Ch. XIV.] 



181 



bordering the Atlantic does not exeeed 100 feet, althoug-h it is sometimes 

 several hundred feet high. Its width in the middle and southern states 

 is very commonly from 100 to 150 miles. It consists, in the south, as in 

 Georgia, Alabama, and South Carolina, almost exclusively of Eocene de- 

 posits ; but in North Carolina, Maryland, Virginia, Delaware, more 

 modern strata predominate, which, after examining them in 1842, I sup- 

 posed to be of the age of the English crag and Faluns of Touraine * If, 

 chronologically speaking, they can be truly said to be the representatives 

 of these two European formations, they may range in age from the Older 

 Pliocene to the Miocene epoch, according to the classification of European, 

 strata adopted in this chapter. 



The proportion of fossil shells agreeing with recent, out of 14Y species 

 collected by me, amounted to about 17 per cent., or one-sixth of the 

 whole ; but as the fossils so assimilated were almost always the same as 

 species now living in the neighboring Atlantic, the number may hereafter 

 be augmented, when the recent fauna of that ocean is better known. 

 In different localities, also, the proportion of recent species varied con- 

 siderably. 



On the banks of the James River, in Virginia, about 20 miles below 

 Richmond, in a cliff about 30 feet high, I observed yellow and white 

 sands overlying an Eocene marl, just as the yellow sands of the crag lie 

 on the blue London clay in Suffolk and Essex in England. In the Vir- 

 ginian sands, we find a profusion of an Astarte (A. undulata, Conrad), 

 which resembles closely, and may possibJy be a variety of, one of the 

 commonest fossils of the Suffolk Crag [A. hipartita) ; the other shells 

 also, of the genera Natica^ Fissurella^ Artemis^ Lucina, Cliama^ Pectun- 

 culus, and Fecten, are analogous to shells both of the English crag and 

 French faluns, although the species are almost all distinct. Out of 147 

 of these American fossils I could only find 13 species common to Europe, 

 and these occur partly in the Suffolk Crag, and partly in the faluns of 



Fig. 164. 



Fig. 165. 



Fulgur canalieulatus. Maryland Fusus quadricosiatus, Say. Maryland. 



Touraine ; but it is an important characteristic of the American group, 

 that it not only contains many peculiar extinct forms, such as Fusus 



* Proceed, of the Geo]. Soc. vol. iv. part 3, 1845, p. 547. 



