52 F\ REPORT OF PROGRESS. E. W. CLATPOLE 



The Niagara Group wanting. 



Prom the identification here established it follows that 

 nothing is left to represent the Niagara group in Perry 

 county. If any representation of it existed it should lie 

 at the top of the iron ore capping the Clinton group. But 

 the green shale of the passage bed has yielded no fossils 

 that can characterize a bed of that age. They hold, as 

 shown above, a mingled fauna of the Clinton and Lower 

 Helderberg ages. Consequently the Niagara group cannot 

 be recognized in Perry county. 



The rapid thinning of the Niagara group in New York 

 would prepare us for this conclusion. Two hundred and 

 forty feet thick at Niagara Falls, it dwindles down to 

 about one hundred and thirty feet in Wayne county near 

 Rochester. In southwest Ohio it scarcely exceeds 50 feet. 



The Onondaga group. (Vb.) 



Immediately overlying the beds just described at the top 

 of the Clinton group, is a mass of shale with a few inter- 

 bedded sandstones 1500 or 1600 feet thick. These constitut- 

 ing the upper part of Rogers' No. V, should occupy the 

 place of the Onondaga of the New York series. 



The Onondaga, Salina, Salt, or Gypsiferous group of New 

 Yoik consists, like the above-mentioned strata, of a mass 

 of shales of various colors, and as the names imply yielding 

 salt and gypsum. The total thickness given by Yanuxem 

 in the report of the Third district is about 700 feet, divided 

 as shown below. The section in Perry county is given in 

 another colnmn for comparison. 



New York: Perry co., Penna, 



Magnesian rock=limestone with 



styolites. 



Gypseous bed, (upper,) . . ^ 



Porous (vermicular) lime- I 



, j> . Gray calcareous shale, 200 feet. 



Gypseous bed, (lower,) . . j 



Variegated shale, red and green, . Variegated shale, red and green, 700 ft. 



Bloomsburg red shale, Red shale, 700 ft. 



The thickness of the group in New York varies from 300 



