48 T. W. E. DAVID. 



region, lying between 104- 128 miles east of Brisbane are 

 probably of recent origin. These have been referred to by 

 C. Hedley, 1 and are shown on the accompanying fig. 9. 



Fig. 9 

 N.W S.E. 



Submarine 

 Silurian Great artesian Basin Main VolcanicPwsks 



Clonciirry Winton Longreach BlackaH .,„.,, '"^dSSUS^? PostTerhary' 



■\ „„.,_„: «- 1. o.„.. ..„ lu ,J^ a JL^. an .J and?tones ^salt Brisbane .*thom 



Marine '■ Cretaceous Strata on Marine Cretaceous 



Level iZO 



Granite-Granite- faults- 



The highest of these mountains is about 14,000 feet in 

 height, at Lat. 28° 42' 2", Long. 155° 37' E. As far as can 

 be judged from the soundings these submarine volcanoes 

 have a general N. by W. to N.W. trend. 



As regards unit (2) the Queensland portion of the Great 

 Artesian basin, little need be said from a tectonic point of 

 view, except that the basin represents an area which was 

 partly covered by great warp lakes in Trias-Jura time, and 

 wholly covered by sea in Cretaceous time. The basin was 

 deepest near its centre just over the border of South Aus- 

 tralia from Queensland. There the sediments of Cretaceous 

 and perhaps Trias- Jura age in part are a mile in thickness. 

 Between Cloncurry and Hughenden (J. B. Henderson) 2 a 

 large sill of Palaeozoic rocks, rising to within about 1,000 

 feet of the surface of the ground, forms a partial subter- 

 raneous barrier to the Artesian basin. It trends in an E. 

 to W, direction. The north-westward flowing tributaries 

 of the Darling, such as the Bogan, Macquarie, Castlereagh, 

 Namoi, GWyder in New South Wales formerly entered the 

 south-eastern shore line of this Cretaceous sea by separate 

 mouths. Subsequently, in Eocene time, a broad epeirogenic 

 uplift supervened raiding the whole basin, especially in the 



1 Proc. Linn. Soc. N.S. Wales, Vol. xxxvi.pt. 1, pp. 32, 33. 



2 Hydraulic Engineer's Beport. By authority, Brisbane. 



