SENECA COUNTY. 
451 
Noting the amount of dip in this rock, and finding it to occur frequently for a distance of 
several miles, we might, at first view, be disposed to estimate it as of great thickness ; but 
in each of these quarries we find precisely the same rocks repeated, and the whole apparent 
thickness consists of a few strata which have been several times broken up. 
In one of these faults, arises a copious spring of pure cold water, from the bed of which, 
and over an area of twenty feet, nitrogen- gas is abundantly emitted. No deposit of any kind 
is left by the water, which through its whole course to the lake is remarkably clear and limpid. 
The water from this spring, and another similar but much smaller one near, supplies the 
Canoga flouring mills, a saw-mill and some other machinery. From no other spring in this 
part of the State is nitrogen gas known to issue, all others known in the State being near the 
junction of transition with primitive or metamorphic rocks. 
The principal quarries of the Corniferous limestone are those of M'Allister, Rorison, and 
one belonging to the county, adjoining the latter; half a mile south of the last is another 
extensive quarry, and also one half a mile southwest of the Canoga spring. The stone is 
quarried for buildings and enclosures, as well as for burning into lime. The layers do not 
generally exceed a foot in thickness, and are separated by thin seams of shale. From six 
to eight courses of the stone are to be seen in each quarry, which are generally separated 
by thin seams of shale, and sometimes by a layer of hornstone; two or three of the latter 
sometimes occur in the same quarry, separating the courses of limestone. The hornstone is 
more commonly in courses of nodules in the limestone ; sometimes one, and at other times 
several courses, occurring in the same stratum of the different quarries. When dressed with 
the chisel, it forms an elegant and durable material for stepstones, door and window caps and 
sills. 
The Marcellus shale and the Hamilton group occupy a broad belt in this county. The 
different members of the latter are well developed on the shores of both the Cayuga and Se¬ 
neca lakes. These shales are chiefly interesting in the vast number of fossils which they 
contain, and in the production of a calcareous soil. 
Succeeding the Hamilton group we find the Tully limestone, the Genesee slate, and the 
shales and flagstones of the Portage group. 
Almost all the ravines where the Hamilton group is exposed, appear to have formerly been 
large water courses, the present streams cutting a narrow channel in the bottom, which is 
composed, sometimes to great depth, of water-worn fragments of shale and the rocks above, 
and covered with soil supporting the largest forest trees. Along the banks of the ravines, the 
destruction of the shale has produced a thin but rich soil, which, though the rains are constantly 
washing it down into the valleys below, produces a small growth of trees, and a luxuriant one 
of flowers, of which a greater variety and in greater beauty can scarcely be seen. The family 
of Trillium, the Corydalis, Dentaria, Caulophyllum, Tiarella, and the delicate Mitella, 
with hundreds of others, spring up in the greatest perfection and profusion. As beautiful 
objects of natural scenery, these ravines cannot be surpassed. 
Localities of the shale of this group are so numerous that it is unnecessary to enumerate 
them all. The shore of Seneca lake, from three miles above the outlet to Goff’s point, pre- 
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