2i6 
SCENERY OF SWITZERLAND. 
SO that these glens open at some distance up the 
side of the valley, and their waters join the Reuss by 
rapids or waterfalls. 
The Andermatt terrace is not, however, the 
oldest or highest. At a level of 2000 metres there 
IS a terrace even more ancient, but still clearly 
visible, indeed the one which was first observed, and 
which was represented by Agassiz long ago iL his 
view of the Bromberghdrner. Above it the rock sur- 
face shows no trace of glacial action. 
There is also a third less conspicuous terrace, at 
a height of about 800 metres, on which Gurtnellen 
stands, which represents the lowest level to which 
the ice has reached. Below it we find evidence of 
river action only. 
We have then four “thalwegs,” all rising to the 
south, but with veiy different inclinations, the steepest 
being the present Reuss Valley. They all converge 
upwards; the Gurtnellen terrace joins the present 
Reuss level at Wyler, the terrace of the side valleys 
at Andermatt, the 2000 metre terrace on the shoulders 
of the St. Gotthard, at Monte Fibbia, and Monte 
Prosa. 
These terraces are not of course continuous; in 
many places they have been washed away; they have 
been cut into by lateral torrents, but here and there 
