164 ALEX. L. DU T01T. 



stretches a belt of water with over 20 grains of common 

 salt, becoming very saline indeed along the southern margin 

 of the Basin, well seen for example between Hergott and 

 Oodnadatta. 



It is surprising indeed to find that, after travelling under- 

 ground through sediments, a distance of almost 600 miles, 

 as one has to suppose, the bore waters at Goyder's Lagoon 

 and Mungeranie in South Australia, actually possess only 

 8*2 and 9*7 grains of NaCl respectively, a fact that is all 

 the more remarkable, considering the extremely high tem- 

 peratures and pressures prevailing in the depths of the 

 reservoir hereabouts. That the hot but very dilute alkaline 

 solutions have reacted to a limited extent upon the quartz 

 and silicates, is nevertheless proved by the return of from 

 1 to over 3 grains of silicic acid and soluble silicates in the 

 analyses of waters from some of the bores and hot springs. 



Sulphates as a rule are either absent or present in very 

 small amount, and this is worth remembering when com- 

 parisons are being made with artesian waters from other 

 parts of the world, e.g,, Texas, Wisconsin and Iowa. In 

 the Ooonamble district sulphates are pretty well confined 

 to an area within which corrosion of casing is rife; they 

 are also found in Queensland at Roma (Govt.), Afton Downs 

 and Murweh, but are in much larger quantity along the 

 shallowing margin in South Australia in some bores and 

 certain springs, e.g., Catt's and Sulphur Springs (I. p. 191 ; 

 IT. p. 268). The presence of sulphate of magnesium along 

 with that of sodium points to the marine Cretaceous beds 

 as their probable source, although, from the fact that the 

 sulphate waters may be low in sodic carbonate and often 

 contain free carbon dioxide, it is possible that part of the 

 sulphate may have arisen through the oxidation of sulphide 

 of iron, nodules of which are known to occur in the strata 

 of that quarter of the Basin ; yet it seems very unlikely, 



