144 N. R. Jutmer : 



yield of Oram's reef. Hence, no conelusions can be drawn with 

 certainty regarding the effects of secondary enrichment on these 

 reefs, but the evidence, such as it is. suj^ports the conclusion that 

 the values liave not been greatly affected. The thin character of 

 the reefs, combined wtili their compai-ative density, tends to inhibit 

 extensive circulation of surface solutions, and hence to prevent 

 solution of the gold. The rich patches found near the surface at 

 One Tree Hill might be considered as suggestive of secondary 

 enrichment, but the evidence, although not conclusive, does not 

 support such a view. It appears fairly evident from the nuggets 

 found in the alluvial at Cobbler's Gully, that the former upward 

 extension of the Swedish reef was as rich, or even richer, than the 

 portion now exposed to denudation and vadose solutions. It seems 

 very likely, therefore, that the distriliution of the gold in the 

 Swedish reef near the surface, is not due to the present-day vadose 

 circulation, but is due to conditions determining the primary de- 

 position of the gold. Of such factors influencing the primary 

 deposition, decrease of temperature and pressuie, admixture with 

 surface solutions, and indicator effects are the most important. 

 There is fairly good reason to believe that the formation of these 

 reefs took place soon after the folding of the sediments, and it is 

 certain tliat several thousands of feet of these have been denuded 

 away. Hence the assumj^tion does not seem to be unwarranted 

 that tlie primary deposition of the gold, in the portion of the reef 

 now exposed, was not affected by admixture with surface solutions, 

 and presumably not to any marked degree by reduction of tem- 

 perature and pressure. We are left to deal with the effects of 

 indicators. At Ballarat East, where nuggety gold occurs in the 

 reefs, often at considerable depths, the nuggets are localised to 

 near the intersection of the vein quartz Avith tlieir seams termed 

 " indicators." Unfortunately, the Swedish reef at One Tree Hill 

 was not being worked at the time of my visit, and the records do 

 not mention the mode of the occurrence of the gold, so that positive 

 evidence, bearing on this question, is not forthcoming. However, 

 Mr. Hirt, Avho, as previously mentioned, has lieen on this field most 

 of his life, and whose word I have no reasoji to doubt, has informed 

 me that the ricli patches of gold, from the Swedish reef, were 

 generally localised to near the intersection of the main reef with 

 rather flat leaders of pinkish coloured quartz, two inches or so in 

 width. If this is so, there appears to me to be no valid reason 

 why other " indicator " veins and rich patches of gold should not 

 ])e found in depth. A.s far as I am aware, tlie Swedish reef has not 



