vii 



place takes it name from enormous indurated masses evidently 

 broken off from the upper portion of the bank : these are com- 

 posed of sand charged with shells, casts, and abundance of a 

 small species of Echinus, rarely occurring in the inferior stra- 

 ta. 



The Upper Marine formation is distinguished by a multipli- 

 city of species, chiefly of bivalve shells, for the univalves are 

 comparatively rare and particular species occur very abundantly 

 in certain localities, which are rare or wanting in others but 

 a few miles distant. The same circumstance is observable in 

 the habits of recent species. M. Marcel De Serres, in his work 

 on the Geology of the South of France, gives an interesting 

 view of facts connected with this subject, and shews that even 

 difference of seasons may have influenced local depositions. 



It has been remarked that organic remains found in cold or 

 temperate climates are analogous to, or identical with those of 

 the tropics, or at least of a less degree of latitude than the 

 fossil localities ; but in Virginia and North Carolina, some 

 species are found, in no respect differing from shells living on 

 the coasts of Rhode Island and Massachusetts. These are 

 associated with extinct species, and embrace Mactra tellinoides, 

 M. later alis, Nucula limatula, N.proxima, Lucina contracta, 

 L.divaricata, and several others. 



The recent shells have been sought with avidity on the shores 

 of every sea, to adorn the cabinets of the curious with the sym- 

 metry and beauty of their forms, or the brilliancy of their co- 

 lours ; but the science of Geology has given to the more home- 

 ly fossils, a charm which amply compensates for the loss of a 

 portion of exterior ornament, inasmuch as they are mute in- 

 terpreters of those strange revolutions, of which the memory of 

 man has preserved not a solitary trace. They chronicle the 

 various eras of an unknown world, where one ocean has re- 

 tired to give place to another with its peculiar tribes of anima- 

 ted beings, whose silent eloquence reveals the mysterious ope- 

 rations of Nature, when the sudden elevation of mountains, ir- 

 ruption of seas, and destruction of various races of animals and 

 plants, were forming in the crust of our globe those numerous 

 strata, the study of which must ever be an inexhaustible source 

 of pleasure and instruction. Thus have long periods of violence 

 and revolution been necessary to create the beautiful variety of 



