308 THE BEAUTIES OF NATURE CHAP, 
The Schyn also gradually worked its way 
upwards from Thusis till it succeeded in 
sapping the Albula, and carried it down the 
vacua 
Fig. 48. — River system round Chur, as it used to be. 
valley to join the Vorder Rhine near Thusis. 
In what is now the main valley of the Rhine 
above Chur another stream ate its way 
back, and eventually tapped the main river 
