ROCK SALT. 291 



Cairo, extending, according to Horneman, for many 

 miles. The salt rocks of Tegara, near Cape Blanc, 

 are noted ; as are those of Had Delfa in the district of 

 Tunis, of Bamba, and of Congo ; forming one of the 

 most important articles of interior commerce in these 

 countries. As in Cararnania, Herodotus informs us 

 that rock salt was antiently used in the desert of 

 Lihya for the purposes of building. 



It was already noticed that salt is found in Peru ten 

 thousand feet above the level of the sea ; and, on the 

 western side of the Missouri, it occurs in different 

 places, along a ridge of mountains extending for eighty 

 miles. Salt springs abound in Kentucky ; and the 

 saline soils of northern America have long been cele- 

 brated for the resort of wild animals, and for the an- 

 tient skeletons buried in their vicinity. I need scarcely 

 say that the geography thus detailed is nearly a repe- 

 tition of that of the red marl. 



The disposition of rock salt is not rigidly the same 

 every where, nor does it ever seem to form such conti- 

 nuous strata as those of the accompanying rocks. At 

 Thorda, it is said to be found in horizontal and undu- 

 lated beds. In Spain and elsewhere, though asserted 

 to form continuous beds, and even mountains, more 

 accurate examination has shown that these consist 

 chiefly of the clay and sandstone which constitute its 

 repositories. The supposed strata of salt are thus, 

 rather, strata of earthy matters, among which it is 

 disposed in irregular portions of beds, and in shapeless 

 masses of all dimensions, surrounded by the rocks 

 and earthy substances with which it is associated. 



The disposition of the salt of Cheshire is remark- 

 able. Though the general mass appears continuous 

 and compact, it is divided into irregular columnar 

 shapes, or into rounded bodies which appear mutually 



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