36 
The Queensland Naturalist. 
August, 1934. 
fore, have started its career above the present Mt. 
Edwards, which must have been entirely covered by some 
later formation. Subsequent denudation exposed the re- 
sistant trachyte, down through which the creek has suc- 
ceeded in cutting its gorge, much as a saw cuts in its 
groove. 
The only later rocks which we know of that could 
have covered the trachyte mass are the basaltic flows, and 
these in portions of the Main Range do cover trachytic 
material. It seems highly probable that these basalt flows 
of the Main Range and Darling Downs formerly covered 
also the Fassifern district, and that the streams were first 
formed on their surface. The comparative shortness of 
the east-flowing streams has enabled them to grade down 
their valleys to the softer rocks below the basalt, and thus 
lead to the great difference in levels on the two sides of 
the main Divide. Many writers have attributed this 
difference to a block faulting, but denudation is the 
simpler explanation. 
Mt. Edwards thus forms the key to the physiographic 
problem, and supports Mr. J. H. Reid, who pointed out on 
structural grounds that the fault theory was inconsistent 
with the geological mapping. 
BOTANY, MOUNT EDWARDS AND DISTRICT. 
(A) GENERAL. 
By C. T. WHITE , Government Botanist . 
The camp was pitched in open forest country border- 
ing on Reynolds Creek. The surrounding country was 
timbered mainly by Eucalypts of different species, notably 
E. tessellaris — Moreton Bay Ash, E. creba — Narrow-leaved 
Ironbark, E. mierocorys — Tallow-wood, and E. acmeni- 
oides var. carnea — the Yellow Stringy -bark. On the rocky 
slopes of Little Mount Edwards, E. exserta in dwarfed 
trees was very common. As undergrowth Leptospermum 
microcarpum formed dense thickets. On the flats Ango- 
phera subvelutina — Apple Tree — was abundant. 
Along the banks of Reynolds Creek typical trees 
were Callistemon viminalis — Red Bottle-brush, Melaleuca 
bracteata — River Tea-tree, Oasuarina Cunninghamiana- 
River Oak, Acacia decurrens var. pauciglandulosa in full 
flower, Acacia Maidenii and Notelaea longifolia var. 
velutina (only a few’ trees seen). 
In the rain forest clothing the slopes of Mount Ed- 
wards Gorge, the commonest tree w r as the Hoop Pine- 
Araucaria Cunninghamii. Further up towards the moun- 
tain the rain forest again gave w r ay to open forest, and on 
