8 
Fig. 8. 
Banded Chert, Mt. Hunt, East Coolgardie Goldfield. 
One very great and iini)orlant ])roblein in connection with our 
Pre-Cambrian or Archaean Rocks i.s their division into series 
which may be correlated from district to district, and during the 
working out of the stratigraphical relationship of these, the pro- 
blem is not really so hopeless as it may at first sight appear. 
It is only by the ap]>lication of stratigraphical methods (using 
this term in the widest scientific sense) to these ancient crystalline 
schists, that a clasvsification quite as satisfactory as that of the 
rocks much higher on the geological column, can be arrived at 
'I'hese crystalline schists have been invaded by huge maSvSes 
atid veins of granite, which occupy some hundreds of square miles 
in parts of the State, d'he intrusion of the granite is perhaps, 
from the economic point of view, the most imiiortant geological 
event at this ])erod, in as much as most of the gold deposits, which 
places Western Australia in the front rank of mining countries in 
the Pritish Ifmpire. hear some genetic relation thereto. 
The mining centre of Tamhourah ( Hhg. h ) in the Pilbara Gold- 
field is one in which the intrusive nature of the granite may be readi- 
ly studied, here the country is very nearly destitute of soil, and the 
rocks lie ready for ins])ection anywhere. At this locality the 
granite may be seen to have wandered through the schists, in addi- 
tion to having engul])hed and lloatcd olf extensive masses along 
its margin. 
These granite rocks constitute composite liatlioliths occupying 
hundreds of square miles, and there seem some geological reasons 
for believing them to have digested and replaced very large masses 
of sediments. When considered in the light of their metaniori)hic 
