Onondaga Formation

Medium-gray calcareous shale; marine fossils; medium-gray argillaceous limestone of Selinsgrove Member at top; called ""Needmore Formation"" west of 78ø longitude; Tioga bentonite at top.
State Pennsylvania
Name Onondaga Formation
Geologic age Devonian
Lithologic constituents
Major
Sedimentary > Clastic > Mudstone > Shale (Calcareous)Medium-gray calcareous shale; marine fossils
Sedimentary > Carbonate > Limestone (Bed)medium-gray argillaceous limestone of Selinsgrove Member at top; called ""Needmore Formation"" west of 78° longitude
Minor
Sedimentary > Clastic > Mudstone > Claystone > Bentonite (Bed)Tioga bentonite at top
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 Huntingdon