72 
The Queensland Naturalist 
November, 1943 
new areas. Consequently 1 have no new field on which to 
address you, but instead propose an 
“ Excursion in Local Geological History.” 
This contains nothing new, nothing that is not familiar 
to all local geologists, but it may perhaps give a little more 
connected view to those of us who only get disconnected 
glimpses on our field excursions, and may point out the 
great gaps in our knowledge and the many problems for 
which we seek information in the field. 
Prom the geologist’s point of view we in Brisbane are 
very fortunate in having a great variety of structures and 
formations within our reach, even within the city quarried 
sections, show a geological rarity, a fossil land surface. By 
the ordinary citizen our schist areas, though providing 
nice hills for residential purposes, are regarded with dis- 
favour because of the poor and stony soil which gives the 
would-be gardener such a heartache and backache in try- 
ing to make, and such a pride in achieving, a garden. But 
what gardener thinks of these rocks as being ancient sedi- 
ments deposited in a long-ago palaeozoic sea or considers 
that they must have been derived from a land of still older 
rocks? These Brisbane schists are the oldest rocks we 
know of in south-east Queensland. Whence did their 
material come? The sands and muds, mostly fine, may 
have been transported great distances by water currents, 
so the land from which they were derived was not neces- 
sarily very near. Could a study of the schists from a petro- 
logical aspect give any information regarding the place of 
origin or the nature of the land? 
Mr. C. C. Morton has suggested that the Greywackes 
which form part of the schist series and show fresh felspar 
fragments, indicate that the condition of denudation had 
been either frozen or arid. 
The schists vary immensely from what are little alter- 
ed shales and sandstones to quartzites, mica-schists and 
greywackes and include altered igneous rocks. Mr. Den- 
mead regards them as being of three series: — 
1. The Greenstones — altered basic igneous rocks, as 
seen at Petrie and Mt. Mee, and elsewhere. 
2. The Phyllites, such as we have in Brisbane and 
vicinity. 
3. The Greywackes, the dense hardened massive 
sediments such as we see on the eastern side of 
Tamborine Mountain, 
