The

Mississippian Mississippian may refer to: * Mississippian (geology), a subperiod of the Carboniferous period in the geologic timescale, roughly 360 to 325 million years ago *Mississippian culture, a culture of Native American mound-builders from 900 to 1500 AD ...

Pocono Formation is a mapped bedrock unit in

Pennsylvania Pennsylvania (; (Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, Ma ...

Maryland Maryland ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid-Atlantic region of the United States. It shares borders with Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; ...

, and

West Virginia West Virginia is a state in the Appalachian, Mid-Atlantic and Southeastern regions of the United States.The Census Bureau and the Association of American Geographers classify West Virginia as part of the Southern United States while the ...

, in the United States. It is also known as the Pocono Group in Maryland and West Virginia, and the upper part of the Pocono Formation is sometimes called the Burgoon Formation or Burgoon Sandstone in Pennsylvania. The Pocono is a major

ridge-former A cliff-former is a geological unit of bedrock that is more resistant to erosion than overlying or underlying strata and consequently produces outcrops with high slope angles. It is more or less equivalent to ''ridge-former'', and may be contrast ...

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 division and are also a belt within the Appalachian Mountains extendin ...

of the eastern

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...

The Pocono is also a lateral equivalent of the Purslane Sandstone in Maryland and West Virginia. D. Brezinski of Maryland Geological Survey recommended abandoning use of the term Pocono in Maryland in favor of "Purslane" in 1989.

Description

The Pocono is a dominantly gray color with

quartzitic Quartzite is a hard, non- foliated metamorphic rock which was originally pure quartz sandstone.Essentials of Geology, 3rd Edition, Stephen Marshak, p 182 Sandstone is converted into quartzite through heating and pressure usually related to ...

medium to coarse-grained

sandstones Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

. The base of the Pocono Formation is marked by conglomerate. Sideling Hill cut MD1

Notable exposures

* The type section of the Burgoon Sandstone is in the valley of Burgoon Run, above Kittanning Point,

Blair County, Pennsylvania Blair County is a county in the Commonwealth of Pennsylvania. As of the 2020 census, the population was 122,822. Its county seat is Hollidaysburg. The county was created on February 26, 1846, from parts of Huntingdon and Bedford counties. Bl ...

. * A spectacular exposure of the Purslane Sandstone (equivalent to the Pocono) is at the I-68 road cut through

Sideling Hill Sideling Hill, also Side Long Hill, is a long, steep, narrow mountain ridge in the Ridge-and-Valley (or Allegheny Mountains) physiographic province of the Appalachian Mountains, located in Washington County in western Maryland and adjacent West ...

in Maryland.

Age

Relative age dating of the Pocono places it in the lower Mississippian period. The lower boundary is with the Spetchy Kopf Formation and Huntley Mountain Formation. In South-central Pennsylvania, the Pocono often interfingers with the

Rockwell Formation The Rockwell Formation is a late Devonian and early Mississippian mapped bedrock unit in West Virginia, Maryland, and Pennsylvania, in the United States. Description The Rockwell Formation was described at its type section at Rockwell Run in West ...

.Berg, T.M., Edmunds, W.E., Geyer, A.R. and others, compilers, (1980). Geologic Map of Pennsylvania: Pennsylvania Geologic Survey, Map 1, scale 1:250,000.

References

Geologic formations of Pennsylvania Geologic formations of West Virginia Geologic formations of Maryland Carboniferous System of North America Conglomerate formations Sandstone formations of the United States Mississippian United States Carboniferous geology of Pennsylvania Carboniferous West Virginia Carboniferous Maryland Devonian geology of Pennsylvania Devonian Maryland Devonian West Virginia Cliff-formers Devonian southern paleotemperate deposits Carboniferous southern paleotemperate deposits Carboniferous southern paleotropical deposits {{US-geologic-formation-stub

Description

Notable exposures

Age

References

See also