232 CLARK AND MARTIN — THE COAL MEASURES OP MARYLAND 



mian (?) formations in the northern Appalachians as developed in 

 Maryland and adjacent states : 



Group Formation Age 



Dunkard Permian (?) 



Monongahela 



Coal Measures { Conemaugh 



Allegheny 



s Pottsville }■ Carboniferous 



Mauch Chunk 



Greenbrier 



Pocono 



