Williams.] WORTHEN, ASHBURNER. 113 



feet in thickness, aud one of the most persistent and characteristic 

 members of the Vespertine. With this should probably be couuted 500 

 feet of underlying, more argillaceous flags, giving a total of 560 feet 

 for tbe lower member of the strata in this section. The middle mem- 

 ber, 350 feet thick, is characterized by the predominance of gray sand- 

 stones containing coal. The upper member consists almost entirely of 

 red marlites, with a thickness of about 250 feet, giving the group a to- 

 tal thickness of 1,160 feet. Although the author does not altogether 

 agree with Prof. Eogers in his measurements, he thinks that they show 

 a considerable thickening of the red overlying strata to the south. 



In Augusta County there is great contortion and disturbance of the 

 strata. To the west of this they have suffered much from erosion, and 

 show only the lower and middle members. Tbe Vespertine of Mont- 

 gomery County is treated at great length. The two areas of Brush 

 Mountain and Price's Mountain, separated from each other by a nar- 

 row belt of Lower Silurian limestoue, are described, aud a detailed sec- 

 tion of the lower and middle members of the series exposed at Brush 

 Mountain is given. The lower member shows a thickness of 930 feet, 

 and the middle member is 670 feet thick, but the upper red member is 

 much better displayed at Price's Mountain, where it has a thickness of 

 1,090 feet. 



The conclusion drawn by the author from the facts stated is " that 

 there has been a very marked thickening of the Vespertine as we pro- 

 ceed from north to south through the State, accompanied by an increase 

 in the amount of coal contained in it. Thisincrease seems to belargely 

 at tbe expense of the supposed Catskill beds. It is in conformity with 

 a law of increase which holds good for all the strata from the Devonian 

 to, aud iucluding, the Lower Barren Measures of the Upper Coals." 1 



But few species of plants were found, but these were marked by the 

 great number of individuals exhibited. The most important were forms 

 of Lepidodendron, Palceopteris, and Triphyllopteris, and one specimen of 

 Neuropteris. 



In 1878, 2 C. A. Ashburner, reported the following section across south- 

 ern Huntingdon County. 3 



Feet. 



XIII. Carboniferous, Lower Productive Co al Measures, Alleghany River series 256 



XII. Potts ville Conglomerate (= Serai Conglomerate) 280 



XI. Mauch Chunk (Umbral) red shale and Mountain limestone 



XIc. Upper Mauch Chunk shales and sandstones 910 



XI6. Mountain limestone 49 



(" Lewisburg limestone " of the Greenbrier region in Virginia ; 

 St. Louis and Chester limestone of the Mississippi Valley.) 



XIa. Lower shales and sandstones 141 



»P.122. 



2 Geol. Survey of Pennsylvania, Report of Progress, F : Report on tbe Juniata River district in Mif- 

 flin, Snyder, and Huntiugdou Counties, by J. H. Dewees ; and on the Aughrack Valley and East 

 Broad Top region, in Huntingdon County, by C A. Ashburner, 1878, pp. 305. 

 8 Report of Progress, F, pp. 184-2G0. 



Bull. 80 8 



