A VISIT TO THE NORTHERN GOLD FIELDS.
FROM OUR SPECIAL REPORTER.
No. 19.
The more a practical observer examines the country surrounding the scene of mining operations at the
head of the Uralla, the stronger will be his conviction that, instead of being exhausted, that gold-field
has been as yet but partially developed. Range succeeds range, stretching to the southward and westward
all presenting the same metalliferous indications, the same trappean overflow covering or isolating the
ancient sedimentary formations, which are more or less metamorphosed by the contact; and the same
upheavals of granite and syenite, pierced by dykes and veins of greenstone. Hundreds of streams
hitherto unexplored, having their source on the plateau, or near the summits of the mountains,
either follow the course of some natural fissure, or have excavated deep basins or chasms in their
descent to the great rivers.
A stream flowing from a wide morass at the base of a range of heights on the plateau pursues a sluggish
course over the level trappean formations, now loitering in some stagnant pool, then expanding in a marsh
and again collecting its waters in a channel which deepens until the pipeclays and drifts are penetrated.
If these marine accumulations are auriferous although the sands and gravel may disappear, borne onward by
the floods, much of the gold will remain and may be discovered in the banks, in the alluvial flats,
and in the detritus of the creek. The wealth of such a locality will depend upon the extent of the
area denuded, ledges of rock crossing the watercourse, tributary streams, and the general facilities
afforded for the accumulation of so heavy a metal as gold. As the stream descends and enters the
non-auriferous strata the precious metal will become more and more scarce, and gradually disappear.
A stream of the above description passing in its descent through but a single stratum of auriferous drift,
will be payable in a very limited portion of its course; and for miles both above und below the level
of that stratum, it may not even yield the colour. It will derive its chief value and importance from
the probability of its leading the miner to surfacing and hill sinking, if the drift contains sufficient
gold to re-munerate him for following it under the trappean crust.
A second stream having removed the traps, will denude the wreck of an ancient arenaceous or slate
formation carrying veins and bands of quartz, and reposing upon granite. This patch of the sedimentary
formations may have been isolated. The granite is now eroded; the schists and quartz have been broken up,
and their fragments alone can be detected amidst the shingle on the bed of the creek, but the gold
that they once contained will be discovered buried beneath the detritus, mingled with schorlaceous
black sand and minute gems -- an evidence that the granite has not yet suffered any very considerable
disintegration, as these formations are usually on its surface. As the stream descends, it enters
deeper into the granites, which become more compact; huge blocks may be observed rising on the slopes
of the ranges. The whole surface of the country consists of an unmixed granitic debris, and gold,
schorlaceous black sand, and gems disappear.
A third creek, on leaving the traps, encounters vast masses of quartziferous schist, tilted,
partially transmuted, and mantling round the flanks of an upheaval of granite, one of the many quartz
veins has been auriferous, but an enormous disintegration has taken place, and the stream now
flowing through a deep chasm leaps from ledge to ledge on its precipitous descent, until reaching
the lower levels, it meanders through a broad valley, where the gold, derived from the destroyed reef,
finds a resting place. Here the auriferous alluvium (rich near the falls) becomes poorer and poorer
as it recedes from the spot where the igneous and sedimentary formations come in contact.
There are local conditions, however, such as a succession of streams descending from the summit of
a main range, or the margin of a plateau, into a creek flowing at its base, which act as feeders,
enriching various points and bends below their junction, and continuing the auriferous character
of the stream for a long distance. Such instances of which M'Leod's Creek and the Tooloom are an
example are extremely rare, and where they do exist are much more easily discovered than the solitary
patch in a mountain streamlet, of which no other portion of its channel presents any indication to
the ordinary prospector.
It is therefore evident that the heaviest deposits of alluvial gold exist in very limited portions of
the basins and channels of minor tributaries which, rising on the highest elevations, intersect all
the formations resting upon the granites in their descent to the main rivers; these being for
the most part far below the metalliferous rocks, will be found to contain but a very small quantity
of auriferous drift, only valuable as a guide to the treasures of the mountain streams. The gold
bearing portion of these latter, will be confined to that passing through the auriferous formations,
and its extent will depend in a great degree upon the rapidity of their fall, or the angle of declination,
with other local conditions already noticed. Above the auriferous rocks these streams are barren,
and below them they soon cease to be ptoductive.
The gold bearing rocks will be found to follow the line of granitic upheavals and igneous eruptions
and fissures, under whatever aspect they may now present themselves, and whatever physical alterations
may have been effected on the surface of the country, in endeavouring to trace them, and studying the
vast areas of denudation now exhibited on the slopes of the main range, the destroyed formations should
be mentally restored, and the probable action of floods, springs, and glaciers taken into consideration.
As a general rule, in districts similar in formation to that of New England, alluvial gold may be reasonably
sought for under two distinct conditions, the first in the neighbourhood of the trappean crust, beneath
which it may have existed as an oceanic accumulation originally set at liberty by breaker action,
the second in the vicinity of masses of transmuted quartziferous schist, a portion of which in
immediate contact with the granites may have been auriferous, from this it has been disengaged by
the process of subaerial disintegration: that a small quantity of gold derived from either of
these sources has become entangled in many modern concretes is highly probable, and we may thus account
to some extent for its universal diffusion in the district, I believe that throughout the wide extent
of New England, there are but few streams falling from the heights of the main range, either to the
eastward or westwatd, that are not auriferous in some portion of their course, however limited it
may be, and that as our miners become more conversant with the physical features of the country,
and acquire a greater degree of scientific information, these rich deposits will be brought to light.
Prospecting for minerals in the wilds of an unexplored mountain region, under the most favourable
circumstances is attended by a degree of exposure, privation, and labour, that few can appreciate,
and which a still smaller number of persons have been found willing to endure for any lengthened period.
It is universally conceded by those entitled to form an opinion on the subject, that some slight
knowledge of the geology and mineralogy of the country would facilitate this pursuit, save the prospector
much unprofitable labour, and probably guide him to the object of his search. And yet, important as
the labours of the gold miner have become to all classes of the community, we have done nothing to
lighten his labour or promote his professional improvement. We seem to entertain the highest respect
for his gold, but despise the man himself, and send him forth a Pariah into the wilderness without maps,
official reports, or anything to guide him to success. As an indication of the feeling in Sydney on
this subject, I would simply inquire how it is that no geological class has been instituted in the School
of Arts? How is it that a set of geological works are not to be found in the library of that
institution? How is it that no mining journals are to be found in the reading room, while space
can be found for a pile of American trash only fit for pipelights? Ihey manage these matters better
in Melbourne.