248 AN ESTIMATE OF THE GEOLOGICAL AGE OF THE EARTH. 



as subsidence and elevation are possible, tides exist, and evaporation 

 progresses, this state can not be attained. To-day we find ourselves 

 in the midst of these cycles. We perceive soils formed under sub- 

 aerial actions, partly from former igneous rocks, partly from former 

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

 they are exposed, and then carried away under new molecular arrange- 

 ments to the conmion 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 the}' are placed. Thus the land would be melted 

 down into the sea if the disturbed gravitational balance— as well as 

 other causes — did not constantl}^ upraise it from the water, maintain- 

 ing the C3"cle of operations. 



That these actions have progressed, l)roadl3^ speaking, at a uniform 

 rate since the earliest recognizable sediments were laid down is a tenet 

 which has not serioush' been impugned. It has been claimed that the 

 rate of removal of the subaerial land surface — b}' solution and trans- 

 portation — has been, on the whole, uniform. Of course probabilities 

 onl}' can be advanced in support of such views, which must probably 

 forever 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 constanc}^ 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 con- 

 densation of the water upon the land — did not contain the amount of 

 dissolved sodium now entering so largely into its constitution. 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 recognizable which enter also into the constituents of the solid 

 part of the earth's crust. In the rivers these elements are also recog- 

 nizable as being continually poured into the ocean. Very accurate 

 estimates of the quantities of these elements in the ocean exist. The 

 dissolvent 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 with- 

 drawn, but is, in a word, "trapped" therein, reappears as no exten- 



