Harrell Shale

Harrell Shale Group
Harrell Shale Group
Stratigraphic range: Frasnian
Type	Group
Sub-units	Burket Shale
Underlies	Brallier Formation, Sonyea Formation, Trimmers Rock Formation
Overlies	Mahantango Formation, Millboro Shale, and Tully Limestone
Lithology
Primary	shale, sandstone
Location
Region	Appalachian Mountains
Country	United States
Type section
Named by	Charles Butts, 1918

The Devonian Harrell Formation is a mapped bedrock unit in Pennsylvania, Maryland, West Virginia, and Virginia.

^ de Witt, Wallace, Jr., Roen, J.B., and Wallace, L.G., 1993, Stratigraphy of Devonian black shales and associated rocks in the Appalachian basin, IN Roen, J.B., and Kepferle, R.C., eds., Petroleum geology of the Devonian and Mississippian black shale of eastern North America: U.S. Geological Survey Bulletin, 1909-B, p. B1-B57.
^ Butts, Charles, 1918, Geologic section of Blair and Huntingdon Counties, central Pennsylvania: American Journal of Science, 4th series, v. 46, p. 523-537.