PALEOZOIC TIME — UPPER SILURIAN. 



555 



below must be on as large a scale. These sulphur springs often produce 

 sulphuric acid, by the oxidation of the sulphuretted hydrogen. There is a 

 noted acid spring in Byron, Genesee County, N.Y., first noticed by Amos 

 Eaton (Am. Jour. Sc, xv., 1829), whose waters Beck showed to have a 

 specific gravity of 1-113. The laminae which pass through the gypsum unal- 

 tered, as in Fig. 792, are those which consist of clay instead of limestone. 



793. 



Beds of gypsum (g) in limestone and calcareous shales. Hall. 



The gypsum is usually of an earthy variety, of dull gray, reddish and brown- 

 ish, sometimes black, colors. That all the gypsum of the formation had 

 this source is reasonably questioned. It may have been in part a deposit 

 from the same sea waters that supplied the salt. 



Water-lime Group. 



The Water-lime rock, so-called because it is a hydraulic limestone, is an 

 impure, thin-bedded magnesian limestone of usually a drab color. It some- 

 times contains a little petroleum. It owes its hydraulic character to its impur- 

 ities, as explained on page 79 (under Rocks). The group has, in general, the 

 distribution above given for the Onondaga series. In the Helderberg Moun- 

 tains it is about 150 feet thick, and nearly the same in the central part ; but 

 farther north, near Oriskany Falls in Oneida County, it runs out. It con- 

 tains much gypsum, and quarries of it are worked near Syracuse, and also in 

 Cayuga and Genesee counties. In ISTorthern Ohio, where the Onondaga series 

 has a thickness of 600 feet, it contains layers of shale ; and gypsum is abun- 

 dant at Gypsum, 10 miles west of Sandusky. Hydraulic cement is made 

 extensively from it in Ulster County, N.Y., at Rosendale near Eondout, 

 whence the oft-used name "Rosendale cement," but not in Ohio, where the 

 limestone is not suited for it. The presence of chert is one cause of the 

 unfitness of the beds for the purpose. 



In the New York report by Vanuxem, the salt group between Oneida Creek and 

 Cayuga Lake is stated to consist of (1) red shales with green spots, 1' to 500' thick ; 

 (2) the Lower Gypseous shales^ light green and drab, alternating with No. 1 near the plane 

 of junction ; (3) beds containing two ranges of gypsum in masses, and often containing hop- 

 per-shaped cavities due to crystallized salt, the Vermicular limerock of Eaton ; and (4) im- 

 pure limestone containing " Epsomites," or vertically grooved surfaces formerly supposec' 

 to have been made by the crystallizing of Epsom salts (the Stylolites, mentioned above). 



In middle Pennsylvania there are 700' of red shales, overlaid by 700' of variegated 

 shale and 200' of gray shale (Claypole). The thickness of the formations overlying the 

 Salina near the New York and Pennsylvania boundary is so great that no borings have 

 yet penetrated to them. On the salt and gypsum industries of New York, see the Report 

 of F. J. H. MerviW, Bull. N. Y. State Mus., iii., 1893, which contains maps showing the 

 distribution. 



