GEOLOGY OF THE AUBURN-GENOA QUADRANGLES J 



The 21 geologic units into which the surface rocks of these 

 quadrangles are divided have an aggregate thickness approximately of 

 1920 feet, of which 1080 feet appear in ascending from 380 A. T. in 

 the northwestern corner of the Auburn quadrangle to 1460 A. T. in 

 the southwest corner of the Genoa quadrangle and 840 feet are 

 brought up by the northward elevation of the strata at an average of 

 about 25 feet per mile for the whole distance, though the dip is ex- 

 tremely variable and for a few miles in the southern part of the Genoa 

 quadrangle actually reversed. 



FORMATIONS IN ASCENDING ORDER 

 SILURIC 



Camillus shale 



This formation is that subdivision of the Salina group which, along 

 the line of outcrop, succeeds the red Vernon shale and at or near the 

 base of which the New York rock salt beds are reached in the deep 

 borings at Tully, Ithaca, Watkins and farther west. 



The lower part is composed of thin, somewhat uneven layers of 

 dark dolomite and gray marly shales, and the upper of a bed of gypse- 

 ous shale 35 to 45 feet thick in which thin limestones like those below 

 occur. 



This is the well known '' land plaster " or gypsum bed that ex- 

 tends from Madison county to Genesee county, the rock which, when 

 pulverized, was for many years considered valuable and extensively 

 quarried as a fertilizer and one of the most important of the 

 economic resources of the State. At present though fallen into 

 disuse for that purpose, it is utilized as an important component in 

 the production of prepared wall plaster. The formation received 

 its name from the town of Camillus, Onondaga co., where the first 

 discovery of gypsum in tlie United States was made in the year 

 1792. 



A large number of gypsum quarries were formerly operated in the 

 Camillus in the region on the east side of Cayuga lake north of Union 

 Springs but nearly all of them have been long abandoned and afford 

 only small exposures of the gypsum and overlying limestones. The 

 large quarry of the Cayuga Land Plaster Company, formerly known 

 as the Backus quarry, situated east of the railroad at Cayuga Junc- 

 tion shows very favorably nearly all of the gypsum bed and a few feet 

 of the Bertie waterlime that succeeds it. There are several old pits 

 on Hibiscus point, also near Crossroads, and ly^ miles farther north. 



