Wills Creek Formation
| Wills Creek Formation | |
|---|---|
| Stratigraphic range: Silurian | |
 Tight anticlinal fold in the Wills Creek Formation, along Route 22, Neff, Huntingdon County, Pennsylvania | |
| Type | sedimentary |
| Underlies | Tonoloway Formation |
| Overlies | Bloomsburg Formation |
| Lithology | |
| Primary | sandstone, shale |
| Other | siltstone, limestone, dolostone |
| Location | |
| Region | Appalachian Mountains |
| Extent | Pennsylvania, Maryland, Virginia, West Virginia |
| Type section | |
| Named for | Wills Creek |
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.[1]
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.[2]
Fossils
The Wills Creek Limestone contain fossils from the Pridoli to the Ludlow epoch, or 422.9 to 418.1 Ma.[3]
Notable Exposures
- Roundtop Hill, Maryland, along railroad grade
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.[4]
Economic Uses
The Wills Creek is a poor source of construction material and is only suitable as common fill.[5]
References
- ^ McElroy, Thomas A. (2004). Bedrock Geologic Map of the Lewistown Quadrangle, Mifflin and Juniata Counties, Pennsylvania (pfd) (Map). Pennsylvania Geological Survey.
- ^ "Table 1. Paleozoic Stratigraphic Section in Central Pennsylvania" (PDF). Geological Report On The Skytop Road Cuts. Pennsylvania State University Department of Geosciences. 2004.
- ^ "Wills Creek Limestone Formation". Advisory Board of the Paleobiology Database. Retrieved 2008-01-26.
- ^ "Allegheny Plateau and Valley and Ridge". Maryland Geological Survey. 1968. Retrieved 2008-01-26.
- ^ Doden, Arnold G. and Gold, David P. (2008). "Bedrock Geologic Map of The Mc Alevys Fort Quadrangle, Huntingdon, Centre, and Mifflin Counties, Pennsylvania" (pdf). Pennsylvania Geological Survey.
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See also
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