24 JoLY — An Estimate of the Geological Age of the Earth. 



former sediments, decaying year by year under the solvent actions to which they 

 are exposed, and then carried away under new molecular arrangements to the 

 common reservoir of the ocean. There further changes of molecular bonding 

 arise, and part become diffused in solution — increasing the density of the ocean — 

 while part form precipitates under the actions of the living or dead molecular 

 forces existing in the new conditions in which they are placed. Thus the land 

 would be melted down into the sea if the disturbed gravitational balance — as 

 well as other causes — did not constantly upraise it from the water, maintaining 

 the cycle of operations. 



That these actions have progressed, broadly speaking, at a uniform rate since 

 the earliest recognizable sediments were laid down, is a tenet which has not 

 seriously been impugned. It has been claimed that the rate of removal of the 

 subaerial land surface — by solution and transportation — has been, on the whole, 

 uniform. Of course probabilities only can be advanced in support of such views 

 which must probably for ever remain in the domain of speculative geology. 



In the method of approaching the question of the Age of the Earth advanced 

 in this paper, the foregoing tenet requires only acceptation in part — that part of 

 it which refers to the removal of the land surface by solution. It has to be accepted 

 as a preliminary step that this, on the whole, has been constant. Herein are 

 involved a constancy, within certain fairly wide limits, of rainfall over the land 

 areas ; a constancy within fairly wide limits (which can roughly be defined) of the 

 exposed land area, and a constancy in the nature and rate of solvent actions going 

 on over the land surfaces. The grounds on which this amount of uniformity is 

 accepted are given in this paper. One other tenet must be accepted, that the 

 primeval ocean — that formed on first condensation of the water upon the land — 

 did not contain the amount of dissolved sodium now entering so largely into its con- 

 stitution. The grounds upon which this is claimed are also dealt with further on. 



How can these data be used to determine what may be termed the Epigene Age 

 of the Earth ? In the sea or in its deposits those elements are recognisable which 

 enter also into the constituents of the solid part of the Earth's crust. In the rivers 

 these elements are also recognizable as being continually poured into the ocean. 

 Very accurate estimates of the quantities of these elements in the ocean exist. 

 The dissolved contents of many of the great rivers of the Earth and the mean 

 composition and mean volume of the entire river discharge have been estimated. 



Now if any of the elements entering the ocean is not again withdrawn, but is, 

 in a word, " trapped " therein, re-appears as no extensive marine deposit, and is not 

 laid down sensibly upon its floor ; and if the amount of Uniformity already defined 

 is accepted, evidently in the rate of annual accretion by the ocean from the rivers 

 of this substance and the amount of it now in the ocean, the whole period since 

 the beginning of its supply can be estimated. 



