WHITE.] POTTSVILLE FORMATION ALONG SHARP MOUNTAIN. 843 



cross section. A more complete columnar section of the Productive 

 Coal ^Measures is presented on columnar-section sheet viii, Pt. IV of 

 the Anthracite Atlas. In PI. CLXXXVI, Fig. 3, I give an imperfect 

 section, which is extended in PI. CLXXXVII, Fig. 1, to include the 

 Pottsville formation. In this, as well as in the gaps on either side of 

 Gold Mine, the immense amount of coarse conglomerate blocks, 

 largely furnished by the upper plexus of conglomerates which form 

 the sharp crest of the mountain, usually conceals everything but por- 

 tions of the most enduring ledges. It is, therefore, only by some 

 effort that outcrops of more than the most prominent beds are to 

 be found. For the same reason I have not attempted to definitely 

 show the upper boundarj" of the red shales, which I am convinced 

 can hardly be less than 1,130 feet below the horizon of the Buck 

 Mountain (Twin) coal. 



It is interesting to note a certain degree of regularity in the group 

 of conglomerates at the top of the Pottsville. This appears on a com- 

 parison of the Gold ]Mine Gap section with the sections at Rausch 

 Gap (PI. CLXXXVII, Fig. 2) and Black Spring Gap (PI. CLXXXVI, 

 Fig. 2), to both of which these outcropping backbone ledges may 

 easih' be traced. A similar development exists at the Rausch Gap in 

 Schuylkill County (Station 4, PI. CLXXX), in which the Buck Moun- 

 tain coal is similarly disposed. 



From the mine dump, consisting of material from probably more 

 than one of the coals drifted on the east side of the gap, were obtained 

 the following species, which evidently represent a characteristically 

 Productive Coal Measures flora: 



Pecopteris unita Brongn. 



Pecopteris arguta Sternb.? 



Pecopteris arborescens (Schloth.) Brongn. 



Pecopteris squamosa Lx. 



Pecopteris oreopteridia (Schloth.) Sternb. 



Pecopteris cf. elHptica Bunb. ? 



Pecopteris polymorpha Brongn. 



Alethopteris pennsylvanica Lx.? 



Caniptericlium Grandini (Brongn.) Lx. ? 



Neuroi^teris ovata Hoffm. 

 Neuropteris vermicularis Lx. 

 Neuropteris fimbriata Lx. 

 Neuropteris Clarksoni Lx. 

 Neuropteris Scheuchzeri Hoffm. 

 Neuropteris Rogersi Lx. 

 LepidophyUum inajus Brongn. ? 

 Cordaites sp. 



The following species were also collected on the west side in the gap: 



Pecopteris polymorpha Brongn. 

 Pecopteris cf. Newberryi F. and W. 

 Neuropteris ovata Hoffm. 

 Neuropteris Scheuchzeri Hoffm. 



Annularia sphenophylloides (Zenk.) 



Gutb. 

 Sphenophyllnm cf. tiliculnie Lx. 



SECTION AT RAUSCH GAP, LEBANON COUNTY. 



(Station 21, Pl. CLXXX.) 



The Lower Coal Pleasures and the upper beds of the Pottsville forma- 

 tion at Rausch Gap, 3^ miles west of Gold Mine Gap, have been the 



