ALLEGHENY AND CONEMAUGH IN ANTHRACITE FIELDS 217 



Feet 



24. Interval 180 



25. Little Orchard coal bed 



26. Interval 27 



27. Orchard coal bed 



28. Interval 110 



29. Primrose coal bed 



30. Interval 55 



31. Holmes coal bed 



32. Interval 115 



33. Seven-foOt coal bed 



34. Interval 20 



35. Mammoth coal bed 



36. Interval 75 



37. Skidmore coal bed 



38. Interval 143 



39. Buck Mountain coal bed 



each of the intervals being true only for the single locality at which the 

 measurement was made.* 



The Buck Mountain coal bed is the conventional boundary between 

 Pottsville and higher measures, and it is taken here as the bottom of the 

 Allegheny, to conform with usage in an earlier part of this work; but 

 Mr David White has offered cogent reasons against accepting this plane 

 of division. They will be referred to in another connection. The beds 

 below the Holmes are known as "White ash," while that bed and those 

 above are known as "Bed Ash" beds. This distinction, however, is not 

 absolute, as ash from the Mammoth and lower beds frequently shows the 

 red tint, f 



Several of the coal beds in both fields divide and subdivide even more 

 perplexingly than do those of the Pottsville, in the Kanawha region, and 

 intervals between the principal coal beds show abrupt variations. Were 

 it not for great mining operations, extending continuously, in some cases 

 for many miles, positive correlation would be impossible; but in those 

 mines the "splits" have been followed as they separated and again 

 united, so that no doubt remains respecting some of the most remarkable 

 variations within the beds and in the intervals separating them. 



The Buck Mountain coal bed is present in both fields. It is hardly 

 recognizable in the western prongs of the southern field, but is 2 feet to 3 

 feet 6 inches thick just east from the union of the prongs, where it is 

 slaty and impure; thence eastwardly it increases in importance until at 

 Pottsville and beyond it is inferior only to the Mammoth, the thickness on 



* Final Report, plate 366, opposite p. 2076. 



j- According to analyses tabulated by Mr Asbburner in Annual Report for 1885, pp. 

 314-315. 



