Luther — Geology of the Salt District 



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caused by the oxidation of a thin layer of iron pyrites, occupying the position 

 of the Tullv limestone, and almost continuous from Canandaigua lake to lake 

 Erie. It appears to have been deposited in lenticular patches, from a few 

 square rods to several acres in extent, that sometimes coalesce and at others 

 are separated for a short distance. It is never more than four inches thick 

 and generally between one and two, very hard and heavy. When freshly 

 broken it is of a brassy yellowish white and contains, somewhat sparsely, 

 small (roniatitex. CJionetes and other fossils. It is usually disintegrated for a 

 few inches where exposed to the atmosphere, but is preserved under water. 

 It is uniform in character and condition for the entire length of its line of 

 outcrop in the salt district. 



Its exposures are seen in many ravines and along the shores of Canandai- 

 gua lake, at the cascade in Fall brook near Geneseo, and in several ravines 

 north of Moscow, at Griswold and Darien in Genesee county, at Iron Bridge 

 mills on Cayuga creek in Erie county, and at many intermediate points 



At Ithaca, the Tullv limestone is 177i feet above the top of the salt, 

 and at Tully, 1075 feet. 



At the Livonia shaft the pyrites layer occured at 1089 feet. At the 

 Lackawanna well near Mt. Morris, 1117 feet, and at the Crystal salt well, 

 near Warsaw, 1117 feet above the salt. 



The mouth of the Pavilion well, in which salt was reached at 1019 feet, 

 is very nearly in the horizon of the Tully limestone. 



Genesee slate. This formation extends entirely across the salt district 

 from east to west, but is much more characteristically developed west of 

 Seneca lake, and receives its name from the Genesee river and valley where 

 it is abundantly exposed. 



In the hills south of the Tully salt wells, this formation appears as a 

 mass of black carbonaceous laminated shale thirty to forty feet thick resting 

 on the Tully limestone. Its thickness increases to about 100 feet on Cayuga 

 lake and 150 feet on Seneca lake. In this region it contains a few septaria, 

 but is otherwise very uniform in character It is highly developed in the 

 vicinity of Canandaigua lake and attains a thickness of about 200 feet. 



Several peculiar layers of very dark, hard limestone occur near the 

 middle of the formation, separated by thin layers of shale. Thev are 

 composed almost entirely of the shells of a minute pteropod, Styliolina jissur- 

 ella, and are collectively known as the Styliola band. Some of the layers are 

 very even and compact, while others are concretionary and nodular, and at 

 some localities quite shaly. Plant remains, crinoids, fish remains and other 



