122 THE VICTORIAN NATURALIST. 
perfectly upright, and extend in unbroken columns as far as the 
depth of the excavation allows them to be seen. This is only 
about eight feet, but they probably remain entire for a long way 
down. ‘They are so loosely held together as to be easily separated, 
and by means of a pointed bar of iron, I was able at a recent 
visit to obtain some beautiful specimens, a few of which have 
been sent to the Technological Museum, Melbourne. 
Cropping out on the top of the same hill are basaltic rocks, 
showing no prismatic fornis, but as they have never been quarried, 
no opportunity is afforded of examining them deeper down. Not 
very far away, however, ina dome-shaped volcanic hill a quarry 
exists, and there the lava is roughly prismatic. 
Whether the basalt of the Koolomert hill is prismatic or pot, 
at a greater depth, the volcanic outflow has certainly induced 
that structure upon the neighbouring sandstone to an eminent 
degree. 
In the heart of the Victoria Valley, between the Serra and 
Victoria Ranges, is a considerable body of porous, amygdaloidal 
lava, but no crater is discernible from which it has flowed, the 
country being perfectly flat. 
On the east and south of the Serra, basalt comes close up to 
the base of the ranges, the only separation being the River Wannon, 
which for miles of its course has basalt on its left bank and sand- 
stone on its right. The assertion has been made by some that 
the basalt crosses the Wannen from the north, near Dunkeld, 
proceeding from a hill lying between Mounts Abrupt and Sturgeon, 
but this is entirely wrong, that hill known locally as the “ Picaninny 
Mountain” being wholly composed of sandstone. ‘The source of 
the veleanie rocks in the neighbourhood of Dunkeld, is doubtless 
Mt. cane an extinct volcano eighteen miles to the south. 
Along the flank of the Dundas Range, and im the synelinal 
valley of Victoria and Dundas, is a remarkable outcrop of felsite 
porphyry. It is first seen 2bout twelve miles south from Balmoral, 
and extends in a generally south direction as far as the Grange 
Creek, near its junction with the Wannon, more than twenty miles, 
It is, of course, not visible for the whole of the distance, but may 
be easily traced by its occasional appearance on the suriace. 
At Nigretta, the passage of the River Wannon over the porphyry 
has formed a splendid waterfall, one of the most picturesque sights 
of the western district. 
The rock presents the same appearance wherever seen, allowing 
for slight differences in the oxidation of the small amount of iron 
contained in it, and for the greater or less weathering it has 
experienced. In a felsitic base, are scattered macroscopie erystals of 
quartz and orthoclase felspar, the quartz in well marked hexagonal 
forms, and the felspar in long stoutish prisms. It is not connected 
