Page:A Treatise on Geology, volume 1.djvu/227

 CHAP. VI. but we shall present a short view of some of the principal conditions ascertained to accompany these deposits.

First, as to the Rocks which inclose Salt.—The great abundance of this valuable substance in the red sandstone and red marl of England, as well as in the contemporaneous rocks of Germany, naturally produced a general impression that salt was peculiarly the product of that geological era; and it was sometimes assumed without evidence that all the well-known salt works of Switzerland, Poland, Spain, &c., drew their supplies from the new red sandstone formation. The inference was extended not only to the salt lakes and springs of European, but also of Asiatic, Russia, to the sands of Persia and salt-houses of Ormuz, and the salt works of India, between the Indus and the Chellum. Even the American salt deposits were thought to belong to the red sandstone formation of Europe.

The progress of information has corrected this over extension of a well-grounded inference: salt springs rise in Durham and Northumberland, and Leicestershire, from the coal system; some of the salt works of the Alps are supplied from the oolitic system: the famous mines of Cardona and Wieliczka have been referred, the former to green sand, the latter to tertiary rocks; and, to complete the series, salt springs abound in the volcanic regions of Sicily and Auvergne.

It appears then that salt is derived by the action of water from almost every stratum, formerly left by the sea, and from many volcanic and other products, and that large beds of salt occur at several stages of the series of marine formations, but that in Europe they are remarkable and frequent in the new red sandstone system. This may still, and without impropriety, be called the saliferous system.

Hence we may securely infer that although salt was more or less diffused through all the marine deposits, the enormous accumulation of this substance in certain places can only have happened in consequence of local peculiarities several times recurring, but at least, in