( 144 ) 
which therefore also applies to the supposition, that Radiolarian ooze 
is only deposited in the deepest portions of the oceans. Thodlet’s 
doubt arose from his observing stratification in some specimens of 
deep-sea ooze, in such a way that layers of Radiolarian ooze altern¬ 
ated with Globigerina ooze. 
Philippi and Murray l ) observed in the specimens of deep-sea 
deposits collected by the Valdivia, that such a stratification is of 
common occurrence in deep-sea sediments. They showed that the 
power to dissolve calcium carbonate belongs especially to the ice-cold 
water from the polar regions which sinks down at high latitudes 
and moves very slowly along the bottom of the ocean to the lower 
latitudes. As this ice-cold water slowly gives off its oxygen it . gra¬ 
dually loses its power of oxidizing organic substances into carbon di¬ 
oxide, and consequently of dissolving calcium carbonate. In consequence 
the upper limit at which red clay and Radiolarian ooze occur, is 
deepest at the equator, namely at 5500 M., whereas at higher lati¬ 
tudes in the sub-arctic parts of the oceans, this upper limit is already 
found between 2000 and 3000 Meters. The position of this limit 
■ must therefore be dependent on climatic conditions and in general 
would be less deep in cold periods with strong development of the 
polar ice caps, than during warmer periods, when the ice-cold polar 
water only descends in smaller quantities and at very high altitudes. 
Philippi believes that the variations in the extent of the polar ice 
coverings, which certainly have taken place, explain the stratification 
of deep-sea sediments in a quite satisfactory manner, and that it is 
not permissible to doubt the correctness of the hypothesis that at 
great depths calcium carbonate is dissolved by sea water. 
For the present I too find no reason for doubting that Radiolarian 
ooze and red clay in equatorial regions are only formed at grea 
depths, below 5000 Meters, and just as well were formed exclusive y 
at such depths in former ages, and that therefore the Radiolarian 
cherts and hornstones and the red cherty clay-shales of the Danau 
formation in Borneo must have been deposited in an ocean of simi ar 
great depth 2 ). 
!) J. Murray and E. Phillippi, Die Grundproben der Deutschen Tiefeee E*!** 
dition. Wiss. Ergebnisse der Deutsche Tiefsee Expedition. Bd. X. p- 200, 
E. Philippi. Ueber Schichtbildung am Boden der heutigen und v ° rv?eltl * 
Meere. Intern. Revue der ges. Hydrobiologie und Hydrographie II. p. 1-Leipzig- ^ 
2 ) E. Philippi. Ueber das Problem der Schichtung und fiber Schicht 
Boden der heutigen Meere. Zeitschr. der deutschen geol. Ges. LX, P- ' 
Philippi suggests that during warm epochs in the earth’s history wit a ^ 
climate prevailing even in the polar regions, the oceanic sediments lai 0 
the bottom of the oceans could possess a high percentage of carbonate o 
