this subject which I have had the opportunity of seeing, is one by M. Hassenfratz, contained in the eleventh volume of the Annales de Chimie. From this memoir it would appear that the general situation of the Rock-salt in Transylvania and Poland is very similar to that which it occupies in Cheshire; the beds of this mineral being disposed in small plains, bounded by hills of inconsiderable height, forming a kind of basin or hollow, from which there is usually only a narrow egress for the waters. The situation of the Austrian salt mines near Salzburgh is however very different. The mineral here appears to be disposed in beds of great thickness, which occur near the summit of limestone hills, at a great elevation above the adjoining country.[1] This fact is a singular one; and if we admit the idea that rock-salt is formed from the waters of the sea, makes it necessary to suppose the occurrence on this spot of the most vast and wonderful changes. M. Hassenfratz states it as a general fact, that in countries where salt-mines occur, fragments of primitive rocks appear in great abundance over these beds. It does not seem, however, that any deduction of importance can be connected with this fact.
The disposition of the beds of salt in the continental mines seems to be very generally a horizontal one, and as in the English mines, they are separated by strata of clay of a varying thickness. It would appear, however, with respect to extent of dimensions, that they are in general, greatly inferior to the bodies of rock-salt met with in our own island. In Hungary and Poland these beds do not present a thickness of more than one or two feet, and are separated by layers of
- ↑ I am informed by Mr. Greenough that the lapelsgraben, which is the highest gallery, of the salt mine at Halstadt, is stated in Von Buch's Travels through Germany and Italy to be two thousand nine hundred and seventy-five feet above the sea, and that the salt mines at Hall in the Tyrol are at a much more considerable elevation.
