BY A. B. WALKOM. 5^ 



meteoric origin, and that the belt of Lower Mesozoic rocks ex- 

 tending, probably without interruption, from near Dubbo in New 

 South Wales, to the Cape York Peninsula, forms the intake-beds 

 of the Great Australian Artesian Basin. Probably also a small 

 percentage of the water is of plutonic origin. It is also now 

 generally agreed among Australian geologists that, in the Great 

 Australian Artesian Basin, the rocks, from which all the large 

 flows of water are obtained, are of Lower Mesozoic age, under- 

 lying the Marine Cretaceous (Rolling Downs) Series. 



An examination of the bore-records shows conclusively that 

 the sandstones of the Walloon Series in Queensland, and the 

 Artesian Series in New South Wales, extend continuously in a 

 westerly and south-westerly direction into the north-eastern por- 

 tion of South Australia. The depths at which the sandstone is 

 found vary, but, in genei al, the deepest occurrences are in the 

 north-eastern corner of South Australia, not far from the Queens- 

 land border. 



It must be noted here, that, near the border between Queens- 

 land and New South Wales, in the vicinity of Hungerford, there 

 are patches of granite at the surface, and also that some of the 

 bores in that vicinity have struck granite at comparatively 

 shallow depths There is here, then, indication of an island in 

 Lower Mesozoic time. 



In the north-east of South Austialia, where the Lower Meso- 

 zoic sandstones are at great depths, it seems probable that the 

 strata above them include Cainozoic, Cretaceous freshwater-beds 

 (equivalent to the Winton Series of Western Queensland), and 

 Cretaceous marine beds (Rolling Downs Series). This is in- 

 ferred from a comparison with conditions in parts of Queensland; 

 in the great majority of bores, unfortunately, the records kept 

 are of little value for detailed geological purposes. In the case 

 of the Patchawarra Ijore in South Australia, which was aban- 

 doned at 5,458 feet without reaching the water-bearing strata, 

 it appears that the bore, when abandoned, was still in the Cre- 

 taceous rocks, and there is nothing to indicate that the Artesian 

 Series of sandstones does not exist further down. I am in- 

 debted to Mr. L. Keith AVard, Governnient Geologist of South 



