In carrying out a real prospecting effort it is necessary on each field—
1.
To ascertain as much as possible concerning the nature of the
corrugation of the rock-beds, and their association with the bumpy and
ridgy contours of granite below and in places through them.
2.
To ascertain the relationship of rock layers (particularly of slate) of
each arch and trough of the general corrugation to each other.
3.
To ascertain as much as possible concerning the general cracking in the
rock beds produced by their shrinkage and expansion, and by the
un-evenness of the contours of the rising granite that apparently
displaced and corrugated them.
4.
To ascertain as-much as possible concerning the relationship of dyke
intrusions to the fracture lines occupied by the lodes and to mineral
deposits found in the latter.
5.
To ascertain as much as possible concerning the reason why gold
deposits in payable form are found associated more with slate layers
than with sandstone or dyke rocks, although the latter in many
instances are heavily charged with mundic (sulphide of iron).
The
first step to take in this matter would be the cross-cutting by shallow
trenching of, let us say, the Pyrenees mountains. This would mean at
least five lines of trenches, each, on an average, 20 miles in length.
This at £50 per mile (for opening and filling again) means £5,000. Then
an investigation of the folding of the sedimentary rock layers of
these mountains could be made, that would throw much light on the
relationships of the gold-slate with cracks, and the latter's quartz
lodes and dykes, and also of those " settling pits " in lode lines,
known as shoots and patches of payable deposit, to each other in each
separate system of cracks. Even a slight knowledge in these matters
would tend to lift the mining community out of the gamble of
uncertainty into the realm of investment mining.
From
Landsborough to Stawell the flats are broader, and the ranges lower.
The valley of the Wimmera River is crossed. The wash-dirt deposits of
this valley remain unsampled, excepting at its headlands, and the
hundreds of lode formations, all associated with dyke material, going
in parallel lines in low ranges, show their outcrops through the
remnants of iron-cemented wash-dirt deposits in many places. The whole;
country is very much iron-stained, and I have noticed during my rambles
that the lines of the most cracked part—the lines of the main lode
systems—are represented, by belts of red-coloured surface, the colour
being due to the oxidizing (rusting) of the iron sulphide (mundic) in
the lode caps and parts of the lodes long since removed by surface
wearing.
Crossing
wide flats in the Green's Creek and Doctor's Creek areas, with the
usual intervening elevations of gold-bearing slate and sandstone
country, in due course the range is reached on the western slope of
which the mining township of Stawell is built. From this elevation,
looking west and southwest across a valley 20 miles, perhaps, in
width, is visible the rugged grandeur of the Grampian mountains. Here,
at Stawell, the slate and sandstone formation tapers out to the west
on to a granite range. Indeed, the corrugated slate and sandstone of
the gold-fields of this district have received a great wearing down,
the outcrops of granite appearing through them as islands do in the
Greek Archipelago.
Before
I descended any of the mines, an inspection of the locality showed me
that the general structural features are very similar to those of the
St. Arnaud field. One could hardly expect to find matters otherwise,
seeing that the whole cracking of the Pyrenees mountains area (which
includes Stawell and Ararat) is the result of the one system of
thrusts in the
