Keyser and Tonoloway Formations, undivided

In descending order: Keyser Formation--medium-gray, crystalline to nodular, fossiliferous limestone; upper part laminated and mud-cracked; not present east of Harrisburg; passes into lower Coeymans, Rondout, and Decker Formations in the east. Tonoloway Formation--medium-gray, laminated, mud-cracked limestone containing some medium-dark- or olive-gray shale interbeds; lower part passes into Wills Creek Formation east and south; passes into Bossardville and Poxono Island beds in the east.
State Pennsylvania
Name Keyser and Tonoloway Formations, undivided
Geologic age Devonian and Silurian
Lithologic constituents
Major
Sedimentary > Carbonate > Limestone (Bed)Keyser Formation--medium-gray, crystalline to nodular, fossiliferous limestone; upper part laminated and mud cracked; not present east of Harrisburg; passes into lower Coeymans, Rondout, and Decker Formations in the east. Tonoloway Formation--medium-gray, laminated, mud-cracked limestone
Minor
Sedimentary > Clastic > Mudstone > Shale (Bed)Tonoloway Formation--containing some medium-dark- or olive-gray shale interbeds
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 Bedford - Blair - Clinton - Columbia - Franklin - Fulton - Huntingdon - Juniata - Luzerne - Lycoming - Mifflin - Montour - Northumberland - Perry - Snyder - Union