The Devonian Harrell Formation is a mapped bedrock unit in Pennsylvania, Maryland, West Virginia, and Virginia.
Description The Harrell Formation was first described by Charles Butts in 1918. Hasson and Dennison (1978) state "The Harrell Shale consists of very dark gray, thinly laminated, platy- to sheety-weathering shale underlain in certain areas by the grayish black shale of the Burket Member."
Fossils Hasson and Dennison reported the following fossils from several outcrops of the Harrell:Hasson, Kenneth O., and Dennison, John M., 1978, STRATIGRAPHY OF THE DEVONIAN HARRELL AND MILLBORO SHALES IN PARTS OF PENNSYLVANIA, MARYLAND, WEST VIRGINIA, AND VIRGINIA, Project Final Report for Energy Research and Development Administration Contract #EY-77-C-21-8153, May 1978 Bivalvia: Buchiola livonae (?), B. retrostriata, Paracardium doris, Pterochaenia fragilis, Lunlulicardium (?) Cephalopoda: Bactrites aciculum, Probeloceras lutheri Cricoconarida (class of Mollusca): Styliolina fissurella
Notable Exposures Type locality is at Horrell Station, Blair County, Pennsylvania (). In 1918, when Butts described and named the type section, the USGS topo map spelled the location "Harrell", but the local spelling was "Horrell".
Age Relative age dating places the Harrell in the late Devonian.
References