I3O STRATIGRAPHY THE MONONGAHELA SERIES. 



Ft. Jn. 



The cannel bone, coming at the middle of the seam, rep- 

 resents the three bands of bony coal usually found throughout 

 northern West Virginia and western Pennsylvania. Not only 

 have two of these bands disappeared in Gilmer, but also the 

 . one remaining is pure enough to burn as freely as the re- 

 mainder of the seam, and hence is not separated in mining. 



The outcrop of the coal, in those regions where it has 

 minable thickness, is shown on Map II. In other regions 

 where its horizon outcrops, but has little or no thickness, it is 

 not shown as a coal outcrop, but its position may readily be 

 noted on the map by the base of the Monongahela Series, 

 with which it coincides. 



The thickness, chemical quality and distribution, to- 

 gether with numerous detailed sections of mines examined, 

 will be presented in detail in Chapter XI, under the subject 

 of "Coal." 



