378 
GEOLOGY OF THE FOURTH DISTRICT. 
of ice on the strata seem even more efficient than the wearing of water. The loosening of 
masses near the edge, at least, enables the water afterwards to remove them with greater 
facility. 
Where we find these falls upon streams half a mile from their junction with a large lake, 
it is difficult to conceive how they have once commenced their operation on its margin, and 
we are readily disposed to admit any hypothesis that will account for the previous excavation 
of a lateral valley to this distance from the main one. Where these channels expand rapidly 
toward their outlets, and slope gradually upward, it seems a fair inference that some agency 
other than the wearing of the stream has had a share in producing its present condition; but 
where we find a regular chasm with perpendicular and nearly parallel sides, with a fall of 
water at its extremity, we are compelled, from all analogy, to admit that the stream has been 
the agent producing it. 
In the sketch at the head of the chapter, there seems originally to have been a broad shallow 
depression, in which the stream commenced flowing towards the lake. In its passage, it first 
produced a series of falls and rapids, but finally receded so as to form but a single fall. This 
is caused by the higher strata being so much harder than those below, that a firm table is 
formed of these, while those below are undermined. At the present time the fall is about a 
mile from the lake shore, and one hundred and ninety feet in perpendicular height, being the 
highest fall in the State. The water is precipitated into a deep chasm, with cliffs on either 
side of three hundred feet in height. The stream becomes almost lost in spray before reaching 
the bottom, where it is gathered in a circular pool, from which it flows over the rocky bottom 
to the lake. The fall is usually approached from the lake, and it forms one of the most 
romantic and picturesque scenes in the whole of Western New-York. The stream, insignifi¬ 
cant as it appears, is nevertheless during freshets of great power, carrying forward huge slabs, 
which are piled up below the fall in a manner such as we are accustomed to attribute only to 
the agency of more mighty streams. 
Although there may have been originally an indentation at this point, from the valley of 
Cayuga lake, yet there seems conclusive evidence that the stream has been the chief agent in 
producing this immense chasm. The numerous seams freely admit the water, which during 
winter is frozen, and thus from the whole face of the cliff immense quantities are detached. 
In this way the upper portion is left projecting beyond the lower, till it is broken off, and falls 
down. The first process is constant; and during an interval between my visits to this place, 
I observed that a mass of fragments, scarcely less than fifty tons, had fallen down. This is 
doubtless but a small part of what is annually separated by freezing water, and the more quiet 
operation of moisture and air during the milder season.* 
* The lower of the two more prominent arenaceous strata, about half way up the cliff, is the one presenting the fine casts of 
striae, alluded to in the description of these under Portage group. Beautiful specimens may be obtained at this place after the 
falling of a mass, or by approaching the stratum at some accessible point. Many of the strata in the channel of the stream above 
the fall present these casts in great perfection. 
