CHAMBERLIN— THE AGE OF THE EARTH. 261 



deductions drawn from such a complication of cycles differ in very- 

 important respects from the deductions drawn from a simple match- 

 ing of the content of the igneous rocks with the content of the ocean 

 solutions and the sediments. 



Now, in respect to sodium, it is, of course, recognized that it 

 returns to the solid state in less degree than potassium, magnesium, 

 and calcium. It is held, nevertheless, on good evidence, that the 

 sodium does return to the solid state in minor equilibrium degree and 

 is recounted. The reactions involved are controlled by the law of 

 mass action and the mutual effects of the constituents on one another. 

 The reactions are particularly affected by the degrees of concentra- 

 tion, which are very low in the fresh-water solutions and quite high 

 in the sea solutions. The trend of the reactions is toward equilibrium 

 between the constituents, not toward any exclusive or monopolistic 

 combination. Specifically, it is held that when the state of concentra- 

 tion favors the sodium, it will displace either potassium, magnesium, 

 or calcium, and that such displacements take place as a standard fea- 

 ture in the processes of disintegration and solution, though only in an 

 appropriate minor degree. 



Let us now turn to such determinations as are available for testing 

 the validity of these contrasted interpretations. 



Discrepancies in the Matching of Igneous Rocks with Sediments 

 and Solutions. — The differences between the content of the igneous 

 rocks and that of the sediments and the salts of the ocean have been 

 put in definite form by Leith and Mead.^^ Comparing first the 

 igneous rocks with the sediments, they find the following excesses and 

 deficiencies: (i) a deficiency of 3.1 per cent, in iron; (2) a deficiency 

 of 26 per cent, in magnesium; (3) an excess of 32 per cent, in cal- 

 cium; (4) a deficiency of 64 per cent, in sodium; and (5) an excess 

 of 2 per cent, in potassium. If the corresponding constituents in the 

 ocean are added to these severally, some of the discrepancies will be 

 lessened, while others will be increased; the discrepancies do not 

 disappear, though they are somewhat mitigated. 



2. It is recognized on all hands that the land waters vary greatly 

 according to the nature of the drainage area from which they are 



16 C. K. Leith and W. J. Mead, " Metamorphic Geology" (1915), p. 69 et 

 seq., particularly pp. 83-88. 



