Cocalico Formation (PAOco;21)

State	Pennsylvania
Name	Cocalico Formation
Geologic age	Ordovician
Original map label	Oco
Primary rock type	shale
Secondary rock type	siltstone
Other rock types	sandstone
Lithologic constituents	Major Sedimentary > Clastic > Mudstone > Shale (Bed)gray phyllitic shale, maroon shale, and silty, siliceous shale Sedimentary > Clastic > Siltstone (Bed) Minor Sedimentary > Clastic > Sandstone (Bed)some interbedded argillaceous and quartzose sandstone; predominantly allochthonous, and probably closely related to Hamburg sequence, but includes some autochthonous elements.
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 [http://www.dcnr.state.pa.us/topogeo/map1/bedmap.aspx]
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 [http://www.dcnr.state.pa.us/topogeo/map1/bedmap.aspx]
Geographic coverage	Bucks - Lancaster