16 If. .1. VenrU-Jh —Berea Formal ion. 



The former described it under the heading of Oil Lake 

 group, which consists in descending order of the Corrj sand- 

 stone, CussewagO shales and Oussewago sandstone. Mr. Butts 

 published a continuous section along the Allegheny River from 

 the New York state line to Emlenton in the southern part of 

 Venango Co., Pa. (See fig. 2.) In discussing the section he 

 states: "The Berea sandstone lying 300 feet above the Sala- 

 manca can be identified by its characteristic fossils in every 

 section down to the bend of the river 2 miles south of Tionesta, 

 where it passes below the railroad grade. About 160 feet 

 above the Berea and separated from it mainly by blue shale, is 

 a rather thin-bedded, generally fine-grained, sandstone. This 

 was traced with a good degree of certainty from two miles 

 south of Tidioute to a point about one mile south of Hunter, 

 from which point it is exposed at many places near railroad 

 level and was traced continuously to Oleopolis. A similar and 

 probably the same sandstone is exposed at Oil City at railroad 

 level and dips below the railroad about one and one-half miles 

 south of Oil City."* 



From the above it will be seen that the literature covered 

 pretty thoroughly the correlation of the Berea in Ohio and 

 Pennsylvania, as well as the extent of the formation in north- 

 eastern Ohio, Crawford and Erie counties in Pennsylvania, and 

 apparently along the Allegheny River. There remained sim- 

 ply to fill in the gap between Crawford Co. and the Allegheny 

 River, involving a survey of parts of Venango, Forest and 

 Warren counties. (Compare fig. 2.) This part of the work 

 was undertaken by the writer during the summer of 1915. 

 After a careful study of the Berea in Ohio it was traced con- 

 tinuously from the boundary line of Ohio and Pennsylvania 

 across Crawford Co. to the Allegheny River. Many sections 

 were made along this line, the most important of which will be 

 found in fig. 1, and in greater detail at the end of this discus- 

 sion. As a result of this work the following conclusions were 

 reached : 



1. The Berea formation is represented in Pennsylvania by 

 the Corry sandstone, and the Cussewago shale and sandstone 

 of I. C. White. 



2. The Corry sandstone increases in thickness when followed 

 eastward from the state line, attaining a thickness of about 50 

 feet along the Allegheny River. (See fig. 1, section E and 

 following sections.) 



3. The Corry sandstone becomes gradually coarser toward 

 the east, changing from a rather fine-grained, even-textured 

 rock along the state line to a coarse-grained, pebbly sandrock 

 (at least in its upper part) on the Allegheny River. 



* Idem, p. 192. 



