DEEP-SEA RADIUM 131 



should State there are "immense quantities of uranium 

 and radium on the deep ocean floor." We see the state- 

 ment is not founded on fact. 



Among the radioactive elements which lend them- 

 selves to age determinations we may nowadays include 

 also the radioactive isotope of carbon, C^^, produced 

 from carbon dioxide in the atmosphere through nuclear 

 collisions and subsequently deposited as carbonates 

 on the ocean floor. The method of radiocarbon dating 

 developed by W. Libby in the Institute for Nuclear 

 Studies in Chicago has proved eminently useful to 

 archaeology for dating wood, peat, and other vegetable 

 remains found on prehistoric sites. The time range of 

 such age determinations is, however, limited to less 

 than 20,000 years, as the time for disintegration of 

 radiocarbon to 50^ c of its original amount is only 

 5,568 years. This method has recently been applied 

 also in attempts to date the upper layers in one of the 

 "Albatross" cores from the eastern Pacific Ocean, in- 

 vestigated by Arrhenius (in collaboration with Libby 

 and Kjellberg) . Since the quantity of calcium carbonate 

 required for obtaining a dependable value of the radio- 

 carbon present is fairly large, it was necessary to work 

 on the material in a core length of 45 centimeters, span- 

 ning a total time of deposition of more than 14,000 

 years, that is, nearly three times the half-value period 

 of radiocarbon already mentioned. This obviously 

 makes the resuhs less accurate than if a core of a much 

 larger section could have been used. In such a case a 



