BASALTS OF BATHURST AND NEIGHBOURING DISTRICTS. 309 
system. The water parting between the Belubula and the 
Macquarie appears to be near King’s Plains, north-east of Blay- 
ney. The country is considerably higher than Bathurst, Blayney 
being 2,840 feet above sea, but there does not seem to be any 
evidence that the Bathurst basalts are related to the Blayney- 
Carcoar series, 
Near Orange igneous rocks are extensively developed. The 
Canoblas hills appear to be almost wholly volcanic and the 
summit of the Pinnacle is a coarse grained, apparently plutonic 
rock but so much altered by weathering that it was useless to 
have a section cut from specimens which I collected. Near the 
foot of the hills there is plenty of tolerably fresh columnar basalt. 
The Rev. J. M. Curran has numerous slices of Orange basalt, which 
are so much like mine, that there can be no doubt that they are 
practically the same rock. I find it microscopically to bea coarse- 
grained rock largely made up of felspar, with augite and a little 
olivine. There is not much magnetite, but the section (5) and 
microphotograph shew a very perfect octahedron of that mineral 
in the very centre of a crystal of augite. The rock appears to be 
rather of the ophitic type, and, as already mentioned, it resembles 
the Mount Apsley rock in microscopic characters. Examined 
chemically, however, there is a marked difference. The silica 
obtained ranged from 55:75 to 56 per cent., alumina about 15 
per cent., ferric oxide 10-1 per cent., magnesia 7°) per cent., 
lime 7-3 per cent. Specific gravity 2°74. 
Tt is evident that this differs considerably from any of the 
Bathurst basalts, and macroscopically, in hand specimens, it has 
also a distinct character. The country around Orange is much 
higher than Bathurst, O ge itself being 2,844 feet al -level 
Pinnacle, Canoblas, by aneroid, is 1,150 feet above Orange. The 
hydrography of the district would have to be very different from 
What it is now, however, to allow of lava flowing down a river 
channel from Orange to Bathurst. On all grounds, therefore, it 
1s unlikely that our basalt was derived from Orange. 
Lastly, we come to the Swatchfield area. I have not examined 
this district personally, but the late Mr. C. 8. Wilkinson compiled 
