BY H. I. JENSEN, D.SC. 195 



Gregory's view receives considerable support from 

 the folloA^'ing facts : — 



(1) Springs are rare in the artesian area, but abundant 

 outside this area. They frequently occur on the summits 

 of high mountains, Avhere the catchment area is insufficient 

 to account for their permanent flow. [29] 



(2) The water bearing beds of the Artesian area are 

 often sand and boulder di^ifts, and not sandstone : they 

 frequently seem to be mere lenticular patches. 



(3) Very pervious rocks like the Blythesdale Braystone 

 are rarely met Avith. 



(4) Artesian Water is generally hottest and purest 

 when tapped from the lower strata : while the water with 

 most solid matter in solution comes from the upper strata. 



If the meteoric theory is right, we should expect 

 the water to become more and more impure the farther 

 it is from the intake, and the shallow bore waters should 

 be the freshest. The reverse happens to be the general 

 rule. On the Plutonic theory, the superficial beds contain 

 water which has travelled much further through assimilable 

 sediments, and should therefore be most saline. Experi- 

 ence shows this to be the case. 



Probably each of these two rival theories is true for 

 some places. While recognising the meteoric theory as 

 affording a correct explanation for some cases, the writer 

 firmly believes that the plutonic theory must account for 

 the origin of many bore waters. 



Proof of a conclusive nature will not be possible until 

 a systematic survey is made of the artesian basin, including 

 chemical and physical investigation of the waters at different 

 depths. 



It would be well to state here that whether the meteoric 

 or plutonic theory be found to be true for the greater part 

 of our artesian basin, there is little danger of speedy 

 exhaustion of the water supplies. It is true that bores 

 have frequently ceased to flow, but in every case the cause 

 has been either (1) corrosion of the casing allowing the 

 water to escape into dry sandbeds ; or (2) the scouring of 

 a water channel between the casing and the walls of the 

 borehole, allowing similar escape of the water. Sometimes 

 the latter cause of stoppage has been aided by tinkering 

 with the bore, t.g., by temporarily shutting the bore. 



