AGENCIES IN DEPOSITION OF CALCIUM CARBONATE 735 



studied silt grains taken from various parts of the Gulf of 

 Lyons, and observed upon them films of calcium carbonate which 

 had been precipitated during the process of sedimentation; this 

 shows, therefore, that the water of the Gulf of Lyons is substantially 

 saturated with CaC0 3 . Recent experiments of A. G. Mayer 1 show 

 that the sea-water about the coast of Florida is likewise substantially 

 saturated, for shells exposed to it for a year lost no significant weight. 

 Moreover, the investigations of T. W. Vaughan 2 on coral reefs " show 

 that submarine solution is not effective there [about Florida] as all 

 the bays, sounds, and lagoons are being filled with sediment," a con- 

 clusion which accords "with the conclusions reached by numerous 

 investigators in the Pacific, which are that the more or less continu- 

 ous walls inclosing lagoons have been formed by constructional geo- 

 logic processes and that lagoon channels and atoll lagoons are not 

 due to submarine solution." 



The evidence just presented leads us, therefore, to the opinion 

 that the surface layers of the ocean, except in the polar regions and 

 within currents of cold water — -in other words, the warmer portions 

 of the ocean water — are substantially saturated with CaC0 3 . We 

 wish to point out specifically, however, that this belief cannot be 

 regarded as established (or indeed disproved) until trustworthy deter- 

 minations of the several quantities concerned have been made; 

 indeed, to emphasize the necessity of such investigations is the prime 

 purpose of this paper. But in this connection it may be remarked 

 that a permanent deposit of limestone can hardly result unless (1) the 

 final solution locally in contact with it is saturated, or (2) the pre- 

 cipitated carbonate is protected from the water by an organic tissue 

 or otherwise, or (3) the process of deposition is rapid, in water circu- 

 lating very slowly or not at all, under which conditions re-solution 

 by diffusion is very slow. 



In this paper, which is dealing primarily with the chemical argu- 

 ments, it would be out of place to take up the geologic lines of evi- 

 dence which indicate that the ocean as a whole is not saturated with 

 CaC0 3 , for this point is not at issue; but we may fitly advert to the 



1 A. G. Mayer, Proc. Nat. Acad., II (1916), 28. 



2 T. W. Vaughan, Am. Jour. Sci., XLI (1916J, 133. See also his earlier papers, 

 especially in the Year Books of the Carnegie Institution of Washington. 



