MONONGAHELA FORMATION 43 



more divided and the parting clays show abrupt variations in thickness. 

 This subdivision is characteristic not only in southwest Pennsylvania, 

 but also in Maryland, where the coal is mined on commercial scale. The 

 extreme subdivision was seen in northern Greene county of Pennsyl- 

 vania, where the measurement is : 



Feet Indies 



Coal 1 



Clay 1 



Bone 6 



Coal 1 3 



Clay 6 



Coal 2 2 



Clay 3 



Coal 3 



Clay 4 



Coal 5 



Shale 10 



Coal 8 



in all, 21 feet; but the lowest parting quickly decreases to 2 feet and 

 soon disappears, as do most of the others; so that within 3 miles the 

 bed is double, averages 6 feet in thickness, and shows these variations : 



Inches 



Coal 12 to 18 



Clay 12 to 48 



Coal 12 to 42 



The Waynesburg coal bed is persistent in Monongalia, Marion, eastern 

 Wetzel, northern Doddrige, and northern Harrison of West Virginia, 

 with its chief thickness at the east in the first two coimties, where it at 

 times reaches to almost 12 feet, inclusive of the moderately thick part- 

 ings. Southwardly it disapepars or is so thin that drillers of oil wells 

 thought it not worth recording. It is wanting along the southeastern 

 and southern outcrop, except perhaps at Arbuekle, in Mason county, 

 where Doctor White found a multiple coal bed 268 feet above the Pitts- 

 burg and underlying a pebbly sandstone. This overl3ring rock resembles 

 very closely that seen 240 to 250 feet above the Pittsburg at Antiquity, 

 on the Ohio river, 20 miles north from Arbuekle. That is the Waynes- 

 burg sandstone of the Dunkard. The sandstone observed at Arbuekle 

 seems to be persistent on the southern outcrop, but the underlying coal 

 bed is not. 



Eed beds are unimportant in by far the greater part of the Mononga- 

 hela area; they appear to be wholly absent from Maryland, Pennsyl- 

 vania, northern Ohio, and insignificant along the northern border of 



