Map of mining in George's Creek

This map from the 1968 Maryland Geological Survey shows the location of coal in the George's Creek valley, from Frostburg to Westernport, with Lonaconing roughly halfway between the two towns. The purple color labeled PM is the Monongahela Formation, containing coal. The Maryland Geological Survey webpage has additional information:
http://www.mgs.md.gov/esic/geo/allw.html

Map of Georges Creek Coal Basin showing the location of mining properties and the areal extent of the Pittsburg ("Big Vein") and Lower Coals.
Maryland Geological Survey,
Wm. Bullock Clark, State Geologist
1903.

Mining Properties by B. S. Randolph
Geology by G. C. Martin
Typology by the Maryland Geological Survey in cooperation with the U. S. Geological Survey