g northward from the village of Niagara Falls by the
side of the river, we have to our left the deep and comparatively
narrow gorge, through which the Niagara flows. The bounding cliffs of
this gorge are from 300 to 350 feet high. We reach the whirlpool,
trend to the north-east, and after a little time gradually resume our
northward course. Finally, at about seven miles from the present
falls, we come to the edge of a declivity, which informs us that we
have been hitherto walking on table-land. At some hundreds of feet
below us is a comparatively level plain, which stretches to Lake
Ontario. The declivity marks the end of the precipitous gorge of the
Niagara. Here the river escapes from its steep mural boundaries, and
in a widened bed pursues its way to the lake which finally receives
its waters.

The fact that in historic times, even within the memory of man, the
fall has sensibly receded, prompts the question, How far has this
recession gone? At what point did the ledge which thus continually
creeps backwards begin its retrograde course? To minds disciplined in
such researches the answer has been, and will be--At the precipitous
declivity which crossed the Niagara from Lewiston on the American to
Queenston on the Canadian side. Over this transverse barrier the
united affluents of all the upper lakes once poured their waters, and
here the work of erosion began. The dam, moreover, was demonstrably
of sufficient height to cause the river above it to submerge Goat
Island; and this would perfectly account for the finding by Sir
Charles Lyell, Mr. Hall, and others, in the sand and gravel of the
island, the same fluviatile shells as are now found in the Niagara
River higher up. It would also account for those deposits along the
sides of the river, the discovery of which enabled Lyell, Hall, and
Ramsay to reduce to demonstration the popular belief that the Niagara
once flowed through a shallow valley.

The physics of the problem of excavation, which I made clear to my
mind before quitting Niagara, are revealed by a close inspection of
the present Horseshoe Fall. We see evidently that the greatest weight
of water bends over the very apex of the Horseshoe. In a passage in
his excellent chapter on Niagara Falls, Mr. Hall alludes to this fact.
Here we have the most copious and the most violent whirling of the
shattered liquid; here the most powerful eddies recoil against the
shale. From this portion of the fall, i