The Sun.
London, England, 1853-02-12 00:00:00

GOLD FIELDS OF AUSTRALIA.

At a recent meeting of the Geological Society a paper
was read "On the Gold Fields of Victoria, or Port
Philip, communicated by P. N. Johnson, F.G.5.," from
which it appeared that the " Australian Alps" are a
series of distinct mountain ranges, that pass round the
south-eastern corner of Australia (nearly parallel to the
coast line, and from 50 to 80 miles from the sea), and
form a part of the main chain of the continent. This
mountain chain, in Victoria, consists of clay slates, mica
slates, and flinty slates, together with granite, in a suc-
cessional arrangement, forming collectively a recurring
series. The strata are nearly or quite vertical, with a
north and south strike, and are intersected by numerous
quartz veins, running at an acute angle with the
slate. Vast plains of trap, forming high table lands,
run up to the base of the mountain, and probably
cover their lower slopes. It is in the valleys and
gullies of these mountains, and not very far from
their junction with the trappean plains, that the rich
deposits of gold are found. Gold has been discovered
at several points along this zone of mountains ; but the
richest deposits opened in the colony of Victoria are
those of Ballarat and Mount Alexander. The former is
about 55 miles N.W. of Geelong • and the latter about
35 miles N.W. of Melbourne. The enormous amount
of gold which the latter district has yielded has chiefly
been derived from two valleys with their gullies and
ravines. These valleys are known by the names of the
streams or " creeks' that run through them. One of
these, Forest Creek, takes its rise in the granite forming
the central mass of Mount Alexander ; the other has its
source in the high and broken ranges of slate that environ
the mount. Both creeks are tributaries of the river
Loddon, on the banks of which, also, gold is found in
small quantities. The Ballarat gold-field lies at the
junction of the slate with a trappean tract about seven
miles from an extinct volcano, known as Mount Benin-
yong. The original matrix of the gold seems to be the
above-mentioned quartz veins that traverse the slate
generally in a north and south direction. The wear-
ing away of the slate rocks and their quartz veins
by the action of the weather and by aqueous agency
have given rise to the auriferous beds of gravel and clay
occupying the beds of the ravines and valleys at the pre-
sent day. Occasionally the gold is found at or near the
surface of the soil, diffused through the gravel ; some-
times it lies as much as thirty feet beneath the surface,
embedded in clay, either immediately upon the rough
rock surface below, or just above a white clay, known
by the miners as " the pipe-clay ;" and it may be met
with in other localities at every intermediate depth. In
some places boulders of quartz and beds of hard concrete
of quartz and slate pebbles occur in the auriferous clays.
These different conditions of the auriferous beds depend
upon the physical characters of the gullies and the valleys
down which the drifted materials have been carried, and
upon the varying force of the water power that at dif-
ferent times and at different places has been brought to
bear upon this shingle, sand, and mud.. Thus in the
creeks the deposits in their channels are richest at points
where the stream has been impeded in its course either
by frequent sinuosities or by being crossed by a bar of
rock ; this holds good with the deserted channel of
streams also. 'When auriferous clays and gravels occur
in the dry gullies descending from the higher ranges, the
richest deposits are always found in the ancient channel
or bed of the gully, often occupying a very narrow area ;
but when these gullies contract at their junction with the
larger valleys, the auriferous clays are often continued
up the sides of the inclosing hills, even to, their crests,
and the distribution of the beds and of the gold is
very variable under these circumstances, as though the
beds had been here deposited by means of strong con-
flicting eddies and currents. It appears that, with regard
to Victoria, the gold has been arrested in the small
mountain ravines and gullies, and was not washed down
to the larger streams. Auriferous sands in river
banks, or in alluvial plans of the low lands, are unknown
in this colony. The methods of working the gold-bear-
ing alluvia, either at the surface or by pits and "holes,"
vary, of course, according to the depth to be attained
and the means at the .command of the miners. The
methods of separating the gold from the gravels and
clays are the same as those used elsewhere in New South
Wales and California.

[Besides the Ballarat and Mount Alexander gold-fields,
" diggings" have been opened at Mount Blackwood, and
on the Moorabool River, near Ballarat ; on the Plenty
and the Yarra Yarra Rivers, N.E. of Melbourne; on the
Mitta Mitta River and Lake Omeo ; in the N.E. part
of the colony, as well as at several points along the
eastern portion of the boundary line between Victoria
and New South Wales.]