PROBLEM OF THE GREAT AUSTRALIAN ARTESIAN BASIN. 171 



The general coincidence of the area of corrosion of bore- 

 casing with that in which the waters carry free 00 3 (and 

 O) is now well known, and it is therefore highly suggestive 

 to find that the bores in which such destructive action is 

 taking place are arranged upon a long arc stretching from 

 Saxby Downs in Queensland, through Hughenden, Aramac, 

 Oharleville, Ounnamulla, to Coonamble in New South Wales; 

 at either end corrosion is particularly active. Although 

 only a small proportion of the bores along this line are 

 affected, fresh cases are now coming to light, while it must 

 be remembered that about Coonamble several of the bores 

 were not troubled in this way until after deepening; also 

 at Saxby Downs the deeper flows are corrosive. 



Still mere depth alone along this arc, does not necessarily 

 imply corrosive action, and the suggestion is thrown out of 

 a concealed fracture in the artesian basement through 

 which OOs has been, and perhaps is still being contributed 

 at points along its length. At the head of the Flinders 

 River to the north of Hughenden, the artesian beds are 

 thrown down against the schists by a "pre-basalt" fault, 

 striking south-east, so that the tectonic assumption made 

 is not without warrant. 



The work of Gautier 1 has shown that considerable 

 volumes of gases can be obtained by the dry heating of 

 granite and other igneous rocks, comprising in their order 

 of abundance H, 0O 2 , CO, 0H 4 , NH 3 , N and sometimes 

 traces of H 2 S, similar in fact to those evolved during the 

 eruptions of Mount Pelee and Santorin; the N is accom- 

 panied by Ar. Suess has pointed out that in the case of 

 gaseous emanations the evolution of chlorine comes to an 

 end first, and that the OO a continues its escape longest. 

 Water in the form of vapour would be driven out of rocks 



1 A. G-autier, Genesis of Thermal Waters, Econ. Geology Vol. 1, p. 688, 

 1906. 



