GEOLOGY OF THE SALT AND GYPSUM 25 



'magnesian deposit." The red shale forming the lower 

 division of the group is well developed, but in the third dis- 

 trict has not been found west of the Genesee river. It ap- 

 pears 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 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 re- 

 mains 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-shaped 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 hy- 

 draulic cement and is now worked by the Buffalo Cement Co. 



In their studies of the Salina group, Profs. Hall and 

 Vanuxem found no rock-salt because this soluble mineral 

 cannot remain at the surface. However from various wells 

 and shafts, sunk during the past 1 1 years, we have sections 

 of the Salina group which show the position and relation of 

 the salt beds. 



Through the courtesy of Prof. James Hall, State Geologist, 

 I am permitted to quote the following synopsis of the record 

 of the Livonia salt shaft, made under Prof. Hall's direction 

 by Mr D. D. Luther. 



4 



