62 Dr Daubeny on Thermal Springs, 



Wiesbaden are found near the base of the Taunus Mountains, 

 whilst the cold effervescing ones of Schwalbach and Fachingen 

 occur higher up in the same chain ; thus, too, the same district 

 which gives rise to the thermal waters of Aix la Chapelle, fur- 

 nishes the chalybeates of Spa near the summit of the hills above. 

 This renders it probable, that such carbonated springs may in 

 reahty have acquired warmth from the focus of the same vol- 

 cano, which served to heat the thermal waters of the low coun- 

 try, but that they have been robbed of this excess of tempera- 

 ture by passing through so much greater an extent of rock. 



The only warm spring in England, which has been passed 

 over in the preceding enumeration, is Bath, and this, though 

 not immediately connected with any signs of disturbance, occurs, 

 if I am rightly informed, in the vicinity of several large and ex- 

 tenave faults*. The warmth of this spring has indeed been 

 attributed to the decomposition of pyrites, in which the lias 

 clay, from whence it issues, abounds ; but to this it may be ob- 

 jected, that the same stratum, though equally charged through- 

 out with this mineral, nowhere else throws out springs pos- 

 sessing more than the medium temperature, and yet the sul- 

 phuretted hydrogen which the latter so frequently contains, 

 shews a decomposition of pyrites to be going on in several other 

 places. Neither do the Bath waters manifest any traces either 

 of sulphur or of sulphate of iron, both which ought to be present, 

 if their heat arose from the cause assigned. 



The only thermal water known to exist in Wales is in the val- 

 ley of the Taafe, about six miles north of Cardiff, Glamorgan- 

 shire ; and it will be seen by reference to the geological sketch 

 (PI. III. rig. 1.) of this district*, with which I was some time 

 ago favoured by Mr Conybeare, that its position is near the point, 

 at which the beds of pennant, of shale, of millstone grit, and of 

 mountain-limestone, begin to rise at a considerable angle towards 

 the south. Thus, the occurrence of a fault, or a dislocation of 

 the strata, at a spot where they appear to be inclined at so high 



• I believe I may quote Mr Lonsdale, Secretary to the Geological Society,' 

 in support of this assertion, and it is well known that I could not appeal to 

 any one more thoroughly acquainted with the stratification in the neigh- 

 bourhood of Bath, than that gentleman. 



