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Geology and Physical Geography: 
CHAPTER XIII. 
Alluvial Gold Drifts . — Auriferous Miocene Gravel. Auri- 
ferous Palaeozoic Conglomerates. Tertiary Gold Drifts 
of different periods. Different Classes of Alluvial Gold 
Mining. General Geological History of Gold Drifts. 
Under this head I here include any auriferous detrital deposit in 
the form of earth, rubble, clay, sand, drift, gravel, conglomerate, 
or cement — as distinguished from vein-quartz or matrix rock — 
whether deep or shallow, loose and incoherent, or consolidated, 
and of whatever geological age, from Upper Palmozoic to Post 
Tertiary. All Victorian gold drifts yet worked are of Tertiary 
or Post Tertiary age, and were provisionally classified by Mr. 
Selwyn in three principal groups, referable respectively to the 
Older Pliocene, Newer Pliocene, and Post Pliocene epochs. 
About twenty years ago, Mr. Selwyn advanced a strong opinion 
as to the non-auriferous character of gravels of Miocene or Middle 
Tertiary age, and based it on the non-discovery of gold in certain 
gravels of that age which were prospected by the geological 
survey party then at work near Steiglitz, and the alleged failure 
of a mining company to obtain gold in a very deep deposit of 
Miocene age at Morrison’s diggings, on the Moorabool, though 
the Pliocene gravels resting on the “ false bottom” formed by the 
Miocene deposit had been profitably worked. 
I have been informed, however, that, during the operations of 
the company in question, a small quantity of gold was obtained 
on reaching the Silurian bed-rock, but that work was discontinued 
before reaching the deepest ground, where any considerable 
quantity of gold that might exist would naturally be expected to 
bo found. 
Subsequent investigations have shown that payably auriferous 
gravels of the Miocene period occur beneath the older basalt of 
various parts of Gippsland, and in the Yarra basin, so that the 
mere fact of a gravel or drift being of that period is no evidence 
as to its being non-auriferous. In New South Wales, a conglo- 
merate of Upper Palaeozoic age resting on Silurian rocks has been 
found to contain alluvial gold in fair quantity, and in pieces up to 
several ounces in weight, so that there is no reason whatever to 
doubt the possibility of finding payable gold in any detrital 
deposit younger than and resting on Silurian rocks. There is 
very good evidence to the effect that the quartz reefs and their 
associated gold had been deposited in the vein fissures prior to the 
formation of the Upper Palreozoic rocks, and, therefore, such 
gravels or conglomerates of Upper Palaeozoic or more recent date, 
