1865.] CHEMISTRY OF NATURAL WATERS. 297 



§ 79. The extended series of analyses which we have given in 

 the preceding pages presents many points of interest. Nowhere 

 else, it is believed, has such a complete systematic examination of 

 the waters of a region, and of a great geological series been made. 

 Additional importance is given to these results by the fact that 

 the waters are all derived from paleozoic strata, and we are thus 

 enabled to compare these saline materials of an ancient period 

 with those which issue from, and in may cases owe their saline 

 impregnation to strata of comparatively modern origin. Compari- 

 sons of this kind, such as I have already instituted between brines 

 of different geological epochs in § 39, possess great geological 

 interest. 



It is a consideration not without interest, that the valley of the 

 St. Lawrence under different meteorological conditions might 

 become a region abounding with saline lakes, affording sea-salt, na- 

 tron and borax, the results of the evaporation of the numerous 

 saline and alkaline springs which have just been described. 



§ 80. A few considerations are here suggested by the fact already 

 mentioned of the apparent absence of mineral springs from the 

 altered paleozoic strata of the Quebec group. Metamorphism 

 and disturbance or displacement of strata are generally concomi- 

 tants, not, as I conceive, because the process of alteration is in 

 any way connected with the disturbance of the rocks, but 

 because a great accumulation of superincumbent' strata, a necessary 

 preliminary of metamorphism, is the efficient cause of the fold- 

 ing of the deeply buried and subsiding rocks, in a way which I 

 have already elsewhere pointed out.* The subsequent continental 

 uplifting of the altered, plicated, and more or less fissured strata, 

 and their irregular erosion, give rise to the broken surfaces of meta- 

 morphic regions, and at the same time permit the saline solutions 

 impregnating the strata to flow out ; while solid soluble salts, unless 

 enclosed by impermeable strata, are removed by lixiviation. Hence 

 we shall rarely find muriated waters issuing from crystalline and dis- 

 turbed strata. Those saline products which result from the decom- 

 position of feldspathic minerals, and the separation of alkaline car- 

 bonates ; or from the decomposition by these, or other agents, of the 

 gypsum which is often present in metamorphic strata, may, however, 

 readily give rise to waters of the fourth and sixth classes ; so that 

 we are not surprised to find alkaline and sulphated waters issuing 

 from crystalline strata. 



* Silliman's Journal [2], xxxi, 412. 



