The Stratigraphic Position of the Portage Sandstones in the 

 Naples Valley and the Adjoining Region. 



By D. Dana Luther. 



The deep wells that have penetrated the great beds of rock salt Lying at 

 varying depths below the surface of a large section of country in western and 

 central New York, have demonstrated that the northern limit of these beds is 

 approximately the line of outcrop of the Corniferons limestone, the top of 

 w hich is but little more than 500 feet above the salt horizon. 



South from this line, owing to the dip of the strata and the generally 

 increased elevation of the surface, deeper drilling is required, as the strata that 

 compose the Marcellus, Hamilton, Genesee, Portage and Chemung groups are 

 successively added to those that intervene between the surface and the salt. 



In the Warsaw or Oatka valley, in Wyoming county, the sandstones at 

 the top of the Portage group are a little more than 2,000 feet above the salt. 

 This distance increases slightly toward the east, and more rapidly tow ard the 



south. 



Nearly all of the deep north and south valleys that are so numerous in 

 this section of country, have been excavated in the soft shales of the Hamilton, 

 Genesee and Portage groups, and end at the south in the harder and heavier 

 bedded Upper Portage and Chemung sandstones. Although the salt beds are 

 known to increase in thickness toward the south, those reached by the wells in 

 these valleys have been found abundantly sufficient for all purposes, and but 

 two plants, the Duncan Salt Co.'s, at Silver Springs, and that at" Castile, have 

 been put into operation where the stratigraphic horizon of the mouths of the 

 salt wells is above the top of the Portage sandstones, and in those w ells the 

 thickness of Chemung rock included in the sections is not great. 



As these " Portage sandstones," so designated on account of their great 

 development and abundant exposure at the upper Portage falls, on the 

 Genesee river, and described by Professor Hall in the Report on the Geology 

 of the Fourth District, 1848, can be easily identified by any careful observer, 

 and are fairly persistent in character from Tompkins county to the shores of 

 lake Erie, their line of outcrop may, for the reasons previously mentioned, be 

 considered as marking the southern limit of that part of the salt-producing 



