360 
PACIFIC SCIENCE, VoL VIII, July, 1954 
years of uninterrupted sedimentation are re- 
quired. 
Only a few words about these radioactive 
age-determinations, as applied to submarine 
chronology. Some 15 years ago I ventured 
to explain the mysteriously high radium con- 
tent of the Red clay and of the Radiolarian 
ooze as due to a precipitation onto the ocean 
bottom of radium’s mother element, ionium, 
together with ferric hydroxide. Granting this 
to be true, the content of "ionium-supported” 
radium in the deposit should decrease with 
increasing distance below the sediment sur- 
face at a rate correlated with the half-period 
of ionium decay, that is, to 50 per cent in 
83,000 years, to 25 per cent in 166,000 years, 
etc. This presupposes that there is no sensible 
amount of the ancestral element, uranium, 
present in the deposit. Both assumptions, a 
lack of uranium and a surplus of ionium near 
the sediment surface, have been confirmed 
recently through investigations on "Alba- 
tross” cores by Professor F. Hecht in Vienna 
and by Dr. E. Picciotto in Brussels, whereas 
Dr. V. Kroll in Goteborg has carried out 
most of the radium determinations. 
However, age-determinations from radium 
measurements alone are not such a simple, 
straightforward work as the ionium-precipi- 
tation hypothesis would lead us to believe, 
possibly because of radium’s tendency to mi- 
grate downward in the sediment column, 
leaving behind its more stationary mother- 
element, ionium.^ Although this makes the 
technique more complicated, it is still possi- 
ble, with due precautions, to use measure- 
ments of the vertical distribution of radio- 
activity along a sediment core as a means 
of determining its past rate of deposition. 
There are, however, also other, more in- 
direct methods for attacking the difficult 
problem of submarine geochronology, for 
example, the dating of different sediment lay- 
^ Recent ionium determinations in our Red clay 
samples do not lend support to this migration hypo- 
thesis, except possibly as a contributory influence on 
the radium distribution in the cores. 
ers. One of these methods depends on a 
careful analysis of the calcareous Foramini- 
fera shells present in different strata and the 
presence of more or less heat-loving or "ther- 
mophile” species. This really amounts to a 
paleoclimatological study of the temperature 
variations in the surface layers of the ocean 
which have become reflected in the plankton 
organisms it has contained. In this manner, 
indications by the "thermometer” which a 
sediment core represents can be linked up 
with known and datable variations in the 
temperature on the continents due to cold 
(glacial) and warm (interglacial) ages. This, 
so to say, biological age-determination was 
first extensively used on cores from the Ger- 
man "Meteor” expedition by W. Schott and 
later on "Albatross” cores by Schott in Gote- 
borg, by C. D. Ovey in London, and especially 
by F. Phleger, F. Parker, and J. Pierson in 
the Scripps Institution of Oceanography in 
La Jolla. 
The geologist of our expedition, Dr. G. 
Arrhenius, a year ago published a compre- 
hensive study of the "Albatross” cores from 
the eastern Pacific Ocean. In this pioneer 
work of great importance to deep-sea research, 
Arrhenius has very carefully compared differ- 
ent sediment components such as carbonate 
of lime, humus-carbon, nitrogen, phosphor- 
us, iron, manganese, titanium, etc. In this 
manner and utilizing also the biogenic com- 
ponents, Arrhenius was able to correlate the 
different strata in cores from very wide re- 
gions and to ascribe these strata to different 
stages and substages of continental glaciation. 
Assuming titanium to be the least variable 
of all the inorganic components in the de- 
posits, Arrhenius calculated the rate of ac- 
cruement of titanium to the sediment from the 
"lutite veil,” that is, the finest clay-particles 
suspended in ocean water. In this manner he 
calculated the "titanium age” of the different 
layers in different cores. He further obtained a 
basis for this chronology from measurements 
by the radio-carbon dating method made in 
collaboration with F. Libby and Kjellberg of 
