178 
HELDERBERG DIVISION. 
Table exhibiting the thickness of the rocks composing the Helderberg division, at different places in the 
State of JYew-York. 
NAMES OF ROCKS. 
Columbia county. 
1 Hudson. 
Albany county. 
New-Scotland. 
Schoharie county. 
Schoharie. 
Oneida county. 
Madison county. 
Otsego county. 
Cherryvalley. 
Onondaga county. 
Manlius. 
Cayuqa county. 
| Genesee county. 
1 
Erie county. 
Blackrook. 
Maximum thickness. 
Feet. 
Feet. 
Feet. 
Feet. 
Feet. 
Feet 
Feet 
Feet 
Feet. 
Feet. 
Feet. 
Red shale. 
80 
500 
700 
500* 
500 
Green shale, gypseous rock & waterlime, 
60 
60 
100 
100 
700* 
700* 
70f 
40f 
700 
Pentamerus limestone. 
20 
25 
25 
80 
4 
80 
Delthyris shaly limestone. 
70 
60 
60 
20 
70 
Encrinal limestone. 
30 
10 
10 
li 
30 
Upper Pentamerus limestone .... 
3 
4 
n 
4 
Oriskany Sandstone. 
2 
2 
2 
Cauda-galli gt it. 
60 
60 
10 
60 
Schoharie grit. 
4 
4 
4 
Onondaga and Corniferous limestone 
60 
80 
100 
75f 
50 
100 
1550 
*' Vanuxem. 
t Hall. 
The Onondaga limestone , the superior rock of the Helderberg division. The importance 
of this rock is seen in another ancl different point of view, namely, in forming a distinct 
line of demarkation between two divisions of rocks, which, though intended only as geo¬ 
graphical lines in this instance at least, yet really defines the end of a series in the system. 
Lithologically the end of the series with this rock is indicated, though it could not be 
proved. If, however, organic bodies are permitted to speak, they tell us that such is the 
fact; for it is rare that those of this rock go up into the succeeding deposits, and still less 
probable is it that any of the rocks below the Onondaga limestone reach the shales and 
sandstones of the Erie division. This rock, then, forms or marks an era in the New- 
York system, which must always be regarded as important; and this is true, in whatever 
light we may regard this system ; or whatever classification we may adopt, this rock must 
form the termination of one of the divisions. It is true that the upper portions are dark 
colored, and the layers are separated by seams of shale ; still this only proves that the 
change which was about to take place was not sudden or immediate, but gradual. It is 
probable the dark color of much of the upper part of the Corniferous limestone is of the 
same nature as that of the Marcellus slate, the mass which reposes upon it. 
On referring to what is said in the closing remarks upon the Champlain division, it will 
now be seen that we have at least two very satisfactory divisions in the New-York system : 
the first, ending with the gray sandstone of the Champlain division ; and the second, with 
the Onondaga limestone. Between the lower division and the next succeeding, the On¬ 
tario division, the affinity or resemblance is only slight. There is, however, a greater 
resemblance between the Helderberg division and the Erie, probably, than between the 
