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 alxformis, 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. 
e 





= ¢ |Alluvium 
=) |—_—_——______ 
= Erratic group 
Sif Quarternary, or Newer Pliocene 
ban) _ 
3 : : 
‘6 4 |Upper Marine, or Older Pliocene 
o $m. 
7 London clay, or Eocene 
> OS ee 
S Calcareous strata O S 
Bae sit Sold noe 68 
(a) ° fe] 
© ( |Ferruginous sand ge 
a & 
* Trans. Geol. Soc. of London, vol. iii. (N. 8.) p. 360. 
