57 
of auriferous gravels represents the former course of the stream that flowed 
down the valley. All the detrital matter which covers the gravel to a depth 
of 300 feet has accumulated since Newer Pliocene times, and the granite 
area has contributed by far the larger portion of the material under which 
the old river bed lies buried. 
The relations of the hills to the valleys when the ancient river flowed 
over the quartz pebbles that now form the wash-dirt, must have been vastly 
different to the relation of these same hills to the present water-course. 
When the auriferous gravel was deposited, the ancient river bed was 
not only 300 feet below the bed of the present water-course, but the hills 
were probably 300 feet higher than they are present, and it is the material 
derived from the denudation of the hills since the old valley was excavated 
and the gravel laid down, which has sufficed to fill the valleys and cover the 
wash-dirt to a depth of 300 feet. 
The ancient hills then probably rose 600 feet higher above the old 
river bed than the existing hills rise above the modern river. 
When the gravel was deposited, the extreme limit of denudation had 
been reached, and the valleys were scoured out to their greatest depths and 
except in the bottom of the river course, the bare rocks were exposed. An 
elevatory movement of the southern portion of the continent may have been 
the cause. 
A further oscillation by which the land was depressed relatively to the 
ocean to the extent of 300 or 400 feet may have been the cause of the 
accumulation of the great deposit of silt above the gravel. 
Although the alluvial deposits consist principally of granitic material", 
the bedrock on which this material rests is slate and sandstone of Ordovician 
age. In the reef-drives 60 feet below the surface off the bedrock, the beds 
are yellowish and reddish altered slates and sandstones with much limonite 
in parts, while in the wash-dirt levels driven partly in the top portion of 
the Ordovician strata at its contact with the overlying wash-dirt, the sand¬ 
stones and slates are off very light-yellow colour, much altered and reduced 
to soft pipeclay in part. 
The gold obtained consists of partly water-worn grains and pellets 
seldom weighing up to a few pennyweights. It is of good quality and 
worth over 2s. per oz. Probably some off the attrition off the particles 
of gold is due to the treatment it receives in the puddling machines. About 
2 feet of the bottom of the gravel is sent to the puddling machines, and at 
the same time a few inches of the floor off the lead which consists to a 
considerable extent off 11 pipeclay 55 or slate which has become altered and 
softened to the consistency off clay. 
It is worthy off note that in a general way the nature of the gold in 
alluvial wash may be told from, an examination of the pebbles. If these 
are angular or sub-angular the gold will be sharp and hackly, if moderately 
well rounded the particles of gold correspond. If most off the pebbles are 
moderately well rounded, but occasional pebbles of completely rounded 
character are met with, so among the moderately rounded gold some 
completely rounded grains will occur. If the gravel is highly rounded, 
then the gold particles will be also thoroughly waterworn. The differences 
in the character as regards the degree off rounding and the quality as shown 
by the colour, asi well as the differences of form, are of the utmost value to 
the prospector. There are distinctive characters in gold samples derived 
even from adjacent reefs or neighbouring gullies which enable them to be 
distinguished from each other. 
Besides the ordinary water-worn gold found in the washdirt with quartz 
pebbles, a remarkably finely divided gold, called slum gold, is obtained 
from the slimes. This is so fine that if it once dries it floats on the surface 
