OcTOBER 29, 1897. ] 
field for procuring argillite boulders, with 
an occasional one of quartz or jasper, from 
which to make their favorite implements ; 
while the conditions connected with the 
head of tide-water doubtless made it then, 
as later, a favorite hunting and fishing 
ground. Few things have ever impressed 
me so much as the abundance of life of all 
sorts at the head of the inlets, both in Alaska 
and Greenland, into which large glaciers 
pour their currents of ice-cold water. The 
implements and chips lost by the natives 
on these temporarily abandoned stretches 
of gravel and sand bordering the main cur- 
rent are the ones mingled with scattering 
pebbles which were sweptinto their present 
position upon the Lalor farm by the subse- 
quent floods of the season. 
But this condition of things did not re- 
main long. After the flooded Delaware 
ceased to receive superabundant glacial 
débris and an excessive supply of water from 
the melting ice it not only ceased to build 
up the terrace, but began speedily to cut 
and enlarge its present channel, leaving the 
surface of the delta terrace forever after 
undisturbed by its action. The terrace is 
now about forty feet above the flood-plain. 
Thus we have a natural and perfectly 
credible method for accounting for the phe- 
nomena in question. 
It is, however, not only incumbent to 
provide an adequate cause for such phe- 
nomena, but we are in duty bound to give 
sound reasons for excluding other hypoth- 
eses which may be supposed to account 
for the facts. One hypothesis is that the 
clay band No. 2 has been produced by seg- 
regation, and so may haye been formed 
over the implements found underneath it 
since their deposition. But the stratum 
contains only a slight amount of iron in ex- 
cess of that found throughout the entire 
sand deposit. There still remains the ex- 
cessive amount of clay which characterizes 
the stratum. It can scarcely be. possible 
SCIENCE. 
643 
that that was segregated over so extensive 
an area after the whole had been deposited. 
Besides there must be something to account 
for the slight excess of iron which char- 
acterizes the red stratum. It is not only 
slightly excessive in amount above what is 
found in the accompanying sand, but is 
different in color; that being yellow and 
this red. 
The suggestion that this clayey stratum 
No. 2 is an old wind-blown surface encoun- 
ters several insuperable objections. 
1. Its extent and uniformity are greater 
than could be obtained by a wind accumula- 
tion. 
2. It contains large numbers of pebbles 
too great for removal by winds. As already 
mentioned, one of these was several inches 
in its longest diameter, and many were over 
an inch in diameter. To the suggestion 
that these may have been brought upon the 
surface by human agencies at the same time 
that the chipped flakes were lost, it can be 
answered that many of these were too small 
to have offered any inducement to anybody 
to have brought them up into that place, 
and they are scattered through the forma- 
tion so uniformly that they indicate distri- 
bution by natural agencies ; while their oc- 
currence in the clayey stratum points to 
water, and not to wind, for their distribu- 
tion. Especially significant were the two 
or three small pebbles underneath the large 
one which lay as if pressed by the weight 
of the larger pebble into and almost through 
the clayey stratum. 
To the suggestion that these pebbles had 
been brought up from the lower strata by 
overturning of trees, it is to be said that if 
that was the case it must have been before 
the formation of the clayey stratum since 
that by actual observation was continuous 
and undisturbed for a distance of many feet 
on either side of many of these pebbles. 
To the theory which would account for 
the iron in the stratum through the oxida- 
