POTTS VILLE CONGLOMERATE. G 5 . 51 



county, close up to the Wayne county line ; beyond which 

 the bed has not been found, and does not probably exist ; 

 for the rise in that direction is rapid. 



The Bottom conglomerate is separated from the top rock 

 (Scranton sandstone) by 179' or 188' of measures, at Scran- 

 ton, (Figs. 1 and 2,) and 179' at Forest City, (Fig. 3,) sup- 

 posing the 13' sandstone of the bore hole to represent the 

 bottom layers of the Scranton sandstone, and the 28' 1" of 

 the bore hole to represent the upper member of the bottom 

 conglomerate. But the details of this interval, in both the 

 Scranton sections, were not measured with absolute accuracy, 

 the rise being pretty steep ; but their relative thicknesses 

 must be a close approximation to the truth ; the maximum 

 of error in either section cannot exceed 10' or 15'. 



The sand-rock layers in this interval are mostly bluish - 

 gray ; quite hard ; generally free from pebbles ; and, indi- 

 vidually considered, variable in thickness, without affecting 

 seriously the regular thickness of the whole. 



Tlie Bottom conglomerate, which at Scranton, on Roaring 

 run, is about 100' thick, * very massive, but split into several 

 distinct layers, separated by very thin shales or coaly slates, 

 is subdivided in the same manner at Forest City, as the dia- 

 mond-drill record shows. 



The rock is always quite pebbly, although a few of its lay- 

 ers may be quite free from them ; but towards the bottom 

 the pebbles become more plentiful and larger ; often 2" to 

 3" long by 1" to 2" thick ; most of them rounded, or water- 

 rolled ; most of them of white quartz, sometimes stained a 

 dirty, yellowish brown ; imbedded in a matrix of coarse 

 sand, varying in color from buff to gray, and occasionally of 

 a somber mud color. I met with places where the lower part 

 of the mass was a mere mass of pebbles (quartz) cemented 

 together. Between Way mart and Carbondale, for example, 

 a 20' ledge of snow-white quartz pebbles, at the very base 

 of XII, has been quarried for glass sand. 



In the few hundred acres occupied by this formation on 



* Prof. Rogers makes the average thickness of XII in the Scranton coal- 

 field 80'. (See Geol. Penn. 1858, Vol. II., p. 239.) 



