234 



PALEOZOIC TIME. 



The beds, especially those of the upper half, are much intersected 

 by shrinkage-cracks, — effects of the drying of the mud of the ancient 

 mud-flat by the sun. 



Minerals. — The gypsum does not constitute layers in the strata,, 

 but lies in imbedded masses, as shown in the annexed figures. The 



Fig. 455. 



lines of stratification sometimes run through it, as in Fig. 456 ; and 

 in other cases the layers of the shale are bulged up around the 

 nodular masses (Fig. 455). In all such cases, the gypsum was formed 

 after the beds were deposited. Sulphur springs are now common in 

 New York, and especially about Salina and Syracuse. Dr. Beck 

 describes several occurring in this region, and mentions one near 

 Manlius, which is " a natural sulphur-bath, a mile and a half long, 

 half a mile wide, and 168 feet deep, — a fact exhibiting in a most 

 striking manner the extent and power of the agency concerned in the 

 evolution of the gas," and showing, it may be added, that the effects 

 on the rocks below must be on as grand a scale. These sulphur- 

 springs often produce sulphuric acid, by an oxydation of the sulphur- 

 etted hydrogen. There is a noted " acid spring " in Byron, Genesee 

 County, N. Y., connected with the Onondaga formation, besides others 

 in the town of Alabama. This sulphuric acid, acting on limestone 

 (carbonate of lime), drives off its carbonic acid and makes sulphate of 

 lime, or gypsum ; and this is the true theory of its formation in New 

 York. The lamina? which pass through the gypsum unaltered, as in 

 Fig. 456, are those which consist of clay instead of limestone. The 

 gypsum is usually an earthy variety, of dull gray, reddish and brownish, 

 sometimes black, colors. It may have been produced at any time 

 since the deposition of the rocks ; and it is beyond doubt now form- 

 ing at some places in the State. 



The salt of the rocks in New York has been found only in solution, 

 in waters issuing from the strata. The wells at Salina are 150 to 

 310 feet deep, and, at Syracuse, between 255 and 340. 35 to 45 gal- 

 lons of the water afford a bushel of salt ; while it takes 350 gallons 

 of sea-water for the same result. At Goderich, in Canada, Rock salt 

 has been obtained at a depth of from 964 to 1,180 feet, and is reported 

 to exist in beds from 14 to 40 feet in thickness. 



