30 
wash-dirt has been lost to the company. In the Main Reef drive, No. i 
east branch, the section is as under: — 
Fig. 9. 
The position of the pebbles, which are evidently derived from the wash- 
dirt, is about 40 feet below the bottom of the gutter. They indicate the 
direction in which the valuable wash-dirt has disappeared, but not the 
extent of the subsidence. Bore holes sunk further eastward prove that 
the subsidence amounts to hundreds of feet. This is probably the only 
instance known in the State where a portion of an alluvial lead has been 
lost through subsidence. At Mount Greenock, a volcano broke through the 
alluvial lead, and interrupted it. The material in this case was hurled 
out with other ejectmenta, and also borne out by the stream of molten 
rock. The lead was recovered and worked on the other side of the vol¬ 
canic neck. Still another instance of an alluvial lead being interrupted by 
volcanic agency is at Wombat Hill, Daylesford, where the lead was 
broken through by basalt. Near the basalt the wash-dirt was pushed 
upward. A portion of the lead was entirely removed, and its position 
was occupied by basalt. 
In some cases the levels of the deep alluvial leads have been materially 
altered, with the result that the level of a down-stream portion has been 
raised above a point higher up stream, as in the case of the Grand Duke 
Company, Timor, also at Huntly, near Bendigo, where borings prove that 
similar disturbances have taken place. Such occurrences accentuate the 
necessity for elaborate and exhaustive boring on the course of a deep lead 
before the site for the shaft is determined on, and before the direction of 
the main reef drives is settled. Hitherto the practice has been to fix the 
site of the shaft, and run out the main reef levels on the minimum amount 
of boring, and the result is that the shafts of many of the deep alluvial 
mines are wrongly placed, and the levels are so disposed as to entail the 
maximum of cost in working the mine, and in handling the wash-dirt. 
These errors might be greatly reduced, if not eliminated, by liberal boring 
as a preliminary to actual mining operations. 
[Report sent in Jth July, igoj.] 
THE OCCURRENCE OF QUARTZ SPURS AT BENDIGO. 
(no. 16 on locality map.) 
By E. J. Dunn, F.G.S., Director, Geological Survey. 
At Bendigo, besides the regular saddle-reefs and legs which conform 
to the bedding of the country-rock, and the well formed and lengthy quartz 
reefs that fill certain lines of faults, and cut nearly vertically almost at 
