Wills Creek Formation
Wills Creek Formation is a mapped Silurian bedrock unit in Pennsylvania, Maryland, Virginia, and West Virginia.
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, dolomite, 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.The Wills Creek forms the bedrock of the valley around and to the east of Lewistown, Pennsylvania.
Fossils
The Wills Creek Limestone contain fossils from the Pridoli to the Ludlow epoch, or 422.9 to 418.1 Ma.Dean et al. describe the Wills Creek as sparsely fossiliferous.
Conodonts have been identified in the Wills Creek in Virginia.
Notable outcrops
- Type section at Wills Creek at Cumberland, Allegany County, Maryland
- Roundtop Hill, Maryland, along railroad grade