980 
the abrupt breaks in them must be accounted 
for in some other way. So far as I could 
make out, there was nothing except these 
reddish streaks which could by any possi- 
bility be mistaken for structure, and had I 
not known at the time of my second visit 
that they had been taken by others for 
stratification plains, I should not have sup- 
posed this interpretation a possible one. 
Concerning the age and origin of the 
sand which contains the relics, no positive 
affirmation can be made, and it is only fair 
to say that this statement is made on the 
basis of a somewhat full knowledge of the 
surrounding region. So far as its strati- 
graphic relations are concerned, the relic- 
bearing sand might represent the last phase 
of deposition by glacial waters, or it might 
belong to any later epoch. Its absence of 
structure does not show that it was not de- 
posited by water, for in the nature of the 
case it could not now be expected to show 
structure, whatever its origin. This would 
be true whether it represents (1) the last 
phase of deposition by glacial waters, (2) 
an estuarine deposit of later age, or (3) 
eolian sand; for the continually renewed 
perforation of the sand to the depth of sev- 
eral feet by the roots of plants, the con- 
tinual borings of burrowing mammals, 
worms and insects, all of which frequently 
go down to the bottom of the sand over- 
lying the gravel of glacialage, would quite 
certainly have destroyed all traces of strati- 
fication which the sand may once have had. 
If this were not enough, the freezing and 
thawing, and the wetting and drying, would 
have completed the obliteration of any 
original structure. For this result even a 
very few centuries would suffice. It cannot 
be asserted, therefore, that the sand was 
not once stratified. 
On the other hand, the sand in which the 
relics are found may have been blown to its 
present position. The fact that the immedi- 
ate edge of the bluff is slightly higher than 
SCIENCE. 
[N.S. Vou. VI. No. 157. 
the plain farther back lends color to this 
view, but the rise next to the edge of the 
bluff is very slight, and the conclusion that 
it is due, at this particular point, to an ac- 
cumulation of wind-blown material is not 
necessitated. The explanation of eolian 
sand in this position would be easy. While 
the river was cutting its valley in the plain, 
the bluffs were bare. The bare face of the 
bluff was made of loose sand and gravel, and 
the prevailing westerly winds might well 
have blown sand front the slope to the top of 
the bluffabove. This is just the situation in 
which dune sand would be expected to ac- 
cumulate under such circumstances, is in- 
deed just the situation in which it has 
accumulated at many other points along 
the Delaware and its tributaries. It is 
probably not exaggeration to say that dune 
sand occurs in greater or less quantity along 
the Jersey side of the river, more than half 
the way between Trenton and Camden, and 
throughout the stretch its favorite position 
is on the edge of the river bluff. The dune 
sand along the tributaries to the Delaware 
between Trenton and Camden occurs in the 
same relations. The very general presence 
in the region of wind-blown sand on the 
crests of valley bluffs leads one to suspect 
the same origin for sands in similar situa- 
tions, such as that in which the relics are 
found, even when they cannot be proved to 
be eolian. The case is still further strength- 
ened by the fact that human relics are 
very generally found in the sand which is 
demonstrably eolian. 
In the presence of the stones there is an 
apparent difficulty in the way of ascribing 
the sands in question to the wind. If, how- 
ever, the sands were accumulated by the 
wind after the occupation of the region by 
early peoples, the larger stones may have 
been dropped by men upon the surface at 
the same time with the argillite chips and 
half-fashioned implements, while the smaller 
ones might have been blownin. But we 
