No. 275. 1 309 
Tin-ker's quarry from the gray and blue limestones above, is the repre- 
sentative of this rock, which, we learn from Mr. Vanuxem's report, 
attains in the Third District a thickness of thirty feet, and contains 
abundance of pecuhar fossils. This rock, the " shell grit" of Prof. 
Eaton, is a well characterized mass in the Helderberg range, interposed 
between the upper and lower limestones. 
The " gray crinoidal^'^^ or Onondaga limestone^ which follows the 
Oriskany sandstone, is well characterized, and distinguished from any 
other by its peculiar gray or grayish blue colour, and compact crystal- 
line structure. It is tough, breaking with a large conchoidal fracture. 
When free from seams, it is perhaps the most durable of the limestones, 
and one of the most beautiful for buildings. For this purpose it is 
much quarried; and at Oak's corners, its eastern limit in Ontario coun- 
ty, it is also burned for lime. It is very abundant as a surface rock. — 
In several localities there is a gradual merging of the w^ater limestone 
into this rock, the Oriskany sandstone, which should intervene, not being 
in place. In most instances the strata succeeding the water lime are an 
irregular gray limestone, containing abundance of fossils, mostly in frag- 
ments, or single valves of shells. Fragments of Calymene are very 
numerous, but perfect specimens are rarely or never found. Stropho- 
mena rugosa, Orthis affinis, and several others, are abundant. A large 
species of Orthis, peculiar to the Oriskany sandstone, or " shell grit," 
sometimes accompanies the other fossils in this part of the formation, 
and Madreporites, Cyathophyllites, &c. are found above the more shelly 
portions of the rock. 
West of Vienna this limestone spreads out over a great surface, co- 
vered only with a thin coating of soil, and having its northern termina- 
tion about a quarter of a mile south of the Canandaigua outlet. It ex- 
tends to Flint creek. The principal quarries in this neighborhood are 
McBurney's and Wayland's, within two miles of Vienna, which fur- 
nish materials for locks on the canal, for building and step stones, and 
some partially crystalline portions, from the unequal expansion, form a 
good firestone for the ordinary heat of a fire place. At these quarries 
four layers of limestone are exposed, two of which only are workable, 
the others being too thin, or separated by seams. The upper one has 
in many places been nearly destroyed by the action of running water. 
Sometimes layers of chert, or hornstone, are interspersed between those 
of the limestone; and some of these contain much of that mineral, 
while in others it occurs only in small nodules. In such cases it does 
not injure the quality of the stone, but where it occurs in large masses 
