394 



MINERAL AND THERMAL SPRINGS. 



[Ch. XVII, 



but with perfect eyes."* The nearest ponds or lakes were 

 at a great distance on the surface of the desert, and in this 

 and the other cases before mentioned of the subterranean 

 transportation of shells, fish, and fragments of plants, we 

 see evidence of the water not having been simply filtered 

 through porous rock, but having flowed through continuous 

 underground channels. Such examples suggest the idea that 

 the leaky beds of rivers are often the feeders of springs. 



MINERAL AND THERMAL SPRINGS. 



Almost all springs, even those which we consider the purest 



im 



chemical solution, are so intimately 



the water, as not to affect its clearness, while they render it, 

 in general, more agreeable to our taste, and more nutritious 

 than simple rain-water. But the sprin 



miner 



matter 



impre 



form 



Many of these springs are thermal, or have a higher tempera- 

 ture than that which belongs to ordinary springs in the same 

 neighbourhood, and they rise up through all kinds of rock; 

 as, for example, through granite, gneiss, limestone, or lava, 

 but are most frequent in volcanic regions, or where violent 

 earthquakes have occurred at eras comparatively modern. 



The water given out by hot springs is generally more volu- 

 minous and less variable in quantity at different seasons than 

 that proceeding from any others. In many volcanic regions, 

 jets of steam, called by the Italians ' stufas,' issue from 

 fissures, at a temperature high above the boiling point, as m 

 the neighbourhood of Naples, and in the Lipari Isles, and are 



disengaged unceasingly for ages. Now 



mixed 



condensed before reaching the surface by coming in con 



tact 



may 



r 



mineral springs of every degree of temp 



ise to ther- 



It 



is, indeed, by such means rather than by hydrostatic pressure 



* Gazette do Lausanne, Jan. 1864, 



O 



*tf 



11 



bo# eS 

 ftui 



a 



W& 



i 



ga 



,ses ; 



si 



tate 



acti^ 



less 



i 



•nil 







•ffrite: 

 abun( 

 them 

 ;reat 



jreat 



been 



perio 



great 



sprin 



inth 



dislo 

 byii 



Tl 



sighi 



^ve ii 



Ala 



] 



can 







DlOV. 



out, 

 men 



< 



igi 



at 



tin* 

 at) 



8 



01] 





