WHITE] vvestp:rn limit of sharp mountain fault. 841 



Pottsville in the Black Spring Gap. in order to eonlirni the relation of 

 the coals in Fishing- Creek Gap to the Pottsville formation, since an 

 examination of the south slope of the mountain a half mile west of 

 Fishing Creek Gap leaves little room to doubt that long ])efore we 

 reach a point in Sharp Mountain opposite the Fishing Creek Gap in 

 the Second ^Mountain the entire thickness of the Pottsville formation 

 is present in normal sequence between the Mauch Chunk and the 

 Lower Coal Measures. 



In this connection it is interesting to observe that the displacement 

 involved in the reappearance of the Pottsville and the restoration in 

 its normal attitude of the red shale is compensated ])y a marked offset 

 of the Pocono (Vespertine) and Catskill in Second Mountain east of 

 and at the Fishing Creek Gap in the latter. This feature is clearh^ 

 brought out on the Pine Grove sheet of the Topographic Atlas of the 

 United States.' 



In passing it is proper to observe that the position of the '•South" 

 coal in the Fishing Creek Gap at 350 feet or more above the horizon 

 of the Buck Mountain bed effectually precludes the existence of any 

 considerable portion of the Pottsville formation 'at the south end of 

 the section in the Lorberry Gap, provided the coi-relation of the 

 lower coals in ])oth gaps by the Penns3"lvania geologists is well 

 founded. For my ©wn part, I am slightl}^ disposed to consider the 

 '■"South" bed at the latter gap as not very far above the base of the 

 Lower Coal Measures. 



If we hypothetically treat the South bed as a possible representative 

 of the Skidmore coal, farther to the east along Sharp Mountain, the 

 Lorljerr}' Gap section may with great interest be better compared 

 with that of the water-level tunnel at Dundas colliery No. 0, at the 

 foot of Sharp ^Mountain, a few miles to the eastward, pul)lished in 

 columnar-section sheet viii. Atlas Southei'n Anthracite Field, Pt. IV. 

 If the Fishing Creek section, PI. CLXXXVI, Fig. 1, be also compared 

 with the Dundas section, the stratigraphic sequence in the region of 

 the lower coals in the former will l)e found to be highl}' suggestive of 

 that in the vit-inity of the Homes and Primrose coals at Dundas. 



POSITION OF the pottsville FORMATION ALONG SHARP 



MOUNTAIN. 



T© ignorance of the striitigraphic displacement at Lorberry Gap 

 and Fishing Creek Gap, and the consequent erroneous identification 

 of the coals in those gaps as Lykens coals, is directlj^ due the omis- 

 sion of the true Pottsville formation from the region to the west 

 mapped as coal-l)earing. For, since, in tracing these Coal Measures 

 coals westward, they were f oun d to lie wholly to the north of the 



'Lorberry Gajj and the gaps occupied by Fishing Creek in both Sharp and Second mountains 

 evidently owe their existence to the structural weakness near the displacements. 



