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NEW YORK STATE MUSEUM 



atmospheric influences, the rock is blue, like ordinary blue clays, 

 with bands of red or brown. This portion and that succeeding 

 it are often green and spotted, and contains seams of fibrous 

 gypsum and small masses of reddish selenite and compact 

 gypsum. From this it becomes gradually more gray with a thin 

 stratum of clayey limestone, which is sometimes dark, though 

 generally of the same color as the surrounding mass. The forma- 

 tion terminates upward with a gray or drab limestone called by 

 Vanuxem the " magnesian deposit." The red shale forming the 

 lower division of the group is well developed, but in the third 

 district has not been found west of the Genesee river. It appears 

 in the eastern part of Wayne county as indicated by the deep 

 red color of the soil which overlies it. 



At Lockville a greenish-blue and marl with bands of red has 

 been quarried from the bed of the Erie canal. West of the 

 Genesee this is the last of the visible mass. The red shale has 

 either thinned out or lost itself, gradually becoming a bluish- 

 green, while otherwise the lithological character remains the 

 same. On first exposure it is compact and brittle, presenting an 

 earthy fracture. But few days are necessary to commence 

 the work of destruction, which goes on until the whole becomes 

 a clayey mass. The prevailing features of the second division 

 of the group are the green and ashy marl with seams of fibrous 

 gypsum and red or transparent selenite often embracing nodules 

 of compact gypsum. The third division comprises'all the gypsum 

 beds of the fourth district which are of economic importance. In 

 this third division hopper-shapped cavities occur in Wayne and 

 Monroe counties, but rarely in Genesee or Erie. 



There is scarcely any well-defined division between the shales 

 and shaly limestones of the third division and the so called 

 magnesian deposit which overlies it. This limestone in the 

 western part of the State is used extensively for hydraulic 

 cement and is now worked by the Cummings Cement Company 

 of Akron and the Buffalo Cement Company. 



In their studies of the Salina group, Professors Hall and 

 Vanuxem found no rock-salt because this soluble mineral can not 

 remain at the surf ace. However from various wells and shafts, 

 sunk during the past 11 years, we have sections of the Salina 

 group which show the position and relation of the salt beds. 



