Dr. Du Riche Preller — Mineral Springs of Baden. 149 



II. — The Mineral Springs of the Baden District (Switzerland). 

 By C. S. Du Riche Preller, M.A., Ph.D., M.I.E.E., F.G.S., F.C.S. 



AS is well known, there are in Switzerland a good many cold 

 mineral, but very few powerful thermal springs, 1 a fact which 

 is in a great measure due to the scarcity of the younger series of 

 eruptive rocks, such as give rise to the abundant hot springs of 

 Bohemia, the Taunus and Eiffel districts, Auvergne, the Pyrenees, 

 and other localities possessing similar geological features. 



The only really powerful and abundant thermal, but non- volcanic, 

 springs in Switzerland are those of Pfiivers (Ragatz) in the Rhine 

 valley, of Loueche in the Rhone valley, and of Baden in the Limmat 

 valley. At Pfiivers, as at Loueche, the springs are confined to one 

 locality,, whilst the Baden district comprises, besides the springs of 

 Baden proper, a whole cluster of different mineral springs, spread 

 over an area of about ten square miles. It is this area which the 

 writer has lately had an opportunity of examining. 



At first sight, it seems remarkable that so great a number and 

 variety of mineral springs should be met with in the Molasse for- 

 mation, which, broadly speaking, constitutes the Subalpine hills east 

 of the river Aare ; but on closer examination, it is found that all 

 those springs are situated along the same zone — to wit, at the base of 

 an isolated Jurassic ridge which lies between the Jura range and the 

 Central Alps, and, like these two mountain chains, was raised and 

 folded in Miocene times. The Jurassic outcrop extends for about 

 sixteen miles from the left bank of the river Aare, near Aarau, to 

 about seven miles beyond Baden, its strike being south-west to 

 north-Hast, that is, in the main parallel to the strike of the Jura and 

 the Central Alps. 



€ 



G = Glacial. 



M = Molasse. 



J = Jura (Upper and Middle . 



T = Trias (Keupen. 



• = Mineral spring?. 



Fig. 1. — Plan of the Baden District. 250000 • 



As is seen from the plan and longitudinal section (Figs. 1 and 2), 

 the Jurassic ridge rises at both ends to the considerable elevation of 



1 Among the cold mineral springs, the most notable and abundant are those of 

 St. Moritz and Tarasp, in the Eugadine, and of Itheinfelden, near Bale. 



