Keyser Formation through Mifflintown Formation, undivided

In descending order: Keyser Formation--limestone; Tonoloway Formation--limestone and interbedded shale; Wills Creek Formation--interbedded shale, siltstone, limestone, and dolomite; Bloomsburg Formation--grayish-red and greenish-gray shale, siltstone, sandstone, and mudstone; Mifflintown Formation--interbedded shale and limestone.
State Pennsylvania
Name Keyser Formation through Mifflintown Formation, undivided
Geologic age Devonian and Silurian
Lithologic constituents
Major
Sedimentary > Clastic > Mudstone (Bed)Bloomsburg Formation--grayish-red and greenish-gray shale, siltstone, sandstone, and mudstone;
Sedimentary > Carbonate > Limestone (Bed)Tonoloway Formation--limestone; Wills Creek Formation--limestone; Mifflintown Formation--interbedded shale and limestone.
Sedimentary > Clastic > Mudstone > Shale (Bed)Tonoloway Formation--interbedded shale; Wills Creek Formation--interbedded shale; Bloomsburg Formation--grayish-red and greenish-gray shale; Mifflintown Formation--interbedded shale
Minor
Sedimentary > Clastic > Sandstone (Bed)Bloomsburg Formation--grayish-red and greenish-gray shale, siltstone, sandstone, and mudstone
Sedimentary > Clastic > Siltstone (Bed)Wills Creek Formation--interbedded shale, siltstone, limestone, and dolomite; Bloomsburg Formation--grayish-red and greenish-gray shale, siltstone, sandstone, and mudstone.
Sedimentary > Carbonate > Dolostone (Bed)Wills Creek Formation--interbedded shale, siltstone, limestone, and dolomite
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 Blair - Centre - Clinton - Franklin - Fulton - Huntingdon - Juniata - Lycoming - Snyder