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{{short description|Bedrock unit in the Eastern United States}}
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The [[Silurian]] '''Wills Creek Formation''' (Swc) is a mapped bedrock unit in [[Pennsylvania]], [[Maryland]] and [[West Virginia]]. It forms the bedrock of the valley around and to the east of [[Lewistown, Pennsylvania]].<ref>{{cite map|url=http://www.dcnr.state.pa.us/topogeo/openfile/lewistown.pdf|format=pfd|title=Bedrock Geologic Map of the Lewistown Quadrangle, Mifflin and Juniata Counties, Pennsylvania| author = McElroy, Thomas A.| year = 2004 | publisher = Pennsylvania Geological Survey}}</ref>
{{Infobox rockunit
| name = Wills Creek Formation
| image = Wills Creek Fm fold.jpg
| caption = Tight [[anticline|anticlinal]] fold in the Wills Creek Formation, along [[U.S. Route 22 in Pennsylvania|Route 22]], Neff, [[Huntingdon County, Pennsylvania]]
| type = sedimentary
| age = [[Silurian]]
| period = Silurian
| prilithology = [[Sandstone]], [[shale]]
| otherlithology = [[Siltstone]], [[limestone]], [[Dolomite (rock)|dolomite]]
| namedfor = [[Wills Creek (North Branch Potomac River)|Wills Creek]] at [[Cumberland, Maryland|Cumberland]], [[Allegany County, Maryland]]
| namedby = P. R. Uhler, 1905<ref>Uhler, P.R., 1905, The Niagara period and its associates near Cumberland, Maryland: Maryland Academy of Science Transactions, v. 2, p. 19-26.</ref>
| region = [[Appalachian Mountains]]
| country =
| coordinates =
| unitof =
| subunits =
| underlies = [[Tonoloway Formation]]
| overlies = [[Bloomsburg Formation]] and [[Williamsport Formation]]
| thickness =
| extent = [[Pennsylvania]], [[Maryland]], [[Virginia]], [[West Virginia]]
| area =
| map =
| map_caption =
}}


'''Wills Creek Formation''' is a mapped [[Silurian]] bedrock unit in [[Pennsylvania]], [[Maryland]], [[Virginia]], and [[West Virginia]].
==Description==
⚫
The Wills Creek is defined as a moderately well bedded greenish-gray shale containing local limestone and sandstone zones, or more specifically as an olive to yellowish-gray, thin-bedded [[sandstone]], [[calcareous]] [[shale]], [[dolostone]], [[argillaceous]] [[limestone]], and [[sandstone]]. Red shale and siltstone occur in the lower part of the formation. The formation has a thickness between 450 feet and 600 feet in Maryland and 445 to 620 feet in Pennsylvania.<ref>{{cite web | url = http://www.geosc.psu.edu/news/features/gold/Final%20report%20%20Gold%20&%20Doden/Final%20Tables/Table%201%20Strat%20section.pdf| title = Table 1. Paleozoic Stratigraphic Section in Central Pennsylvania | work = Geological Report On The Skytop Road Cuts| publisher = [[Pennsylvania State University]] Department of Geosciences | year = 2004}}


==Fossils==
== Description ==
⚫
The Wills Creek is defined as a moderately well bedded greenish-gray shale containing local limestone and sandstone zones, or more specifically as an olive to yellowish-gray, thin-bedded [[sandstone]], [[calcareous]] [[shale]], [[Dolomite (rock)|dolomite]], [[argillaceous]] [[limestone]], and [[sandstone]]. Red shale and siltstone occur in the lower part of the formation. The formation has a thickness between 450 feet and 600 feet in Maryland and 445 to 620 feet in Pennsylvania.<ref>{{cite web | url = http://www.geosc.psu.edu/news/features/gold/Final%20report%20%20Gold%20&%20Doden/Final%20Tables/Table%201%20Strat%20section.pdf| title = Table 1. Paleozoic Stratigraphic Section in Central Pennsylvania | work = Geological Report On The Skytop Road Cuts| publisher = [[Pennsylvania State University]] Department of Geosciences | year = 2004}}</ref>
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The Wills Creek Limestone contain fossils from the [[Pridoli]] to the [[Ludlow epoch]], or 422.9 to 418.1 [[Megaannum|Ma]].<ref name="titleThe Paleobiology Database">{{cite web |url=http://paleodb.org/cgi-bin/bridge.pl?action=displayStrata&group_hint=&group_formation_member=Wills%20Creek%20Limestone |title= Wills Creek Limestone Formation| publisher= Advisory Board of the Paleobiology Database | work= The Paleobiology Database| accessdate=2008-01-26 |format= |work=}}</ref>


