president's address. 21 



Pacific. The plain on which they rise is here claimed to be 

 a relic of the old Tertiary peneplain of east Australia. As a 

 geological monument a peneplain might be reasonably ex- 

 pected to outlast a mountain range, since it is safest from 

 denudation. 



Dr. R. L. Jack writes: "The divide between the waters 

 falling into the Gulf of Carpentaria and others which flow to 

 the south was quite imperceptible." And again, "The ex- 

 treme horizontality of the surface is due to the fact that tlie 

 almost horizontal beds of the 'desert sandstone' formation 

 cover the district without interruption."* 



Mr. E. C. Andrews, who has paid special consideration to 

 the Tertiary peneplain, has kindly given me the following 

 expression of his views: — "A short time ago, geologically 

 speaking, no mountains existed along the whole eastern side 

 of Australia. At that time a gently rolling plain dotted 

 with moderately sized hills stretched from New Guinea to 

 Tasmania. Then enormous deluges of lava covered much 

 of this great plain of Eastern Australia. Afterwards came 

 a revolution in the appearance of the plain. The earth was 

 slowly forced up until it could no longer bear the strain and 

 finally broke along a hundred lines running in north and 

 south directions. Thus some blocks were forced high up to 

 make mountain masses like Kosciusko, while others fell down 

 alongside them for thousands of feet in terrace form, such as 

 the Snowy Valley under Kosciusko at Jindabyne. Never- 

 theless, so slowly was this uplift carried out that many rivers 

 were not even turned out of their ways by the formation 

 thus of the mountains against their courses, but they actii- 

 ally cut their way down into the mountains as fast as the 

 land rose against them. The Lower Plawkesbury is an 

 example of such action." 



The whole course of the Fitzroy and Burdekin is excep- 

 tional, showing the characters of age in infancy and the 



* R. L. Jack, Queensland Parliamentary Papers, Report Transcontinental 

 Railway, 188'2, p. 16 ; and Coal Discoveries on the Flinders, 1888, pi. 



