150 Niagara. (April, 
ridge of gravel, without washing both it and the terrace of 
unconsolidated till away; and it seems to me that we have 
here a proof, of what appeared before to be probable, that 
the river has at this point only re-opened the ancient gorge, 
the clay and stones that filled the widened part having been 
washed out by water from below, not from above, as would 
be necessary to excavate the gorge itself. I concluded, 
therefore, that the pre-glacial falls had been situated at least 
as high up as this point, and I thought that the narrowing 
of the gorge upwards, though it was still wider than that 
leading to Queenstown, might mark the commencement of 
the present river’s work above the whirlpool. 
On examining the gorge higher up, I however discovered 
that there were several places where it widened suddenly 
out, and at two of these I found similar proofs of the gorge 
not having been excavated by the present river. Thus, on 
the American side, between the railway and the suspension 
bridge, there are two or more widenings of the gorge, and I 
noticed a terrace of till at the upper one cut off by the 
setting back of the gorge. On the Canadian side, about a 
quarter of a mile below the suspension bridge, there is one 
of these sudden widenings or bulgings out of the gorge. 
Higher up a ridge of till, capped by river gravels containing 
fresh-water shells, marks a former channel of the river, and 
runs down about 50 yards from the gorge. ‘This ridge does 
not wind round the widened part of the gorge, but runs 
down to it, and is abruptly cut off by it, similarly to the one 
above the whirlpool. Exactly the same argument may be 
used to prove that the present river has not cut out the 
gorge at this point, but only emptied it of the glacial clays 
and sands with which the old pre-glacial gorge was choked 
up. This example of a river ridge cut off by the re-excava- 
tion of an older gorge, is the nearest to the fall that I could 
find. From thence, upwards, the river terrace is back from 
the gorge, and uninterrupted by it. 
The argument resolves itself into this form: above the 
whirlpool the gorge approaches both in direction and width 
nearer to the old one leading to St. David’s than to the 
post-glacial one leading to Queenstown. That it is pre- 
glacial is strongly indicated by the fact of the post-glacial 
ridges being cut off by it in consequence of its re-excavation, 
whilst there has not been a single argument advanced in 
favour of the theory that it is post-glacial, which was simply 
founded on an assumption that does not bear investigation. 
The conclusion at which I arrive is, that the gorge was cut 
back from the whirlpool up to at least within three-quarters 
