Pottsville Formation

Pottsville Formation Stratigraphic range: Pennsylvanian
Typical Pottsville Formation at Worlds End State Park, Sullivan County, Pennsylvania
Type	sedimentary
Sub-units	see Stratigraphy section
Underlies	Brookville Coal of Allegheny Formation (OH, PA)
Overlies	Mauch Chunk Formation
Lithology
Primary	sandstone, conglomerate
Other	limestone, shale, coal
Location
Region	Appalachian Mountains
Extent	Pennsylvania, Maryland, West Virginia, Ohio
Type section
Named for	Pottsville, Pennsylvania
Named by	J. P. Lesley, 1876

The Pennsylvanian Pottsville Formation is a mapped bedrock unit in Pennsylvania, western Maryland, West Virginia, and Ohio. The formation is also recognized in Alabama. It is a major ridge-former in the Ridge-and-Valley Appalachians of the eastern United States. The Pottsville Formation is conspicuous at many sites along the Allegheny Front, the eastern escarpment of the Allegheny or Appalachian Plateau.

The Pottsville Formation consists of a gray conglomerate, fine to coarse grained sandstone, and is known to contain limestone, siltstone and shale, as well as anthracite and bituminous coal. It is considered a classic orogenic molasse. The formation was first described from a railroad cut south of Pottsville, Pennsylvania.

The relationship to the term "Pottsville" and actual lithologic units is complex. Most fundamentally, the unit may be considered a Formation or a Group.

As a Formation, the Pottsville may encompass the following members depending on the state in which it occurs: Alton Coal Member, Anthony Shale Member, Bear Run Member, Bedford Clay Bed, Boggs Member, Boyles Sandstone Member, Bremen Sandstone Member, Brookville Clay Member, Camp Branch Sandstone Member, Campbell Ledge Shale Member, Chestnut Sandstone Member, Connoquenessing Sandstone Member, Dundee Sandstone Member, Flint Ridge Clay Bed or Flint Ridge Shale Member, Harrison Member, Homewood Sandstone Member, Huckleberry Clay Bed, Kanawha Member, Lick Creek Sandstone Member, Lowellville Limestone Member, Lower Mercer Limestone Member, Massilon Sandstone Member, McArthur Member, Mercer Member, Middle Mercer Shale Member, Mount Savage Clay Bed, Olean Conglomerate Member of Olean Sandstone Member, Pine Sandstone Member, Poverty Run Member, Razburg Sandstone Member, Rocky Ridge Sandstone Member, Schuylkill Member, Sciotoville Clay Member, Shades Sandstone Member, Sharon Coal Bed, Sharon Member, Sharp Mountain Member, Straight Ridge Sandstone Member, Straven Conglomerate Member, Tionesta Clay Bed, Tumbling Run Member, Upper Mercer Limestone Member or Upper Mercer Bed, Vandusen Shale Member, Wolf Ridge Sandstone Member.