6^ FOURTH REPORT— 1834. 



to prove, contrary to general opinion, that the organic races of 

 remote regions diflfered as much during a part of the secondary 

 sera as during the more modern tertiary and recent periods. 



It certainly seems difficult to explain, upon a distinction fre- 

 quently admitted between secondary and tertiary formations, — 

 namely, that the former are deep sea deposits, while the latter 

 have been formed in more confined and local basins, — why the 

 range of the species should have been actually less in the earlier 

 aera than during the more modern dates of the tertiary. So far as 

 relates to the superior secondary formations of the United States, 

 I can perceive no evidence whatever that they were produced in 

 a deeper sea than the tertiary beds which succeeded them. The 

 secondary rocks have fully as much the appearance as the ter- 

 tiary of having been the bed of a shallow sea, like that which en- 

 circles our Atlantic coast with so wide a belt of soundings at the 

 present day. It must be borne in mind that all this portion of 

 North America is, and has been since the period of the coal forma- 

 tion, remarkably exempt from agitation by volcanic causes ; so 

 that the Atlantic plain offers no resemhlance, in its uni\ersally 

 horizontal beds, to the broken, contorted, and denuded strata 

 which diversify the tertiary and secondary scenery of the western 

 regions of Europe. We are not likely ever to discover the 

 modern formations of this country resting among the Alleg- 

 hanies, as the cretaceous formations of Europe cap the Alps and 

 Apennines. For the same reason we may look in vain over 

 the whole of North America for a structure like that seen in 

 the Weald, or in other well-known disturbed districts along the 

 southern coast of, England. So many successive upheavings 

 and submersions as those shores have experienced, betoken the 

 long-continued activity of subterranean forces during a time 

 when the similar actions upon this side of North America were 

 almost dormant. 



We are presented with no pheenomena along the flat mono- 

 tonous coast of the United States, like those which lend so 

 high a charm to the geology and scenery of the cliff- lined coast 

 of the English Channel. 



So small an amount of distvirbing action ought to favour the 

 wide dispersion of the marine inhabitants of this region ; and 

 we are therefore not to be astonished at seeing, as we do, many 

 of the New Jersey fossils in Alabama, or at finding, as we have 

 every reason to anticipate, the same group of species in the 

 strata vipon the Missouri, 2000 miles west from the cretaceous 

 formations vipon the Atlantic. 



Similar reasons should lead us to look for a somewhat gra- 

 dual transition from the secondary to the tertiary series of 



