and their Contact Zones. 85 



dykes.* But they will be more applicable if we regard the 

 fissures in such cases as penetrating the strata to varying, 

 but as yet not ascertained, depths at which the igneous 

 (granitic) masses underlie all Victoria. 



On these views it would be reasonable to conclude that 

 such contacts and fissures would, during periods of great 

 igneous (volcanic) activity, give passage to heated waters 

 and water vapours permeating the strata, and which, in 

 passing through heated rocks, could carry minerals in solu- 

 tion and ultimately deposit them. " In these deposits we 

 could recognise the mode in which the various metals were 

 brought up from deep down in the earth's crust, and de- 

 posited in holes and crannies which are accessible to man 

 as mineral veins."")" If these views are well founded, and if, 

 as seems to me, regional metamorphism and vulcanicity are 

 intimately connected, we should expect that during all 

 periods of volcanic activity or of metamorphism mineral 

 veins should be formed. 



In that part of the geological record which remains to us 

 in Victoria, as exhibited in North Gippsland, we have 

 evidence of volcanic action on a grand scale at the close of 

 the Lower paloeozoic ages, and in a less scale throughout 

 the succeeding record until its abrupt termination at the 

 close of the Devonian period. In Tertiary and in more recent 

 times volcanic activity has left the plainest records for our 

 study. Thus, if the views I have stated can be supported, 

 we should expect to find a succession of mineral and 

 auriferous veins commencing with the earliest regional 

 metamorphism of the Silurian strata and extending on- 

 wards. Such a succession of veins I suspect there is, for 

 they are found penetrating Silurian strata which are overlaid 

 unconformably by Devonian sediments, and not passing up- 

 ward into the latter. The discovery of an auriferous quartz 

 vein at Freestone Creek in strata which are most probably of 

 Middle Devonian age, and the occurrence of alluvial gold in 

 situations which suggest that it has been derived from the 

 Upper Devonian Iguana Creek beds, supports this belief. But 

 the greatest number of auriferous veins seem to me to have 

 been formed at the close of the Upper palaeozoic age. In other 



* As at the Crooked Elver— e.g., the G-ood Hope Mine. 



f Professor Boyd Dawkins, as reported in Chambers' Journal, 31st May, 

 1877, at the Manchester Geological Society, May, 1877, when describing his 

 visit to Vesuvius. 



