June 1947 The Queensland Natulalist 
43 
NOTES ON THE GEOLOGY OF THE NOOSA DISTRICT 
By DOROTHY HILL 
The t rea between Cooroy and Noosa is of great variety 
geologic-ally, for the Palaeozoic, Mesozoic, Tertiary and 
post-Tertiary eras are all represented by sedimentary or 
igneous rocks. 
Palaeozoic rocks are first met with on the bus route 
from Cooroy to Tewantin. These are biscuit-colon, red 
phyllites — very fissile, glistening rocks, seen in the gutters 
of Cooroy, and for some distance along the road. They 
are fine and even grained, rather monotonously uniform, 
and are believed to be the southerly continuation of the 
Kin Kin phyllites. They are fine sediments which have 
been converted into phyllites by the great heat- and pres- 
sure of metamorphic processes, and they have been folded 
so that their original bedding planes are now at high 
angles to the horizontal. No fossils have ever been found 
in them, but they are thought to have been laid down 
under the sea. According to some geologists these Kin 
Kin phyllites are to be correlated with the older Palaeo- 
zoic Brisbane Schist Series; but others consider them to 
be younger Palaeozoic, equivalent to the barren slates at 
the top of the Permian Gympie Series. To the south of 
the road, these phyllites are intruded by the granodior- 
itie mass of Mt. Cooroy, of unknown age. 
Dark green to black lava flows and ashes, believed 
to be Mesozoic in age, replace these Palaeozoic rocks 
nearly at the road junction about a quarter-mile west of 
the road metal quarry in the property called “Fairview, ” 
on the Cooroy 1-inch military map. These are andesitic, 
and can be examined in this quarry. These relics of 
ancient volcanic activity give place, at the road junction 
at the top of the divide, to a series of brownish sand- 
stones and shales. The sediments have been tilted so 
so that their original bedding planes are now at high angles 
from 10° to 20° to the ENE., but there is a little varia- 
tion in their attitude. In the road cuttings they are seen 
to be intruded by a number of thin sheets of acid, light- 
coloured igneous rocks. Some of them, dykes, were injected 
in the molten state along joint planes ; others, sills, were 
similarly injected along the bedding planes of the sediments. 
Cooling was so rapid in sune of these dykes and sills that 
they show margins of super-cooled glass, where they touch 
