- Tuscarora Formation
The
Silurian Tuscarora Formation (St) is a mappedbedrock unit inPennsylvania ,Maryland ,Virginia andWest Virginia . It is also sometimes referred to as the Tuscarora Sandstone or the Tuscarora Quartzite.Description
The Tuscarora is a thin- to thick-bedded fine-grained to coarse-grained
orthoquartzite . It is a white to medium-gray or gray-greensubgraywacke ,sandstone ,siltstone andshale , cross-stratified and conglomeratic conglomerate in parts, containing a fewshale interbeds.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.] cite web |url=http://www.dcnr.state.pa.us/topogeo/openfile/midsusque.pdf |title= Preliminary Bedrock Geologic Map of the Middle Portion of the Susquehanna River Valley, Cumberland, Dauphin, And Perry Counties, Pennsylvania |year=2007|accessdate=2008-01-26 |author= Jackson, Margaret S.; Hanley, Peter M.; and Sak, Peter B. |publisher=Pennsylvania Geological Survey |format=pdf |work=Open File Report OFBM-07-05.0] cite web |url=http://www.mgs.md.gov/esic/geo/lgdalleg.html |title=Geologic Maps of Maryland: |accessdate=2008-01-26 |format= |work=] There is one named member of this formation: Castanea (Stc), occurring at the top, leaving the Lower and Middle Tuscarora Formation (Stlm) at the bottom.cite paper|url=http://www.dcnr.state.pa.us/topogeo/openfile/mcalevysfort.pdf|format=pdf|author= Doden, Arnold G. and Gold, David P.|year=2008|title=Bedrock Geologic Map of The Mc Alevys Fort Quadrangle, Huntingdon, Centre, and Mifflin Counties, Pennsylvania|publisher=Pennsylvania Geological Survey]The Tuscarora is a lateral equivalent of the Minsi and Weiders members of the
Shawangunk Formation in easternPennsylvania ,New Jersey , andNew York , and of theMassanutten Formation sandstone inVirginia . The Tuscarora and its lateral equivalents are the primaryridge-former s of theRidge-and-Valley Appalachians in the easternUnited States cite web |url=http://daac.gsfc.nasa.gov/geomorphology/GEO_2/GEO_PLATE_T-12.shtml |title=Geomorphology : Chapter 2 Plate T-12 : Folded Appalachians | date = 2007-01-19 |accessdate=2008-03-16 |publisher=NASA , Goddard Earth Sciences (GES), Data and Information Services Center (DISC) |first=Steve | last = Kempler|work=|quote=The major ridge makers are the Tuscarora (T), Pocono (Po), and Pottsville (Pt) Formations.] It is typically 935 feet thick in Pennsylvania, and in Maryland varies from 60 feet to 400 feet thick from east to west.The Tuscarora has always been intrepreted as
molasse resulting from theTaconic orogeny . It is thought to represent a vast sand shoal along the margin of theIapetus Ocean .Fossils
Very few fossils exist in the Tuscarora, and most of them are
trace fossils . Ripple marks are seldom found.Age
Relative age dating of the Tuscarora places it in the Lower
Silurian period, being deposited between 440 to 417 (±10) million years ago. It rests conformably atop theJuniata Formation and conformably below theClinton Group inPennsylvania . [Berg, T.M., et al., (1983). Stratagraphic Correlation Chart of Pennsylvania: G75, Pennsylvania Geologic Survey, Harrisburg, Pennsylvania.]Economic uses
The Tuscarora may have been used as a
ganister for making furnace liners in 19th centuryiron smelting blast furnace s of central Pennsylvania.References
ee also
*
Big Mountain (Pennsylvania)
*Bald Eagle Mountain
*Brush Mountain
*Germany Valley
*Geology of Pennsylvania
*Massanutten Mountain
*Mount Nittany
*North Fork Mountain
*Tussey Mountain
*River Knobs (West Virginia) *
Seneca Rocks
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