108 VOLCANIC ROCKS OF SOUTH-EASTERN QUEENSLAND 



this paper many of the views put forward by previous 

 w^riters as to the extent and age of the volcanic rocks, a 

 resume of the conclusions drawn by the several investigators- 

 is desirable. 



A. C. Gregory, in 1875 and 1879, referred the basaltic 

 rocks in this area to a very recent date in the Tertiary era. 

 W. H. Rands, in 1887 and 1889, placed the Brisbane tuffs 

 at the base of the Trias-Jura : the Woodhill trachyte as 

 contemporaneous with what are now called the Walloon 

 or uppermost Trias- Jura measures; and the Tamborine 

 Plateau and MacPherson's Range basalts and andesites as 

 older than the Desert Sandstone (Upper Cretaceous). 

 Rands regarded a certain deposit at the head of the Nerang 

 River as being of Desert Sandstone age, but this, as shown 

 further on, the author believes to be really rhyolitic pyro- 

 clastic material which has been found extensively developed 

 in that area, and resting usually upon underlying basalt 

 flows. In ]902. Dr. Jack was of the opinion that the 

 basalts of the ]\Iain Range at Toowoomba, and also the 

 Ipswich basalt, were contemporaneous with the Trias-Jura 

 rocks in each of these places, but that the basalts at Clifton 

 on the Darling Downs were j^ounger than the Trias- Jura. 



In 1898, S. B. J. Skertchly referred to the Toowoomba 

 basalts as Tertiary in age. H. I. Jensen, in several papers 

 in the Proceedings of the Linnean Society of New South 

 Wales and elsewhere during the period 1906-1909, dealt 

 fully with the alkaline rocks of the Glass House Mountains, 

 and the ]\Iount Flinders-Fassifern areas. He showed that 

 the alkaline trachytes &c.. intruded the Upper Trias-Jura, 

 and, on account of their similarity with the Warrumbungle 

 rocks, he set the Queensland rocks down as early Tertiary 

 — Eocene or Lower Miocene. He also considered the South 

 Queensland basalts Pliocene in age. 



E. C. Andrews, in 1903, set down the ( ?) trachytes 

 and basalts of MacPherson's Range district as Trias- Jura 

 in age, but he has subsec|uently withdrawn this, and is. 

 now inclined to view them as Tertiary in age. 



Wearne and Woolnough,"^ in 1911, described the 

 occurrence of the rhyolites, trachytes, andesites and basalts- 



= Proc. Eoy. Soc, N.S.W., xlv., p. 137. 



