80-4 FLORAL ZONES OF THE POTTSVILLE FORMATION. 



be made with precision or close approxinmtion. lias an important l)ear- 

 ing on the geographic extent and economic condition of the several coals. 

 AVith few exceptions the beds discussed are located on the mine maps, 

 while generally they will be found approximately if not exactly 

 identitied in the cross-section and columnar-section sheets of the Atlas 

 of the Southern Anthracite Field. 



Proceeding along the upturned edge of the coal field in Sharp 

 Mountain, west of Pottsville, we shall consider: 



1. Drifts! hi tlu' Loicer Lyl'ens division in Swcdara Gap. Station 3, 

 PI. CLXXX. Two of the Pottsville coals have been drifted at a little 

 above water level in this gap. The geographic positions of the open- 

 ings are shown in mine sheet xvi. Atlas Southern Anthracite Field, 

 Pt. III. The structure of this portion of the basin is illustrated in 

 section 23, cross-section sheet xvi. Atlas Southern Anthracite Field, 

 Pt. VI. From the upper of the coals, which is about \AS) feet below 

 the "Buck Mountain "" (Twin) coal, as identified by the State survey in 

 this gap. no fossil plants were obtained. The roof shales from the 

 lower coal, mined to a slight extent on both sides of the gap. have fur- 

 nished species as follows: 



Xeuropteris Smithsii. 

 Whittleseya Campbelli. 



Mariopteris pottsvillea. 



Neuropteris Pocahontas. 



Xeuropteris Pocahontas var. iniiequalis. 



These species, though few. are always common in the roof shales of 

 Lykens coal No, 4, of which the first and fourth named are especially 

 characteristic. The inference that this coal, which was mapped by 

 the late State survey as Lykens coal No. 6, is more probably the 

 Lykens coal No. 4, as indicated by the fossils, is further supported by 

 the thickness of the rock (about 600 feet) between it and the Buck 

 Mountain coal. That this coal is as old as Lykens coal No. 6 seems 

 very improljable. 



2. Bausch Gap^ Schuylkill County. Station -I, PI. CLXXX. At 

 Rausch Gap, 1 mile west of Swatara Gap, two of the Lykens coals have 

 ] )een driven into for some distance. The district is shownon mine sheet 

 xvi, Pt. Ill of the Atlas of the Southern Anthracite Field. The struc- 

 ture, consisting of a slightly overturned (70^ dip) south liml) of the 

 deep Coal Measures basin, is similar to that at Swatara Gap. The 

 section at this point, as compiled from the incomplete conglomerate 

 exposures in the gap. is shown in PI. CLXXXV, Fig. 1. 



From the lower of the two coals mentioned, about 975 feet below 

 the representative of the Buck ^Mountain coal, at the opening on the 

 east side of the gap, there have been gathered the following: 



Mariopteris eremopteroicles ? Lepi'lostrobiis inMiiisylvanicus. 



Neuropteris Pocahontas var. inaMiualis. \ Trigonocarpuni anipulkeforme. 



