Allentown Formation

Medium- to medium-dark-gray, thick-bedded dolomite and impure limestone; dark-gray chert stringers and nodules; laminated; oolitic and stromatolitic; some orange-brown-weathering calcareous siltstone at base.
State Pennsylvania
Name Allentown Formation
Geologic age Cambrian
Lithologic constituents
Sedimentary > Carbonate > Dolostone (Bed)medium- to medium-dark-gray, thick-bedded dolomite
Sedimentary > Carbonate > Limestone (Bed)medium- to medium-dark-gray, impure limestone
Sedimentary > Clastic > Siltstone (Bed, Calcareous)some orange-brown-weathering calcareous siltstone at base
Sedimentary > Chemical > Chert (Bed)dark-gray chert stringers and nodules; laminated; oolitic and stromatolitic

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 Berks - Bucks - Lehigh - Northampton