560 DR. C. S. DU EICHE PRELLER OK" GLACIAL [Aug. 1 896, 



which was pushed farther out into the Subalpine valle) s, resolves 

 itself, in my view, mainly into a retran sport, by glacio-fluviatile 

 agency, of Miocene fluviatile material deposited in three mighty 

 zones, one in front of the other, at the foot of the Alps. 



III. Glacial Deposits. 



In briefly describing the salient features of the various additional 

 glacial deposits examined in the Zurich district, and extending over 

 an area more than 40 miles in length, it will be convenient to 

 begin at the lowest point, namely, at the confluence of the river 

 Limmat with the Aare near Turgi, and thence proceed up the 

 valley. The various deposits are marked in the map of the district 

 (fig. 1, p. 558). 



Turgi. — This locality is undoubtedly one of the most interesting 

 in the Swiss lowlands, for it is here that the three principal rivers 

 of Central Switzerland and main affluents of the Upper Khine must 

 have converged ever since Subalpine valleys were formed. As is 

 shown in the sketch-map (fig. 2), there are high-level deposits of 

 Deckenschotter at two points of the trough which marks the 

 confluence of the three rivers — namely, on the two spurs called the 

 Gebensdorfer Horn and the Siggenberg at the extreme end of the 

 Limmat valley, 1 to the former of which I have already referred in a 

 previous paper. These deposits are each about 60 metres in depth, 

 very similar in character, and rest direct on Molasse without inter- 

 vening moraine, the contact being on the Gebensdorfer Horn at 

 contour 480 (metres), while on the Siggenberg it is at contour 550, or 

 70 metres higher. In the trough itself, where the mean river-level 

 coincides with contour-line 330, the gravels deposited by the three 

 rivers are so intermingled that it is extremely difficult to define their 

 derivation, except that the Aare pebbles, having travelled a longer 

 distance, are generally much smaller than those of the Eeuss and the 

 Limmat. At any rate, all the gravels at this point belong to the 

 younger series, and, with the exception of some isolated blocks, the 

 repeated powerful re-erosion at the junction of the three rivers has 

 apparently left no vestige of Deckenschotter. 



Baden. — The peculiar feature of this locality consists in a re- 

 markable anticlinal Jurassic fold called the Laegern, which, tra- 

 versing the Limmat valley almost at right angles, rises to 856 metres 

 above sea-level, and towers fully 200 metres above the surrounding 

 Molasse hills. In this saddle, a trough or basin with a steep, 

 narrow, V-shaped passage for the river at each end, has been scooped 

 out by fluviatile action, and it is in this basin that several ex- 

 tremely interesting glacial sections are exposed. 



As is seen from the sketch-map (fig. 2), the lowest of these 

 sections occurs close to the edge on the left bank of the Limmat at 

 contour 360, near the lower end of the basin, and a few hundred 

 metres beyond the sharp bend of the river where the sulphur 



1 According to Dr. Da Pasquier (op. cit.), there is a cap of Deckenschotter 

 also on the Bruggerberg, an isolated, oblong-shaped hill on the left bank of 

 the Aare. 



