36 



NEW RED SANDSTONE, ETC. 



valent in the higher or pyritous beds of the Lias, the oxide of iron being at the same 

 time more or less completely separated. By such means, it is presumed, these mineral 

 waters, which are simply brine springs at great depth, acquire additional and valuable 

 properties in their ascent. In suggesting this explanation, we must not, however, 

 overlook the fact, that fresh water is perpetually falling from the atmosphere upon the 

 surface of the Lias clay, and, more or less, percolating its uppermost strata. Many of 

 the saline springs must therefore be affected by this cause, and the existing condition 

 of the various wells in the Vale of Gloucester, may ultimately depend upon three 

 causes : — 



1 . The supply of salt water from the marls of the New Red System, in the manner 

 above described ; 



2. The chemical action produced during the filtration of the salt water as it rises 

 through the various strata of the Lias ; 



3. The supply of fresh water from the atmosphere. 



The chemical relations, and medicinal virtues of these waters, have been well described 

 in other treatises, and they are only mentioned in this place to convey a clear notion of 

 their origin, and their dependence upon the geological structure of the district. 



This reasoning respecting the origin of the Gloucestershire mineral waters may be 

 applied to all the mineral springs which rise through the Lias of the Vales of Worcester 

 and Warwick. 



2. Sandstone and Quartzose Conglomerates. 



Foreign Synonyms.—" Bunter Sandstein " (Ger.), " Gres bigarre " (Fr.) 



The great arenaceous formation of red and variegated sandstones, constituting the 

 Bunter Sandstein or Gres bigarre of continental geologists, is very largely developed in 

 England, particularly in the counties of Salop, Stafford, and Worcester. In Germany, 

 Poland, and the eastern parts of France, this formation is distinctly separated from the 

 Keuper (our saliferous marls and sandstone), by the " Muschelkalk" or shelly limestone. 

 (See note, p. 30.) In England we have not yet succeeded in recognising the equi- 

 valent of this limestone, and hence we have always wanted a clear line of separation 

 between the formation described in the last chapter, and that which we are now to con- 

 sider. When, however, we look to the vast development of the saliferous marls of our 

 island the maximum thickness of which, including subordinate courses of sandstone, 

 amounts to six or seven hundred feet, we should naturally be disposed to think that 

 these comprise the whole German formation called the 4 'Keuper," and that the true 

 equivalent of the Muschelkalk would be found rising from beneath these red and green 

 marls, and surmounting the sandstones and conglomerates which constitute the central 

 or chief masses of our New Red Sandstone. Now although I cannot yet completely 

 obviate the difficulty arising from the absence of the Muschelkalk, I may observe that 



