IX.] CHEMISTRY OF NATURAL WATERS. 155 



limestone of the New York geologists, and is non-magnesian, 

 enclosing beds of chert, silicified fossils, and petroleum ; in all 

 of which characters it resembles the Corniferous limestone 

 above. In like manner the Potsdam is represented by the 

 Hudson River and Medina formations, while the gypsiferous 

 dolomite of the so-called Calciferous sand-rock corresponds to 

 the great mass of dolomite which constitutes Nos. 9, 10, and 

 11, and includes the gypsum and the salt-bearing strata of 

 the Onondaga formation. These repetitions of similar strata 

 mark successive recurrences of similar geological and geo- 

 graphical conditions, which form great cycles in- the history of 

 the continent. 



74. [Within 'the eastern border of this basin, stretching 

 along the western base of the Green Mountains, and thence 

 northeast to Quebec, and beyond it on the southeast shore of 

 the St. Lawrence, is spread a great series including about 7,000 

 feet of limestones, dolomites, shales, and sandstones. These 

 rocks, which are more or less disturbed, constitute what Logan 

 has called the Quebec group, and are the Taconic of Emmons, 

 or the Primal and Auroral of Eogers, containing organic remains 

 of the first palaeozoic fauna, and corresponding to the Lower 

 and Middle Cambrian of Sedgwick, of which the first three 

 formations in the above table are but incomplete and littoral, 

 or shallow-water deposits. (See further, paper XV., part 3.)] 



None of the waters described in the present paper belong to 

 this Quebec group, which, nevertheless, presents several mineral 

 springs, some of which are described in the Geology of Canada. 

 Of these, the salines of Cacouna, Green Island, Riviere Ouelle, 

 and Ste. Anne de la Pocatiere are bitter waters belonging to 

 the first class ; while a sulphurous spring at the latter place, 

 and another at Quebec, are alkaline waters of the fourth class. 



75. Of the waters of the region which is considered in 

 this paper, many have been qualitatively analyzed which are not 

 here described. Including two from Vermont, twenty-one alka- 

 line waters of the third and fourth classes have been exam- 

 ined. Of these, as already stated, the waters of Caledonia rise 

 from the Trenton group, and that of Fitzroy from the Chazy or 



