EASTERN EDGE OF ALLEGHENY PLATEAU 51 



forms similar to those in the Campbell Ledge shale of the Northern field. 

 Serious objection to this identification was offered at the time because of 

 the small interval to the Pocono ; but this objection is without basis, for 

 the westward thinning of Mauch Chunk and Pocono has been proved 

 abundantly.* Somewhat later Mr Hill made a reconnaissance of this 

 Mehoopany region and succeeded in securing sections which proved that 

 the coal is at the bottom of the Pottsville, as Doctor White had asserted. 

 The coal is 2 feet 10 inches to 3 feet 8 inches thick, impure at the bottom, 

 and resting on fireclay. The Sharon sandstone is absent.f Samples of 

 this coal had been procured in 1879 and were analyzed by Mr A. S. Mc- 

 Creath. It has a fuel ratio of 6.1 and 5.1 in the two benches, thus 

 showing a composition very like that of the Lykens Valley coal. J 



The Bernice coal field of Sullivan, west from Wyoming, was studied 

 by Mr Piatt, who there found two coal beds, A and B, 60 feet apart. 

 He evidently regarded both coal beds as belonging to the Allegheny, for 

 he gives the Pottsville thickness as but 70 feet, that being the distance 

 from the lower coal A to the Lower Carboniferous red shales at the west 

 end of the basin. In one place he refers to a massive conglomerate 

 above coal bed A, and in another describes a lower conglomerate, 

 below the coal bed, as coarser than that above. His sections show that 

 52 feet of massive rock overlie coal bed A, while below it are 60 to 70 

 feet, making the total thickness not far from 120 feet. Mr Ashburner 

 gives the thickness as from 100 to 110 feet.§ 



This little field was studied carefully by Mr Ashburner and also by 

 Mr C. R. Claghorn, whose work is quoted by Mr Smith. They regard 

 both beds as Pottsville, and Mr Claghorn estimates the thickness of the 

 formation at 180 feet. Mr Smith, however, thinks that only the lower 

 bed is Pottsville, looking on the upper bed as the equivalent of the 

 anthracite Buck Mountain. The character of the rocks supports this 

 conclusion, which is strengthened further by the relations of the plant 

 remains, as determined by Mr David White. This is not the Campbells 

 Ledge bed ; it may be at the horizon of the upper bed of the Northern 

 field, at the Mercer horizon. || Clearly the Sharon sandstone is lacking 

 in this area. 



The composition of coal from this lower bed shows strange variations. 

 Samples obtained from the western end of the petty area have a fuel 

 ratio of 8.4 with less than 1.5 per cent of water, whereas two samples from 



* I. C White : Geology of the Susquehanna Region (G 7), 1883, p. 43. 

 |F. A. Hill : Ann. Rep. Geol. Survey for 1885, pp. 486 to 490. 



tA. S. MeCreath, quoted by F. Piatt: Geology of Lycoming and Sullivan Counties (G 2), 1830, 

 p. 226. 



I Franklin Piatt : (G2), pp. 173, 187, 199. 



C. A. Ashburner : Ann. Rep. for 1885, p. 466. 

 || A. DW, Smith : Final Report, 1895, p 2009. 



