PALEOZOIC TIME — CARBONIC. 



649 



ward, among upturned rocks ; and the Pittsburg coal at the west end of the 

 state, although among nearly horizontal rocks, also has its outlying patches. 

 Geological investigation has proved that the two distant areas were once 



1024. 



Map of part of Pennsylvania, showing the coal areas of the state, in black; the Anthracite beds east of the 

 Susquehanna, and the Bituminous beds to the westward. 



united and that the coal once covered 10 times its present area. " Broad 

 Top " in southwestern Pennsylvania is shown by Lesley to be a fragment of 

 the Pittsburg coal-bed, about 80 square miles in area, left in the general 

 denudation of the Appalachian region. 



1025. 



Section of the Panther Creek Anthracite basin at Nesquehoning tunnel. 



Figs. 1025 to 1027 represent sections of portions of the Anthracite region, 

 showing the character of the flexures that led, through denudation, to the 

 breaking of the coal-beds into nearly parallel belts. Fig. 1025 is a vertical 



