Address before the Association of American Geologists. 245 



tity. Besides, in all of them we find limestones of a similar cha- 

 racter, extensive ridges and dykes of greenstone, and ores of cop- 

 per, associated with the sandstones and shales ; — so that there can 

 hardly remain a doubt as to the identity in age of all these de- 

 posits. But can we determine their true place on the geological 

 scale ? 



The Professors Rogers, who have extensively examined this for- 

 mation in the middle states, have ascertained that it is more re- 

 cent than the coal measures ; and with commendable caution, 

 they have called it the middle secondary. With less of pru- 

 dence I long since ventured to denominate it the new red sand- 

 stone ; — and I hope it is not prejudice which makes the argument 

 in favor of this opinion appear to be now almost complete. A 

 careful comparison of numerous specimens of this formation with 

 a series from the new red sandstone of continental Europe, and 

 Great Britain, shows a striking resemblance in- lithological cha- 

 racters. But the argument from the organic remains is the most 

 decisive. In the shales of this formation, especially in New Eng- 

 land and New Jersey, have been found numerous specimens of 

 fossil fishes of the genera Palseoniscus and Catopterus, all of 

 which have heterocercal tails.* Now in Europe, Prof. Agassiz 

 finds that such fish rarely, if ever, occur in any rock above the 

 new red sandstone. But in that formation he finds not less than 

 a dozen species of the genera just mentioned. They occur, how- 

 ever, in the coal formations, beneath the red sandstone. But it 

 seems to be admitted on all hands, that the group in our country 

 under consideration, is more recent than the coal measures. And 

 since the heterocercal fishes found in it show that it must be 

 older than the lias, I see no escape from the conckision that it is 

 the new red sandstone. There are other arguments to the same 

 point ; but they are less decisive. Whether we shall find all the 

 subdivisions of this formation in our country that exist in Eu- 

 rope, remains to be seen. I have little doubt, however, that 

 several of them may be easily recognized ; as, for example, the 

 variegated marls and sandstone, the new red conglomerate, [Rathe 

 todte liegende,) and the zechstein. 



* I am informed by Messrs. Redfield, the father and the son, who have so suc- 

 cesiifully devoted themselves to an examination of our fossil fishes, that they have 

 found not less than nine species of these genera in our rocks. 



