PROBLEM OF THE GREAT AUSTRALIAN ARTESIAN BASIN. 147 



on the dip, etc. of the beds, there would seem, as Gregory 

 has contended, to be quite a possibility that some of the 

 rainfall on the Toowoomba Plateau should enter the strata 

 wherever the covering of basalt is absent, and percolate 

 downwards along lenticular sheets of sandstone, and thus 

 make its way down to lower levels on the seaward side of 

 the great escarpment. 



Further to the south in New South Wales, where the 

 Jurassics rest upon Permo-carboniferous and Triassic sand- 

 stones in certain places, it would be possible for some of 

 the artesian water to have been derived from these older 

 formations, more especially as they frequently outcrop on 

 high ground to the east and possess a westerly dip below 

 the Jurassics, e.g., in the Nandewar and Warrumbungle 

 Mountains. The artesian bore in the "coal-measures" at 

 Ballimore near Dubbo is a valuable piece of evidence in 

 this connection. 



The variability in thickness and number of the water- 

 bearing layers, with their accompanying impervious or 

 semi-pervious shaly partings, is considerable (See II. pis. 

 16 — 20, and sections in the Ann. Reports of the Hydraulic 

 Engineer, Q'land), as would only be expected in view of 

 their mode of origin, and this seems to be rather marked 

 on the north-western side of the basin. It might be re- 

 marked that it is just in this quarter, a little south of 

 Oorindi Station on the Oloncurry railway that there is a 

 local rise of potential against the sloping floor of palaeozoic 

 rocks. 



Whether this indicates the proximity of a local intake is 

 not clear, but, if so, this is the sole occurrence giving 

 definite support to the view that water might be con- 

 tributed from meteoric sources along the north-western 

 edge of the basin. 



