The next exposure of rock that we will find, or a glance 
at the stone fences around us, will readily show that we 
are in the midst of a limestone formation, and that we 
have left the shales of the Salina Period in the gentle 
slope toward the north. These limestones belong to the 
next great limestone formation, the Lower Helderberg. 
As but one group of this period, the Waterlime Group, 
occurs in our county, the other groups having thinned out 
and disappeared to the east of us, we will speak of this 
group as the Lower Helderberg Period. It comes to view 
in many places in the county, and like the remaining 
periods it can be more easily studied than those already 
found. ‘The rocks to the north being deeply covered with 
soil and drift, while those to the south, situated among 
the hills, are only,covered with a thin layer of soil, and 
can be easily studied in any of the numerous gorges or 
ravines, 
Although in our county the Lower Helderberg is en- 
tirely a limestone formation, nevertheless there are two 
kinds; they are called the blue and the drab. The former 
is extensively burned in the manufacture of the ordinary 
quicklime, and the latter for the waterlime of commerce. 
Immense quantities of both kinds are packed, either in 
sacks or barrels, and transported by the carload to all parts 
of the country. Owing to the fact that hydraulic cement, 
so named because it will form a cement which sets under 
water, is made in large quantities from the waterlime- 
stone, the drab is often called hydraulic limestone. 
The two kinds usually occur conjointly, being in alter- 
nate layers. At Behan’s Quarry, near Manlius village, 
there are two alternate layers of each, neither being more 
than four feet thick. The entire exposure at this place is 
about sixteen feet in thickness. At Alvord’s Quarry, but 
a short distance from the preceding, we have the same 
state of affairs. In the perpendicular face of rock at the 
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