1902-3. J The Pal^ochemistry of the Ocean. 557 



uniformly maintained for an indefinitely long period. It may even be 

 claimed that, in the case of Lake Baikal, of Reindeer Lake, and 

 other lakes supplied from Archaean areas the proportions have obtained 

 from pre-Cambrian times, and further, that the river discharge of that 

 period, coming as it did from pre-Cambrian rock areas wholly, would 

 contain the four elements in these or similar proportions. That would 

 postulate that the primeval ocean was merely a gigantic body of fresh 

 water, in which the sodium, potassium, calcium, and magnesium obtained 

 in quantities and proportions as they now obtain in a lake situated in 

 Archaean area. As already pointed out, these proportions gave place to 

 others, and to-day, as in the past, the relative amounts of each element 

 are changing, so that in a few million years hence the composition of 

 ocean water will be appreciably different from what it is now. 



One can, indeed, illustrate what changes have taken place in the 

 ocean by reference to such a large body of fresh water as Lake Superior. 

 If the latterwere to lose its outlet no doubtits area would be larger than it is 

 now, but when that had attained a certain extent the evaporation would 

 balance the inflow as in the case of the Caspian Sea, and in consequence 

 the salts held in solution would constantly increase in amount, but each 

 at different rates up to a certain point, when the proportions would begin 

 to approximate those in ocean water. One cannot of course say that 

 this is what has happened in the case of either the Caspian or the Sea 

 of Aral, for these bodies of water were connected with the ocean as late as 

 the beginning of the Tertiary age, but it may be pointed out that if their 

 composition was, to start with, the same as that of the ocean in Tertiary 

 times, their present composition is strong evidence of the effect that the 

 salts derived from leaching of the land areas have in modifying the 

 proportions, for in that respect either is markedly different from the 

 other and from the ocean. 



The Great Salt Lake of Utah may be adduced as an instance of the 

 change of a body of fresh water into one which presents a high degree 

 of salinity and which in the proportions of its salts is remarkably not 

 unlike the ocean. This lake, which is in part of the area covered by the 

 glacial Lake Bonneville, is considered by G. K. Gilbert to have been a 

 body of fresh water about 25,000 years ago. He arrived at this result 

 by determining the discharge of chlorine into the lake by river water 

 and comparing it with the quantity at present obtaining in the lake. 

 Lake Bonneville had* an outlet delivering its waters into a tributary of 

 the Columbia River and thus the lake was kept fresh. When, however, 

 this outlet was lost, changes climatic and physical operated to reduce 



Monographs of the U. S. Geol. Survey, Vol. i, Lake Bonneville, tSgo, p. 254. 



