THE LIFELESS EARTH 29 



Estimates of Time Required eor the Processes of Past Deposition and 



Sedimentation at Rates Similar to Those Observed at 



THE Present Day ' 



i860. John Phillips 38- 96 million years. 



1890. De Lapparent 67- 90 million years. 



1893. Walcolt 55- 70 million years. 



(27,640,000 years since the base of the Cam- 

 brian Palaeozoic; 17,500,000 years or up- 

 ward for the pre-Palaeozoic.) 



1899. Geikie 100-400 million years. 



(Minimum 100 million years; maximum — 

 slowest known rates of deposition — 400 

 million years.) 



1909. Sollas 34- 80 million years. 



(The larger estimate of 80 million years on the 

 theory that pre-Pala?ozoic sediments took 

 as much time as those from the base of 

 the Cambrian upward, allowing for gaps 

 in the stratigraphic column.) 



These estimates give a maximum of sixty-four miles as the 

 total accumulation of sedimentary rocks, which is equivalent 

 to a layer 2,300 feet thick over the entire face of the earth. '-^ 

 From these purely geologic data the time ratio of the entire 

 life period is now calculated in terms of millions of years, 

 assuming the approximate reliability of the geologic time scale. 

 The actual amount of rock weathered and deposited was prob- 

 ably far greater than that which has been preserved. 



In general, these estimates are broadly concordant with 

 those reached by an entirely different method, namely, the 

 amount of sodium chloride (common salt) contained in the 

 ocean,'' to understand which we must first take another glance 

 at the geography and chemistry of the primordial earth. 



The lifeless primordial earth can best be imagined by look- 

 ing at the lifeless surface of the moon, featured by volcanic 



' Becker, George F., 1910, pp. 2, 3, 5. 



^ Clarke, F. W., 1916, p. 30. 



^ See Salt as a Measure of the Age of the Ocean, p. 35. 



