Vol. 52.] DEPOSIT8, ETC., IS 8T7BALPINE SWITZERLAND. 579 



It is on the ancient flat and broad ridge which, at the advent of 

 the Ice-age, extended continuously from the Albishorn to the 

 Uetliberg, Baden, and the Gebensdorfer Horn, 1 that the various 

 deposits of old conglomerate were formed during the first glaciation ; 

 and seeing that they occur at irregular intervals, each of them 

 marks, in my view, a stage in the general but intermittent recession 

 of the ice-sheet. As regards the evidence of the Preglacial floor 

 of the lower Aare valley, whose course along the foot of tbe Jura 

 lies, moreover, in a natural synclinal channel between that range 



Transverse Sections of the Zurich Valley. 

 Fig. 13. — Lauffohr to Baden. 



[Width=2-21 kilom. ; depth=157 metres.] 

 Fig. 14. — Baden to Zurich. 



[Width=4-82 kilom.; depth=191 metres.] 

 Fig. 15. — Zurich to Ufenau. 



[Width =9-7 kilom. ; depth =400 metres.] 

 Fig. 16. — Mean transverse section. 



[Width=7 kilom. ; depth=300 metres.] 

 Scale =1 : 100,000. 



and the Subalpine Molasse, I have traced the solid rock close to the 

 river's edge at Brugg, near the confluence with the Reuss, as well 

 as at Lauffohr, as already mentioned, while, according to Dr. Du 

 Pasquier, it also appears in many places above Brugg, as well as 

 at several points between Lauffohr and the confluence of the Aare 

 and Rhine. 



Again, in the last-named valley, both below and above that 

 confluence, long stretches of solid rock at river-level are mentioned 

 by the same writer, who is himself led to the conclusion that this 

 valley was already formed before the first glaciation, the Decken- 



1 Various small transverse valleys and depressions were, during subsequent 

 interglacial periods and in Postglacial times, formed iu this ridge by erosion 

 and landslips ; it is, therefore ,no longer continuous at the pregent day. 



