Monongahela Formation

Interbedded claystone, argillaceous limestone, shale, sandstone, and coal beds; Waynesburg coal at top; Pittsburg coal at base; thickness 240 feet in west, increases to 375 feet in east.
State Maryland
Name Monongahela Formation
Geologic age Pennsylvanian
Lithologic constituents
Sedimentary > Carbonate > Limestone
Sedimentary > Clastic > Mudstone > Claystone
Sedimentary > Clastic > Mudstone > Shale
Sedimentary > Coal
Sedimentary > Clastic > Sandstone

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

NGMDB product
Counties Allegany - Garrett