34 GF. Wright—Niagara River and the Glacial Period. 
emerges from the whirlpool could not have been much over five 
hundred feet in width, since the first three streams entering into 
the whirlpool cut through the till to the rock, and descend in 
cataracts of varying heights; and the distance from the rock 
escarpment disclosed by the third stream to the escarpment. 
upon the none ae of the whirlpool is not much more than 
five hundre 
naturally made by a united stream that had worn back its 
channel to a point whee two or three branches came together. 
Secondly, ei length of the gorge from St. David’s,—about 
six miles,—even if it extended to near the present site of the 
falls, is satieedy too short to represent the work done during 
preglacial ages by a stream of anything near the size of the 
Niagara. This follows upon comparison with the enormous : 
amount of preglacial erosion that is everywhere manifest 
south of the glaciated area, where the “Tdeetges channels pet § 
not been buried. Waterfalls may 
south of the glaciated area. The broth of the Ohio River Bi 
its ora up the Allegheny—for a distance of fifteen hun-_ 
dred miles—has been formed by erosion, such as is going on at 
Ningare and may be taken to represent in amount what would 
have been done by the Niagara River had it flowed in its pres- 
ent channel during preglacia al ages. Thirdly, we > know from di- — 
iahiesk 6 or oa is ow endent of the edunldzion that there must 
have been such an outlet somewhere. Whatever erosion, there- — 
ore, was done in preglacial times along the present course of the | 
Niagara must have been accomplished by some small stream 
draining a limited area. 
t seems to me probable that the Niagara River has itself — 
worn the whole of the g° rge from Queenston to the falls, with, — 
elp from preglacial erosion above t G4 
whirlpool; though this is a point difficult of absolute deter- 
- perhaps, a very little 
mination. 
As to the rate of erosion, it now seems that that fixed upon by s 
