GEOLOGY. 363 



THE PROBLEMS OF THE OCEAN. 



It has been evident for some years that the inherited interpretations of the 

 ocean and of its saline contents need fundamental reconsideration in the light 

 of advances in related lines of inquiry. Since the ocean is regarded as, in 

 some special sense, a residual product of the action of the atmosphere and its 

 precipitates on the lithosphere, it is not unnatural that the ocean should be 

 the last to be reached in the application of the revolutionary results of chemical 

 and physical as well as geological and cosmological researches. The most out- 

 standing and tangible of the incongruities in the interpretation of the oceanic 

 solutions lies in the extraordinarily high proportion of oceanic chlorine to 

 oceanic sodium on the assumption commonly made that both are mainly 

 derived directly from the decomposition of the "crust" of the earth. This 

 incongruity is the more remarkable because chlorine and sodium are the 

 leading constituents of the oceanic salinity, and form, by their simple union, 

 the most common of the oceanic salts. In the igneous rocks of the crust the 

 average content of chlorine, according to the latest compilations of Clarke and 

 Washington, 1 is 0.096, while that of sodium is 2.83. But in the ocean the 

 proportions are about 1.8 chlorine to 1 sodium. On the assumption that the 

 proportions of chlorine to sodium in the ocean should be essentially those in 

 the parent rocks, the discrepancy is of the order of 50 to 1. Now, since it 

 will only increase the incongruity to suppose that chlorine and its compounds 

 lack solubility or that by recombination chlorine goes back into a solid state 

 after entering the ocean, the whole burden of removing the discrepancy is to 

 be sought in some modification of the interpretation of the action of the sodium. 

 With certain exceptions to be mentioned presently, it has been commonly 

 held that sodium does not systematically recombine with the sea-sediments in 

 any appreciable degree and thus habitually return to the solid state as a con- 

 stituent of the sea-deposits. It is recognized that potassium, calcium, and 

 magnesium, the most common alkaline associates of sodium, do thus return 

 to the solid state as constituents of the marine shales, limestones, and dolo- 

 mites, but, except in negligible amount, it has been affirmed that this is not 

 true of the sodium, because of the higher solubility of its compounds. Esti- 

 mates of the age of the ocean have been based on the persistent accumulation 

 of the sodium thus postulated and these have been widely accepted. It has, 

 indeed, been recognized that winds blowing from the sea to the land carry 

 back sea-salts, and allowances have been made for the repeated reckoning of 

 these as though derivatives from disintegration. So, also, it has been recog- 

 nized that sea-salts are entrapped in the pores of marine sediments and that 

 later these are sometimes raised above the sea-level and drained into the 

 streams and so re-counted; allowances have been made for these duplications. 

 So also, allowance has been made for salt-deposits embraced in the sedimentary 

 deposits. But when allowances have been made for all these, the accounts of 

 sodium and of chlorine fall far short of balancing. Some further mitigation of 

 the discrepancy has been found in the supposition that a part of the chlorine 

 came from volcanic gases rather than the decomposition of the surface rocks, 

 but to assume that the amount of this is sufficient to match the unchlorinized 



i Frank W. Clarke and Henry S. Washington, U. S. Geol. Surv., and Geophya. Lab. Carnegie 

 Inst. Wash., The average composition of the igneous rocks, Proc. Nat. Acad. Sci., vol.8, No. 3 

 (May 1922). 



