Igneous > Volcanic > Mafic-volcanic > Basalt (Diabase)Medium- to coarse-grained, quartz-normative tholeiite; composed of labradorite and various pyroxenes; occurs as dikes, sheets, and a few small flows
|Comments||Digital map differences from 1980 map: age changed from Triassic to Jurassic; map symbol changed from Trd (printed) to Jd (digital). See digital map reference.|
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, Miles, C.E., and Whitfield, T.G., compilers, 2001, Bedrock Geology of Pennsylvania, edition: 1.0, digital map, scale 1:250,000.
|Counties||Adams - Berks - Bucks - Chester - Cumberland - Dauphin - Lancaster - Lebanon - Lehigh - Montgomery - York|