38 NEW YORK STATE MUSEUM 



prove of cominerci'al value. The gypsum is all of the quality known 

 as " mixed," i. e. consisting of selenite plates, reddish, granular and 

 fibrous gypsum interstratified and seamed with clay shales, marlites, 

 impure shaly gypsum, etc. ; and it is found in small irregular 

 deposits. 



Ontario county 



The Salina group is represented throughout the county by fre- 

 quent exposures of Camillus shale, Bertie waterlime, while the over- 

 lying Cobleskill waterlime and in the eastern part of the co'Unty 

 the Rondout waterlime are also encountered. Of these the Camillus 

 shale is the only one of present interest and in it are found 'all the 

 gypsum deposits. This shale occupies the entire noTthern portion 

 of the county, and varies in width from 6 miles in the eastern por- 

 tion to 2 miles in the western. In character it varies but little 

 from its general type, a greenisih or dark shale becoming light gray 

 on exposure and containing interstratified platten dolomites at inter- 

 vals. Where exposed, it frequently contains the pockety beds of 

 .gypsum 90 characteristic of the beds to the east. lu the greater 

 portion of the area, however, actual exposures are rare, owing to 

 the heavy drift mantle. 



Beginning ''in the eastern part of the county, the first exposures 

 of gypsum are those brought to light by the Canandaigua outlet 

 between Phelps and Gypsum. Of these the best grade of rock is 

 represented by the beds of the Empire Plaster Co., owned by Mr 

 A. D. Miller of Phelps. Mr Miller's main quarry lies on the north- 

 ern bank of the outlet i mile north-northeast of Phelps Junction, 

 near the bridge. The rock is a gray, impure gypsum, heavily 

 seamed with fibrous white gypsum varying from ^ to i^ inches 

 in width. It occurs in masses of 100 up to 3500 tons in weight and 

 is gotten out by blasting. The material is hauled by wiagons to the 

 mill, located near the bridge, i mile west on the outlet. This mill 

 is equipped with a cracker, nipper and buhrstones and is run by 

 water power. The mill has been idle for two years but formerly 

 carried on an active business in land plaster. 



Across the road f>rom the mill is an abandoned quarry from which 

 Mr Miller formerly extracted gypsum masses from 25 to 3,000 tons 

 in weight. In early times many mills were in operation in and 

 around Phelps and Gypsum, and the annual production of land 

 plaster in the early forties along the outlet was 6000 tons. 



From Manchester on to Victor the Salina beds are heavily cov- 

 ered or swampy, and no gypsum has been reported although well 



