Mafic gneiss

Dark, medium grained; includes rocks of probable sedimentary origin; may be equivalent to pCAmgh in places.
State Pennsylvania
Name Mafic gneiss
Geologic age Probably lower Paleozoic
Lithologic constituents
Major
Metamorphic > Gneissmafic gneiss; dark, medium grained; includes rocks of probable sedimentary origin; may be equivalent to pCAmgh in places
Minor
Metamorphic > Metasedimentary > Paragneissincludes rocks of probable sedimentary origin; may be equivalent to pCAmgh in places
Comments Digital map differences from 1980 printed map: name changed from (Mafic gneiss, hornblende-bearing).
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, Miles, C.E., and Whitfield, T.G., compilers, 2001, Bedrock Geology of Pennsylvania, edition: 1.0, digital map, scale 1:250,000.

NGMDB product
Counties Bucks - Chester - Delaware - Montgomery - Philadelphia