IMPLEMENTS IN THE RIVER DRIFT AT TRENTON, N. J. 209 
and beneath an undisturbed stratum of fine sand about twenty 
inches in thickness. It is above this stratum of sand, in the gravel 
that has only the loam above it, that very many of the rude imple- 
ments have occurred, to which attention was called in the Naru- 
RALIST, in March of the past year. 
Figure 38 represents the third specimen of drift implements 
which we have so far discovered in the Trenton gravels. It is a 
flake of sandstone rock, six and one-half inches in length by 
three and one-half inches in width. This specimen differs materi- 
ally from the preceding, in being perfectly flat upon the under 
surface, and flaked to the edges, from a point upon the other side, 
by detaching large scales, all starting from this one point or ‘* bulb 
of percussion.” This specimen, therefore, bears much resemblance 
to the rude implements we frequently find on the surface, and 
which are popularly called “turtle backs.” They are either fin- 
ished implements or “ cones,” from which flakes for arrowheads 
were detached. We incline to the former opinion. 
This drift implement (Fig. 38) was found within fifty yards of 
the first specimen we described, but above it geologically, having 
but a single layer of undisturbed sand above it. The specimen 
itself was found by the writer, in situ, immediately beneath this 
layer of sand, at a depth of about eight and one-half feet from the 
brow of the hill. 
To briefly sum up the reasons for separating the above described 
specimens from the relics of the surface, and the rude implements 
of the upper gravel and surface, we have but to say that having 
found them in position, beneath undisturbed strata of sand, we 
cannot but maintain their greater age ; and as we have found three 
specimens, we consider that each proves the human origin of the 
other, and that collectively they show that they are true drift im- 
plements, fashioned and used by a people far antedating the peo- 
ple who subsequently occupied this same territory, and have left 
such abundant traces of their presence. 
ad but a single specimen been found, we might reasonably, 
perhaps, applied to it the doctrine of chances, and maintained 
that it was merely a freak of nature, but the occurrence of three 
Specimens so near each other effectually disposes of the justice of 
such an opinion, and we must admit the antiquity of American 
man to be greater than the advent of the so-called + Indian.” 
AMER. NATURALIST, VOL. VII. 
