388 
GEOLOGY OF THE FOURTH DISTRICT. 
of the chasm at the top is nearly twice as great as that of the stream below. The declivity 
of the bed of the river, from the falls to Lewiston, is one hundred and four feet, or nearly 
fifteen feet in the mile.* 
At one place, about a mile below the falls, and where the channel is narrowest, the stream 
glides with comparative stillness; while below this, where the channel is broader, it is driven 
along with great velocity. Again, below the whirlpool the surface of the river is more 
smooth, and the current more gentle, though the channel is narrower than above. These 
appearances, which have seemed inexplicable upon the common theory, and which have been 
used as arguments against the recession of the falls, have their cause in the geological struc¬ 
ture of the place. Below the whirlpool there are no hard rocks in the bed of the river; con¬ 
sequently the channel is deeper, and the water is more quiet than where such rocks exist. 
At the whirlpool, and above that place, the hard sandstone No. 2 is at and near the level of 
the river, and consequently the channel is not worn so deep. Again, after this hard mass has 
dipped beneath the surface, the bed of the river is excavated in softer rocks ; hence the nar¬ 
row channel and smooth water a mile below the falls. Near the falls, the higher beds of 
sandstone, and the limestone of the Clinton group, approach the level of the river, and thus 
cause a wider, shallow channel, and more tumultuous water. Such I conceive to be the 
explanation of the variable width of the chasm, and the greater or less violence of the water. 
In the course of this gorge, there is a single exception to the parallel sides and nearly 
vertical cliffs; this is upon the west bank of the river, at the whirlpool, as can be seen by 
referring to the plate. Standing upon the east bank of the river, it appears like a depression 
worn by the eddying current, which is partially obstructed in its course by the sandstone No. 
2. Not having made particular examinations upon the Canada side of the river, I had over¬ 
looked the true cause of this indentation, till during the summer of 1841, while in company 
with Mr. Lyell, we examined this place, and found it to be an ancient gorge filled with drift, 
except a narrow ravine through which a small stream flows into the river. In the channel of 
this stream, near the river, there are one or two places where the rocks are exposed, proving 
this gorge to be less deeply excavated than that in which the Niagara now flows. The ravine 
may be traced for nearly two miles in a northwest direction, where it comes out to the gene¬ 
ral level of the surrounding country. From the point of its termination, and following the 
same direction for about one mile, we again commence descending through another deep gorge, 
which terminates upon the plateau at the base of the escarpment at St. Davids, four miles 
west of Queenston. It will be perceived by referring to the map, that the course of the river 
before coming to the whirlpool, if continued, would lead in the direction of St. Davids. 
From this fact it has been inferred that there is a continuous ancient gorge filled with drift, 
from the whirlpool to this place. This inference seems substantiated by facts ; for upon the 
* A considerable declivity is required in the bed of such a stream, in order to give it power to remove obstacles which are con¬ 
stantly impeding its course. In any stream excavating its own channel, the declivity of iis bed will be, in some degree, pro¬ 
portioned to the weight of the fallen masses which it has to remove; and if its channel be in soft shale, the descent will be very 
gradual, while the intercalation of harder strata increases the descent according to their proportion. 
