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PETROGRAPHICAL NOTES ON SOME SOUTH AUSTRALIAN 
QUARTZITES, SANDSTONES, AND RELATED Rocks. 
Ву W. 3. WoorwoucH, D.Sc., F.G.S. 
[Read October 4, 1904.] 
PLates XXXIIT. акр XXXIV. 
When this paper was undertaken it was intended that it 
should be the frst of a series dealing with the petrography of 
South Australia. As South Australia is remarkable for the 
comparative scarcity of its eruptive rocks, I began with those 
of sedimentary origin. I examined the arenaceous rocks 
first, as being of simplest mineral composition, and there- 
fore most likely to retain their original characters in regions 
where metamorphie forces have been active. My removal 
from the State renders it impossible for me to complete the 
scheme outlined above, and I bring forward these isolated 
observations in the hope that they may stimulate some other 
observer to carry out what promises to be an extremely in- 
teresting and very valuable piece of research. 
A detailed and systematic investigation of the microscopi- 
cal petrography of the sedimentary rocks of South Australia 
is rendered absolutely necessary for the purpose of strati- 
graphical correlation, by the paucity of fossils in the Paleo- 
zoic, and probable absence of them from the pre-Cambrian, 
rocks. 
Quartzites and sandstones from upwards of fifty different 
localities have been examined, and thirty-eight of the types 
are briefly described in the following pages. More attention 
has been paid to the microscopic than to the macroscopic 
characters. 
One of the most important horizons of arenaceous rocks 
is the immensely thick series of quartzites, sandstones, and 
phyllitie slates which underlies the Cambrian glacial bed in 
the type district of the Sturt River, and which forms the 
whole of the western portion of the Mount Lofty Ranges in 
the immediate neighbourhood of Adelaide. "There are pro- 
bably several bands о? quartzite in this series with almost 
identical lithological features. In absence of a very detailed 
outcrop map of this intensely folded and faulted region it is 
impossible to correlate the various outerops at present. 
Specimens from different parts of the district differ very 
considerably in texture and general appearance, but all agree 
in certain well-defined characteristics. 
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