SCENERY OF SWITZERLAND. 
164 
bably the outermost, while those of Zurich and 
Rapperschwyl represented long periods of arrest 
and standstill of the glaciers during their general 
retreat. 
In theory this explanation is clear and simple, 
but it is not always easy to identify the beds. The 
“Deckenschotter,” or upper and older bed, can in- 
deed be generally recognised by the numerous 
cavities, the “rotten” condition of many of the 
pebbles, by its being much more frequently 
cemented together, and in some districts by the 
nature of the pebbles; in the Zurich Valley, for in- 
stance, by the absence or great scarcity of Sernifite 
and of the Alpine siliceous rocks, and by the fre- 
quency of Hochgebirgskalk, which does not occur in 
the Miocene Nagel flue;* but there are many glacial 
deposits the exact age of which is very uncertain. 
The following table gives the periods, the deposits, 
and the great characteristic Mammalia, according to 
Dr. Du Pasquier:** — 
* Appeli, Beitr. z. Geol. K. d. Schw L. xxxiv. 
** Beitr. z. Geol. K. d. Schw., L. xxxi. ' 
