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GEOLOGY OF THE FOURTH DISTRICT. 
2. Niagara Limestone. 
A silico-argillaceous limestone forms the beds of passage from the soft shale below, to the 
purer limestone above. When freshly exposed, it is often of a dark or bluish color, but soon 
changes to light grey or ashen; and though variable in character, it is a constant accompani¬ 
ment of the group as far as observed. It forms a good hydraulic cement, where it has been 
used for that purpose. 
In the eastern part of the district, these beds of passage are succeeded by a dark bluish 
grey, subcrystalline limestone, of a rough fracture, and separated into thin courses by dark 
shaly matter. When not too much divided by seams, it forms a durable building material. 
This, again, is succeeded by a coarse-grained concretionary mass in irregular layers, exhibiting 
an appearance as if much disturbed while in a semi-fluid or yielding condition. The concre¬ 
tions often present cavities lined with crystals, or the remains of some fossil body. The upper 
strata are finer grained, with a resinous lustre; and on weathering, the surface is harsh and 
sandy to the touch; this, however, seems due to the presence of magnesia rather than silex. 
In the western part of Monroe county, the hydraulic layers are succeeded by a light co¬ 
lored and very porous encrinital limestone ; which, farther west, becomes the compact crinoidal 
limestone of Lockport. 
In the western part of the district, this crinoidal mass is succeeded by a light grey limestone 
with cavities, and containing many corals. Above is a darker colored mass, still with cavities 
lined with crystals of spar ; and the series is terminated by a thin-bedded concretionary lime¬ 
stone, strongly bituminous, the layers separated by shining black carbonaceous shale. 
This rock first appears in the district at Roe’s quarry in the town of Butler, Wayne county, 
where the hydraulic layers are not seen, and the rock has the character of a dark blue lime¬ 
stone, very fine-grained and compact, yielding a bituminous odor on percussion. It is mostly 
thin-bedded, and exhibits little tendency to a concretionary structure, being readily quarried, 
and furnishing a good building material where heavy blocks are not required ; its principal 
use, however, is for burning to lime. Farther west the rock outcrops by the roadside, but has 
not been quarried. It here exhibits the dark greyish color of the higher strata. 
This limestone is likewise quarried at Henderson’s in the same town, exhibiting a thick- 
bedded structure, and regular stratification. 
It again appears in the town of Rose, at Uttoe’s or Miner’s quarry, on the head waters of 
Sheldon’s creek. At this place it is thicker bedded than farther east, appearing in courses of 
two or three feet, having a dark color and granular texture. 
It has been quarried at two places on the line of the Sodus canal, where it presents ap¬ 
pearances similar to those just mentioned. It is also exposed in the towns of Marion and 
Walworth, passing thence into Monroe county. The whole length of its outcrop in Wayne 
county is marked by a range of limekilns, which always indicate the proximity of the rock. 
The variations which it undergoes in this distance are principally an increase in thickness, 
and a gradual change to a lighter color in the central portions of the mass. Its concretionary 
