REPORT ON THE PROPOSED SUNNYSIDE TUNNEL, MOUNT 
WILLS GOLD-FIELD. AND ON CERTAIN REEFS AND ALLU¬ 
VIAL WORKINGS IN THAT DISTRICT, WITH PLAN AND 
SECTION (PLATE XXIII.). 
By E. J. Dunn , F.G.S., Director , Geological Survey of Victoria. 
Situation. 
The proposal is to drive a tunnel in from a point near the United 
Brothers battery, on Wombat Creek, towards the north-eastern corner of the 
John Bull lease. From the mouth the direction would be about W. 20 deg. 
Sor nearly at right angles to the strike of the country. The Antiope and 
Linked Brothers reefs would be cut in about the centre of their length, and 
the Gentle Annie reef would be cut on its northern end. The distance from 
the mouth of the tunnel to the first reef now worked—the Antiope—would 
be about 1,870 feet. To the United Brothers reef the distance from the 
mouth would be about 2,600 feet. To the Gentle Annie reef the distance 
would be about 4.000 feet. 
Accurate levelling would have to be done to determine the exact amount 
of “backs’' that such a tunnel would render available. Only rough 
mjeasurements were taken, and from these it would appear that on the 
Antiope reef about 350 feet of “ backs ” below the bottom workings would 
be made available. At the United Brothers the “ backs ” below the ground 
already worked out would be about 250 feet. At the Gentle Annie reef 
several hundred feet of “backs ’’ would be available if the tunnel were 
extended so far. This, however, would imply not only the driving of the 
tunnel through many hundreds of feet of unaltered granite, but also the 
sinking of several hundreds of feet through the same material. One argu¬ 
ment used in favour of the tunnel is that in driving across the “ country 
lodes and veins that do not show at the surface might* be cut. This, 
however, rarely happens. 
Rocks. 
Mount Wills is a granite mass rising to an altitude of 5,758 feet above 
sea-level. On the eastern flank schistose rocks prevail; they occur a few 
chains east of the Gentle Annie reef and continue easterly beyond Sunny 
side. At the surface the granite is much altered, and as far down as the 
workings have penetrated the rock is still changed. About the least altered 
granite met with in the neighbourhood is in the Star of the West tunnel, 
but the heart stone, which is beyond the influences of the atmosphere and 
percolating waters, will be much harder than anything yet encountered. 
Schists of silky appearance, knotted schists, &c., are prominent, and 
are undoubtedly the direct result of intrusions of granite acting on sedi¬ 
mentary rocks, apparentlv of Ordovician age. The strike of the schists 
where good observations were possible is about N. 20 deg. W. The beds 
are nearly vertical. Auriferous quartz reefs intersect both granite and 
schist “ country.” 
Reefs. 
A complicated svstem of fractures intersects the country at Sunnyside. 
Lode material fills some of these lines, but not continuously, for in working 
the reefs the walls are in some places in contact and no ore is : present. 
[Report sent in 7 th March , 1905 .] 
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