452 
GEOLOl Y OF THE FOURTH DISTICT. 
sents an almost continuous exposure of greater or less height. The western shore of Cayuga 
lake, and for nearly the same distance, exhibits these shales, but not in high cliffs as on the 
other side of the county. 
The Tully limestone is one of the most important rocks of the county, furnishing a supply 
of lime along its line of outcrop, from ten to twelve miles south of the Corniferous limestone. 
There are a few localities where this rock is very compact; the layers are from one to two 
feet thick, and it can be quarried of any required dimensions. Its northern edge extends in 
a curve entirely across the county. From where it is first seen, it may be followed in a north¬ 
easterly direction to a point two miles north of Ovid village, where it is quarried for burning 
into lime, and for various other purposes, on the land of Mr. Thompson Johnson. This point 
is the greatest northern extension of the curve. From here it gradually bends to the southeast, 
and appears on the Cayuga lake shore, in a line nearly east from its point of appearance on 
the shore of Seneca lake. This curved outcropping of the mass is merely the effect of erosion; 
the greatest force of the northern current being in the channels of the two lakes, its power was 
diminished towards the centre of the county, which consequently left the limestone extending 
farther north at this point. 
The Genesee slate, resembling very nearly in appearance the black shale of the coal for 
mation, has been mistaken for the same; and explorations for coal have frequently been 
undertaken at great expense, resulting in final disappointment and loss. Most of the excava¬ 
tions for coal in this part of the State are made in this shale, or the next succeeding group, 
which often contains fragments of vegetables. The emission of inflammable gas, particularly 
when arising from this rock, is supposed to proceed from beds of bituminous coal. Although 
the fallacy of such a supposition has been frequently shown, the opinion is still entertained. 
In the rocks of the Portage group, in this county, we find large numbers of fragments of 
what appear to be terrestrial vegetables; some of these are several feet long, producing a 
seam of coal of the same dimensions. These appearances have been sufficient to induce a 
belief in the existence of workable beds of coal, but I need not say that such a supposition is 
entirely unfounded. 
About four miles south of Lodi village, an excavation for coal has been made in the rocks 
of this group. The principal inducement in this case appears to have been iron pyrites and 
the sulphurous odor of the water, which is covered with a film so common in water flowing 
through pyritous or other rocks. Petroleum also occurred in globules on the lower surfaces 
of the slaty layers, which circumstance w'as considered by an “ old miner,” who directed the 
excavation, as a sure indication of coal. When I saw the place, the original excavation was 
filled with dirty water, and the shales thrown out were nearly dissolved into soil. 
Some good flag-stones are obtained from this group in the town of Lodi, and there are nu¬ 
merous localities where these may be obtained in this part of the county. 
This group is exposed in many of the ravines south of Lodi village, on the Seneca lake 
shore; also in the same latitude on the Cayuga shore, in the south part of Covert, and in the 
ravines extending towards the middle of the county. 
