842 FLOKAL ZONES OF THE POTTSVILLE FOKMATION. 



crest of Sharp Mountain, it was concluded that the crest of the moun- 

 tain had shifted to the lower conglomerates of the Pottsville forma- 

 tion. Hence it was natural that, as we shall presently see, the approx- 

 imate outcrop of the Buck Mountain bed, or its equivalent, should be 

 mapped from Black Spring Gap to Rattling Run, a distance of over 

 12 miles, as the "lowest Lj'kens Valley' " bed. 



SECTION AT BLACK SPRING GAP. 



(Station 19, Pi.. CLXXX.) 



The section at Black Spring Gap has been described by both Taylor^ 

 and Rogers." A somewhat complete ' representation of the coal beds 

 above the Pottsville formation is given in section 7, columnar-section 

 sheet viii, Atlas Southern Anthracite Field, Pt. IV. A cross section 

 is given on cross-section sheet xxi, Pt. VI of the Atlas. Reference 

 to these publications reveals the fact that the sections begin with the 

 top bed of Pottsville conglomerates and extend upward in the Coal 

 Measures. This, as was just remarked, is the natural result of the 

 identification of the lower coals in the Lower Coal Measures with the 

 Lykens coals. The section which I give in PI. CLXXXVI, Fig. 2, is 

 an imperfect one, since only a portion of the thickness of the massive 

 conglomerates of the Pottsville is visible. It will be observed, how- 

 ever, that the upper ])ed of the red shale, which is fixed with a fair 

 degree of precision in the section, is approximately 1,150 feet below 

 the horizon of the coal I suppose to represent the Buck Mountain 

 (Twin) b(Hl. It will be noted, also, that the composition of the forma- 

 tion in the Dauphin Basin is essentialh^ the same as that along Sharp 

 Mountain, in the region of Pottsville. Especially noticeable is the 

 great group of conglomerates which occur at the top of the formation, 

 and which form the crest of Sharp Mountain from Fishing Creek 

 nearly to the Big Flats. No evidence of serious search for the Lykens 

 coals appears in this region within the limits of the Pottsville formation. 



SECTION AT <;OLI) MINE (iAP. 

 (Statio.n 'JO, PL. CLXXX. I 



The topography of Sharp Mountain in this district and the locations 

 of the drifts at Gold Mine Gap are shown in mine sheet xxii. Atlas 

 Southern Anthracite Field. Pt. IV. The topography may be seen on 

 the Lykens sheet of the Topographic Atlas of the United States. 

 Descriptions of the coals north of the crest of the mountain are given 

 by Taylor,^ Rogers,* and Smith," the fornuM- of whom ])ublishe(l a 



'Report on the Stony Creek Estate, Pt. II, p. 16, pi. 147, fig. (i. 



-Geol. Pennsylviiniii, Vol. II, Pt. I, p. 195, fig. 181. See also Taylor's Report on tlie Swuturu .Mining 

 District, l.s:59, p. IH. 



^ Report on the Stony Creek E.stttte, Pt. II. i>. 19, pi. 117, fig. 5. 



njeol. Pennsylvania. Vol. II, Pt. I, p. P.t.i. 



•'•Summary Final Kciiorl, Vol. III. Pt. I. p. 'Jill. De.scriptive notes are also cDiitained in the early 

 Report on the .'rwatara Mine Distriet, l.s;i9. ]>. is. 



