi-bin/bridge.pl?action=displayStrata&group_hint=&group_formation_member=Wills%20Creek%20Limestone |title= Wills Creek Limestone Formation| publisher= Advisory Board of the Paleobiology Database | work= The Paleobiology Database| accessdate=2008-01-26 |format= |work=]

Age

Relative age dating of the Wills Creek places it in the Silurian period. It rests conformably a top the Bloomsburg Formation and below the Tonoloway Formation.cite web |url=http://www.mgs.md.gov/esic/geo/lgdalleg.html |title=Allegheny Plateau and Valley and Ridge | work = Geologic Map of Maryland | year = 1968 | publisher=Maryland Geological Survey|accessdate=2008-01-26 |format= |work=]

Economic Uses

The Wills Creek is a poor source of construction material and is only suitable as common fill.cite paper|url=http://www.dcnr.state.pa.us/topogeo/openfile/mcalevysfort.pdf|format=pdf|author= Doden, Arnold G. and Gold, David P.|year=2008|title=Bedrock Geologic Map of The Mc Alevys Fort Quadrangle, Huntingdon, Centre, and Mifflin Counties, Pennsylvania|publisher=Pennsylvania Geological Survey]

References

ee also

*Geology of Pennsylvania