640 
No. 1, and about two inches thick, thinning 
out, however, in places to half an inch or 
slightly less. 
Then occurs another stratum of yellow- 
ish sand, about four inches thick. 
Still lower comes reddish clay, * ten inches 
thick, partly divided by an irregular stra- 
tum of sand, two or three inches thick, run- 
ning through the middle of it. In some 
places, however, the clay bands coalesce, 
and the sand continues along the line in 
lenticular masses. This clay stratum rests 
upon the more completely washed sand and 
gravels which form the great mass of the 
terrace. 
Analysis of these Strata.—The predominant 
material in the entire thickness examined 
is sand, but there is mixed with it a vary- 
ing amount of clay and iron, both being 
specially concentrated in the red bands. I 
have had specimens from these strata ana- 
lyzed to determine the relative amount of 
clay, sand and iron contained in them. 
The specimens were first thoroughly and 
repeatedly soaked and shaken in water, 
which was poured off immediately, carry- 
ing everything which could be held in sus- 
pension, and leaving the sand thoroughly 
washed. After being allowed to settle 
twenty-four hours, the water was siphoned 
off and the residue thoroughly dried. This 
was then compared in bulk with the residue 
of sand which had also been dried. All the 
specimens were treated in a similar manner. 
The results were, beginning at the top: 
Ist sand stratum, 18% suspended mat- 
ter; 2d sand, 16% ; 3d sand, 14% ; under- 
lying sand, 7%. Of the red bands, Ist red 
stratum, 24% suspended matter; 2d red 
stratum, 27% ; 3d stratum, 27% ; 4th (or 
lower part of 3d) stratum, 387%. The 
amount of iron contained in the fine sedi- 
ments so far as analyzed was as follows: 
* Throughout I use clay as signifying simply sedi- 
ment so fine that it is held in suspension in water for 
an appreciable time. 
SCIENCE. 
[N. 8. Von. VI. No. 148. 
from the 2d sand, one-half of one per cent. 
of the whole amount; of the 2d red stra- 
tum, one and one-half per cent. of the whole 
amount, and the same for the 4th red stra- 
tum. These red bands, therefore, are not 
to any appreciable extent segregations of 
iron. The iron scarcely more than suffices 
to give the color. The analysis shows, 
therefore, that these red bands contain from 
25% to 33% more clay than is found in the 
interstratified strata of sand. 
While the water-worn pebbles were dis- 
tributed more or less through the entire 
mass, they are specially abundant in and 
below the second, third and fourth reddish 
clayey accumulations. These pebbles vary 
in size, as has been said, from those several 
inches in diameter down to small pieces of 
gravel. Pebbles from one to two inches 
are numerous. The largest one referred to 
was imbedded in the clayey stratum, No. 2, 
just as if dropped into the clay and pressed 
nearly through it, crowding lower down 
two or three smaller ones which underlay 
it. This was found in the longer trench, 
thirty-two inches below the surface, or 
seventeen inches below our selected zone 
of doubt. This was about three- feet dis- 
tant from the locality of one of our best- 
formed chipped argillite scrapers, which oc- 
curred three inches lower down in the 
deposit, and beneath the clayey stratum. 
As I personally removed with my trowel all 
material in this section, I know that the 
clayey stratum containing the large pebble 
was continuous and unbroken, not only be- 
tween the pebble and the point directly over 
the argillite implement, but for two or three 
feet upon the other side, and that pebbles, 
large and small, were frequently struck by 
the trowel along the entire distance. 
The implement above referred to was lo- 
cated carefully and photographed by us. 
The first clayey band over it was here about 
two inches thick and so compact as to give 
distinct special resistance to the trowel 
