568 COAL MEASURES OF MARYLAND 



Page 



Thickness 581 



Underlying beds 581 



Sections of critical series of the Lower Conemaugh from Ohio 



to Pittsburgh, Pennsylvania 581 



Meigs County. Ohio 581 



Muskingum Count^', Ohio 582 



"Wheeling. West Virginia 582 



Pittsburgh. Pennsylvania 582 



Sections of critical series of the Lower Conemaugh from Pitts- 

 burgh, Pennsylvania, to Maryland via West Virginia 583 



Morgantown, Monongalia County, West Virginia 583 



Preston County. West Virginia 583 



Upper Youghiogheny basin, West Virginia and Maryland. . . . 584 



Upper Potomac basin, Maryland 584 



Sections of critical series of Lower Conemaugh from Pitt.sburgh. 



to Maryland via western Pennsylvania 585 



Freeport, Pennsylvania 585 



Latrobe. Pennsylvania 586 



Somerset County, Pennsylvania 586 



Castleman basin. Pennsylvania-Maryland 586 



Georges Creek basin. Maryland 587 



Persistence of critical series 587 



Correlation of formations 589 



In general 589 



Monongahela formation 589 



Conemaugh formation 590 



Allegheny formation 591 



Pottsville formation 592 



Conclusions and summary 592 



Explanation of plates 594 



Inteoductiox 



AREA 



The Coal Measures are found in Allegany and Garrett counties. Mary- 

 land, situated in the western part of the State, where they underlie a 

 large part of the region between the Alleghany front and the West Vir- 

 ginia-Maryland State line. The strata occupy three major structural 

 troughs whose axes trend northeast-southwest, parallel to the trend of 

 the mountains. The most westerly trough is called the Lower Youghio- 

 gheny, or Friendsville, basin. The middle basin is divided into two parts 

 by a transverse minor anticline, thus forming the Upper Youghiogheny 

 basin on the southwest and the Castleman basin on the northeast. The 

 eastern trough is cut into two parts by the Potomac Eiver, which turns 



