206 IMPLEMENTS IN THE RIVER DRIFT AT TRENTON, N. J. 
to see their geological construction at a glance. This construction 
is in each case alternate layers of fine sand and gravel, the latter 
being far in excess of the former; and we have designated the 
specimens here figured as ‘ drift implements,” and consider them 
as wholly different from the rude implements already referred to, 
inasmuch as all three were taken from this gravel at great depth, 
and all beneath undisturbed layers of fine sand 
Figure 36 represents the first of the three ‘‘ drift” implements 
found deeply in drift gravel. It was brought to light in September, 
1872, in removing the steep hillside that formed the east side of 
Cooper street, near Factory street, in the city of Trenton. The 
specimen itself, when discovered by us, was lying in situ, sur- 
Fig. 36, 
6|~ 
rounded by gravel, and there were two layers of undisturbed sand | 
of one foot and twenty inches respectively in thickness above it; 
between these sand strata was a heavy stratum of fine gravel; 
above them another; and the loam above that. The stratum of 
gravel in which the specimen was found was three feet in thickness 
above the specimen, which was about two feet above the level of 
the street. The depth from the surface of the ground to the speci- 
men, which was ascertained before the removal of the implement 
from its bed, was sixteen feet. The specimen was lying in a hori- 
zontal position, in fine gravel, and attention was drawn to it by 
| the cutting edge projecting from the face of the hillside or bluff. 
os We were assured by the men who were carting this gravel, that 
_ the week 
previous a had met with two slabs of stone, a foot or 
