40 LIFE: ITS NATURE AND ORIGIN 



"Age" means the time elapsed since the final solidification of the rock or mineral 

 containing the radioactive element. 



23 For further details, see a paper by Professors Clark Goodman and Robley D. 

 Evans (M.I.T.), Bull. Geol. Soc. of America, April 1st, 1941, pp. 492-541. 



24 /. Wash. Acad. Sci., 1924, 14, 459-472; Trans. Am. Geophys. Union, 1930, 

 pp. 309-41. 



25 The Byrd expedition reported (1947) the presence of two "oases" in Antarctica. 

 Coal is mined in Spitsbergen, only ten degrees from the North Pole. About li/ 2 

 billion years ago radioactivity from TJ 235 alone was four times what it is at present. 

 J. A. 



26 See also A. Knopf, in "A Textbook of Geology," by Longwell, Knopf and Flint, 

 Part I, 2nd ed., J. Wiley & Sons, Inc., New York, 1939. 



27 For further details, see W. D. Harkins, Science, March 8th, 1946, p. 293, and 

 Smyth Report, 9.14. 



28 Scientific Monthly, Sept., 1934. 

 ^Encylo. Brit., 11th ed., 1910, 8, 626. 



