ROCK-SALT IN THE ALPS. 



175 



ble intermixture of common salt ; and masses of rock-salt occur in 

 other parts of the island, imbedded in clay.* In these, and in some 

 other instances, it is probable that subterranean fire, by evaporating 

 the waters of salt lakes, or of countries recently emerged from the 

 ocean, may have been an active agent in the formation of rock-salt. 



The rapid formation of rock-salt in Syria, during one of those 

 igneous eruptions which have, at times, overwhelmed certain portions 

 of the globe, is, perhaps, obscurely alluded to by the sacred writer, 

 who has narrated the early history of the human race. Gen. chap, 

 xix.f The salt lakes existing in that country are well known. 



Whether all the repositories of rock-salt above enumerated occur 

 in the red marl, cannot, in the present state of our information, be 

 accurately ascertained. The great formation of rock-salt and gyp- 

 sum near Bex in Switzerland, constitutes two large and extensive 

 beds. The lowest rests upon black limestone, argillaceous limestone 

 and sandstone; and between the lower gypsum and the upper, there 

 are thick beds of argillaceous limestone, and similar argillaceous 

 limestone forms caps over the upper gypsum. The gypsum in the 

 large beds is anhydrous, and contains particles of rock-salt and com- 

 mon gypsum disseminated through it. The prevailing fossils are 

 ammonites and belemnites. — (Travels in the Tarentaise.) 



The mineral characters of the strata at Bex, and the imbedded , 

 fossils, incline me rather to refer the argillaceous limestone, over 

 and under the gypsum and salt beds, to the English lias, than to 

 magnesian limestone. Many beds of the lias in England contains 

 much muriate of soda and sulphate of magnesia. 



The saliferous gypsum, in the Tarentaise, is anhydrous, and con- 

 tains a considerable quantity of silex ; it occurs interstratified with 

 limestone which bears a nearer resemblance to the magnesian lime- 

 stone than to lias. The tops of some of the mountains are covered 

 with beds of common gypsum, intermixed with native sulphur. In 

 one of the rocks associated with the gypsum formation, I discovered 

 a fossil Patella. Though a branch of the Ecole des Mines, with 

 able instructors from Paris, had been for some years established at 

 Moutiers, close to the salt formations, a very erroneous opinion res- 

 pecting the gypsum of the Tarentaise was maintained by the profes- 

 sors; namely, that the gypsum merely formed an unconformable 

 covering over the adjacent mountains. I observed it in several parts 

 of the valley of the Doron near Moutiers, as distinctly interstratified 

 in the calcareous mountains, as the gypsum of Monlmartre is inter- 

 stratified between the tertiary formations near Paris. In one of the 



* Travels in Sicily, by Lieut. Gen. Cockburn. 



t Jerome, who resided in Syria, in the fourth century, informs us, that the rock 

 of salt was existing in his time ; and fancifully relates certain peculiarities res- 

 pecting it, which equal in absurdity the legends of the darkest ages of papal su- 

 perstition. , 



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