504 GEOLOGY OF THE WESTERN DISTRICTS OF CANADA. 
terrace cut out in the clay or drift formation which covers the whole 
country. This deposit, in which also the remains of a Mastodon have 
been found, occupies the place which the ancient bed, and alluvial plain 
of the Niagara would naturally have filled, if the river had extended 
farther northwards at a level sufficiently high to cover the greater 
part of Goat Island. At that period the ravine could not have 
existed, and the river must have been dammed back several miles lower 
down. The old river banks are distinctly traceable facing each other 
on both sides or the gorge, at least as far down as the Whirlpool, and 
vary in width from about thirty to three hundred feet from the brink 
of the precipice. At the summit of the cliffs overhanging the 
Whirlpool on the American side, there occurs a deposit forty feet 
thick of fluviatile strata, precisely identical with those on Goat 
Island ; and it must be borne in mind that nowhere do these deposits 
extend, or can they be traced, beyond the old river banks. 
Here then we have the most unequivocal evidence that at a date 
comparatively modern in the geological epochs, though very remote 
as regards the history of our race, the great Falls must have been 
situated at least four miles below their present site; and in the absence 
of distinct traces of their existence still further northward we may 
reasonably and justly infer that they must have primarily been situated 
at the escarpment at Queenston. There is no ground for supposing 
that the excavation was assisted by an original rent m the rocks, and 
no appearance of a fissure occurs at the present site of the Falls. 
The dip of the strata being twenty-five feet to the mile southward, 
and the slope of the river bed about fifteen feet in a mile northwards, 
these two inclinations combined have occasioned a diminution of 
forty feet in the perpendicular height of the Falls for every mile that 
they have receded southwards. When they were situated at the Whizl- 
pool, the hard quartzose sandstone was at the base of the precipice, and 
here the cataract may have remained stationary for ages. Even now 
the obstruction occasioned by this ledge in the bottom of the river causes 
a partial damming back of the water, which, overleaping this 
barrier, rushes with still more fearful velocity down the gorge. This 
phenomenon, together with a remarkable break (which I shall after- 
wards advert to) in the continuity of the strata on the Canadian side 
at this point have no doubt given rise to the Whirlpool. In regard to 
the future retrocession of the Falls it is susceptible of clear proof 
that when they have travelled back two miles or opposite to the 
