118 



on tlic occurrence of gold in the PaLTOzoic rocks, tlie late 

 8ir Roderick Murcliison, wlio propounded in his '* Siluria," 

 1859, wlien writing of the Victorian gold-fields, the hypothesis 

 that the gold in quartz reefs would gradually decrease in 

 quantity downward and ultimately run out, or at least cease to 

 be payable to work at a limited depth. His reasons for the 

 prognostication were based upon mining experiences in other 

 gold countries than Australia. But the exploitations of the 

 A^ictorian reefs have proved that some at least are payable 

 even at depths which certainly do not deserve to be called 

 limited. In later years the results of deep mining in Victoria 

 have still more fairly established the downward extent of the 

 gold, aud several reefs are at present being profitable w^orked 

 at depths of a thousand feet and upwards; the recent discovery 

 of an auriferous lode at Stawell is likely to carry the depth 

 down to 1,700 feet. Sir E. Murchison, in his last edition of 

 " Siluria," 1867, acknowledged that the results of quartz- 

 mining in Victoria put former general experience at fault, and 

 inferred that quartz reefs of similar character and geological 

 relations might offer similar chances of success in depth. 

 jSTevertheless, " though rich yields from great depths are by no 

 meaus rare, we do not, on the whole, find such rich quartz in 

 the deeper levels of our mines as was obtained from the surface 

 outcrops." — 'R. A. F. Murray, F.G.S., G-eol. Surv. of Victoria, 

 in Australasian, Sept. 24, 1881. 



Is this new experience applicable in judging of the chances 

 of similar quartz reefs occurring here? My own observations 

 have led me to hold the opinion that the reefs do not resemble 

 each other, having a similarity neither of character nor of geo- 

 logical relations. 



Firstly, as to the geological relations of the auriferous veins 

 in Victoria and in South Australia. Sir R. Murchison writes : 

 — " The most prolific sources seem to have been the quartzose 

 veinstones which traverse the Lower Silurian slaty rocks." 

 Now, Mr. Selwyn has satisfied himself — and it is generally 

 accepted — that the gold quartz veins of Victoria are confined 

 to rocks of Lower Silurian age, chiefly those which are in- 

 cluded between the Llandeilo and Upper Llandovery forma- 

 tions. "In every part of the colony," says he, "where such 

 rocks appear on the surface they are intersected almost in- 

 variably in a meridional direction by quartz veins, from the 

 thickness of a thread to the dimensions of 10 or 15 feet, and 

 in marvellous abundance. Not one per cent, of these " quartz 

 reefs" has as yet been touched by the uiiner, and therefore the 

 only evidence we have at present of their containing gold is in 

 the richly auriferous and widely spread Tertiary de})()sits, which 

 everywhere accompany them, and which have undoubtedly 



