CLINTON GROUP. 
61 
is about two feet. Between this place and the Genesee river, it is scarcely to be found ex¬ 
posed, though constantly near the surface. On the Genesee, its thickness is about fourteen 
inches, showing a diminution from Ontario of ten inches in about twenty miles. Westward 
from the Genesee, the rock immediately above is often ferruginous, but I have nowhere seen 
the ore as a separate stratum. At Medina, Albion, Lockport and other places which offer 
good sections, as far west as the Niagara river, the ore is absent. 
This diminution and final disappearance westward would indicate the place of its origin to 
be farther east, and beyond the limits of the Fourth district. The existence of large beds of 
specular and micaceous ore on the northwestern slope of the primary chain of northern 
New-York, where denudation has been extensive, and large quantities removed, may be the 
source. A more probable origin of the ore, however, is in the decomposition of iron pyrites, 
and the production of this oxide of iron. The oolitic form seems, according to the facts pre¬ 
sented by Mr. Vanuxem, due to the influence of thermal waters. Such a condition of the 
menstruum would hasten the decomposition of the pyrites and the formation of the oolitic ore. 
The second bed of iron ore appears but in few places in the Fourth district, and in all 
except one locality is too thin to be of economical importance. Another fact which is some¬ 
what remarkable, is that the two beds never appear in succession at the same locality, or in 
the same line of section. In places where the lower one occurs, the upper is wanting; and 
where the upper occurs, the lower one is not found. This circumstance farther confirms the 
opinion, that the materials were in a state of mechanical suspension, and the place of their 
final deposition only determined by the solidification of the strata which opposed their descent. 
The deposition of all matter forming rocky strata would take place inversely as their solu¬ 
bility, if in solution, and directly as their specific gravity, if in suspension. The ore is rarely 
if ever found diffused through the shale, except where that mass contains calcareous matter; 
but in such points it often pervades several feet in thickness. The iron and carbonate of lime, 
from their nature, would remain much longer in the menstruum than the clay. The iron, 
though more soluble than the calcareous matter, would still be carried down by that body on 
its deposition, and thus what forms a thin band of ore in one place may be diffused through 
several feet of calcareous strata in another. 
The Wolcott ore bed, which is wrought to supply the furnace in that town, appears, so far 
as I can examine the rocks above and below it, to be the upper of the beds mentioned. Its 
thickness is much greater here than elsewhere, and it is succeeded by a shaly rock containing 
a peculiar association of fossils. 
At Wolcott furnace, six miles west of this, the upper ore bed is but a few inches thick, and 
quite insufficient for working; it is seen in the creek, associated with thin beds of impure 
limestone, shale, etc. At this place it is impossible to ascertain whether the lower bed occurs 
or not, but in excavations in the Pentamerus limestone there has been no iron ore seen, or at 
least none has been thrown out with the limestone. In several other localities between this 
place and Sodus point, iron ore has been discovered, but so far as I could ascertain they are 
