PROBLEM OF THE GREAT AUSTRALIAN ARTESIAN BASIN. 183 



margin of the Basin cannot be doubted, for Jack has given 

 a list of large water-courses in Queensland that lose water 

 rapidly in their channels — to this Gregory's criticism no 

 longer applies, as the strata over which they flow are 

 probably all Jurassic and not Cretaceous — , Gibb Maitland 

 has cited the Cambridge River, a tributary of the Flinders 

 (I. §§ 116-8), while there is also the section of the Mac- 

 quarie just below Dubbo. 



Altogether, recollecting that the mean annual rainfall 

 on the Maiu Dividing Range ranges from 22 to 30 inches 

 along its length, there should be no reluctance in acknow- 

 ledging the correctness of the view generally held, that 

 meteoric water must be making its way at the present 

 time below the Rolling Downs Series and thus feeding the 

 reservoir. 



(2) Transmission of Water. — Pittman having admitted 

 Gregory's contention that the Blythesdale Braystones will 

 not be porous enough to transmit large enough volumes of 

 water underground, it now remains to submit the Jurassic 

 sandstones to a critical examination as to their capabilities 

 in this direction. 



Pittman's determination of their average porosity as 

 equalling 25% may even be accepted without demur, with 

 the proviso that some of the sandstones of the lower zones 

 in the east are not unlikely to be a good deal more compact. 

 In view of the fact, however, that the water-bearing beds 

 are in depth often very friable and in the state termed 

 "sand rock," the higher figure of 30% has been adopted in 

 the following calculations, as to the rate at which water 

 will be transmitted under definite heads. 



Through the kindness of Messrs. B. Dunstan, L.K.Ward 

 and R. F. Jenkins, I have been enabled to examine hand- 

 specimens of typical intake sandstones as well as drillings 

 from a number of bores iu each of the States. 



