250 Notes on. American Geology. 
wanerte by the Editors: 
Th eelinigih to the difference of opinion between Mr. Conrad and 
Prof. Henry D. Rogers, we take leave to state, that having been 
occasionally in communication on geological subjects with the 
last named gentleman, and knowing his opinions in the present 
case, we presume our much respected correspondent, Mr. Conrad, 
(with whose able. communications this Journal has been, from 
time to time, enriched, ) will be gratified to know the grounds, on 
which Professor Rogers differs from him. Should that gentleman 
choose to give his own explanations, this Journal is, of course, 
open to his communications, and should Mr. Conrad wish it, to 
his rejoinder; but in the mean time, the publie confidence in 
both gentlemen will be increased by being informed, that the pe- 
culiar opinions of each are sustained by appropriate and important 
reasons ; and it is, moreover, very-desirable, that our Baie ee 
should deedeistated each other. 
We proceed then to state, that Professor Rogers, as we have un- 
derstood from himself, has examined, with considerable care, the 
localities designated by Professor Eaton,- where the “ graywacke 
of the Hudson” is said to be highly insdlined, and to have the 
“ caleiferous sandrock” resting unconformably on its edges; and - 
that he has left these places fully satisfied, that the strata, sup- 
posed to belong to two formations of distinct epochs, are, in 
reality, but adjacent beds of one great formation, differing in 
mineral character, and seeming, at first glance, to meet. uncon- 
formably, in consequence of the numerous local ‘irregularities of 
dip, so common to this rock on the Hudson. In other words, he 
regards the calciferous sandrock of Eaton, (the first formation’of 
his report,) as every where lower in geological order, than this 
so called graywacke, which has been traced uninterrupted from 
the Hudson, through New York, New Jersey, Pennsylvania,, and 
the States Gaadser South as far as Tennessee, every where occu- 
pying the ¢hird place in the ascending series. » 
He supposes he has evidence to show, that a goologiei sec- 
tion, corresponding with a line drawn from the mouth of the 
Susquehanna river, a little east of north, through Pennsylvania: 
and New York, to the country of primary rocks, north of Utica, 
would represent ihe entire series of thirteen formations, described 
