PROBLEM OF THE GREAT AUSTRALIAN ARTESIAN BASIN. 159 



V. The Salinity of the Waters. 

 Sufficient stress has not been laid upon the peculiar fact 

 that the suite of waters in the Basin belongs to that rare 

 class with predominant sodic carbonate and possessing 

 therefore high "primary alkalinity." Alkaline carbonate 

 waters are distinctly uncommon among sedimentary types, 

 one good example being those of Montreal; 1 the analyses 

 from the last are closely comparable with those of Australia, 

 but in certain localities, sulphates of sodium and of lime 

 take the place of much of the sodic carbonate. Of the 

 waters of the Texas Cretaceous basin, 2 with which an 

 analogy has been expressed, only two are really comparable, 

 since in those that carry sodic carbonate, this salt is sub- 

 ordinate to sodic chloride, and, when in excess, is accom- 

 panied by sulphates of sodium, lime and magnesium. 



The suite of the Great Basin differs again most markedly 

 from all the other artesian basins in Australia — palaeozoic, 

 mesozoic and tertiary — in possessing only rather minute 

 quantities of calcium and magnesium carbonates, a general 

 absence of sulphates, and, conspicuously, a distinctly low 

 proportion of sodic (and occasionally potassic) chloride. In 

 the other basins the amount of sodic chloride is usually five 

 or six times as high — very much more so indeed in the 

 Murray Tertiary Basin — carbonates of lime and magnesium 

 are somewhat higher, especially in the Adelaide Plains 

 Artesian Slope, and also chlorides and sulphates of Mg or 

 of Oa; sodic carbonate is only present now and then, and 

 invariably in small quantity. 



Gregory pointed out that upon the meteoric hypothesis 

 the salinity should increase in a more or less definite man- 

 ner in a westerly or south-westerly direction from the 

 assumed intake, inasmuch as soluble matters would be 



1 dimming, Geol. Sur. Canada, Mem. 72, 1915. 

 2 R. T. Hill, U.S.G.S.. 21st Ann. Kept., Vol. 7, 448-450, 1901. 



