342 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1914. 
in the ooze; but it is chiefly m the Antarctic Seas that they come 
strongly into consideration, attaining 16 per cent. 
We have just indicated the distribution of these various oozes. 
Let us see how they are formed and what they become. 
First of all we note the influence of surface currents, which accord- 
ing to their temperature develop more or less organized life of this or 
that character. Along warm currents the surface organism descends 
into the sea, serving to nourish other life deeper down which in turn 
descends still lower. On the surface borders of these currents the 
variations of temperature sometimes produce great slaughter. 
Finally there is formed near the bottom a slow chute of organic 
particles, some calcareous, others siliceous. 
These particles before reaching the bottom certainly undergo 
partial dissolution and some chemical reactions, the more accentu- 
ated as they take more time to descend. This is the beginning of 
the transformations that we call diagenesis. Some of the above- 
mentioned differences between deposits of various depths arise 
from this. Thus the fragile shells of pteropods are usually dissolved 
before reaching a depth of 3,000 meters and for that reason they are 
not found deeper down. The globigerina have greater resistance, 
but end by disappearing in their turn in the great depths. This 
is why in the Pacific, deeper than the Atlantic, so few of them are 
found at great depths, although they may be abundant at the surface. 
Once deposited at the sea bottom the oozes continue to undergo 
like transformations which must gradually give a different aspect 
to like deposits according to their age of formation, or, when these 
deposits have later been brought back to daylight in geologic ages, 
according to the duration of their sojourn in the sea. 
These reactions are not yet well known. Chemically there would 
be opportunity here to study what effect may be produced in oozes 
of various compositions by sea water at about 2° of temperature 
and at the great pressure there. 
In reviewing some of the observations made on this subject I am 
struck by the apparently close analogy between these phenomena 
and those which characterize the superficial alterations of our strata 
in the line of peroxidation, directly exposed to waters strongly 
aérated and charged with carbonic acid. Some very different condi- 
tions lead to the same result. The first fact, for example, is the 
elimination of lime, decalcification. We have already remarked 
that the deeper the ocean bottom the less do calcareous shells appear 
there, hence at great depths we find manganiferous red clay like that 
which decalcification and lateritization produce on our plateaus. 
The Gauss expedition at the center of the Atlantic brought up some 
soundings in which there was clearly less lime at the bottom than at 
