BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



Vol. 19, pp. 113-146 JUNE 18, 1908 



EELATIONS OF EADIOACTIVITY TO COSMOGONY AND 



GEOLOGY 1 



BY GEORGE E. BECKER 



{Presented for publication at the Decemher meeting, 1907) 



co:n"tents 



Page 



Introduction 113 



Outline of radioactivity 113 



Origin of uranium and thorium 120 



Radioactivity and the earth's age 127 



Distribution of radioactivity in depth 135 



Summary 144 



Introductiox 



Even during the jjrogress of a campaign, when complete information is 

 necessarily unattainable, it is well to assemble facts and probabilities in 

 an orderljr manner, and to make a review of the situation as a guide to 

 further action. It is as yet far too early to pronounce finally upon the 

 part which radioactivity will eventually play in cosmogonic theories, but 

 not too early to consider the bearing of recent discoveries on the genesis 

 and past history of the globe. Since geologists to whom this paper is 

 addressed can not be expected to be very familiar with radioactivity, I 

 shall first make an attempt to sketch in outline such features of that 

 subject as seem to me of especial interest to us; next I shall try to show 

 under what conditions radioactive substances can come into existence, and 

 finally discuss the geological effects which may be expected from them. 



Outline of Eadioactivity 



Investigations in radioactivity have developed out of the study of the 

 cathode rays and the Eoentgen rays, the properties of which amazed the 



1 Manuscript received by the Secretary of the Society April 1, 1908. 

 This paper was not read at the meeting or presented by title, hut was offered for 

 publication and accepted by a unanimous vote of the Publication Committee. 



XII— Bull. Geol. Soc. Am., Vol. 19, 1907 (113) 



