94 ON THE SECONDARY AND TERTIARY FORMATIONS 



been accustomed to employ ; differing very little, I perceive, from 

 those used by the gentleman last mentioned. 



Before closing this subject, permit me to allude to the new 

 geological map of England and Wales, by ]\Ii\ Greenough. As 

 a finished specimen of art, it is probably the most beautiful pro- 

 duction of the age, and may, with great advantage, be consulted, 

 for the extreme clearness of its details. 



Observations on the Secondary and Tertiary Formations 

 OF THE Southern Atlantic States ; by James T. Hodge. 

 With an Appendix, by T. A. Conrad. 



During tlie last year I spent a few months in making a tour on 

 horseback through parts of the Southern Atlantic states. My ob- 

 ject was to obtain from my own notice a general idea of a large 

 portion of our country not familiarly known ; but so rapidly did I 

 pass tln-ough it, that my notes are crude and imperfect. From 

 the investigations of Mr. Conrad, to whose instructions I am much 

 indebted, the accompanying lists of fossil shells, which I there 

 collected, were made out, and a few new species are now added 

 to our catalogue of the tertiary fossils. 



Until I arrived in the southern part of Virginia I was unable 

 to see much of the " marl beds " of the tertiary, owing to the 

 snow and ice that covered the gi'ound. I found, however, that 

 the marl extended all along the eastern section of the State, and 

 that it was extensively used as a manure by the planters. On tlie 

 Rappahannock, seven miles below Fredericksburg, tl\e bed is at 

 least ten feet thick, and so conveniently exposed that vessels might 

 come alongside and load with it, if it wei?e important enough to 

 transport. It here abounds in shells, and also contains teeth of 

 sharks, and fossil bones. Neai'ly all belong to extinct species, 

 and the genera besides are those most common to the lower 

 tertiary. The fertilizing properties of the marl appear to depend 



