82-1: FLORAL ZONES OF THE POTTSVILLE FORMATION. 



Roo-ors. for a long distance. It is probable that the errors, which 

 un(lou])tedl3' exist, in the identitication of this horizon in the more 

 distant portions of the field fall within a vertical distance of loo feet, 

 except in tlie Dauphin Basin, which will be specially considered in a 

 lat(>r section. As to the correlation of the A coal at Locust Gap, 

 nortii of Taniacjua. there is still a difference of opinion; and again, in 

 the western i)ortion of the Wiconisco Basin, the place of the Buck 

 ISIountain coal is a matter of speculation. 



The })rol)al)le approximate position of the TavIm coal, wiiich has 

 ))een agr(H>d upon by all the State geologists who have worked in this 

 region as the equivalent of the Buck Mountain coal, along Sharp 

 Mountain throughout the central portion of the field, to which for 

 the present we shall confine ourselves, is shown in mine sheets xiv, 

 xi\(/. XV. and xvi, in the third part of the Atlas of the Southern 

 Anthracite Field. 



FLORA IN THE ROOF SHALES OF THE TWIN COAL. 



Since the fioor of the Buck ^Mountain coal, or its supposed equiva- 

 lent, the Twin coal, forms the ar])itrary line between the Pottsville 

 formation and the succtHnling Coal Measures, the flora in the roof 

 shales of this coal maj^ be regarded as representing the basal horizon 

 of the Lower Coal Measures.^ It therefore marks the upper limit of 

 the Pottsvilh^, as that formation has, so far as I can learn, been defined, 

 with reference to the type section, ])v the various geologists of the 

 State. The localities whose plants are listed below are all mines or 

 drifts, chosen from the central regions of the field, l)etween the Potts- 

 ville^ Cap on the east and Tremont on the west. Over these the Twin 

 coal has l)een probably correctly I'ecognized. it being of good body 

 and (juality over nuich of this territory. 



(A) Pottsville Gap: Station 1. PI. CLXXX.' P'rom the Twin coal, 

 whose position in the type section is illustrated in PI. CLXXXI. were 

 ol)taiiied the following species:* 



IVcopteris ck'iitata Brongn. 

 Pec'uptcriH arguta Sternh). 

 Pecopteris viiiita Brongn. 

 Pecopteris CandoUiana Brongn. 

 PfcopterisorcopU'ridia (Schloth.) Sternb. 

 Pfciipti'ris ^liltniii Artis. 



Neuroptoris Seheuclizeri Hoffni. 

 Annularia s^teUata (Sohloth.) "Wood. 

 Splienophylluni eniarginatnin Brongn. 

 Lepidodendron np. indct. 

 Bigillaria tessellata (iSteinh.) Urongn. 



(T.) Swatara Gap: Station 8, PI. CLXXX. Li this gap the Twin 

 coal was formerh^ mined on l)oth sides, the more extensive operation 



'Rogers, Geo). Pennsylvania, Vol. H, Pt. I, p. 140. 



-Atlu.'f Soull^eni Anthnicitu Field, Pt. II, mine sheet.s xiv, xiva. 



•'It should be distinctly understood that the identifications on which arc ba.sed the following lists 

 of species from the Productive Coal Mea.sures in the Southern Anthracite field are merely temporary 

 and provisional. As such they are subject to revisicm. Most of the names here given may be inter- 

 preted as designating the sjime forms to which they were npi>lie<l by Professor Lesciuereux. 



