OF THE UNITED STATES. 



13 



By reference to the following synopsis, it will be re- 

 marked that there is a striking analogy between the Ame- 

 rican calcareous strata and the upper chalk of Europe. 



The opinion is held by some geologists, that a transi- 

 tion group exists between the Secondary and Tertiary 

 deposits of some parts of Europe : thus at Gosau,* in 

 the eastern Alps, Trigonia alseformis, Pecten quinque- 

 costatus, and a few other well known secondary fossils, 

 are said to be associated with a variety of tertiary re- 

 mains. M. Dufresnoy also observed among two hundred 

 fossils of the Pyrenean chalk, fifty species possessing 

 tertiary characters. I am aware that M. Deshayes doubts 

 the accuracy of the observations in reference to Gosau, 

 but Mr. Conrad has verified the geological fact of the 

 mixed nature of some formations, during his late re- 

 searches in Alabama, of which notice will be taken in 

 another place. 



The following diagram will serve to convey an idea of 

 the cretaceous group, in reference to the other formations 

 in this country : no known section, however, exhibits all 

 these strata in conjunction. 



Alluvium 



Erratic group 



Quarternary, or Newer Pliocene 



Upper Marine, or Older Pliocene 



London clay, or Eocene 



Calcareous strata 

 Ferruginous sand 



-5 & 

 V o 



* Trans. Geol. Soc. of London, vol. iii. (N. S.) p. 360. 



