312 W. J. CLUNIES ROSS. 
went to after passing Mount Pleasant. For some distance down 
the Macquarie there are no indications of basalt, but at Rock 
Forest, about six or eight miles below the Mount, there are some 
basalt-capped hills, where attempts are now being made to test 
the underlying drifts for gold. Not being able to visit the locality 
personally, I am indebted to Mr. J. J. Sullivan, of Rock Forest, 
for specimens. The rock is very compact and fine grained ; under 
the microscope it somewhat resembles the Mount Pleasant rock. 
I obtained 52-5 per cent. of silica, and found the specific gravity 
to be 2°65. 
For comparison with our western rocks, a section of Kiama 
basalt may be interesting, and one is exhibited. An analysis 
gave, silica 56-2; alumina 16-5; ferric oxide 12:5; lime 7:28; 
magnesia 4:68. It is evidently a much weathered rock, but — 
microliths and larger crystals of felspar are visible. 
SUMMARY. 
It has been shewn that the basalts of the Bald Hills are similar 
in microscopic and chemical character wherever obtained ; speci- 
mens having been tested from places three miles apart, and at 
heights ranging from five to seven hundred feet above Bathurst. 
The detached outlier of Mount Apsley is found to differ consider- 
ably in microscopic characters, but to be similar in chemical 
composition. The difference may be due to different rates, OF 
varying conditions, of cooling. At Apsley it may have filled a 
deep pool in the river, any lava which followed having passed over 
it. The Mount Pleasant basalt is rather richer in silica and of 
lower specific gravity. Lower down the Macquarie there is 
another exposure of basalt at Rock Forest. It is of similar 
character and probably belongs to the same flow as the Mount 
Pleasant rock. The attempt to prove the existence of several 
distinct flows of lava has, so far, not been successful. 
As a result of testing basalts from neighbouring districts, it has 
been proved that the Orange basalt has a higher percentage of 
silica than the Bathurst rocks, although it shews a curious 
similarity in microscopic structure to the Apsley basalt. The 
