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Conestoga Formation

Conestoga Formation - Light-gray, thin-bedded, impure, contorted limestone having shale partings; conglomeratic at base; in Chester Valley, includes micaceous limestone in upper part, phyllite in middle, and alternating dolomite and limestone in lower part.
StatePennsylvania
NameConestoga Formation
Geologic ageOrdovician and Cambrian
Original map labelOCc
Primary rock typelimestone
Secondary rock typephyllite
Other rock typesconglomerate; dolostone (dolomite); shale
Lithologic constituents
Major
Sedimentary > Carbonate > Limestone (Bed)Light-gray, thin-bedded, impure, contorted limestone; in Chester Valley, includes micaceous limestone in upper part, phyllite in middle, and alternating dolomite and limestone in lower part
Minor
Metamorphic > Metasedimentary > Metaclastic > Phyllite (Bed)in Chester Valley, includes micaceous limestone in upper part, phyllite in middle, and alternating dolomite and limestone in lower part.
Sedimentary > Carbonate > Dolostone (Bed)in Chester Valley, includes micaceous limestone in upper part, phyllite in middle, and alternating dolomite and limestone in lower part.
Sedimentary > Clastic > Conglomerate (Bed)conglomeratic at base
Incidental
Sedimentary > Clastic > Mudstone > Shale (Bed)contorted limestone having shale partings
Map references
Pennsylvania Bureau of Topographic and Geologic Survey, Department of Conservation and Natural Resources, 2001, Bedrock Geology of Pennsylvania, edition: 1.0, digital map. Retrieved from internet 9-30-2004; <http://www.dcnr.state.pa.us/topogeo/map1/bedmap.aspx> DL Data: pageoexp.zip
Unit references
Berg, T. M., Edmunds, W. E., Geyer, A. R., and others, compilers, 1980, Geologic map of Pennsylvania: Pennsylvania Geological Survey, 4th ser., Map 1, 2nd ed., 3 sheets, scale 1:250,000.
Pennsylvania Bureau of Topographic and Geologic Survey, Department of Conservation and Natural Resources, 2001, Bedrock Geology of Pennsylvania, edition: 1.0, digital map. Retrieved from internet 9-30-2004; <http://www.dcnr.state.pa.us/topogeo/map1/bedmap.aspx> DL Data: pageoexp.zip
Geographic coverageAdams - Chester - Delaware - Lancaster - Montgomery - Philadelphia - York

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