262 Professors A. Heim and A. Penck — 



of Zurich. (Waedensweil, Utznach). We find similar gravels and 

 Nagelfluh far wider distributed at the north-east border of the 

 Glatt Valley, where they lie between the ground-moraine and the 

 upper-moraine. Near Diirnten and Wetzikon, lignites are deposited 

 between the gravel and the ground-moraine. These deposits of 

 rolled materials also, which we here place under (b), are isolated to 

 such an extent, and deposited at such different heights, that they 

 cannot be regarded, at least so far as the valley of the Lake of 

 Zurich is concerned, as the remains of an extended connected valley 

 deposit. 



(c.) The Nagelfluh of the Au peninsula, on the Lake of Zurich, 

 is distinguished by its " delta structure " from the above-men- 

 tioned deposits of rolled materials in the neighbourhood of the 

 Lake, and it has no equivalent in our Bavarian excursion-district. 

 It calls to mind the ancient Kander delta, on the Lake of Thun, and 

 according to Penck (Vergletscherung, etc., p. 343), the Nagelfluh of 

 Biber in the Inn valley, and that of the Monchsberg of Salzburg. Its 

 relation to the moraines is not exposed. From the mode of its oc- 

 currence it very probably belongs to the base of the upper moraine. 



(d.) Of all the Quaternary deposits, the moraines of the Lake of 

 Zurich play the most important part. There is an astonishing con- 

 trast between them and the typical Bavarian moraines. The morainic 

 hills are shown by the prevalence of large, angular, erratic blocks 

 and sand, and the diminished quantity of clayey material, to belong 

 mostly to the upper-moraines ; such are altogether absent in the 

 Bavarian lake district. The pure ground-moraines form in Switzer- 

 land an irregular, but not very thick layer, overlaid by the upper- 

 moraines, or by the gravelly deposits above mentioned. Only the 

 terminal moraines, and not the longitudinal moraines, have obtained 

 a great part of their materials from the ground-moraines. 



Ill- — The Relation of the Upper Bavarian Lakes to the Quaternary 



Deposits. 



The Ammer Lake and Wuerm Lake occur in wide valleys, which 

 form deep bay-shaped indentations in the southern margin of the 

 same deposit of Nagelfluh. In the valleys especially, which have 

 been excavated in the deposit of Nagelfluh, and also in the surround- 

 ing district of the above-named lakes, the gravels (I. 6) are developed, 

 and, indeed, they can be seen with constant characters, in the lower 

 part of both lakes, in the upper part of Ammer Lake, and on the 

 east margin of Wuerm Lake. The Lakes of Staffel and Kieg are 

 situated to the south of the Nagelfluh district, where they extend 

 themselves in a basin in the ancient Molasse, which is partly filled 

 with the gravels I. b. (Schotter). They are bounded above and below 

 by ridges of the dislocated Molasse, whilst between both only 

 horizontal beds of the gravels (I. b) are raised above the surface. 



The moraines form a surface layer, alike on the tops of the hills 

 between the lakes, as on their slopes down to the margins of the 

 lakes, thus, as a rule, covering discordantly the outcrops of Nagelfluh, 

 Miocene Flinz and gravel (I. b) ; so that these various deposits are 

 only exposed in lateral gullys or in steep cliffs. 



