BROAD TOP FIELD 49 



Lackawanna about midway in the field. Its place is approximately 

 that of the Alpha. Dr I. C. White discovered in Lackawanna county a 

 black shale within 3 or 4 feet of the bottom of the Pottsville, which he 

 named " Campbells Ledge black slate." It contains no coal at the typ- 

 ical locality, but near Nanticoke, in Luzerne county, he found it in part 

 a coal shale.* There, according to Mr Smith, it contains 8 inches of 

 impure coal. It has been recognized as far north as the middle of the 

 Jermyn-Priceville division, where it is somewhat coaly. It has 3d elded 

 immense numbers of fossil plants. 



The thinning out of the Pottsville in this northwesterly direction is 

 due to the loss of its lower members. The Lower Pottsville, so thick in 

 the Southern field, is greatly diminished in the western Middle and 

 wholly disappears in the eastern Middle, as evidently does also much of 

 the Upper Pottsville. The stratigraphical evidence is in accord with 

 Mr David White's conclusion, based on the study of the plant remains, 

 that the Campbells Ledge coal bed can not be older than the Lykens 

 Valley coal bed number l.f 



Broad Top field. — The insignificant area of Mississippian in Fulton 

 county of Pennsylvania represents some portion of the Middle Anthra- 

 cite field, while the Broad Top coal field of Fulton, Bedford, and Hunt- 

 ingdon counties is clearly equivalent to the extension of the Northern 

 field. 



Mr Ashburner found a thickness of 280 feet on the east side of Broad 

 Top, which he divided as follows : 



Feet 



Piedmont sandstone 160 



Mount Savage group 40 



Lower member 80 



The Piedmont sandstone is very largely conglomerate, coarsest in the 

 middle. The Mount Savage group shows above the middle a coal bed 

 which was taken to be the same with that which in Maryland had been 

 termed the " Mount Savage," but there is room for doubt respecting the 

 identification. The lower member is described as a hard massive sand- 

 stone with some conglomerate midway. The coal bed is persistent on 

 this side of the field. J 



Dr I. C. White studied the northerly and northwest side of the field, 

 where he found only 160 feet, in which he recognizes the members of the 

 western Pennsylvania section. 



* I. C. White : Geology of the Susquehanna Region (G 7), 1883, pp. 39-42. 



t David White : Op. cit.. p. 819. 



JC. A. Ashburner : Aughwick Valley and East Broad Top District (F), 1878, p. 191. 



