Allegheny Formation and Pottsville Formation (MDPAap;1)

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
Original map label	Pap
Primary rock type	sandstone
Secondary rock type	shale
Other rock types	claystone; siltstone; coal; limestone
Lithologic constituents	Major Sedimentary > Clastic > Mudstone > Shale Sedimentary > Clastic > Sandstone Minor Sedimentary > Clastic > Mudstone > Claystone Sedimentary > Clastic > Siltstone Incidental Sedimentary > Coal
Map references	Cleaves, E.T., Edwards, J., Jr., Glaser, J.D., 1968, Geologic Map of Maryland: Maryland Geological Survey, Baltimore, Maryland, scale 1:250,000.
Unit references	Cleaves, E.T., Edwards, J., Jr., Glaser, J.D., 1968, Geologic Map of Maryland: Maryland Geological Survey, Baltimore, Maryland, scale 1:250,000. Unpublished digital version of the Maryland state geologic map that was digitized by the USGS Water Resources Office in Towson, MD
Geographic coverage	Allegany - Garrett