TRANSACTIONS OF THE SECTIONS. 83 



Remarks illustrative of the Physical Geography of the Pyrenees, parti' 

 cularly in relation to Hot Springs. By Professor Forbes. 



The author attempted to embody in this communication the results, 

 more particularly geological, of a recent tour to the Pyrenees, and which 

 form part of a paper recently read to the Royal Society of London. 

 The intimate relations of hot springs to certain classes of rocks had be- 

 fore been observed, and the occurrence of granite as characterizing these 

 thermal sites is so striking as not to escape the most superficial observer. 

 ITie author remarks in addition that these springs rarely or never ap- 

 pear in the heart of a gi-anite country, but on its borders, or at least 

 near where stratified rocks occur in contact with granite. He quoted 

 many examples in proof of the assertion, but one of the most striking 

 is found in the department of the Pyrenees- Orientales, where an insu- 

 lated deposit of stratified rock surrounded by granite, has its outskirts 

 or line of junction studded with hot springs. 



Stratified rocks under such circumstances are usually altered in their 

 texture and composition, and the author shows that even where the 

 granite does not directly appear its action may be inferred from the 

 metamorphic character of the rocks and frequently from the fissures and 

 contortions which accompany that character. The author includes the 

 whole of Charpentier's " Bareges formation," or primitive trap slates, 

 in this class, and to their occurrence attributes the hot springs of Bareges, 

 St. Sauveur, and Cauteretz. Lastly, he shows that the quantity of 

 metalliferous deposits in the Pyrenees seems intimately connected with 

 the occurrence of the hot springs, being their almost invariable conco- 

 mitants. He showed in a tabular view (which will be published in the 

 Phil. Trans.) the number of coincidences of the five following coordinate 

 pheenomena : — Hot springs, elevatory or intrusive rocks, metamorphic 

 rocks, lines of fissure and elevation, metalliferous veins. 



The author explained the importance which he attaches to an accu- 

 rate determination of the temperature of these springs, and the precau- 

 tions which he observed in order to make them comparable at future 

 periods with observations which may be then made ; and that the very 

 few old observations of any value seem to indicate no decided change 

 of temperature. The principal spring at Bareges cannot have changed 

 half adegree of Fahr. in a century. The author also noticed the capricious 

 intermingling of springs of every kind in such a way as to separate 

 completely the phsenomena of mineralization and high temperature. In 

 some parts of the Pyrenees hot springs of pure water, pure cold springs, 

 mineral hot springs, and mineral cold springs rise within a few yards of 

 one another. 





On certain Phenomena connected with the Metalliferous Veins of Corn- 

 wall. By H. T. De la Beche, F.R.S.. G.S. 



Mr. De la Beche brought forward observations on the directions, 

 breadth, intersection, and other characters of mineral veins; described 

 the relations of the veins to the adjoining rocks, and to the natural 



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