GEOLOGY OF SARATOGA SPRINGS AND VICINITY 163 



Our purpose here is not at all to express disagreement with these 

 views of Kemp. We are not sure that we do disagree with them. 

 Kemp has made an important contribution to the geology of the 

 mineral waters of the region, by elaborating a definite theory con- 

 cerning their origin. We simply wish to emphasize the difficulty 

 and complexity of the subject, and our lack of definite data re- 

 garding it, and to suggest alternative views in one or two respects. 



We feel quite confident, in the first place, that the volcanic knob 

 at Northumberland is no evidence whatever of underground 

 igneous action, in the general region, of sufficient recency to have 

 any bearing on the question of the existence of present-day juvenile 

 waters underground. It does not show^ that such water does not 

 exist. But we think that the evidence for the presence of such 

 water is wholly independent of the presence of the plug, and is 

 neither strengthened nor weakened by it. 



We quite agree that the carbon dioxid and the chlorids have 

 a deep-seated source, but we think Ruedemann's suggestion as to 

 the possibility of the carbon dioxid arising from deep-seated meta- 

 morphism of the rocks is quite worthy of consideration as an al- 

 ternative hypothesis to the juvenile one. 



The tangential pressures which gave rise to the overthrusts may 

 have operated up to very recent times and may still be in opera- 

 tion. They must aid in metamorphosing deeply buried sediments. 

 In such sediments there is generally much lime, partly as beds of 

 pure limestone, partly in impure limestones, calcareous shales and 

 calcareous sandstones. In regions of metamorphosed sediments it 

 is the common experience to find the limestone formations con- 

 verted to marble and retaining all their original carbon dioxid. 

 The impure limestones and the calcareous shales, on the contrary, 

 recrystallize to schists containing little or no calcium carbonate, 

 but much calcium silicate in such minerals as pyroxenes, am- 

 phiboles, garnets etc., and we must assume that the calcium has 

 been recombined and carbon dioxid set free. Kemp lists this 

 process as one of the methods of the manufacture of uncombined 

 carbon dioxid below ground, and states its possible applicability 

 to the Saratoga region, but dismisses it as, to his mind, less likely 

 than an igneous source. But when com])ined with Ruedemann's 

 theory of the eastern source of the water it seems to us to take on 

 greater probability and to be worth considering as a source of 

 the gas. 



Nor do we feel at all certain that connate waters are to be en- 

 tirely ruled out of the question. The lack of sulphates in the 



