~>4 II". A. Wnriebe — Berea Formation. 



Thus L. H. Woolsey* defines the Pocono as extending from 

 the top of the Burgoon to the base of the Berea, which is cor- 

 rectly identified in this bulletin, and lies about 350 feet below 

 the top of the Burgoon. No doubt other investigators had 

 this in mind when they included the rocks down to the base of 

 the Hundred-foot in the Pocono, since they considered it the 

 equivalent of the Berea. 



Summarizing briefly the above, we would then have the fol- 

 lowing correlation of oil sands in western Pennsylvania : 



Burgoon = = Big Injun (as explained above) 



Pocono \ ( Murrysville or 



Berea = = 1 Butler Gas or 1st sand 



( Butler Thirty-foot , 



( Hundred-foot or Gantz & Fifty- 

 Venango 1st = = •<] foot 



( Butler 2d. 



The literature dealing with the stratigraphy to the north is 

 not so voluminous. Perhaps the most important recent work 

 published is that of the Warren quadranglef and the section 

 along the Allegheny Kivei'4 The latter was discussed some- 

 what in the preceding pages. It may be added that it appears 

 probable that the interval between the 1st Venango oil sand 

 (called " Berea ") and the Shenango sandstone was named 

 Cuyahoga simply because the Berea was used as the key forma- 

 tion and hence with a total disregard of other evidence. This 

 interval corresponds to the Riceville in its lower part (from the 

 top of the Venango oil sand (Berea) to the base of the Berea 

 (middle Cuyahoga sandstone), and would be left without a 

 name in Butts's classification. That part of the section between 

 Butts's middle Cuyahoga sandstone and the base of the She- 

 nango sandstone will then become the Cuyahoga formation and 

 l-epresent it in toto. The section along the Allegheny River, 

 reconstructed in this manner, will then appear as in section K 2 

 of fig. 1. 



The Berea can be traced with ease along the Allegheny from 

 Venango county north toward Warren ; and it will be found 

 to disappear from the section about a mile south of Tidioute, 

 being absent north of this point because of erosion. This fact 

 will necessitate a revision of the geologic section in the Warren 

 quadrangle. The succession in the quadrangle is given as 

 follows :§ 



*Eeon. Geol. Beaver Quad. , U. S. G. S., Bull. No. 286, 1906. 

 t Butts, Chas., U. S. Geol. Survey, Folio No. 172, 1910. 

 \ Butts, Chas., Pre-Pennsylvanian Stratigraphy, Eept. Topog. & Geol. 

 Surv. Comm. of Pennsylvania, 190G-1908. 

 § U. S. Geol. Survey, Folio No. 172, p. 23, fig. 5, 1910. 



