No. 275.j 
325 
The rocks of that part of the county examined, belong principally 
to the Ithaca and Chemung groups, varying in some slight degree from 
these groups farther east. Along the western shore of Crooked lake 
they consist chiefly of sandy and slaty, or argillaceous shale, the former 
rippled or undulated, showing that each thin layer of the shale was sub- 
jected to the action producing the rippled surfaces, and this action con- 
tinued uniform throughout the whole deposit. Alternating with the 
greenish shale just noticed, is a darker slaty shale containing fossils. 
At some localities occur a few thin layers of sandstone, but these are 
not abundant until we approach the head of the lake. 
Four miles below Haramondsport, in a ravine on the bank of the 
lake, can be seen a concretionary stratum of impure limestone, composed 
of roundish or irregular masses cemented together by an argillo-calcare- 
ous cement. In other localities, the concretionary forms are not so 
distinct, and the whole bears the character of an irregular mass, sepa- 
rated in various directions by thin seams of shaly matter. So far as 
examined, this mass bears a very uniform and constant character; it 
disappears beneath the lake on the east side, one mile below Hara- 
mondsport. This limestone has been burned, but found too impure for 
quick lime, though it possesses some of the characters of water lime. 
At Hammondsport, in the ravine above Mallory's mill, we find 
about three hundred feet of rocks exposed, belonging to" the Ithaca 
group; they are well characterized by the fucoides resembling a bird's 
foot. Few fossils other than fucoides appear through this thickness, 
though higher in the ravine, are some fossils peculiar to the group. The 
mass exposed consists, in the lower part, principally of shale and thin 
layers of sandstone, and at a higher point numerous layers of sandstone 
from four to ten inches thick. The edges of all the layers exposed, 
are covered with crystals of selenite, or crystallized gypsum. 
About one mile from the mouth of this ravine, an excavation for 
coal has been made in the black shale, which alternates with the 
sandstone and olive shale. The indications of coal at this point 
were a few fragments of vegetables, iron pyrites, and the odor of bitu- 
men arising from the shale; all these were supposed to be unfailing 
evidences of coal beneath. The work is at present abandoned until 
some new excitement or reported exhibition of burning gas, shall induce 
others to engage in the enterprise. In the shale thrown from this dig- 
ging, I found Inoceramus, Ptenirea and several other fossils. 
On the east side of the valley, opposite Hammondsport, a similar 
ravine exposes the same strata as those just degcribed. 
