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maximum weight of about 5 ounces have been found. From the mining of
about $35,000,000 of placer gold, representing the concentration from the
wearing away of a great thickness of the country rock and veins, there is
said to have been obtained only one or two nuggets above 30 ounces in
weight. Lack of exploration of the ledges, therefore, may be partly the
reason for the failure to find any but small amounts of coarse quartz gold.
During the time when the country was being reduced to a plain, conditions
were, probably, very favourable for gold enrichment in the upper parts
of the veins. The gold thus formed and released by weathering gravitated
into the old age valleys in the plain. Rejuvenation of the streams by uplift
caused a further concentration in valleys, which coincided nearly with the
ancient valleys. The free gold in the outcrops on the plateau represents
the roots of the ancient enriched zone, the upper parts of which were
removed to the streams. Most of the vein enrichments which produced
coarse gold in the past have thus undergone two concentrations in the stream
beds, leaving only a small part of these enrichments for exploration today.
Ice erosion during Pleistocene time also removed parts of the enriched
zone. It is, therefore, not be expected that the present outcrops of the
veins would be as rich in free gold as the ancient outcrops were. There
is every reason to suppose that, if the oxidized parts of the veins could
have been examined before the plain-like surface of the region was uplifted
and dissected, rich bonanzas of free gold would have been encountered.

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