148 



ALEX. L. DU TOIT. 



H. Y. L. Brown has suggested, and L. K. Ward is in 

 agreement, that in the area north of Charlotte Waters the 

 sandstones and grits of the Goyder and Finke Rivers may 

 act as intakes. This receives support, firstly from the 

 much greater altitude of the region cited, and secondly 

 from the fact that the waters of this marginal stretch are 

 not of the sodic carbonate type, and thirdly from the obser- 

 vations of R. Lockhart Jack, that the potential surface 

 west of Oodnadatta rises to the west and north. The rain- 

 fall on the other hand is extremely low (4 to 6 inches 

 annually) and the evaporation high, but the precipitation 

 may have been higher in the past (see Section XI). 



That the waters possess greater static pressures as well 

 as temperatures in the lower water-bearing zones, together 

 usually with a lesser salinity, is a truism, and, that the 

 supplies at different levels are in many cases quite inde- 

 pendent of one another, can be proved by the constancy of 

 flow between the double casings when the deeper supply is 

 shut off, e.g., Bando No. 3 and Oongoola East (Offham No. 

 2) in Queensland. 



Symmonds deserves credit for having pointed out the 

 "short-circuiting" effect of slotting the casing opposite 

 water-bearing beds having different pressures, a policy 

 which would and probably does account for the rapid falling 

 off of pressure and yield in such bores. The upper waters 

 being more saline, should, if only for agricultural reasons* 

 be prevented from mixing with the main supply. 



While in many bores there is only one water-bearing 

 stratum of importance, in others several are present, 

 occasionally eight, ten, or even more, but of such cases 

 reported from Queensland, the majority are mostly located 

 near the margin of the basin, or on the shallow ridge sepa- 

 rating the sections A and B. 