⚫
The Wills Creek forms the bedrock of the valley around and to the east of [[Lewistown, Pennsylvania]].<ref>{{cite map|url=http://www.dcnr.state.pa.us/topogeo/openfile/lewistown.pdf|archive-url=https://web.archive.org/web/20060328102026/http://www.dcnr.state.pa.us/topogeo/openfile/lewistown.pdf|url-status=dead|archive-date=March 28, 2006|format=pfd|title=Bedrock Geologic Map of the Lewistown Quadrangle, Mifflin and Juniata Counties, Pennsylvania| author = McElroy, Thomas A.| year = 2004 | publisher = Pennsylvania Geological Survey}}</ref>
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==Age==
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Relative age dating of the Wills Creek places it in the [[Silurian]] period. It rests [[unconformity|conformably]] a top the [[Bloomsburg Formation]] and below the [[Tonoloway Formation]].<ref name="titleGeologic Maps of Maryland:">{{cite web |url=http://www.mgs.md.gov/esic/geo/lgdalleg.html |title=Allegheny Plateau and Valley and Ridge | work = Geologic Map of Maryland | year = 1968 | publisher=Maryland Geological Survey|accessdate=2008-01-26 |format= |work=}}</ref>


==References==
=== Fossils ===
⚫
The Wills Creek Limestone contain fossils from the [[Pridoli epoch|Pridoli]] to the [[Ludlow epoch]], or 422.9 to 418.1 [[Megaannum|Ma]].<ref name="titleThe Paleobiology Database">{{cite web |url=https://paleodb.org/cgi-bin/bridge.pl?action=displayStrata&group_hint=&group_formation_member=Wills%20Creek%20Limestone |title= Wills Creek Limestone Formation| publisher= Advisory Board of the Paleobiology Database | work= The Paleobiology Database| access-date=2008-01-26 }}</ref>
<references/>


Dean et al. (1985) describe the Wills Creek as sparsely fossiliferous.<ref>Dean, S.L., Kulander, B.R., and Lessing, Peter, 1985, Geology of the Capon Springs, Mountain Falls, Wardensville, Woodstock, and Yellow Springs quadrangles, Hampshire and Hardy Counties, West Virginia: West Virginia Geological and Economic Survey Map, 26, 1 sheet, scale 1:24,000</ref>
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==See also==
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*[[Geology of Pennsylvania]]
<br>
{{geology-stub}}


Conodonts have been identified in the Wills Creek in Virginia (''[[Ozarkodina snajdri crispa]]'' Zone).<ref>Harris, A.G., Stamm, N.R., Weary, D.J., Repetski, J.E., Stamm, R.G., and Parker, R.A., 1994, Conodont color alteration index (CAI) map and conodont-based age determinations for the Winchester 30' x 60' quadrangle and adjacent area, Virginia, West Virginia, and Maryland: U.S. Geological Survey Miscellaneous Field Studies Map, MF-2239, 40 p., 1 sheet, scale 1:100,000 [http://ngmdb.usgs.gov/Prodesc/proddesc_294.htm]</ref>
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[[Category:Geologic formations]]

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[[Category:Geology of Pennsylvania]]
=== Notable outcrops ===
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[[Category:Geology of West Virginia]]
* Type section at [[Wills Creek (North Branch Potomac River)|Wills Creek]] at [[Cumberland, Maryland|Cumberland]], [[Allegany County, Maryland]]
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[[Category:Geology of Maryland]]
* [[Roundtop Hill (Maryland)|Roundtop Hill]], Maryland, along railroad grade

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== Age ==
⚫
Relative age dating of the Wills Creek places it in the [[Silurian]] period. It rests [[unconformity|conformably]] a top the [[Bloomsburg Formation]] and below the [[Tonoloway Formation]].<ref name="titleGeologic Maps of Maryland:">{{cite web |url=http://www.mgs.md.gov/esic/geo/lgdalleg.html |title=Allegheny Plateau and Valley and Ridge | work = Geologic Map of Maryland | year = 1968 | publisher=Maryland Geological Survey|access-date=2008-01-26 }}</ref>

== Economic use ==
The Wills Creek is a poor source of construction material and is only suitable as common fill.<ref name=mcalevysfort>{{cite journal|url=http://www.dcnr.state.pa.us/topogeo/openfile/mcalevysfort.pdf|archive-url=https://web.archive.org/web/20110609185124/http://www.dcnr.state.pa.us/topogeo/openfile/mcalevysfort.pdf|url-status=dead|archive-date=June 9, 2011|author1=Doden, Arnold G. |author2=Gold, David P. |name-list-style=amp |year=2008|title=Bedrock Geologic Map of The Mc Alevys Fort Quadrangle, Huntingdon, Centre, and Mifflin Counties, Pennsylvania|publisher=Pennsylvania Geological Survey}}</ref>

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== See also ==
⚫
* [[Geology of Pennsylvania]]

