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The Pennsylvanian Pottsville Formation is a mapped
Pennsylvania:
* Bilger's Rocks
* Worlds End State Park
Maryland:
*Dans Rock, on
bedrock
In geology, bedrock is solid rock that lies under loose material ( regolith) within the crust of Earth or another terrestrial planet.
Definition
Bedrock is the solid rock that underlies looser surface material. An exposed portion of bed ...
unit in Pennsylvania
Pennsylvania, officially the Commonwealth of Pennsylvania, is a U.S. state, state spanning the Mid-Atlantic (United States), Mid-Atlantic, Northeastern United States, Northeastern, Appalachian, and Great Lakes region, Great Lakes regions o ...
, western Maryland
Maryland ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid-Atlantic region of the United States. It borders the states of Virginia to its south, West Virginia to its west, Pennsylvania to its north, and Delaware to its east ...
, West Virginia
West Virginia is a mountainous U.S. state, state in the Southern United States, Southern and Mid-Atlantic (United States), Mid-Atlantic regions of the United States.The United States Census Bureau, Census Bureau and the Association of American ...
, Ohio
Ohio ( ) is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Lake Erie to the north, Pennsylvania to the east, West Virginia to the southeast, Kentucky to the southwest, Indiana to the ...
, and Alabama
Alabama ( ) is a U.S. state, state in the Southeastern United States, Southeastern and Deep South, Deep Southern regions of the United States. It borders Tennessee to the north, Georgia (U.S. state), Georgia to the east, Florida and the Gu ...
. It is a major ridge-former in the Ridge-and-Valley Appalachians
The Ridge-and-Valley Appalachians, also called the Ridge and Valley Province or the Valley and Ridge Appalachians, are a physiographic province of the larger Appalachian Highlands division. The physiographic province is divided into three se ...
of the eastern United States
The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
. The Pottsville Formation is conspicuous at many sites along the Allegheny Front
The Allegheny Front is the major southeast- or east-facing escarpment in the Allegheny Mountains in southern Pennsylvania, western Maryland, eastern West Virginia, and western Virginia. The Allegheny Front forms the boundary between the Ridge-an ...
, the eastern escarpment of the Allegheny or Appalachian Plateau.
Description
The Pottsville Formation consists of a gray conglomerate, fine to coarse grainedsandstone
Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...
, and is known to contain limestone
Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...
, siltstone
Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.
Although its permeabil ...
and shale
Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of Clay mineral, clay minerals (hydrous aluminium phyllosilicates, e.g., Kaolinite, kaolin, aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4) and tiny f ...
, as well as anthracite
Anthracite, also known as hard coal and black coal, is a hard, compact variety of coal that has a lustre (mineralogy)#Submetallic lustre, submetallic lustre. It has the highest carbon content, the fewest impurities, and the highest energy densit ...
and bituminous
Bitumen ( , ) is an immensely viscous constituent of petroleum. Depending on its exact composition, it can be a sticky, black liquid or an apparently solid mass that behaves as a liquid over very large time scales. In American English, the m ...
coal.
It is considered a classic orogenic molasse
__NOTOC__
In geology, "molasse" () are sandstones, shales and conglomerates that form as terrestrial or shallow marine deposits in front of rising mountain chains. The molasse deposits accumulate in a foreland basin, especially on top of flys ...
. The formation was first described from a railroad cut south of Pottsville, Pennsylvania
Pottsville is a city and the county seat of Schuylkill County, Pennsylvania, United States. The population was 13,346 at the 2020 census, and is the principal city of the Pottsville, PA Micropolitan Statistical Area. The city lies along the wes ...
.
Nomenclature and stratigraphy
The relationship to the term "Pottsville" and actual lithologic units is complex. Most fundamentally, the unit may be considered a formation or agroup
A group is a number of persons or things that are located, gathered, or classed together.
Groups of people
* Cultural group, a group whose members share the same cultural identity
* Ethnic group, a group whose members share the same ethnic iden ...
.
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.http://ngmdb.usgs.gov/Geolex/NewUnits/unit_3393.html USGS GEOLEX database, Geologic Unit: Pottsville
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.
The Pottsville was previously mapped in the Illinois basin as well at the Formation level, but was renamed the Tradewater Formation in 1997.
Fossils
A 1.3-m interval at the base of the Pottsville in the Broad Top basin in Pennsylvania contains both marine invertebrates and plant fossils of middle Morrowan age.Age
Relative age dating of the Pottsville places it in the Early to Middle Pennsylvanian period.Notable exposures
Pennsylvania:
* Bilger's Rocks
* Worlds End State Park
Maryland:
*Dans Rock, on Dans Mountain
Dans Mountain is located in Allegany County, Maryland, USA between Georges Creek and the North Branch Potomac River. The highest point on Dans Mountain is called Dan's Rock which has an elevation of . The mountain rises above the town of LaVa ...
West Virginia:
* Bear Rocks Preserve, Dolly Sods
* Blackwater Falls and the Blackwater Canyon
* Canaan Valley (surrounding mountains)
* Cheat River Gorge
*Spruce Knob
Spruce Mountain, located in eastern West Virginia, is the highest ridge of the Allegheny Mountains. The whale-backed ridge extends for only from northeast to southwest, but several of its peaks exceed in elevation. The summit, Spruce Knob (), ...
Ohio:
*Thompson Ledges in Thompson Township, Geauga County, Ohio
Thompson Township is one of the sixteen townships of Geauga County, Ohio, United States. As of the 2020 census the population was 2,144.
Geography
Located in the northeastern corner of the county, it borders the following townships:
* Madison ...
See also
* * * * * Upper Mercer flintReferences