102 VOLCANIC AKKA OP EAST MORETON, ETC., DISTRICTS, Q., 



place before the Culm. The folding force, he thinks, came from 

 the west, and the very old Palaeozoic sediments were folded 

 towards the ocean, where a continental massive existed until late 

 geological times. 



A glance at the map of Queensland shows the justifiability of 

 these arguments. 



The D'Aguilar and Blackall Ranges have the usual meridional 

 direction of Australian mountain chains. They are largely 

 composed of Triassic sediments and volcanic rocks; they are 

 moulded upon an older range of Palaeozoic rocks to the westward 

 which conformed to the theory of Suess. The axis of folding of 

 the old metamorphic rocks ran S.S.E.-N.N.W., most of the dips 

 being E.N.E. and W.S. W. The great earth-movements producing 

 it were probably accompanied, or shortly followed, by the 

 intrusions of granitic rocks of Carboniferous or Permian age. 



The result of these processes was an elevation, in early 

 Mesozoic times, of an area which became in part resubmerged in 

 later Mesozoic times (Trias-Jura), though a great part, including 

 the Woodford peneplain, and terminating southwards in Mt. 

 Mee, remained as a peninsula jutting into the Trias- Jura sea. 



That the Woodford peneplain, the Conandale Range, and 

 Yabba country continued during this time as dry land, seems 

 sufficiently proved (a) by no Triassic sediments having been noted 

 over this area; (b) by the existence of porphyries and rhyolites 

 resting directly on granitic and metamorphic rocks; and (c) by 

 the fact that the Trias-Jura sandstones of the Moreton district 

 are very felspathic in places, and seem to have been largely 

 derived from the denudation of the granitic rocks in the back 

 country. 



The formation of the Blackall Range and the northern portion 

 of the D'Aguilar Range appears to have been due to an expansion 

 and uplift, accompanied by volcanic eruptions in Cretaceous and 

 early Tertiary times, and a folding movement by which the 

 newly formed Trias-Jura sediments were pushed up against the 

 existing Palaeozoic massive, giving rise to a monocline. In this 

 way the easterly (S.E. and N.E.) dips of the sandstones of the 



