GEOLOGY OF THE COOMA DISTRICT, N.S.W. 175 
ferous. These are the Berridale granite, the Myalla Road 
syenite, with accompanying dykes of bostonite, and lastly 
an extensive series of quartz-porphyry intrusions. 
Tertiary and recent rocks are represented by basalts 
which are extensively developed over the area, by deposits 
of diatomaceous earth, of chemically-formed limestone and 
of alluvial. Late Paleeozoic and Mesozoic formations are 
entirely absent. The strike of the sedimentary and meta- 
morphic series is approximately meridional, the mean of 
about fifty compass readings being 347°. 
(a) THE METAMORPHIC SERIES.—The rocks constituting 
this series occupy a considerable area on all sides of Cooma 
excepting the east, as may be seen from the map: to the 
south-west of Cooma they disappear under basalt, so that 
their southerly extension cannot be accurately determined. 
Schists, occurring as inliers amid the basalt, have been 
found 64 miles due south of Cooma, and it is quite possible 
that metamorphic rocks extend much farther south. On 
the north the series has not been traced farther than 
Pearman’s Hill, 9 miles north of Cooma along the Sydney 
Road: there is every reason to believe, however, that they 
extend a great many miles beyond this. 
The Schists.—In the centre parts of the complex the 
schists are well crystallized, but on the east and west they 
pass gradually into phyllites: this is most noticeable on 
the west, where there is, beginning from the western side 
of Dairyman’s Plain, a gradual transition into the Slack’s 
Creek phyllites: on the eastern side the phyllite belt is not 
nearly so broad, and it is interrupted in some places by 
intrusions of gneiss, and in other places concealed by basalt 
flows. It is to be noted that the schists have a much 
wider extent to the west than to the east of a meridional 
line through the main outcrops of the Cooma and the blue 
gneisses. The sedimentary origin of these schists is proved 
