160 



ALEX. L. DU TOIT. 



taken up by the waters in the course of their progress 

 across the Basin. In Wisconsin, Weidman and Schultz 1 

 have shown in the clearest manner how the waters are soft 

 throughout the intake area in the central part of the State, 

 but become more and more saline as they progress through 

 the Cambrian reservoir to deeper levels in the south-eastern, 

 southern, and south-western parts of Wisconsin, while after 

 passing into Iowa, 2 this increase of salinity, with distance 

 from the intake, has been found to have become still more 

 pronounced. The distances involved range from 200 to 

 fully 350 miles. 



Gregory's map 3 only too welljshows that the actual depar- 

 ture from a priori expectation is striking, since an area of 

 relatively high salinity is present with Longreach at its 

 centre; there is a second one about Ounnamulla, and* only 

 between Richmond and Oloncurry is the anticipation of 

 progressive increase outwards fulfilled. 



Symmands 4 has rendered great service by proving that 

 in almost every case examined in New South Wales, there 

 is in individual bores a marked decrease in salinity with 

 depth, the smaller upper flows being nearly always more 

 mineralised than the main supplies tapped close to the floor 

 of the Basin; concurrently, there is a small increase in pot- 

 ash and lime. He was also led to conclude that the supplies 

 towards the intake were in many instances more saline 

 than those met with further out. 



Both Gregory and Symmonds lay stress, and rightly too, 

 upon the excessively low amounts of sodic chloride present 

 in the bulk of the deep waters — in some cases reaching 

 only two grains per gallon, a quantity far lower even than 



1 Wisconsin Geol. and Nat. Hist. Survey, Bull. 35, ch. 7, 1915. 



a Iowa, Geol. Surv., vol. 21, p. 205, and pi. iv.. 1912. 



3 J. W. Gregory, The Dead Heart of Australia, p. 312 and map, 1906. 



4 R. S. Symmonds, Our Artesian Waters, p. 22, 1912. 



