74 
The Queensland Naturalist. 
July, 1927* 
Tlie next formation in order of age is the extensive 
Bundanba Sandstone. This is the rock constituting* the 
country (excepting of course alluvial flats), which we 
travelled over from Logan Village to Canungra, and 
which forms the ridge between that township and the 
Coomera. It was also noted for some miles up the Coom- 
era Valley on our way to the National Park. The Bun- 
danba Sandstone is the middle of the three stages into 
which the formerly named “Trias-Jura” is divided. The 
uppermost of the three stages, the Walloon coal measures, 
occurs in the neighbourhood of Beaudesert and is now re- 
garded as of Jurassic age, while the lowermost or Ipswich 
coal measures (regarded as Triassic) occur near Logan 
Village, and outcrop in a narrowing strip running south- 
ward along the schist boundary until that boundary is 
covered by the basalt, of the north end of Tambourine 
Mountain. 
One object to be investigated at Canungra was 
whether the Ipswich measures come to light again to 
the South of Tambourine, or whether the Bundanba 
there rest directly on the schist. It was found that this 
relationship is obscured by volcanic rocks, at least on the 
route which we took. Of these there are two main types, 
the light-coloured rhyolitic or “acid” lavas (here the 
older of the two types) and the basaltic lavas which are 
dark in colour, chemically “basic” and decompose into 
the rich soils popularly known as “volcanic.” 
These basalts and allied rocks form- a capping to all 
the righer mountains in the vicinity — Tambourine, Beech- 
mont. Canungra, and so on to the Roberts Plateau. 
The rocky bar across the Coomera at the camp, and 
the rough, rocky gorge for at least a mile down stream 
therefrom are formed of or in the rhyolite, which extends 
also to the eastwards as far as the boundary of the 
schist. It was also noticed for a considerable way no 
the Beech mont road to the east of the Coomera crossing. 
The occurrence of the rhyolite in the bed of the 
Coomera, at a much lower elevation than the sandstone 
of the ridge between the Coomera and the Canungra, and 
which is directly overlain by the basalt of Tambourine, 
suggest a different relationship and requires further in- 
vestigation. Its occurrence on the boundary of schist and 
mesozoic sediments, is somewhat like that of the Bris- 
bane Tnff, which lies -at the base of the Ipswich. Iti is 
however usually regarded, like the basalt, as being of Ter- 
