388 KID well: analysis of a brine 



in the ancient sea on account of a lesser number of calcium- 

 secreting organisms, or the fact that they had not been active 

 for a sufficient period of time to decrease the calcium content 

 of the old ocean comparable to that of the modern sea. It is 

 difficult to believe, moreover, that organisms could exist in a 

 brine as concentrated as the one here described. 



In order to explain satisfactorily the reversal of the calcium- 

 magnesium ratio in brines of this nature as compared with sea 

 water, the greater concentration of salts in the brines, the higher 

 ratio of calcium to chloride in the brines, and the fact that mere 

 concentration of water such as now constitutes the ocean will 

 not form brines similar to those obtained from supposed fossilized 

 oceans, it must be assumed that extensive alterations of the old 

 ocean waters have occurred since the time of their inclusion. 

 This has been discussed in a most excellent paper by R. Van A. 

 Mills and Roger C. Wells ^ who advance the hypothesis that 

 deep-seated brines are derived in part from waters of sedimenta- 

 tion, often described as "connate waters," and in part from 

 meteoric waters the mixture of which in the lapse of geologic 

 time has suffered vast changes through such geophysical and 

 geochemical changes as concentration, evaporation, leaching of 

 sediments, reduction of some constituents by organic matter, 

 heat, pressure, incursion of petroleum, rock movements, and 

 cementation. Concentration and evaporation have been ma- 

 terially assisted by the expansion or movement of gases through 

 underground passages which have absorbed some of the water 

 as moisture during their contact with it. 



Several possible explanations are offered by Mills and Wells for 

 the predominance of calcium over magnesium in deep-seated 

 brines. At moderate temperatures hydrolysis may occur and 

 the magnesium be precipitated as hydroxide, basic carbonat or 

 carbonate. According to Hunt,^ magnesium silicates and calcium 

 chloride are formed when magnesium chloride reacts with calcium 



* Mills, R. Van A., and Wells, Roger C. The evaporation and concentration 

 of waters associated with petroleum and natural gas. U. S. Geol. Survey Bull. 693. 

 1919. 



5 Hunt, T. S. Chemical and geological essays, p. 122. 1878. 



