CLINTON GROUP. 
149 
formation, but have resulted from the operation of far more modern causes than any which 
have acted upon it. It is true that these rocks form a part of the mountain ridge in Nia¬ 
gara county, extending from Lockport to Lewiston ; still they appear only in an inferior 
slope, which gradually dies away, and is lost in the lower grounds which succeed it towards 
the lake. It is in fact an inconsiderable elevation, rising only three hundred and fifty feet 
above Lake Ontario and the surrounding country. The tortuous course of this ridge, 
however, adds something to the variety of surface. In general the country descends towards 
Lake Ontario, from near Rome to Niagara, in a very gradual manner. At the termination 
of this group, there is a single steep offset; but at Lockport, and most of the intervening 
country, there are two terraces, which are formed by the presence of the sandstone below, 
and the soft shales which succeed, together with the hard limestone that forms the surface 
rock of this part of the district. The uneven surfaces, then, which are due to the rocks of 
this group, exist mostly in Niagara county ; and the hilly surface elsewhere corresponding 
to this group, is formed by the action of diluvial currents, which have brought together 
sand, gravel and boulders, and arranged these materials in the form of ridges and rounded 
hillocks. 
Waterfalls in the Ontario division. I have just referred to the influence of running 
waters upon the soft rocks which compose in the west a large proportion of the Ontario 
division, and by which deep channels are cut. These, if interrupted by hard layers, form 
cascades or falls in the stream, as the waters are longer resisted by these harder deposits. 
Most of the high falls in the State are thus produced, and two remarkable instances have 
just been spoken of. The Niagara fall, the most commanding of all the phenomena of 
this kind, is formed in this division of the New-York rocks ; a part of which, called the 
American Fall, is represented in PI. X. It is inferior in grandeur to the Great Horseshoe 
Fall. It was drawn from the Canada side. 
Agricultural capacity of the soil of the Clinton group. The nature of this formation, at its 
eastern termination, favors the production of a siliceous soil ; while at the west, owing to 
the predominance of argillaceous and calcareous matter in combination, the soil partakes 
of the composition of the parent rocks. It is difficult, however, to estimate the influence 
which this formation exercises on the soil, as it is underlaid at the west by a rock also 
allied to a marl, or which at least decomposes like one. I allude to the parts already 
described of the Medina sandstone, which constantly crumbles by the action of atmospheric 
agents, and passes into soil. So in the superior masses, it is soon succeeded by a marly 
deposit, the only rock which intervenes being the Niagara limestone. It is therefore un¬ 
necessary to dwell upon the influence this mass exerts, as it is merged in the rocks above 
and below, all of which are particularly and nearly equally concerned in the production 
of the peculiar soils of the western counties. Much of the country, however, which is un¬ 
derlaid by the Clinton group, is low and swampy, and hence unfavorably situated for 
exhibiting the true value to be placed upon the soil which it has formed. 
The sandstones and conglomerates of Herkimer decompose slowly ; but the process is 
aided by the interlamination of the green shales, which, however, do not crumble so 
