References to North American Localities. 149 
ty, and in a region where tents and extemporaneous log cabins 
were the only lodgings, it will require no great effort to conceive 
the amount of labor which has been bestowed on the subject of 
this report. The only previous survey of the Bradford district, 
was, we believe, a partial one, made a few years since by R. C. 
Taylor, Esq., but we are not aware that even of this any account 
has been published. The State geological survey of Pennsylva- 
nia has not yet reached Bradford county, but we cannot doubt 
that when it arrives in this region, the investigations of Prof. 
Rogers will fully confirm those of Prof. Johnson. 
Arr. XIX.—References to North American localities, to be appli- 
ed in illustration of the equivalency of Geological Deposits on 
the eastern and western sides of the Atlantic ; by Amos Eaton. 
Brongniart’s theoretical table of succession, is adopted. 
Baxewe t, in his popular and very instructive treatise on geol- 
ogy, manifests a preference for the views of Brongniart. Ameri- 
can geologists who have attempted the application, find a remark- 
able accordance of his system with our own rocks. 
limit myself, in this article, to definite American localities, for 
fixing the limits between the seven classes of M. A. Brongniart, 
as applied to this country. 
For the purpose of making myself understood by those who 
may not have seen the original, I insert a familiar view of the 
outline of his system, as first published in 1829; which, as the 
author has signified to me in the present year, he still adopts. _ 
Ihave been highly interested and much instructed, by the 
striking application of the groups of De. La Beche, to our rocks. 
But the geological deposits of England, appeared to me, (from his 
descriptions, ) to be too limited in extent for giving laws in detail 
to our vastly extended deposits.* : 
Bronentart’s SEVEN CLASSES OF ROCKS AND EARTHS (Roches 
et Terrains). General groups of organic remains are chiefly 
* About seventeen years since, I was severely censured in a public journal, for 
Luc’s estion, that n geologists must cross the Atlantic, to 
find strata of sufficient extent for giving laws of generalization to their own rocks. 
I believe I can congratulate our scientific friends almost with the assurance, that we 
are to expect visiters of similar views, the present summer, of very high standing, 
