W. A. Verwiehe — Berea Formation. 47 



4. A limestone layer (Cussewago limestone) is practically 

 always to be found immediately underlying the Corry, or sepa- 

 rated from it by a few inches of shale. This varies in thick- 

 ness from 8 inches to 1 foot 10 inches. (See sections E, F, 

 and I.) 



5. The Cussewago sandstone thins out and disappears from 

 the section about longitude 80° 5' W.; though it may be repre- 

 sented farther east by a part of the shales and sandstones 

 underlying the Corry. 



6. The Corry sandstone is represented along the Allegheny 

 River by the sandstone indicated on Mr. Butts' diagram as 

 lying about 160 feet above the sandstone labelled " Berea 

 (Corry)." See the quotation above and compare the sections 

 K, L, and M in fig. 1.) 



7. The Berea is absent along the Allegheny River north of 

 Tidioute. The sandstone, regarded by Butts as the Berea, north 

 of this point, is probably the Venango first oil sand. 



The evidence for the conclusions enumerated above is based 

 on paleontology, lithologic character, and on stratigraphic posi- 

 tion. It is a well-known fact that clean sandstones are not 

 adapted to the preservation of life forms. It occasions no sur- 

 prise therefore to find that fossils are very rare in the Berea 

 formation. It is true that some have been reported by Orton, 

 White, and others ; however, for practical stratigraphic pur- 

 poses the formation may be considered unfossiliferons. Still 

 this very fact proves itself an important factor in the identifica- 

 tion of the formation, inasmuch as the sandstones above and 

 below, viz., the Shenango sandstone and the Venango first oil 

 sands are not unfossiliferons. Hence the paleontologic evi- 

 dence, though negative, is considered of importance. 



The lithologic character is rather more valuable. For this 

 purpose the Corry phase is most consistent. It is almost always 

 a fine to medium-grained sandstone, of very uniform texture, 

 and very compact. Also its color is a very persistent charac- 

 teristic, being a bluish-grey in the unaltered rock, and almost 

 invariably a buff in the weathered rock. The Cussewago 

 shales, on the other hand, are very unreliable, inasmuch as they 

 may be arenaceous or argillaceous, bluish-grey, drab, olive-grey 

 or buff ; and are frequently ferruginous and micaceous. In 

 addition they may be largely replaced by flaggy sandstones of 

 a similarly varying nature. The Cussewago sandstone phase 

 when typically developed is unmistakable. It is a coarse, 

 loosely-cemented, much discolored sandstone, breaking down 

 readily into an incoherent mass. However, its extent is very 

 limited, and it seems to be more or less lenticular, which is well 

 illustrated by the sections in fig. 1. So far as the writer is 

 aware it does not occur west of longitude 81° nor east of longi- 

 tude 80° W. 



