LuTflEK 



— Geology of the Salt District. 



193 



In Well No. 30, which is situated at the bottom of the cascade in the 

 ravine of Vesper, brook on the west side of the valley, the Corniferous lime- 

 stone was reached at 675 feet below the surface. Measurement by Locke 

 level from the mouth of the well to the base of the Tully limestone shows the 

 total thickness of the shales between the Corniferous and Tully limestones to 

 be 1173 feet, of which 125 to 150 feet next above the Corniferous are the 

 Marcellus shales and the remainder constitute the Hamilton group. 



In AVell No. 3, Group G, the Corniferous limestone was reached at the 

 depth of 405 feet and in AVell No. 1, Group A, at 718 feet. 



The change from the soft black Alareellus shales to the hard, lio-ht blue- 

 grey cherty Corniferous limestones is such a marked character that it cannot 

 escape the notice of the driller, and it is the most reliable datum plane found 

 in the salt wells. 



The thickness assigned to the Corniferous limestone in the well records 

 varies from 55 to 117 feet, averaging about eighty feet, which is doubtless 

 appr< iximately correct. 



The Oriskany sandstone, is found to lie fifteen to twenty feet thick. Of 

 the strata next below the Oriskany sandstone, consisting mainly of hard blue- 

 black limestone, and doubtless some layers of hydraulic limestone though none 

 are mentioned in the record, 125 to 150 feet are designated as Lower 

 Helderberg. That part of the Salina group that occupies a position above the 

 salt bed is about 25<»feet thick, consisting of grey magnesian limestones and 

 dark gypseous shales, with abed of the latter thirty to forty feet thick, in 

 which some thin magnesian limestones are interstratirled, occurring superjacent 

 to the bed of salt. 



The uneveness of the upper surface of the salt bed is shown by the 

 variation in the different wells of the distance between it and the upper 

 surface of the Corniferous limestone where exposed, which is found to be very 

 regular and even. 



In Well No. 1, Group A, this distance is - - - - 498 feet. 



In AVell No. 2, Group A, this distance is - - 492 feet. 



In AVell No. 3, Group A, this distance is - . - - 492 feet. 



In AVell No. 1, Group B, this distance is 4V»5 feet. 



In AVell No. 3, Group B, this distance is - - - - 518 feet. 



In AVell No. 4, Group B, this distance is - - - 514 feet. 



In AVell No. 5, Group B, this distance is - . - - 520 feet. 



In AVell No. 6, Group B, this distance is - - - 518 feet. 



In AVell No. 1, Group C, this distance is - - - • 500 feet. 



