No. 161.] 
185 
vading strata of every age, under nearly the same generic fornns 
which they present annong existing organizations. Other fanailies, 
both of animals and vegetables, are limited to particular forma- 
tions, there being certain points where entire groups ceased to 
exist, and were replaced by others of a different character. The 
changes of genera and species are still more frequent; hence it has 
been well observed, that to attempt an investigation of the struc- 
ture and revolutions of the earth, witnout applying minute atten- 
tion to the evidences afforded by organic remains, would be no 
less absurd than to undertake to write the history of any ancient 
people, without reference to the documents afforded by their me- 
dals and inscriptions, their monuments, and the ruins of their ci- 
ties and temples."* 
In consequence of the vast extent of horizontal strata, which in 
their original oscillations were agitated in a broad unbroken mass, 
the rocks of western New-York form a regular very obvious or- 
der of succession, strongly contrasted with the same series in 
Pennsylvania, where the disturbing forces have acted with more 
energy, throwing the strata into those intricate mazes which can 
be only understood and divested of all obscurityj by ascending the 
succession of magnificent terraces from Lake Ontario, gaining 
from a knowledge of their fossils that clue which is essential to a 
perfect understanding of the relative position and age of highly in- 
clined and contorted rocks. Thus we learn the identity of strata 
varying in mineral composition, the original continuity of which 
has been interrupted by dislocations, and whatever may be their 
comparative level or inclination, we readily trace them to a com- 
mon origin, gaining practical results, to which no other mode of 
investigation can lead. Thus we consider New-York to be the 
true starting point in investigating the geology of the Union, un- 
folding the order of arrangement in all our rocks, and rapidly ad- 
vancing to maturity those important inductions and general results 
whicTi are to develope all the mineral resources of the different 
States. 
In the course of our survey of the third geological districtf of 
the State, during part of the summer of 1836, we have collected 
* Buckldnd, Bridgewater Treatise, vol. 1, p. 110. 
fThe third geological district comprises the counties of Montgomery, Herkimer, Onei- 
da, Lewis, Jefferson, Oswego, Madison, Onondaga, Cayuga, Wayne, Ontario, Monroe, 
Orleans, Genesee, Livingston. 
[Assem. No. 161.] 
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