ADDRESS. 1 1 



* which can only be derived from original depositions of salt,' and it is 

 also supposed by Dr. T. Sterry Hunt to contain solid rock-salt 115 feet in 

 thickness at the depth of 2,085 feet, near Saginaw Bay in Michigan. 



In the Lower Devonian strata of Russia near Lake Ilmen, Sir R. 

 Murchison describes salt springs at Starai Russa. Sinkings ' made in 

 the hope of penetrating to the source of these salt springs,' reached a 

 depth of 600 feet without the discovery of rock salt, ' and we are left in 

 doubt whether the real source of the salt is in the lowest beds of the 

 Devonian rocks or even in the Silurian system.' 



In the United States brine springs also occur in Ohio, Pennsylvania, 

 and Virginia, in Devonian rocks. 



In Michigan salts are found from the Carboniferous down to the 

 Devonian series; and in other parts of the United States, Western 

 Pennsylvania, Virginia, Ohio, Illinois, and Kentucky, from the lower 

 Coal-measures salts are derived which must have been deposited in inland 

 areas, since even in the depths of inland seas that communicate with the 

 great ocean, such as the Mediterranean and the Red Sea, no great beds 

 of salt can be deposited. Before such strata of salt can be formed, super- 

 saturation must have taken place. 



In the North of England at and near Middlesbrough two deep bore- 

 holes were made some years ago in the hope of reaching the Coal-measures 

 of the Durham coal-field. One of them at Salthome was sunk to a depth 

 of 1,355 feet. First they passed through 74 feet of superficial clay and 

 gravel, next through about 1,175 feet of red sandstones and marls, with 

 beds of rock-salt and gypsum. The whole of these strata (excepting the 

 clay and gravel) evidently belong to the Keuper marls and sandstones of 

 the upper part of our New Red series. Beneath these they passed through 

 67 feet of dolomitic limestone, which in this neighbourhood forms the 

 upper part of the Permian series, and beneath the limestone the strata 

 consist of 27 feet of gypsum and rock-salt and marls, one of the beds of 

 rock-salt having a thickness of 14 feet. This bed of Permian salt is 

 of some importance, since I have been convinced for long that the 

 British Permian strata were deposited, not in the sea, but in salt lakes 

 comparable in some respects to the great salt lake of Utah, and in its 

 restricted fauna to the far greater salt lake of the Caspian Sea. The 

 gypsum, the dolomite or magnesian limestone, the red marls covered with 

 rain-pittings, the sun-cracks, and the impressions of footprints of reptiles 

 made in the soft sandy marls when the water was temporarily lowered by 

 the solar evaporation of successive summers, all point to the fact that our 

 Permian strata were not deposited in the sea, but in a salt lake or lakes 

 once for a time connected with the sea. The same may be said of other 

 Permian areas in the central parts of the Continent of Europe, such as 

 Stassfurt and Anhalt, Halle and Altern in Thuringia, and Sperenberg, 

 near Berlin, and also in India. ^ 



» See 'Physical Geology and Geography of Great Britain,' 5th editidn, where th'^ 

 question is treated in more detail. 



