Natural History of Volcanos and Earthquakes. 59 



has examined, if springs rise in granite, it is just at the bound- 

 ary of that formation with a stratified rock. In a great many 

 cases it happens, tiiat part of the springs rise from gratiite, and 

 part from the slate or limestone in contact with it ; and, he cor- 

 rectly observes, a more striking instance of the immediate con- 

 nexion between thermal waters and disturbed strata could not be 

 desired.* 



According to the observations of several geologists, the tertiary 

 rocks in the Pyrenees extend horizontally to the foot of this 

 chain, without entering, as the chalk, into the composition of 

 any part of its mass. Elie de Beaumont thence infers that the 

 Pyrenees received their position, relatively to the neighboring 

 parts of the earth's surface, between the period of the deposition 

 of green sand and that of chalk (a formation, whose raised strata, 

 according to Dufrenoy's observations, ascend to the crest of this 

 chain,) and before the deposition of the tertiary strata of various 

 ages.f We can very well explain, according to this supposition, 

 why the springs in the Pyrenees issue between the elevated gran- 

 ite and the raised strata of slate and limestone. The circum- 

 stance above quoted from Pallasou, viz., that the temperature of 

 springs becomes lower, in proportion to their distance from the 

 principal granite-mass, may perhaps be of little importance, since, 

 according to the remark of Forbes, cold sulphureous springs are 

 to be found, even within not many yards of others, having a high 

 temperature, and almost an identical mineral composition. Of 

 this he has met with two examples in very different parts of the 

 chain, one at the Eaux Bonnes^ where a perfectly cold spring 

 rises within two hundred yards of the principal hot spring of the 

 place, has similar medicinal properties, and is even more strongly 

 impregnated with sulphur. The other example occurs at Las 

 Escaldas, on the southern declivity of the Eastern Pyrenees, 

 where a most efficacious cold sulphureous spring rises within 

 about one hundred yards of a hot one. When, Forbes contin- 

 ues, to these facts we add others scarcely less curious, of sprmgs 

 of totally ditferent mineral composition issuing from nearly the 



* At St Sauveur and Thiiez, we have the co-ordinate, and, as Forbes p. 602, 

 rightly thinks, connected phenomena of intrusive rocks, dislocations or fissures, 

 metalliferous impregnation, and hot springs. 



t See PoggendorfF's Annalen, t. xxv, p. 26, also p. 58. 



