412 Dr. Traill on the Salt Mines of Cardona. 



the village of Suria, a sandstone, which slightly efFeryesces with acids, 

 makes its appearance. This rock constitutes the sides of the valley 

 which contain the fossil salt. 



The immediate vicinity of the salt mines shews no other rock than 

 a yellowish grey sandstone much charged with scales of mica. 



We find thus that the salt rock of Cardona is accompanied by 

 clay and sandstone, like our Cheshire salt formation. Limestone 

 also is found near it ; but the usual concomitant gypsum appears to 

 be wanting, as well as foetid limestone. The great compactness and 

 purity of this salt merits examination. 



Though the country around Cardona is mountainous and rugged, 

 it is inferior in elevation to the districts between it and the Mediter- 

 ranean j as well as to those which bound it on the north. Imme- 

 diately behind Cardona the mountains begin to ascend with increas- 

 ing boldness until they unite with the grand chain of the Pyrenees. 



I relinquish to others the difficult task of giving a probable 

 explanation of the formation of rock salt ; contented if my obser- 

 vations on the mine of Cardona can add any thing to the mass of 

 facts which should guide us in the obscure but captivating specu- 

 lations of geology. 



