60 Natural History of Volcanos and Earthquakes. 



same spot, and with temperatures from 160° to 180° Fahr., as we 

 see at Ax Siud at Thuez, we are forced to conclude that the 

 source of mineralization must be independent, to a great extent, 

 of that high temperature, and that the arguments, as to the origin 

 of thermal springs founded upon their chemical compositioji, 

 must be to a certain degree fallacious. 



The origin of the sulphureous waters in the Pyrenees can 

 scarcely be sought for in the granite, since no substances are con- 

 tained in it which can be supposed to produce such springs. If 

 such springs are formed by the decomposition of sulphates by 

 means of substances containing carbon, it is very probable,* then 

 we must look for the origin of the Pyrenean sulphureous waters 

 in the secondary formations, perhaps in some coal stratum, or 

 even possibly in the tertiary formations. This inference holds, 

 even if the sulphureous springs are formed in a manner opposite 

 to this view. If, now, the origin of the springs in question, in 

 other words, if the materials necessary for their formation be 

 present in one of the newer parts of the secondary formations, 

 then warm or cold sulphureous springs will result, according as 

 warm or cold water penetrates to this point. The granite plays, 

 then, no other part here, than that of rendering possible the de- 

 scent of meteoric water to great depths, and its re-ascent in con- 

 sequence of the raising of the strata effected by the granite, 

 which circumstance causes the heating of these waters. 



In this point, I think both theories agree ; viz., that which at- 

 tributes the heat of springs to chemical processes, and that which 

 refers its origin to central heat : for those who hold the former opin- 

 ion will doubtless not assign the stratified formations as the seat 

 of these chemical actions, but the granite, or the parts beneath 

 it. According to both theories, then, the meteoric water will be- 

 come warmer in proportion as it approaches nearer to the source 

 of heat, which can be sought for only at great depths. 



As the subterraneous course of springs is subjected to many 

 kinds of local impediments, so veins of springs of similar origin 

 may flow out at points very remote one from another ; and, vice 



* See my memoir in the JVeues Jrhrbuch der Chemie and Phys. t. vi, p. 251, year 

 1832. The proporliQ,nally large quantity of organic matter in the Pyrenean sul- 

 phureous springs (among which that of Bar^gine, so called from the valley of 

 Bareges, is remarkable) speaks but little in favor of their origin from a mountain 

 produced by volcanic fire. 



