178 Parallelism of the Paleozoic Deposits 
favorable condition is there also united to facilitate stratigraphical 
studies, and to give to superposition, and consequently to Paleon- 
tology, of which it is the foundation, a certainty truly scientific. 
Indeed, in the northwest part of the state, the beds incline very 
gradually to the south, in such a manner, that in advancing to- 
wards the north the more ancient beds successively appear at the 
surface. The outline of the surface presents-an inclination pre- 
cisely the reverse; it attains its greatest elevation near the limits 
of Pennsylvania and declines to the north towards Lake Ontario. 
There results from this condition a series of lakes and little rivers, 
which, flowing from south to north, eut the formations trans- 
versely. These streams, profiting, probably, by preéxisting fis- 
sures, indent the surface, as the Niagara, to the depth of two hun- 
ed or three hundred feet, and allow the examination and study 
of the superposition of the successive strata with certainty. We 
have had occasion more than once to compare the natural advan- 
tages of this country, with the difficulties presented by Russia 
in Europe, where the plains are so little broken, and the thick 
diluvial mantle which covers them scarcely rent. 
No country in Europe offers us so complete and uninterrupted 
a development of the Silurian and Devonian systems; to’ ob- 
serve it, it is necessary to cross the Atlantic. From the most 
ancient fossiliferous beds which correspond to the lower strata of 
ilurian system, to the coal period exclusively, there is in the 
state of New York, a continuous succession of deposits which 
are superimposed in regular stratification without however en- 
tirely covering each other. The four official geologists of the state 
of New York are agreed in acknowledging twenty-eight groups 
or subdivisions which they have united in the following manner.” 
ese introductory remarks of M. de Verneuil, which give the 
reader an idea of the scope and object of the paper, are followed 
by a table of the groups and individual rocks of the Paleozoic 
series in the state of New York, and a short description of each 
one in the ascending order. The characteristic fossils of each 
group or rock are also indicated, being to a great extent those al- 
ready given in the Geological Reports of New York, and which 
have likewise appeared in this Journal, in connexion with a re- 
view of the same works. 
The order of the successive groups of this series is now so gen- 
erally known, that it does not appear necessary to repeat the table 
in this place. M.de Verneuil remarks with justice that these 
groups are of unequal value, some of them being but a few feet 
in thickness, while others are many hundreds. This has alread} 
been acknowledged in the published reports, and though it may 
now be easy to make a more perfect grouping, uniting individual 
rocks which in the table have the same value as groups, yet it 
was not an easy task to do this before the publication of the re- 
