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802 V [ Assembly 
ing abundantly thin minute scales of mica, requiring only a higher de- 
gree of heat to have become a micaceous schist. The greater part of 
the mass, except the upper part, is almost, or entirely destitute of fosr 
slls. In this county it is characterized as containing two species of 
Lingula, Orbicula, and a species of Orlhis, which fossils are constant 
associates in the upper part of the mass. Farther west it contains other 
fossils, and finally becomes fossiliferous through its whole thickness. 
This shale can be examined in all the ravines along the lake shore 
from near the north line of Ovid to six miles south. Being succeeded 
by a harder rock, which protects the upper part trom the erosive action 
of water; the black shale is, in some instances, exhibited in nearly its 
whole thickness at one vie w. Among the places where it can be ex- 
amined to great advantage, is at a fall of water on lot No. 26, in Ovid, 
and at Lodi falls on the west side of the county, in several ravines on 
the east side, and at Goodwin's falls in Tompkins county. 
The shale is uniform in texture, and before weathering is quarried in 
symmetrical blocks of various dimensions, being separated by the vertical 
seams, or joints, which traverse the rocks in two directions, one being 
from east to west, or from east by north to west by south, and the other 
varying from NE and SW to N^E and SiW. The direction of these 
joints is never at right angles to each other, but varying, generally cross- 
ing at inclinations of about 75° and 105°, the blocks splitting into 
rhombic forms. Such joints are not confined to the shale, being very 
perceptible in many other rocks of the district, though in none so emi- 
nently as in this. The black shale is used for a fire stone, and when 
laid with the edges of the laminse to the fire, will last for a long time. 
Resembling very nearly in appearance the black shale of the coal for- 
mation, this rock has often been mistaken for the same, and explorations 
for coal have frequently been undertaken at great expense, and resulted 
in final disappointment and loss. Most of the excavations for coal in 
this part of the State are made in the black shale, or the next succeed- 
ing mass, which often contains fragments of vegetables. The emission 
of inflammable gas, particularly when arising from this rock, is suppos- 
ed to proceed from beds of bituminous coal. Although the fallacy of 
such a supposition has been frequently shown, the opinion is still enter- 
tained, and the assertion often repeated. 
The black shale is sometimes succeeded by « well defined layer of 
sandstone, a foot or two in thickness; more generally, however, the 
black shale passes into a more siliceous and compact olive shale, the line 
