§ 4. ORIGIN OF ROCK-SALT. 539 



this a small hole is bored to the river of brine, which is in 

 depth about twenty-two inches, and beneath which is 

 rock-salt. The brine rises rapidly through the aper- 

 ture, and is pumped into a capacious reservoir, whence it 

 is conveyed into iron boilers for evaporation; it is sup- 

 posed to be stronger than any other in the kingdom, and 

 contains above one-fourth part its weight of salt. One of 

 the shafts is sunk to a depth of nearly 500 feet, and passes 

 through four layers of salt, 85 feet in aggregate thick- 

 ness. Some of the beds of salt in Cheshire are from 70 to 

 120 feet thick. A red sandstone, containing vegetable 

 remains, forms the foundation rock of the saliferous deposits 

 of England.* 



4. Origin of Rock-salt. — The origin of these enormous 

 subterranean beds of rock-salt is as enigmatical as that 

 of the saltness of the waters of the ocean. But deposits of 

 salt, though prevailing in England, Hungary, and Poland, 

 in the formation under examination, are not confined 

 to any particular group of strata. The celebrated salt- 

 mines of Galicia belong to the tertiary formations {ante, 

 p. 284) ; while, in the State of New York, salt and gypsum, 

 with variegated marls, are found in the middle of the 

 Silurian system. f It is to be remarked, that deposits of chlo- 

 ride of sodium are almost always accompanied with layers 

 and intercalations of gypsum ; and the circumstance of two 

 v powerful acids, the sulphuric (in the gypsum or sulphate 

 of lime), and the muriatic (in the chloride of sodium), being 



* For a graphic account of the salt-works at Droitwich at the present 

 time, see Mr. Hugh Miller's " Impressions of England and its People/ 7 

 p. 179. 



f In the middle of the horizontal Silurian rocks of the State of New 

 York, there is a formation of red, green, and bluish grey marls, with 

 beds of gypsum, and occasional salt springs, the whole being from 800 

 to 1000 feet thick, and undistinguishable in mineral character from 

 parts of the Trias of Europe.— Mr. L yells Travells in America, p. 54. 



