GEOLOGY OF THE GENEVA-OVID QUADRANGLES 



7 



r Manlius limestone 

 Rondout waterlime 



Cayugan .... J Cobleskill waterlime 



Bertie waterlime 

 ^ Camillus shale 



The strata composing the surface rocks of these quadrangles as 

 delineated on the map have an aggregate thickness of 2140 feet of 

 which 1460 feet are exposed by the gradual elevation of the land 

 from 400 feet A. T. in the northeast corner of the Geneva quad- 

 rangle to i860 feet A. T. near the southeast corner of the Ovid 

 quadrangle and 680 feet are brought up by the elevation of the 

 strata toward the north and east at an average rate of 24 feet per 

 mile. 



It is proper to call attention to the fact that variations in the 

 thickness of the strata and the undulatory condition of the bedding 

 make calculations of the dip of little value except as between any 

 two specified points. 



The lowest and most northern of the rock series exposed on the 

 Geneva quadrangle is the Camillus shale, a small outcrop showing 

 8 feet of the platten dolomites of the lower part of this formation 

 occurring on Black creek 1 mile south of Tyre. 



This is the only rock exposure on these quadrangles north of the 

 Auburn branch of the New York Central Railroad, all of that 

 region having a mantle of drift varying from a few feet in the 

 lower swampy plains to 100 feet or more in the numerous drumlins 

 and kames that diversify the landscape. Therefore the coloring is 

 to be taken as showing the surface area of the rock formations in 

 a plane having a presumed elevation of about 400 feet A. T. 



The Camillus shale is that subdivision of the Salina group that 

 succeeds the Vernon red shale and is composed in the lower part 

 of thin dolomitie limestones and thin layers of soft shale and at the 

 top has a bed of gypseous shale 35 feet thick, some parts of which 

 are of sufficient purety to have, when pulverized, some eco- 

 nomic value as land plaster and wall plaster. Gypsum was quarried 

 about 1840 near Black brook west of Nichols Corners and the bed 

 has been penetrated in the bottom of wells in that vicinity. It is not 

 exposed along that stream now, the exposure south of Tyre being 

 below it. It is well displayed, however, in the cliff along the north 



SILURIC 



Camillus shale 



