250 Notes on American Geology, 



Remarks hy the Editors. 



In relation to the difference of opinion between Mr. Conrad and 

 Prof. Henry D. Rogers, Ave 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 public 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 geologists 

 should understand 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 inclined, and to have the 

 " calciferous 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 further South as far as Tennessee, every where occu- 

 pying the ihii^d place in the ascending series. 



He supposes he has evidence to show, that a geological 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 the entire series of thirteen formations, described 



