198 ALEX. L. DU TOIT. 



These, the similar water at the Zetz Spa (Ballimore) 1 

 east of Dubbo, struck at 550 feet in a bore in Permo-Car- 

 boniferous beds, and highly charged with 00 2 , and the 

 highly alkaline water in the Maria Creek bore on the 

 Central Railway in Queensland in the same system, prove 

 that waters of the Great Basin type can be found in rocks 

 both sedimentary and plutonic older than the Jurassic, 

 while the position of the cold Helidon Spa with its pre- 

 ponderance of sodic carbonate is also significant. From 

 this and from the collateral evidence presented earlier, it 

 seems highly likely that waters carrying carbon dioxide 

 have been and probably are still being fed up into the 

 water-bearing beds through fissures in the basement rocks. 



Of direct evidence within the basin very little could be 

 expected under the circumstances, but there are three 

 items worth citing in support : — (1) the abnormally hot 

 waters struck on the Northern Railway at Strathfield (130° 

 F. at 841 feet), 2 and at Nonda Downs or Clutha Resumption 

 (180° F. at 1,340 feet— if this be correctly printed); (2) the 

 observation that flakes of granite are being brought up by 

 one of the warm mud springs at Mount Browne 3 on the 

 lower Flinders river, presumably from the granite basement 

 known to lie at a shallow depth hereabouts (see earlier); 

 (3) the Oxton Downs bore on the Northern Railway, where 

 the water was tapped in a crack in the granite, the signific- 

 ance of which was pointed out by Gregory. 



The evidence quoted by Pittman 4 shows that, after bor- 

 ing slowly for some weeks in hard granite, the tools dropped 

 suddenly six or eight feet, and that the boring then followed 

 this crack down until the rock became hard again ; flakes 



1 E. F. Pittman, The Mineral Resources of M.S. Wales, p. 449, 1901. 



2 T. W. E. David, Journ. Roy. Soc. N.S.W., Vol. xxvn, p, 423, 1893. 



3 T. W. E. David, ibid., Vol. xxv, p. 294, 1891. 



* E. F. Pittman, Problems of the Artes. Water Supply Austr., GeoL 

 Siirv. N S.W., p. 20, 1908, 



