502 



APPALACHIAN COAL STRATA. 



[Ch. XXV. 



This coal-formation, before its original limits were reduced by denu- 

 dation, must have measured 900 miles in length, and in some places 

 more than 200 miles in breadth. By again referring to the section 

 (fig. 552, p. 497), it will be seen that the strata of coal are horizontal 

 to the westward of the mountains in the region d e, and become more 

 and more inclined and folded as we proceed eastward. Now it is 



