| Pottsville Formation | |
|---|---|
| Stratigraphic range:Pennsylvanian | |
 Typical Pottsville Formation atWorlds End State Park,Sullivan County, Pennsylvania | |
| Type | sedimentary |
| Sub-units | see Stratigraphy section |
| Underlies | Brookville Coal ofAllegheny Formation (OH, PA)[1]Llewellyn Formation |
| Overlies | Coldwater Shale,Cuyahoga Formation,Logan Formation,Mauch Chunk Formation,Maxville Limestone, andParkwood Formation |
| Lithology | |
| Primary | sandstone,conglomerate |
| Other | limestone,shale,coal |
| Location | |
| Region | Appalachian Mountains |
| Extent | Alabama, Maryland, Mississippi, Ohio, Pennsylvania, and West Virginia |
| Type section | |
| Named for | Pottsville, Pennsylvania |
| Named by | J. P. Lesley, 1876[2] |
ThePennsylvanianPottsville Formation is a mappedbedrock unit inPennsylvania, westernMaryland,West Virginia,Ohio, andAlabama. It is a majorridge-former in theRidge-and-Valley Appalachians of the easternUnited States.[3] The Pottsville Formation is conspicuous at many sites along theAllegheny Front, the eastern escarpment of theAllegheny or Appalachian Plateau.
The Pottsville Formation consists of a grayconglomerate, fine to coarse grainedsandstone, and is known to containlimestone,siltstone andshale, as well asanthracite andbituminous coal.[4][5]It is considered a classic orogenicmolasse.[6] The formation was first described from a railroad cut south ofPottsville, Pennsylvania.[4]
The relationship to the term "Pottsville" and actual lithologic units is complex. Most fundamentally, the unit may be considered aformation or agroup.
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, Massillon 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.[7]
As a group, the Pottsville may encompass the following formations depending on the state in which it occurs: Connoquenessing Formation, Curwensville Formation, Elliott Park Formation, Gurnee Formation, Hance Formation, Homewood Formation or Homewood Sandstone, Mercer Formation, New River Formation, Olean Conglomerate or Olean Formation, Pocahontas Formation, Schuylkill Formation, Sharon Formation or Sharon Sandstone, Sharp Mountain Formation, Tumbling Run Formation.[7]
The Pottsville was previously mapped in the Illinois basin as well at the Formation level, but was renamed the Tradewater Formation in 1997.[8]
A 1.3-m interval at the base of the Pottsville in theBroad Top basin in Pennsylvania contains both marine invertebrates and plant fossils of middle Morrowan age.[9]
Relative age dating of the Pottsville places it in the Early to MiddlePennsylvanian period.
Pennsylvania:
Maryland:
West Virginia:
Ohio:
The major ridge makers are the Tuscarora (T), Pocono (Po), and Pottsville (Pt) Formations.
The Carboniferous Pottsville Formation of eastern Pennsylvania in the central Appalachian foreland basin is considered a classic orogenic molasse …