20 Clarence King — Age of the Earth. 



forces we may never know, but all evidences confirm the con- 

 viction that life was continuous from its earliest, or at least 

 an early, appearance and hence climate must have been con- 

 tinuously suitable for the circulation of continental waters. 

 The range of temperature for the time since the beginning of 

 the Huronian must have been well within Newcomb's limits. 

 So that unless the selective absorption of either the sun's 

 atmosphere or the earth's or both have varied reciprocally or 

 concurrently with radiation, solar emission cannot have had a 

 wide range of either secular or paroxysmal change. 



Nevertheless the age assigned to the sun by Helmholtz and 

 Kelvin (15xl0 6 or 20xl0 6 years) communicated a shock from 

 which geologists have never recovered. The thermodynamic 

 reasoning on which the brevity of the sun's life is reached 

 stands undisturbed, yet so powerful is the influence of the 

 old uniformation method of estimating the age of the total 

 stratified crust, that to many geologists it has seemed easier to 

 reject the physical conclusions than to seek a source of error 

 in our own very vulnerable methods. 



If as I hold, Kelvin's suggestions as to ellipticity and tidal 

 retardation do not apply to an earth readily deformable by slow 

 stress as this one evidently is, there remain but three earth-ages 

 to be weighed — Kelvin's value from terrestrial refrigeration 

 which this paper seeks to advance to a new precision, Helmholtz 

 and Kelvin's age of the sun which must sharply limit the date 

 of the redistributed earth crust, and the old stratigraphical 

 method. From this point of view the conclusions of the 

 earlier part of this paper become of interest. The earth's age, 

 about twenty-four millions of years, accords with the fifteen 

 or twenty millions found for the sun. 



In so far as future investigation shall prove a secular aug- 

 mentation of the sun's emission from early to present time in 

 conformity with Lane's law, his age may be lengthened, and 

 further study of terrestrial conductivity will probably extend 

 that of the earth. 



Yet the concordance of results between the ages of sun and 

 earth, certainly strengthens the physical case and throws the 

 burden of proof upon those who hold to the vaguely vast age, 

 derived from sedimentary geology. 



