A. Vaughan Jennings^Geologij of Bad Nauhcim. 363 



a long northward extension of tlie Mediterranean reaching from the 

 Marseilles neighbourhood up the Rhone and lihine valleys, perhaps 

 establishing communication witli tlie North Sea; and that the earfh- 

 moveraents which subsequently completed the upheaval of the 

 Alpine chain separated the northern gulf from the sea to which it 

 had formerly belonged. 



The process of severance was doubtless gradual, and allowed of 

 a transition period in which the marine J/wrea;and JPerna were slowly 

 displaced by the brackish- water Cerilhunn and Cyrena. In the 

 upper strata there are narrow bands in which the fossils indicate 

 the prevalence of purely fresh-water conditions, but the brackish- 

 water tj'pes continued to exist apparently through Miocene times. 



(c) As to the chemical and physical questions connected with the 

 Nauheim springs, anything like a complete discussion is beyond the 

 scope of this paper. Those who wish to know how far the con- 

 sideration of the amount of soluble salts in springs, rivers, and seas 

 may lead them in the discussion of the geological age of our planet, 

 should read Professor Joly's interesting paper in the Transactions of 

 the Royal Dublin Society for 1899. 



So far as the local questions are concerned we can only make 

 a note or two on, firstly, the chemical contents, and secondly, the 

 physical conditions. 



In the first case it is evident tliat we are not dealing with 

 'special' types of springs — saline, chalybeate, or calcareous — but 

 with a combination of all. It would be interesting to know the 

 sources of the different contents, but it is difiicult to make anything 

 but the vaguest suggestions. 



As to the iron, it is evident that a certain amount may come from 

 denudation of the Devonian rocks on the west, and more from the 

 breaking up of the basalts. The extraordinary amount of iron 

 oxides in some beds of the ' Bltittersandstein' suggests that they may 

 have contributed large quantities to the underground supply from 

 which the springs now lise, but they, in turn, must have derived 

 it from neighbouring Palaeozoic or igneous rocks in Tertiary times. 



With respect, again, to the calcareous contents, there seems a much 

 larger proportion than the geological features of the surrounding 

 country would lead one to expect. The limestone strata are of 

 small extent, and anything contributed by the decomposition of the 

 felspars in the basalt would be insignificant. There is, on the other 

 hand, a great quantity of calcareous matter in the Tertiary beds, 

 derived at that date, most likely, from a greater distance and from 

 a larger extent of since denuded limestone in the district. Much of 

 this has been and is still being gradually carried down through 

 fissures to the subterranean reservoirs which the borings have 

 'tapped.' The lime was doubtless largely separated through the 

 agency of organisms, but in beds of this character the shells would 

 almost certainly be to a large extent redissolved. 



It is possible, however, that we have not here sufficient to account 

 for the surface phenomena, especially when we also take into con- 

 sideration the enormous amount of carbon dioxide in the waters 

 of the Sprudel. Probably there are deep-seated calcareous strata, 



