180 
The American Geologist. 
March, 1894 
(1) it may cut back into its old channel to re-erode it, or (2) 
it may cut down to one side or the other of the old channel 
and so find rock at some point. Jn the latter case it may be 
on such a slope that it can wear away the sand on the lower 
side and so work back to its old channel,' or it may cut into 
the rock and form a new channel. In that event the river will 
rapidly enlarge its valley where it has only to carry away the 
soft sands from its old bed, while the size of the new channel 
will depend mainly on the character of the rock through 
which it is cut. The rapids of the Saranac. the beautiful An 
Sable chasm, and the falls of the La Moille, are probably of 
that origin. 
On the Winooski at least two such channels may be seen 
from the railroad. One is about three miles below Water- 
bury, where the railroad passes through a part of the old 
channel a short distance south of the small rock gorge through 
which the river Mows. 
A better example, well worth a visit, is found just above 
Winooski Falls. The accompanying map requires little ex- 
planation. Standing at the quarry and looking up stream, a 
valley perhaps half a mile wide, limited on either side by 
Fig. 1. — Rock gorge near Winooski Fulls, ft. 
