Salt or brine springs occur in various parts of the United States in the _old transition slate_ rocks. Sir Charles Lyell tells us that, “in the middle of the horizontal Silurian rocks, in the State of New York, there is a formation of red, green, and blueish-grey marls, with beds of gypsum, and occasional salt-springs, the whole being from 800 to 1000 feet, and indistinguishable in mineral character from parts of the Trias of Europe.” Salt-springs also occur in England in the coal measures. The rock-salt of Cheshire and the brine-springs of Worcestershire occur in what is called the _old red sandstone_ group. The salt of Ischl, in the Austrian Alps, belongs to the _oolitic_, as does also that found in the Lias of Switzerland. The immense mass or bed of salt near Cordova occurs in the _cretaceous_ group; while the salt deposit of Wieliczka belongs to the _supracretaceous_ group.[45] The reader doubtless remembers, as I stated in the first chapter, that the origin of salt is one of those enigmas of nature which, as yet, has completely frustrated the most accomplished and scientific geologists, and no suggestion has yet been made which will satisfactorily and conclusively account for its formation; for whatever hypothesis has been stated, there is sure to be an objection so difficult to overcome, that the author has been fain to admit that it is thoroughly impracticable, and therefore inadmissible. That it is decidedly not amenable to the received laws of geology, is apparent, which all must admit; therefore one cannot possibly apply them so as to determine the place it occupies in relation to other strata, or practically fix that period of time in which it was deposited; for it is erratic, and its position is anomalous—erratic in the variety of appearances it assumes in creation, and anomalous because it belongs to no particular strata, and therefore no exact period of time can be assigned to it as to other formations. That salt is either due to volcanic agency, marine explosion, or to overflow of sea-water and subsequent evaporation, or resilience, and ultimate deposition, are the only three hypotheses which can with any credibility be advanced to account for its formation. That we have it presented to us in _six_ different conformations are facts which when considered separately seem to point to one common origin, but when taken as a whole indicate a separate inception.