338 



TRANSx\CTIONS OF THE 



The summit line of the lower tertiary is here much un- 

 dulated, and indeed the surface of both formations in this 

 vicinity exhibits strong marks of the action of powerful 

 currents. 



During a recent visit to Long Branch in New Jersey, 

 in company with Mr Vanuxem, I recognised in some 

 casts of shells in a '^marl pit" near that y>lace, a few 

 species of the lower tertiary, such as Voluta Sayana, 

 Cardita alticostata, ^c; and as no secondary species was 

 present, I consider the deposit decidedly as modern as the 

 Claiborne formation. It forms a marked contrast to the 

 arenaceous fossilliferous rock at Tinton, six miles distant, 

 where the usual groupe of cretaceous remains occurs ; for 

 the latter embraces no tertiary, nor the former any 

 secondary fossil whatever. 



In speaking of the eocene period, it may be proper to 

 notice a subformation, which I, in common with most 

 other writers on the subject, considered a distinct forma- 

 tion — the equivalent of the plastic clay of Europe; but 

 a perusal of the third volume of Professor Lyell's Prin- 

 ciples of Geology, convinced me of my error; and in the 

 entire absence of fossil shells, or of any fossil whatever, 

 except lignite, we can correctly classify these strata only 

 when their relative position to contiguous formations, 

 above and below, has been clearly ascertained. 



The beds of clay and lignite in the United States, 

 usually termed plastic clay, seem to have been deposited 

 in fresh water ; for no marine, nor indeed any but vege- 

 table fossils have hitherto been detected in them. Their 

 age has not yet been accurately determined, but as they 

 invariably lie between the primary and tertiary forma- 

 tions, they appear to me to have been formed at the 

 mouths of rivers, when the eocene ocean washed the 

 primary rocks, and to have been converted into dry land 

 by the same convulsions which upheaved the eocene fos- 

 silliferous strata. No reliance can be placed on the re - 



