110 THE DEVONIAN AND CARBONIFEROUS. Ibull.80. 



The Meadville group consists of — 



Meadville upper shales. 

 Meadville upper limestone. 1 

 Meadville lower shales. 

 Sharpsville upper sandstone. 

 Meadville lower limestone. 

 Sharpsville lower sandstone. 

 Orangeville shales. 



The Oil Lake group is correlated with the Berea grit of Ohio, the 

 Pithole Grit of Venango, and the Pocouo sandstone, No. X, of more 

 eastern sections in Pennsylvania. 2 It is composed of the — 



Corry sandstone (= Third Mountain sand of Venango). 

 Cussewago limestone. 



Cussewago shales ( = Bedford red shale formation of Ohio). 

 Cussewago sandstone. 



Regarding the formations below this there was still (1881) considera- 

 ble difference of opinion among the several members of the Second 

 Survey of Pennsylvania. Mr. White, in Report QQQQ, correlated the 

 outcrops of Erie and Crawford Counties as follows: 



Venango oil sand group: 



Venango upper sand (first oil sand). 



Venango upper shale. 



Venango middle sandstone (second oil sand). 



Venango lower shales. 



i Le Bcouf conglomerate. 



Venango lower sandstone < Panama conglomerate. 



( Third oil sand. 



The author reported Chemung fossils from the Venango upper sand, 

 the lower shales, and the lower sandstone. 



The author correlated the Venango as "at least in part of Chemung 

 age." He had identified Chemung fossils in the higher Riceville shales. 3 

 In afoot-note 4 he stated that he was "disposed to look upon the Venango 

 group as Upper CJhemung," and "on account of the fossils, I should pre- 

 fer to call these [called Chemung in the text] Lower Chemung." The 

 State geologist, however, objected to this interpretation and in the 

 prefatory letter stated his objections. The substance of this objection 

 is expressed in the following clause : 



Thus the matter stands at present. Geologists who insist on fossil forms will call 

 the Venango group Upper Chemung, and will explain the McKean sections hy a total 

 disappearance of the oil sand in an increased mass of red beds. Geologists who insist 

 upon lithological data will call the Venango group Catskill, or even Pocono, in spite 

 of Chemung fossils. 6 



The latter course appears to have been Mr. White's preference. Below 



1 Containing fossils which the author concludes indicate correlation with the Lower Keokuk or Upper 

 Burlington. 



2 See Q« chapter x, pp. 91-96. » Q\ p. 97. * Q\ p. 117. 6 Q«,p. xi. 



