246 Notes on American Geology. 



are so much more remote from the axis of elevation than the ter- 

 tiary shells of New York, that the uplift of the Rocky Mountains 

 must have been far greater during the upper tertiary period than 

 was any part of the Atlantic chain. 



I know not what reason can be given for considering the whole 

 of the transition as one group, as Mr. Rogers has done, when 

 with very few exceptions the inhabitants of the seas have been 

 destroyed and new creatures succeeded at five distinct epochs, 

 and one of these groups is no more to be compared with another, 

 than is the oolite with the green sand formation ; yet each of 

 these belongs to a different group in all the systems of geology 

 hitherto published. The term, lower secondary, applied by the 

 same geologist to the transition system, is equally objectionable, 

 as it has scarcely a single feature in common with what has hith- 

 erto been termed secondary by all other geologists, and constitutes 

 an order, not a single series of strata linked together by paleeon- 

 tological affinities. The term, lower secondary, would be far 

 more appropriately given to the strata comprising the magnesian 

 limestone, lias, oolite, &c. as upper secondary has been generally 

 used to designate the cretaceous group. 



Organic Remains of the Transition. 



No remains of reptiles, nor any impressions of the feet of birds 

 or of reptiles, have been found in any of the trilobite rocks of the 

 United States ; but fucoids or marine plants abound in the sand- 

 stones, many of which have a digitate ^r trilobed form, and by 

 the aid of the imagination could be readily converted into orni- 

 thichnites, or reptile trails. I am far from an intention to discredit 

 the science established by Professor Hitchcock, as his descrip- 

 tions apply to more, recent strata than the transition, and which I 

 have never studied, and his arguments are too ingenious for me 

 to doubt ; but I must be permitted to challenge his orniihichnite, 

 of which even he is doubtful^^ in the graywacke of the Hudson 

 river,* one of the oldest transition rocks in New York, deposited 

 at a period so early that scarcely any small islands dotted the 

 boundless waste of waters, and they consisted of naked primary 

 rocks, bearing neither herb nor animal life. 



* Mr. Hitchcock has nowhere maintained the existence of an ornithichnite in 

 the graywacke of Hudson valley ; he found an impression there, having some 

 slight resemblance to the footmarks of the Connecticut valley, and he called this 

 tctrapodichnite, expressing at the same time strong doubts whether it were a real 

 footmark. — Editors. 



