X. 
ABSTRACT OF PROCEEDINGS. 
A symposium on “The Atherton Tableland’ ’ was held. Mr. A. K. 
Denmead discussed the geology of the district. He stated that the 
Atherton Tableland, with an area of some 300,000 acres and an altitude 
of 1,500 to 2,500 feet, is a region of undulating country with volcanic 
hills rising 600 feet above the general level. Its origin is thought to be 
due to a vertical uplift (the Kosciusco Uplift) at the close of the Tertiary 
period, the surface having previously been reduced to a state of pene- 
plantation. The scarps at the eastern edge of the Tableland are believed 
to be due to faulting. The geological formations of the Tableland are 
(1) The Barron River Series, comprising strongly folded schists, slates 
and greywackes of probably pre-Silurian age. (2) Granite and associated 
dykes which are intrusive into the Barron River schists. (3) A thin 
lacustrine deposit consisting of silt, sandstone and gravel. (4) A roughly 
horizontal basalt sheet overlying (3), and (5) volcanic cinders which 
occur in the vicinity of craters. This phase of volcanic activity is con- 
sidered to be of quite recent date. Some of the craters are filled with 
water and are known as the Crater Lakes, such as Lake Barrine. Gold, 
tin, and ores of tungsten occur in lode in the Barron River schists and 
in the granite, while alluvial deposits containing gold and tin are found 
in existing watercourses and in the lacustrine deposits that underlie the 
basalt. 
Mr. S. T. Blake, in discussing the botany of the district, said that 
on the relatively small iarea of the Atherton Tableland there is to be 
found quite a range of climate, soils, and vegetation-types. The rainfall 
varies from a yearly average of 35 inches falling almost entirely in 
summer to an average of about 150 inches without any pronounced dry 
season. Although situated between approximately 17 degrees and 17£ 
degrees south latitude, frosts occur in some of the areas which have been 
cleared of timber. For the most part the soils are either podsol or red 
loams or modifications thereof. Open forests are found on areas where 
the rainfall is about 35-50 inches and where there is a pronounced dry 
season. The forests are dominated by Myrtaceae, chiefly Eumlpytus spp. 
with abundant grass on the ground. In the drier parts the trees 
rarely exceed 30 feet in height, are rather widely spaced, and are often 
crooked with open crowns. Several small, often partly deciduous trees 
are associated. The grasses tend to be tall, Heteropogon triticeus attain- 
ing 8-10 feet when in flower. Communities of Melaleuca spp. replace 
the eucalypts on sandy ill-drained soil; the associated grasses are lower 
and more frequently annual. In the wetter parts the forest is much 
denser and taller and the grasses rather lower with broader leaves; the 
floristic composition is different. Herbaceous plants other than grasses 
and underscrubs occur in all types. Rain-forests at one time covered 
large continuous areas, but to-day they are rather fragmentary. They 
occupied areas with a yearly average rainfall of about 60 inches and 
upwards, usually without a pronounced dry season. These rain-forests 
have the usual characteristics of such communities. They attain a height 
of 90-100 feet and are higher than the lowland forests and have, on the 
whole, larger leaves than extra-tropical communities. The young foliage 
is often brightly coloured. One peculiarity is the tendency shown by 
some trees and shrubs to produce aerial roots from the trunks and by 
the latter from the branches. These forests have a number of species not 
known elsewhere, but there are also to be found many widely distributed 
plants. Many valuable cabinet timbers are cut from the area. Large 
areas have been denuded of forest to make way for artificial pasture and 
v he cultivation of crops. 
