52 American Association of Museums 



Applying these ratios to the hour divisions on the clock dial we 

 have: 



YEAR8 



Pre-Paleozoic Time 36,000,000 



Paleozoic Time 24,000,000 



Mesozoic Time 9,000,000 



Neozoic Time 3,000,000 



72,000,000 



By subdividing each of the time divisions into its appropriate 

 geologic periods the approximate antiquity of each period is indicated. 



The even subdivision of Pre-Paleozoic Time into Azoic and Eozoic 

 is purely arbitrary, as is also the indicated time duration of the 

 several geologic periods, except in connection with the Quaternary, 

 which is assumed to include the last 500,000 years of cosmic time, 

 equivalent to the last ten minutes of the twenty-fourth hour, and to 

 represent the period during which man has been in existence. 



