Geology of Onondaga County, N. Y. 
INTRODUCTION. 
Onondaga County, N. Y., presents to the naturalist 
one of the finest places in the State for the study of geol- 
ogy, and it is doubtful whether we could find another place 
of like dimensions anywhere in the United States which 
would present more features of interest. Not only are 
the rocks presented here extremely regular, but, dipping 
slightly as they do, we have successively brought to the 
surface rocks belonging to the Upper Silurian, and to the 
Lower and Upper Devonian Ages OSOC~C~SO—S 
“The dip of the rock is slightly west of south, and is 
about twenty-six feet to the mile, while the outcrop ex- 
tends in a line running nearly east and west. From the 
preceding statement it will be seen that the dip is not so 
slight as to preSent for study only the unbroken line of 
one formation, neither is it so great as to compel us to 
draw our conclusions from an insufficient number of facts; 
for the periods, with one exception, crop out in lateral 
bands, which are several miles in breadth. 
There are seven different periods found in the county, 
they are: the Niagara, Salina, Lower Helderberg, Oris- 
kany, Corniferous, Hamilton and Chemung. For conven- 
‘ience of description the various geological periods are sub- 
divided into smaller divisions or groups. These groups 
are more local in distribution and character than are the 
larger divisions, and consequently we need not be sur- 
prised because we do not find in our county all the groups 
into which these seven periods are divided. Some of 
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