114 ^ NEW YORK STATE MUSEUM 



shale separating it into two parts. The latter deposits are in the 

 Salina formation. 



The thickest deposit that is known in this State is in the 

 Lehigh salt shaft at Leroy, where at a depth of 389 feet a deposit 

 75 feet in thickness was found. The rock is light colored in some 

 parts, and samples that have been seen bj the author compare 

 well with the rock found at Oakfield and Garbuttsville. A project 

 is on foot to make use of this deposit in the manufacture of 

 stucco. 



In the shaft of the Ketsof mine at Ketsof N. Y., a. bed of gypsum 

 47 feet thick was found at a depth of 613 feet. This deposit is 

 considered the top of the Salina in both the Ketsbf and Lehigh 

 mines, though in the Livonia shaft it is supposed that the lime- 

 stone and hard shale just above the 45 foot bed are Salina.^ 



It will be seen from these sections that the thickness of the 

 deposit increases as we go south of the Salina depression, and 

 from the appearance of this thick bed at practically the same 

 horizon in these three mines, it seems reasonable to expect to find 

 it throughout the greater part of western New York. 



The future developments in gypsum mining in this State will 

 probably be made south of the region from which the supply is 

 now obtained. 



HISTORY 



The use of gypsum as a cementing material has been known for 

 at least 4000 years, as shown by an analysis of the mortar used 

 in the construction of the pyramid of Cheops, and that this use 

 was known among the ancient Greeks is shown by the writings of 

 Theophrastus and others. The precise date when this material 

 was first used in this way is not known. Theophrastus records 

 that plaster casts were first made by Lysistratus, but little use 

 wa^ made of the discovery, and the art was lost. This use was 

 revived by Verocchio about 1450 A. D. and was of service in 



^Luther, D. D. Report on the Geology of the Livonia Salt Shaft; N. Y. 

 State Geol. 13th An. Rep't 1894. p. 25-130. Also N. Y. State Mus. 47th An. 

 Rep't, p. 215-324. 



