GEOLOGY OF THE ATTICA AXD DEPEW QUADRAXGLES 9 



Beside the coral mentioned the following fossils occur in the 

 Cobleskill waterlimes in western New York : 



Nematophyton crassum Penhallow 



Favosites sp. 



Orthothetes interstriatus (Hall) 



Spirifer eriensis Grahau 



Whitfieldella sulcata {Vanuxeni) 



W. nucleolata Hall, vor. 



W. cf. laevis {Vaniixeui) 



Rhynchonella sp. 



Loxonema? 



Pleurotomaria 



Trochoceras gebhardi (Hall) 



The Cobleskill waterlime is well exposed at \\'illiamsville in the old 

 quarries ; in the village of Clarence, and at the larger quarry two 

 and one half miles east of Clarence on the DeWitt quadrangle, and 

 in the Buffalo cement quarry at Buffalo, at Akron, Fallkirk, Indian 

 Falls and Morganville, North LeRoy, East Mctor and Union 

 Springs. It received its name on account of its fine exposure at 

 Cobleskill in Schoharie county, and it may be seen in many other 

 localities in eastern New York. 



The Cobleskill waterlime is the highest formation belonging to 

 the Siluric system in the rock section of New York west of Seneca 

 lake, the Rondout waterlime and the ^lanlius limestone that suc- 

 ceed the Cobleskill in the central and eastern part of the State 

 thinning out and disappearing east of that point. 



In the large cement quarries at Buff'alo and at nearly all ex- 

 posures where the surface or cross sections of the contact with 

 the succeeding formation can be observed, there are evidences 

 of considerable erosion, the Paleodevonic strata resting more or 

 less unconformably upon the Cobleskill. 



DEVONIC 



ORISKANY SAXDSTOXE HORIZOX 



Four Devonic formations, the Coevmans limestone, New Scotland 

 beds, Becraft limestone and Port Ewen limestone, constituting the 

 Helderbergian group in the eastern New York counties are al)sent 

 in the western, the Oriskany sandstone being the lowest of the 

 Devonic subdivisions known here. 



This rock in its typical condition is composed of coarse whit^ 

 or pinkish quartz sand, loosely cemented by calcareous matter. 

 It is not a continuous stratum on the line of its outcrops in central 

 and western New York, but appears in cross sections of broad 



