156 
HELDERBERG DIVISION. 
Localities where it may be observed. Though this rock may exist in Oneida county, yet it 
is too obscure, or too much concealed in its own, or in the debris of other rocks, to at¬ 
tract much attention. 
In Camillus, at the railroad cut, is one of the best localities for studying this division of 
the group. The place is west of Camillus village, and can not fail to attract the attention 
of travellers over this line of conveyance. More than one hundred feet of it is exposed, 
and in all the conditions and with all the products of which I have spoken, except that the 
red rock is not exposed or does not exist at this place. 
Another locality of interest, is about three miles east of Manlius centre, at the Green 
lakes, where the superior part of this division exists with massive beds of plaster. This is 
superior to the rock at the deep railroad cut in Camillus. The limestone shale at the lakes 
is thin-bedded and fragile, but not so much so as the mass below. 
At Cayuga bridge, the same series is exposed in the banks, where many oven-shaped 
cavities exist, from which plaster has been extracted, or from which it has been dissolved 
by water percolating through the strata. 
The lower mass exists still farther west, in the vicinity of Lyons, Newark and Lockville : 
at the latter place, the locks for the enlarged canal are excavated in it. Westward beyond 
the Genesee river, it is exposed in Byron and Alabama ; and at Bergen centre, the railroad 
runs near the excavation for plaster. At Palmyra, it is upon the banks of the canal. In 
Erie county, the beds are concealed by thick beds of drift. Some few excavations expose 
it sufficiently to prove its continuation. 
Fig. 25. 
Section illustrating the position of the lakes, with the vermicular limerock of Eaton, or porous limestone. 
a. Canal, h. Green lakes, sometimes called Lake Sodom, c. Porous limestone: plaster beds above. T. Manlius 
village. The section extends south three miles, passing over the formation embracing the plaster beds; the 
highest strata are the waterlime layers on the slope of the hill. The hill intervening between the Green lakes 
is traversed by fissures, through which most of the water percolates until it reaches the more impervious strata, 
the green shales. The water of the Green lakes (of which there are two) is unpleasant, or rather bitter; con¬ 
tains a great amount of lime : every twig or stick which happens to fall into it becomes incrusted with carbonate 
of lime. They are situated on small but deep depressions or basins, which, unlike many others in the surround¬ 
ing country, are not formed by drift currents, or by streams that have mechanically worn them out; neither are 
they produced by fractures or uplifts, as the strata are undisturbed. To what cause is to be attributed the basin¬ 
shaped depressions in which these lakes are contained, is a matter of speculation, that has not as yet been satis¬ 
factorily determined. 
A general statement of the extent of this division of the Onondaga-salt group. Beginning 
as heretofore, at the east, we find the green shales and gypseous rock first appearing in 
Oneida county, near Vernon village, where, as is stated by Mr. Vanuxem, the constituents 
