Cocalico Formation

Gray phyllitic shale, maroon shale, siltstone, and silty, siliceous shale; some interbedded argillaceous and quartzose sandstone; predominantly allochthonous, and probably closely related to Hamburg sequence, but includes some autochthonous elements.
State Pennsylvania
Name Cocalico Formation
Geologic age Ordovician
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.
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 - Lancaster