Tol. 52.] DEPOSITS, ETC., IN SUB ALPINE SWITZERLAND. 



581 



Jurassic Laegern anticline at Baden, and the anticline of the 

 Albishorn, which trends across the lake between Horgen and Au. 

 The first of these was obviously formed in Miocene times, that is, 

 before the first glaciatiou, and the same applies therefore to the small 

 synclinal folds of the Gebensdorfer Horn and Teufelskeller, lying 

 respectively on the northern and southern flanks of the Laegern 

 fold. If these synclinal folds were of later, that is, Glacial age, 

 the Deckenschotter deposits would show conclusive traces of having 

 shared the displacement of the underlying strata ; but, on the 

 contrary, that conglomerate rests in almost every instance uncon- 

 formably on the Molasse. Thus, on the Gebensdorfer Horn it 

 overlies horizontally the Molasse, which dips north at an angle of 

 about 20° ; at Teufelskeller, in the quarry on the northern slope of 

 the hill, the stratification is likewise perfectly horizontal, while the 

 slight reverse dip of only about 4° at one or two points of the 

 southern cliff is more apparent than real, and therefore so doubtful 

 that any inference drawn from it is devoid of value. Again, at 

 Wettingen, where the Molasse at river-level has a gentle inclination 

 up the valley, the Nagelfluh overlying it near the upper viaduct 

 clearly dips in the opposite direction, and on the Uetliberg, too, as 

 well as on the Albis range generally, the superposition is distinctly 

 un conformable. In face of this evidence, it is clear that all the 

 principal earth-movements in the lower part of the Zurich valley 

 took place before the first Ice-period, and not after the deposition 

 of the Deckenschotter. 



Essentially different, however, is the case of the second or Horgen 

 anticline in the upper part of the valley. From Horgen to Au and 

 Wadenswil, for a distance of about 6 kilometres and on both sides 

 of the lake, the Molasse-terraces of erosion exhibit a distinct reverse 

 dip, which I have also verified in the hills above Au, namely, in the 

 ravine of a stream descending parallel to the lake, from Eiiti to 

 Wadenswil, where the Molasse bank is overlain by Miocene Nagel- 

 fluh. The reverse dip of the terraces of erosion bordering the lake 

 was first pointed out by Prof. Heim 1 ; and although the inclina- 

 tion does not exceed 2 per cent, on an angle of about 1°, and 

 is, indeed, according to my observations, of an undulating rather 

 than uniform character, the phenomenon is yet of unquestionable 

 importance, the more so as the maximum dip of the terraces down 

 the valley is only 09 per cent., that is, about 0\5°, or ^ of the 

 ordinary ratio of slope of the hills towards the lake. Even more 

 decisive proof of a considerable zonal subsidence, extending from 

 that part of the Lake of Zurich across the so-called Hirzel and 

 Menzingen plateau to the Lake of Zug, is afforded by the greatly dis- 

 turbed Molasse strata in the Sihl valley, notably about 1 kilometre 

 above Sihlbrugg, where, close to a sharp bend of the Hirzel 

 road at contour 550, I have verified a dip up the valley of the 

 Molasse of no less than 25°. Other distinctly reverse inclinations 

 of the Molasse occur in the Sihl ravine near Sihlsprung and in 



1 Beitrage z. geol. Karte d. Schweiz, vol. xxv. (1891) p. 476. 



