OF COMMON SALT. 



157 



salt is of aqueous origin, and that it is a marine deposit. The 

 appearances which seem to bar this theory are easily ex- 

 plained away, whilst those which establish it are so numerous 

 and so cogent that the theory passes as a reasonable belief 

 worthy of acceptance. 



We have now to consider the effect of this conclusion 

 upon the composition and qualities of the ancient or 

 palseothalassic sea. We have extracted, in theory, from 

 this sea, an enormous body of common salt. Let us endea- 

 vour to estimate the amount. There are not sufficient data 

 available to form an accurate estimate even as to the quantity 

 of rock salt at present known to exist, but some idea may be 

 formed on the subject, by a passing glance at some of its 

 principal formations. The most extensive mines in the 

 world are those found on the continent of Europe, extending 

 for 500 miles along the Carpathian mountains, stretching 

 out laterally for 100 miles and having a thickness in some 

 places of 1,200 feet. In neighbouring Gralicia the Wieliczka 

 saltmine is the largest known. It has been worked for the 

 last 629 years. Some of its galleries stretch for 40 miles 

 and yet the resources of the mine have scarcely been 

 touched — so great are its conjectured dimensions. The area 

 occupied by the Trans-Indus or Afghan salt region is 

 about 1,000 square miles, and it is estimated that about 

 one-fifth of the entire area is taken up by salt, which 

 frequently occurs in marked exposures. In one place, for 

 a stretch of four miles, the rock salt forms bold cliffs, rising 

 to 200 feet, on either side of the banks of a stream. The 

 bottom of this salt deposit is unknown. Mr. Wynne of 

 the Geological Survey estimates its thickness, in parts, at 

 1,200 feet. The same authority estimates the Cis-Indus, or 

 Indian, salt range, as extending 134 miles in length by 

 about 5 miles in breadth, comprising an area of about 670 

 square miles. The salt zones in this region have a thickness 



