VI 
The beauty, variety, and peculiar character of our Tertiary 
fossils, are such as to recommend them to the notice of the 
mere Conchologist; but when viewed in connexion with Geolo- 
gical phenomena, they will prove, in consequence of their vast 
extent and continuous beds, even more important than the most 
celebrated contemporaneous deposits in Europe. This region 
has scarcely as yet met the eye of a practical Geologist, since 
the importance of extraneous fossils has been duly appreciated, 
or surely we should have had a valuable detailed account of the 
scientific treasures which extend almost without interruption 
from New Jersey, inclusive, to the Gulf of Mexico. 
Three different classes of organic remains will be remarked 
by every observer of the formations in question; and examples 
of each are included in the western peninsula of Maryland. 
The first consists chiefly of extinct species; the second is a mix- 
ture of extinct species with others still inhabiting the coast of the 
United States, and the third embraces existing species alone. 
It is but lately that deposits similar to the latter have attracted 
the attention they merit, and they seem to prove that the Ter- 
tiary formations pass insensibly into each other, and that a new” 
creation of marine shells had gradually taken the place of the 
old. It is certain that the lower, or oldest of these strata, al- 
ways form the western boundary of the newer beds, and the 
most recent strata rest only on the eastern limits of this mid- 
dle class of depositions. In those localities where recent and 
extinct species are indiscriminately mingled, a few shells occur, 
which although they cannot be satisfactorily referred to existing 
species, resemble them in such a manner as to excite a sus- 
picion that they may be varieties occasioned by a difference of 
temperature, &c. between the ancient ocean and the present. 
The banks of the larger rivers of the Tertiary region contain 
incredible numbers of shells, which are profusely scattered on 
the sands beneath. These banks are often high and perpendi- 
cular, composed of sand and clay, so very friable, that immense 
masses, loosened by the frost, frequently fall, strewing the mar- 
gins of these rivers with the Pines which skirt their elevated 
bluffs : thus at a place called the Rocks, on James River, a 
few miles from the village of Smithfield, it is difficult to walk 
along the shore, when the tide is in, in consequence of fallen 
trees, and masses of clay filled with innumerable shells. This 
