182 The American Geologist. March, 1892 
Pleistocene terraces which occupy them. The peninsula rem- 
nants of the high plain are also invaded by steep-sided, lateral 
drainage-ways. The aggregate area of Lafayette formation re- 
maining is, however, more than half of the original amount, and 
the level, monotonous surface of the old plain is the characteristic 
feature of all the higher land of eastern Virginia and Maryland. 
. Inits eastward extension the formation gradually becomes finer- 
grained; the pebbles are small and in less proportion and the 
amount of argillaceous matter increases. The predominant mate- 
rials are orange and buff sands,. with irregularly distributed drifts 
and sprinkling of small pebbles. Near the base of the formation 
in the easternmost localities thin beds of grey clay become conspic- 
uous, but they alternate with beds of sharp sands. The forma- 
tion gradually thickens, also, and finally a thickness of from forty 
to sixty feet is attained. Throughout its eastern extension the 
formation lies unconformably on the east-dipping surface of the 
Chesapeake (Miocene) sands and its base usually includes more or 
less Chesapeake materials. 
It was hoped when the off-shore deposits were studied that fos 
sils would be found, for no traces of organic life had been dis- 
covered in the coarse beds farther westward, and it would be very 
interesting to know something of the life which existed in this re- 
gion in Lafayette times. Careful search finally resulted in the 
discovery of a fossiliferous locality, but theremains throw but little 
light on the question. They consisted of water-worn shell frag- 
ments, and occurred in a thin coarse sand stratum a few feet 
from the base of the formation, in a road-cut a short mile north- 
east of Heathsville, the county seat of Northumberland county, 
Virginia. 
The remains were submitted to Dr. W. M. Dall, of the Smith- 
sonian Institution, and to Dr. W. B. Clark, of Johns Hopkins Uni- 
versity, but as the material was in such poor condition it was diffi- 
cult to identify species. The most abundant individuals were Venus 
mercenuria; & Gnathodon was recognized which Dr. Clark thought 
was probably G. gray, and a badly worn shell suggested Anomia 
simplex to Dr. Dall, but he was very doubtful as to its identity. 
The Venus mercenaria has such a wide range as to be of no ser- 
vice in the present inquiry. Gnathodon grayii isa Miocene form, 
but other Gnathodons occur in the Pliocene, and the genus is still 
living in the seas of the far south. 
