T. S. Hunt on the Chemistry of Natural Waters. 209 
78. Of the above series the Trenton group includes the Birds- 
eye and Black River limestone, as well as the Trenton 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 sandrock corresponds to the great mass of 
dolomite which’constitutes Nos. 10, 11, and 12, and includes the 
ypsum and the salt-bearing strata of the Onondaga formation. 
hese repetitions of similar strata, marking successive recurren- 
ces of similar geological and geographical conditions, which form : 
great cycles in the history of the continent, have been already 
considered in a paper by me on Bitumens, etc., in this Journal, 
[2], XXXV, 166. 
§ 74. In the eastern basin, which includes not only south- 
eastern Canada, but the whole of New England, the strata are 
m an altered and crystalline condition, if we except a narrow 
TS 0 
he western basin, which alone 
bee 
stated, 
donia rise from the Trenton group, and that of Fitzroy from the 
Chazy or Calciferous, while two others at Ste. Martine and Raw- 
a i the Potsdam. All the other 
Waters of these two classes issue from the Hudson-River shales, 
With the exception of those of Varennes and Jacques C 
Which seem to rise from the Utica formation. 
_ Aw. Jour. Sct.—Szconp Serres, Vou. XL, N9. 119.—SePt., 1865. — 
