22 
of the bed has been filled in, and the lead—as worked underground, per¬ 
haps hundreds of feet below the present surface—is somewhat as under— 
The two lines (AB) are the boundaries of the lead, and between them 
the whole space is occupied by wash-dirt. The richest portions of the 
wash-dirt will be in the position shown by dotted areas (C), on the above 
diagram, and very probably the actual channel of the stream will be filled 
in with drift, not so thoroughly sorted, and not so rich in gold. In the 
ordinary surface alluvial workings, the richest portions of the drift have 
been found on the inner side of the bends. In deep alluvial mines, the 
variations in the value of the wash-dirt are great within a small area, and 
the explanation is in some cases as above. Another cause of variation in 
the richness of the auriferous gravels is that where the water holes 
existed in the former course of the stream, the gold is not met with in the 
deepest part, but on the slope where the stream enters the water hole, thus: 
This corresponds to what takes place in an ordinary sluice-box. 
Generally the deeper portions of such depressions are filled in with 
clean-washed gravels, that carry very little or no gold. Where a. strong 
current has run in the old channel, the gold is often found, not in the 
bottom of the channel, but on the sides, as shown in the cross section below. 
Where the gold is shotty, however, or nuggety, it remained in some 
cases on a hard bottom. 
When the beds of streams are rocky, and have much fall, the gold 
has generally been swept down them and deposited in a spot where the 
inclination is less, or where the bottom is more clayey or soft, and there¬ 
fore more favorable for retaining the gold. 
In the deep leads of Ballarat, the channel of the stream was in many 
cases occupied by extremely rich wash-dirt. This was owing to the 
nature of the bottom (pipe-clay), and to the low inclination of the bed of 
the old stream. At Reid’s Creek, near Beechworth, the former creek 
bed was occupied by extremely rich wash-dirt, that in places yielded at 
the rate of i lb. of gold to the square foot of bottom. The wash- 
dirt was about i foot thick, and the pebbles, &c., v r ere commingled with 
fine clay. In this case, the bed of the stream was decomposed granite, 
and the fall was slight. 
[.Re fort sent in gth ]une> ipof.] 
