BY H. I. JENSEN. 101 



the same character as that usually occurring in the district, inter- 

 bedded with carbonaceous shale. This occurrence seems to 

 indicate volcanic action contemporaneously with the deposition 

 of these beds in late Trias-Jura or Cretaceous time. 



(2) The trachytes and comendites were later, a period of greater 

 erosion intervening, so that at Coolum the comendite, a volcanic 

 rock, almost overlies a mass of hypabyssal porpbyrite exposed by 

 the denudation. The Coolum rock envelopes at Mr. Story's well 

 a mass of porphyrite. 



The stratified nature of many of the tuffs and breccias in the 

 Maroochy district shows that this area was a lake or sea-bottom 

 during the first andesite and trachy-rhyolite eruptions. In the 

 Glass House Mountain district the volcanoes were probably near 

 the sea, but not submarine. Very considerable oscillations took 

 place between the andesite and trachy-rhyolite eruptions in the 

 Maroochy district, in the shape of uplifts caused by the earlier 

 intrusions, and faulting relowering parts in the district of 

 greatest activity. 



(3) Eruptions of dacite and andesite followed those of trachy- 

 rhyolite, comendite, &c. Great quantities of tuff and breccia 

 were ejected. 



(4) Later, in Miocene or Pliocene time, the basalts were 

 extruded. 



Unfortunately, I have not been able to obtain any definite 

 fossil evidence of the age of these rocks. Probably the trachytes, 

 rhyoliteSj dacites, and late andesites were all early Tertiary. 



Highly altered andesites of Palaeozoic age occur in the 

 Kin-Kin phyllites. 



(/') Folding and Faultily. — (a). Folding: Suess, in "Das 

 Antlitz der Erde," remarks that the folded chains of the Australian 

 continent form part of a mountain system characterised by certain 

 distinctive features. They are all directed north and south, or 

 disposed in a manner such that, in deviating slightly from the 

 meridian direction, as in the north of Queensland, they form a 

 light curve convex to the east. The folding, according to Suess, 

 antedates the Carboniferous, and in Queensland it probably took 



