82S 



FLOKAL ZONES OF THE POTTSVILLE FORMATION". 



Here the Twin coul has l)oon apparently (lefiiiitely identified at about 830 

 feet above the red shale, and is now ])eing mined. From the roof shales 

 over this coal was obtained a flora whose character will at once be recog- 

 nized as similar to that contained in the Pottsville-Tremont district: 



ERMnopteris! ci. arteiuisiajfolia (Stern b.) : Callipteridium Grandini (Brongn.) Lx. 



Srhimp. 

 Pt^cnidopefopteris Hquaniosa (Lx.). 

 Sphenoj)teris nuininularia Gutb. ? 

 Sphenopteris (n. sp.?). 

 Pecopteris dentata Brongn. 

 Pecopterisoreopteridia (Schloth.) Sternb.? 

 Alethopteris Serlii (Brongn.) Goepp. 



Neuropteris ovata Hoffm. 

 Calamites Suckowii Brongn. 

 Calamitcs Cistii Brongn. 

 Annularia stellata (Hchloth.) Wood. 

 Sphenophyllum emarginatnni Brongn. 

 Lepidophyllum affine Lx. ? 

 Lepidocystis quadrangularis Lx.' 



As has already been remarked, some doubt remains as to the indentity 

 of the Twin or Buck Mountain coal in the Locust Gap, in the opposite 

 side of the basin, al)out a mile and a half north of the last locality. At 

 this point occur two coals, A and B, one or the other of which is sup- 

 posed to represent the Buck Mountain coal. Coal A (16 feet in thick- 

 ness), as shown in PI. CLXXXV, Fig. 2, lies about 750 feet above the 

 red shale. Coal B is reported as 202 feet above A on the west side of 

 the gap, and 260 feet on the east side.^ 



From the roof shales of coal A a small flora was obtained, as 

 follows: 



Mariopterismuricata(Schlotli.) Zeill. var. 



nervosa (Brongn.) Kid.st. 

 Sphenopteris pseudomnrrayana Lx.? 

 Neuropteris capitata Lx. 



Neuropteri.s ovata Hoffni. 

 Pecopteris dentata Brongn. 

 Alethopteris aquiUna (Schloth. 



Goepp. 



It is obvious that this, like the floras previously enumerated, is a 

 distinct!}' Coal Measures flora; and I have no hesitation in concluding 

 that the A coal, which has generally been regarded b}^ the geolo- 

 gists who have worked in this region as l)elonging within the Potts- 

 ville formation, is referable rather to the Lower Coal Measures. It 

 is important to mention in this connection that a flora, probably of no 

 earlier age, is also present in the roof of a thin coal about 72 feet 

 below the Twin coal in the type .section at Pottsville. The shales at 

 this horizon in the latter locality have not ])een systematically searched. 

 They are crowded with great numbers of Neuropteris Scheuchzeri^ 

 among which are ]}ve>ie\\i Neuro2)teris rarl rurius^'AWiX small fragments of 

 AxtrropliijUitrx cf. eiiamdifonnlxi^ thus indicating a Lower Coal IVIeas- 

 ures age for this ]»ed as well. It has been suggested by Mr. Smith" 

 that the A coal, which, at the Nesquehoning railwav tunnel, al)out 

 ;> miles ea.st of Locust (lap, has a thickness of ])ut 1 foot, and which, 



1 Probably a Sigillariostrobus. 



2Rept. Geol. Survey I'CMinsylvania, AA, p. IWi; Summary Fitial Report, Vol. HI, Pt. I, \>. 20'J5. The 

 interval is also j?iven as but 115 feet by Ashburiior in Report A, p. 80. 

 sSummary Final Report, Vol. HI, Pt. I, p. 209G. 



