Allegheny Formation and Pottsville Formation

Allegheny Formation - Interbedded sandstone, siltstone, claystone, shale, and coal beds; Upper Freeport coal at top; where present, Brookville coal defines base; thickness 275 feet in northeast, increases to 325 feet in south and west. And Pottsville Formation - Interbedded sandstone, siltstone, claystone, shale, and coal beds; conglomeratic orthoquartzite and protoquartzite at base; thickness 60 feet in northeast, increases to 440 feet in southwest
State Maryland
Name Allegheny Formation and Pottsville Formation
Geologic age Pennsylvanian
Lithologic constituents
Major
Sedimentary > Clastic > Sandstone
Sedimentary > Clastic > Mudstone > Shale
Minor
Sedimentary > Clastic > Mudstone > Claystone
Sedimentary > Clastic > Siltstone
Incidental
Sedimentary > Coal
References

Cleaves, E.T., Edwards, J., Jr., and Glaser, J.D., 1968, Geologic Map of Maryland: Maryland Geological Survey, Baltimore, Maryland, scale 1:250,000.

In 1995 the Water Resources Division of the U.S. Geological Survey digitized the geologic map of Maryland from the 1968 paper map (Reference MD001). Information about products from the Maryland Geological Survey can be found at http://www.mgs.md.gov/.

NGMDB product
Counties Allegany - Garrett