GEOLOGIC MAP OF THE BUFFALO QUADRANGLE 25 



shale occur, but these are quite rare and very thin, and also rows 

 of spheric or oblong and flattened concretions. Eight feet of the 

 shales at the top of the beds are somewhat darker and harder than 

 those below. 



The Cashaqua beds are 3 2 feet thick in the exposure at the south 

 shore cliffs and in the bed of Pike creek at North Evans. They 

 extend in long flat outcrops in the bed and banks of Smoke's creek, 

 ^ mile south of the upper electric railroad bridge atWindom, and 

 are slightly exposed along the roadside on the hill above the school- 

 house I mile south of Big Tree. 



The average thickness of the formation on this quadrangle is 45 

 feet. The thickness increases toward the east and is 165 feet in 

 the Genesee river gorge at Mt Morris and along Cashaqua creek 

 above Sonyea; and at Naples, in Ontario county, it even attains 

 230 feet. 



Nearly all of the northward flowing streams in the eastern part of 

 Erie county and in Wyoming, Livingston and Ontario counties 

 have excavated ravines in the Cashaqua shales, producing large 

 and favorable exposures. Among the best of these are: the ravine 

 of Murder creek at Griswold on the Erie Railroad 6 miles west of 

 Attica; in the Oatka river valley in the vicinity of Wyoming; 

 in the Genesee river gorge between Mt Morris and Smoky Hollow ; 

 along Cashaqua creek between Sonyea and Tuscarora; in the 

 ravines along the sides of Conesus and Honeoye lakes and in 

 the southern part of the Bristol valley and in Parrish gully and 

 other ravines at Naples. 



Fossils are fairly common in the shales and also in the concretions 

 and they increase in frequency from the lower to the upper beds. 

 The more abundant forms in this vicinity are: 



the goniatites 



Probeloceras lutheri Clarke G. cf. domanicense Holzapfel 



Gephyroceras holzapfeli Clarke 



the lamellibranchs 



Lunulicardiutn pilosum Clarke Buchiola retrostriata {v. Buck) 



Pterochaenia fragilis (Hall) B. lupina Clarke 



P. elmensis Clarke Paleoneilo petila Clarke 



the gastropod 

 Loxonema noe Clarke 



Rhinestreet black shale 



This shale consists of a heavy mass of black, bituminous, slaty 

 shale, in which there are a few thin bands of dark bluish, rather 