== References ==
{{reflist}}
{{Stratigraphic column of West Virginia}}
[[Category:Geologic formations of Maryland]]
[[Category:Geologic formations of Pennsylvania]]
[[Category:Geologic formations of Virginia]]
[[Category:Geologic formations of West Virginia]]
[[Category:Silurian System of North America]]
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[[Category:Mudstone formations]]
[[Category:Limestone formations of the United States]]
[[Category:Sandstone formations of the United States]]
[[Category:Shale formations of the United States]]
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[[Category:Silurian Maryland]]
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[[Category:Silurian geology of Pennsylvania]]
[[Category:Silurian geology of Virginia]]
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[[Category:Silurian West Virginia]]
[[Category:Silurian southern paleotemperate deposits]]

Latest revision as of 20:26, 18 November 2024

Wills Creek Formation
Stratigraphic range: Silurian
Tight anticlinal fold in the Wills Creek Formation, along Route 22, Neff, Huntingdon County, Pennsylvania
Typesedimentary
UnderliesTonoloway Formation
OverliesBloomsburg Formation and Williamsport Formation
Lithology
PrimarySandstone, shale
OtherSiltstone, limestone, dolomite
Location
RegionAppalachian Mountains
ExtentPennsylvania, Maryland, Virginia, West Virginia
Type section
Named forWills Creek at Cumberland, Allegany County, Maryland
Named byP. R. Uhler, 1905[1]

Wills Creek Formation is a mapped Silurian bedrock unit in Pennsylvania, Maryland, Virginia, and West Virginia.

Description

[edit]

The Wills Creek is defined as a moderately well bedded greenish-gray shale containing local limestone and sandstone zones, or more specifically as an olive to yellowish-gray, thin-bedded sandstone, calcareous shale, dolomite, argillaceous limestone, and sandstone. Red shale and siltstone occur in the lower part of the formation. The formation has a thickness between 450 feet and 600 feet in Maryland and 445 to 620 feet in Pennsylvania.[2]

The Wills Creek forms the bedrock of the valley around and to the east of Lewistown, Pennsylvania.[3]

Fossils

[edit]

The Wills Creek Limestone contain fossils from the Pridoli to the Ludlow epoch, or 422.9 to 418.1 Ma.[4]

Dean et al. (1985) describe the Wills Creek as sparsely fossiliferous.[5]

Conodonts have been identified in the Wills Creek in Virginia (Ozarkodina snajdri crispa Zone).[6]

Notable outcrops

[edit]

Age

[edit]

Relative age dating of the Wills Creek places it in the Silurian period. It rests conformably a top the Bloomsburg Formation and below the Tonoloway Formation.[7]

Economic use

[edit]

The Wills Creek is a poor source of construction material and is only suitable as common fill.[8]

See also

[edit]

References

[edit]
  1. ^ Uhler, P.R., 1905, The Niagara period and its associates near Cumberland, Maryland: Maryland Academy of Science Transactions, v. 2, p. 19-26.
  2. ^ "Table 1. Paleozoic Stratigraphic Section in Central Pennsylvania" (PDF). Geological Report On The Skytop Road Cuts. Pennsylvania State University Department of Geosciences. 2004.
  3. ^ McElroy, Thomas A. (2004). Bedrock Geologic Map of the Lewistown Quadrangle, Mifflin and Juniata Counties, Pennsylvania (PDF) (Map). Pennsylvania Geological Survey. Archived from the original (pfd) on March 28, 2006.
  4. ^ "Wills Creek Limestone Formation". The Paleobiology Database. Advisory Board of the Paleobiology Database. Retrieved 2008-01-26.
  5. ^ Dean, S.L., Kulander, B.R., and Lessing, Peter, 1985, Geology of the Capon Springs, Mountain Falls, Wardensville, Woodstock, and Yellow Springs quadrangles, Hampshire and Hardy Counties, West Virginia: West Virginia Geological and Economic Survey Map, 26, 1 sheet, scale 1:24,000
  6. ^ Harris, A.G., Stamm, N.R., Weary, D.J., Repetski, J.E., Stamm, R.G., and Parker, R.A., 1994, Conodont color alteration index (CAI) map and conodont-based age determinations for the Winchester 30' x 60' quadrangle and adjacent area, Virginia, West Virginia, and Maryland: U.S. Geological Survey Miscellaneous Field Studies Map, MF-2239, 40 p., 1 sheet, scale 1:100,000 [1]
  7. ^ "Allegheny Plateau and Valley and Ridge". Geologic Map of Maryland. Maryland Geological Survey. 1968. Retrieved 2008-01-26.
  8. ^ Doden, Arnold G. & Gold, David P. (2008). "Bedrock Geologic Map of The Mc Alevys Fort Quadrangle, Huntingdon, Centre, and Mifflin Counties, Pennsylvania" (PDF). Pennsylvania Geological Survey. Archived from the original (PDF) on June 9, 2011. {{cite journal}}: Cite journal requires |journal= (help)
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