242 
SCENERY OF SWITZERLAND. 
Hence the Upper Engadine at the Maloja is from 
the first a broad valley, because it represents part 
of the course of a stream which has lost its head 
waters. 
Though the evidence is not so striking we find 
a similar state of things on the Lukmanier, the 
St. Gotthard, the Cenis, in fact most of the great 
Alpine passes, and we may say with confidence that 
the watershed between Switzerland and Italy was 
formerly further south, and is gradually, though of 
course very slowly, retreating towards the north. 
Moreover, as already mentioned, the Nagelflue 
(Miocene) deposits of the great Swiss plain between 
the Alps and the Jura contain many pebbles which 
must have come from high mountain ranges to the 
south of the present watershed, being formed of 
rocks which do not occur in Switzerland, but are 
found in the Italian valleys. 
Another result of the change has been the forma- 
tion of the chain of lakes, St. Moritz, Campfer, Silva- 
plana, and Sils, which characterise the Upper Enga- 
dine. Under the former regime the flow of water 
down the main valley was sufficient to carry off the 
materials brought down by the lateral tributaries. 
But since the head waters have been cut off and 
carried away into Italy this is no longer the case; 
