104 0. S. PROSSER DEVONIAN AND SILURIAN ROCKS. 



Kind of rod:. Formation. 



Brownish-red arenaceous shale and sili- 

 cious sandstone, alternating with dark 

 gray, bluish-gray sandstone and olive 



and greenish shale Medina. 



1 ,.i74 * Bottom of well in the red Medina sand- 

 stone " 



Dr Englehardt stated : " I cannot well establish the depth at which 

 the Niagara group passes into the Clinton group below,"* but it seems 

 pretty certain that the green argillaceous shale at 842 feet is in the Clin- 

 ton, and, further, that ''the passage from the Clinton group into the 

 underlying Medina group must be about 1,007 feet from the surface 

 where the first quartz makes its appearance. At 1,020 feet the first sand- 

 stone 'had been passed through and certainly the Medina sandstone 

 reached."! 



To the writer it seems better to call the brownish-red arenaceous shale 

 at 991 feet the top of the Medina. 



On comparing the record of the State and Gale wells it will be noticed 

 that in the State well the Niagara group has a thickness of 332 feet and 

 in the Gale well it is 320 feet. The Clinton is 98 feet thick in the State 

 well, while in the Gale well 149 feet of greenish shale has been referred 

 to the Clinton. Possibly this is too great a thickness for the Clinton, 

 and it certainly seems that there should not be so great a difference in 

 the thickness of the formation for the two wells. The State well passed 

 through the Medina, making a total thickness for that group of 807 feet, 

 and stopped after passing through 150 feet of the Oswego sandstone. 

 The Gale well passed through 583 feet of the Medina group and ceased 

 at a depth of 1,574 feet. 



Tally Well Number J and Section. — The Solvay Process Company of Syra- 

 cuse, New York, in 1888 discovered rock-salt in Tully township, in the 

 southern part of Onondaga county .J More than twenty wells have since 

 been drilled by this company, the depth to the rock-salt ranging from 

 974 to 1,465 feet, which is generally between 40 and 50 feet in thickness.|| 



Through the kindness of Mr G. E. Francis, of the Solvay Process < !om- 

 pany, the writer has had the satisfaction of studying a set of samples 



*The last sample of the set donated to the National Museum is from 1,574 feet, but Or Engle- 

 hardt gives the total depth of this well as ?,600 feet (Ibid., p. 1 1 1. 



t Ibid., p. 15. 



JSee Ann. Rep. Supt. Onondaga Salt Springs for 1889, p. 27. 



I See ibid, for 1890, pp. 2::-27. A general account of 1 1 1 i — region, together with a brief description 

 of twenty-one wells, is given in the Mineral Resources of the United States for the years 1889-90 

 (Washington, 1892), pp, 186, 187. 



