20 INTRODUCTION. 



ness than we can at present, the parallel of these de- 

 posits, and men of science being now engaged in Mary- 

 land, by order of the legislature, to make geological re- 

 searches, we may hope, ere long, to have this, with other 

 deposits of the state, better known than they are at pre- 

 sent. The deposit at Vance's Ferry, South Carolina, has 

 been observed by Dr Blanding to contain one of the 

 characteristic fossils of the Eocene Period, the Venericardia 

 planicosta, and in the cabinet of that naturalist I have 

 observed several other genera, which distinctly identify it 

 with that epoch. 



It is a matter of considerable doubt, if any Tertiary de- 

 posit, contemporaneous with the Miocene Period of Mr 

 Lyell, has yet been observed in our Formations. The de- 

 posits of Bourdeaux, Dax, Turin, Ronca, Vienna, and some 

 other places on the Continent, are of this period, but it is 

 not, I believe, known to exist in England. Future inves- 

 tigations may, in the vast extent of our southern deposits, 

 discover its existence. 



The Older Pliocene Period of Mr Lyell, finds its equiva- 

 lent, I think, in the well known deposit of St Mary's, 

 Maryland. Mr Conrad, who has carefully examined the 

 deposit at this place, has given us a catalogue of fifty-six 

 species observed there by himself. Of these, about one third 

 are known to exist on our coast ; but some of them in more 

 southern latitudes. The deposits of York Town, Smith- 

 field, and Suffolk in Virginia, and those of Easton and St 

 Mary's in Maryland, as well as that of Cumberland county, 

 in New Jersey, are referred by that geologist to the Upper 

 Tertiary, and, without doubt, belong to the Older Pliocene 

 Period of the Tertiary. 



Of the Newer Pliocene Period we have an equivalent 

 in the deposit at the mouth of the Potomac ; the dis- 

 tance of which, in a direct line, is about forty-five miles 

 from the ocean, the intervening country being low and 



