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mediate vicinity of the place where they are now deposited. The ter-- 
tiary in this county is quite limited ^ and is confined to the borders of 
Lake George and the North river. It is the most extensive in Queens- 
bury, and constitutes a valuable section of country; the soil is light and 
sandy; it is still susceptible of the highest cultivation, and may be 
made to produce abundant crops. 
Primitive Limestone. 
Warren county is apparently traversed by a ridge of limestone. Its 
course is nearly east and west. Its continuity is often broken or inter- 
rupted by other rocks. We cannot, therefore, trace it continuously. 
Still its occurrence in this direction at intervals furnishes proof of the 
direction in which it has been more generally produced. In this respect 
those veins or beds are analagous to the greenstone dykeSy which are so 
prevalent in the hypersthene rock. The limestone is generally coarse y 
and mixed more or less with coccolite and hornblende. Its purity, how- 
ever, is such that it forms a useful material for lime. I have found it 
in sufficient abundance in all the towns of the county to meet the wants 
of the community. It is unnecessary to describe or point out the nu- 
merous localities at which it occurs, 
A remarkable fact connected with this formation may with propriety 
be mentioned: it is the occurrence of caves in it in Athol, and, as I 
have learnt, also in Minerva, in Essex county. Those caves are situ- 
ate on the North river, about two miles from Warrensburgh. They are 
from 100 to 150 feet above the river, and as would be conjectured, are 
evidently produced by water. Their entire extent has never been as- 
certained. Persons have explored them for upwards of a hundred feet. 
The period at which those caves were formed was anterior to the ac- 
cumulations of the gravel already noticed. This statement is supported 
by the fact that the openings or mouths are covered by this kind of gra- 
vel, and they have generally been discovered in consequence of the fall- 
ing in of cattle while passing over them. In some instances boulders 
ol rocks foreign to the region are wedged into those openings, and 
partially close them. They have no other interest than the evidence 
they furnish of the period when they were produced, and of the agent 
which was the immediate cause of their production. They contain no 
remains of organic beings, so far as discoveries have yet been made. 
Magnetic Oxide of Iron. 
Some important localities of iron ore have been discovered in this 
county. One in particular on lot No. 80, in Hyde Township. Por- 
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