Drainage Changes in the Moot^s Run Area 229 
divide are now the rock gorges in the second tributary and in 
Mooks Kun. 
The peculiar phenomenon that we observed in the amphitheater 
where the second tributary joins Moot’s Run is explained as 
follows: The collar of drift which now extends across the east 
side of the amphitheater is the remains of a much heavier reces- 
sional moraine, representing the position of the ice and the 
course of the second tributary when it made its first cut through 
the rock divide. But, as the ice began to retreat, the first and 
second tributaries took different courses, the first tributary keep- 
ing to the old course and the second tributary cutting in on the 
near side of the rock, keeping always against the ice front. 
What is known as Moot’s Run on the map did not exist when 
the gorges were cut. This stream has been formed for the most 
part since the glacier left the region. The glacier may, however, 
have given it the initial impulse, by a short halt of the ice where 
the road is now, as there is good evidence of a recessional moraine 
along the Granville Road, bearing to the north of Scott’s Corners. 
It is safe to infer that this part of the stream has been cut by nor- 
mal erosion in fairly recent times. If this were not the case, there 
would not be so many steep cliffs, which characterize young 
streams. This can easily be explained through the agency of 
normal erosion, as the second tributary into which this stream 
flowed was reduced to such a comparatively low gradient by the 
heavy ice marginal drainage. 
There remains one point for which we need to account: the fact 
that at the bridge spanning the second tributary north of the 
Lewis School, the north bank is composed entirely of drift. The 
most plausible interpretation for this is the supposition that the 
ice front formed the north wall of the stream until it had cut 
down far enough to retain its present channel after the ice had 
receded from the area. 
We believe we have shown that neither diastrophism, taking 
the form of a limited differential tilt, nor piracy, can possibly be 
considered as even a partial explanation of the drainage diversion 
in this area. In view of the fact that the only remaining alter- 
native, glaciation, does account in a thoroughly consistent man- 
ner for all the peculiar relations that we have noted, the conclu- 
sions of the following summary appear justified. 
