WHITE] POTTSVILLE FORMATION ALONG SHARP MOUNTAIN. 845 



2 miles in leng'th of the Coal Measures valley, finds an escape. The 

 topography of the vicinity is shown on the Hummelstown sheet of the 

 Topographic Atias of the United States and mine sheet xxiv of the 

 Southern Anthracite Atlas, the latter of which locates the points of 

 exploitation. Descriptions of the coals are given by Tajdor,' and 

 quoted l)y Rogers" and Smith.'' Crosss sections of the basin at this 

 point are given by Taylor, and by the geological survey of the State in 

 cross-section sheet xxi, Pt. VI of the Anthracite Atlas. All the 

 information in the later reports relating to Sharp Mountain appears 

 to have been derived from Taylor's report, printed in 1840. 



At this gap the Pottsville appears to present its ordinary characters 

 and its full thickness. The conditions for the'discovery of the upper 

 boundary of the Mauch Chunk shale are not favorable, but it is quite 

 certain that the red shale is not present at 960 feet below the supposed 

 horizon of the Buck ]Mountain coal. No prospecting appears to have 

 been done in the Pottsville formation at this gap since the publication 

 of the report by Taylor, who states that none of the coals on the south 

 slope of Sharp ]\Iountain had been opened or sought. However, in 

 some early explorations, carried on in 1824, a tunnel driven through 

 the upper portion of the Pottsville formation in the gap penetrated a 

 bed of good coal, which. Dr. Taylor adds, was "not fully proven." 

 The rock dump taken from a shaft which appears to have been located 

 on this bed contains the following species: 



Eremopteris decipieng. 



Mariopteris tennesseeaiia var. hirsuta. 



Sphenopteris palmatiloba var. squarrosa. 



Megalopteris plumosa. 



Neriopteritf lanceolata. 



Neuropteris tennesseeaiia. 



This flora will at once be recognized as clearly referable to the 

 Sewanee zone; and it can hardly be lower than Lykens coal No. 3. 

 The variety of Sjjhenopterls palmatiloha, the variety of Cardiocarpon 

 hkmpklatam, and Bothrodendron arhorescens appear to bind the flora 

 somewhat closely to that of the horizon of Lykens No. 1. Through 

 Ernnopti'vk declpiens and Cardiocarpmi Wilcoxi the flora seems to be 

 related to that of the Sharon coal of northwestern Pennsylvania, and 

 it is worthy of mention that Nenopterh lanceolata, found at Yellow 

 Springs, has hitherto been known only from the sandy shales at some 

 distance above the Sharon coal, in northwestern Ohio. On the whole, 

 I am slightly disposed to regard the horizon of the plants at Yellow 

 Springs as higher than that of the Lykens coal No. 2. 



The stratigraphic distance of this horizon below that of the Buck 



1 Reports on the Stony Greek Estate, Pt. I, p. 52. 

 " Oeol. IVnnsylvania, Vol. II, Pt. I, p. 19(J, fig. 183. 

 asuinmary Final Report, Vol. Ill, Pt. I, p. 2145. 



Calamostachys Knowltoniana. 

 Bothrodendron arboreseeii!^. 

 Cordaites Robbii. 



Cardiocarpon biscupidatuni var.oliioense. 

 Cardiocarpon Wilcoxi. 



