Vol. 51.] AND INTERGLACIAL DEPOSITS IN SWITZERLAND. 



371 



schotter or plateau- gravel, that the Bavarian and Austrian Alps had 

 been visited by three different glaciations ; but as regards the Swiss 

 Alps, even such distinguished glacial geologists as Prof. Heim 

 hesitated to adopt that view, until quite recently, namely in 1891, 

 Dr. Leon Du Pasquier, of Neuchatel, showed in a valuable memoir ] 

 that the fluvio-glacial gravels deposited in the valleys of the 

 principal river-systems in the North of Switzerland admit of being 

 classed in three distinct categories, to wit, Cavernous Nagelfluh (the 

 Swiss equivalent for Deckenschotter), Upper Terrace-, and Lower 

 Terrace-gravels. Dr. Du Pasquier's conclusions, resting as they do 

 on fluvio-glacial evidence, are fully borne out by the morainic 

 deposits in the Zurich district (described in the Geol. Mag. paper 

 already quoted) ; and I now propose to submit some further evidence 

 of so-called ' fluvio-glacial ' and ' interglacial ' deposits which I ex- 

 amined during the summers of 1893 and 1894, in the vicinity of the 

 Lakes of Zurich, Constance, Zug, and Thun, and with reference to 

 some of which my conclusions differ in several important respects 

 from those recently arrived at by Swiss geologists. 



As regards definitions, 1 may say that the term 'fluvio-glacial' 

 refers to deposits which have been formed by rapidly-flowing glacier- 

 streams at or some distance from terminal moraines ; while the term 

 'interglacial' does not, of course, imply that during such a period 

 the Alps were free from ice, but refers to deposits formed during 

 more or less protracted periods intervening between general glacia- 

 tions : that is, to periods during which the glaciers were restricted 

 to the Upper Alpine regions, where they oscillated within compa- 

 ratively narrow limits, as they do in our own da)\ Hence both 

 fluvio-glacial and interglacial gravel-deposits are essentially fluviatile 

 in character, as distinguished from morainic or glacial deposits 

 properly so-called. 



II. Deposits near the Lakes of Zurich and Constance. 



1. Cavernous Nagelfluh. (Figs. 1 to 5.) The remarkable fluvio- 

 glacial deposits of Pliocene, so-called 'looherige' or Cavernous 

 Nagelfluh, on the summit of the Uetliberg near Zurich (fig. 3), and 



Fig. 3. 



Uetli"berg, n. Zurich. 



8781 



Cai'.NagclflithJp 



Miocene 



near Baden, about 15 miles below Zurich (4, fig. 1, p. 369), 

 were described in the paper already quoted (Geol. Mag. 1894). 



1 ' Fluvio-glnciale Ablagerungen in der Nord-Schweiz,' Beitrage zur geol. Karte 

 d. Schweiz, 1891. 



