188 E. LOGAN JACK^ LL.D., F.G.S., ETC., ON 



basins," and the break gives rise to leakage either on land or 

 beneath the sea. 



Speaking of the Tertiary beds of the Llano Estocado, 

 north of the Canadian River, Mr. Maitland says the leakage 

 due to the broken rim of the basin supplies many of the 

 rivers flowing from the Great Plains, Of the Gulf and 

 Atlantic border regions the same author says : — " No dis- 

 charge is witnessed from the water-bearing portions of the 

 strata which crop out beneath the sea ; but that such must 

 be the case may be inferred from the fact that the pressure 

 on the coastal deep wells is not nearly so great as it ought 

 to be were the water confined in a sealed basin. The 

 hydrostatic pressure of the body of water stored in the inland 

 portion of the strata has a tendency to force the fresh water 

 outwards, and thus to cause a permanent seaward flow. The 

 water flows with a velocity due to the difference of level, the 

 intake and the level of discharge, less the frictional resistance 

 of the rock through which it flows." 



8. Theoretical Form of an Artesian Basin. — In the case of 

 a perfect artesian basin, with a rim of permeable strata of 

 equal altitude all round, and witli the necessary impermeable 

 stratum above it — a condition of things which must be 

 rare in Nature — the water would rise in a bore to the 

 altitude of the intake or head of pressure. Should the 

 .surface of the ground at the site of the bore be lower than 

 the head of pressure, the water would overflow. It has been 

 found convenient to call " sub-artesian " water which rises in 

 a bore but does not flow over the surface by reason of the 

 site being higher than the head of pressure. 



9. Report on the Extension of the Underground Waters under 

 the Mallee Scrub. — In 1897, on the invitation of the 

 Minister for Mines and Water Supply of Victoria, I joined 

 Mr. James Stirling, Government Geologist, and Mr. E. 

 Checci, Chief Assistant Engineer of Water Supply, in an 

 investigation of the chances of the Queensland artesian 

 water being found under the agricultural area of the 

 Mallee Scrub. The conclusion arrived at was that, after 

 flowing subterraneously southwards into New South Wales, 

 the Queensland water was prevented from reaching the 

 Mallee country by a bar of palaeozoic rooks, and its possible 

 outlet to the ocean was narroAved down to that part of the 

 southern coast-line between the 124th and 1.34th meridians 

 t)i each longitude. Mr. Checci took infinite pains iu con- 

 structing a model showing, by means of wires planted on a 



