and their Contact Zones. 15 



and to the low-lying, probably lacustrine, deposits of the 

 Upper Murray basin. 



The district of Swift's Creek lies immediately south of 

 the Great Dividing Range, which alone separates it from 

 Onieo, and it may be classed with the upper part of the 

 second and the lower part of the third zone. Swift's Creek 

 takes its rise on a small plateau, which is scarcely more 

 than a ledge, attached to the Omeo tableland, and falls 

 rapidly through deeply eroded valleys to the Tambo River. 

 This plateau is locally known as the Gum Forest. It is 

 thickly grassed, and lightly timbered with white gum; while 

 in the lower part of the stream the valleys are steep, with 

 high-pointed ridges, and clothed with grass and an open 

 forest of white box and apple-tree. Thus we have here 

 those features well defined in miniature which I have 

 indicated as general to the whole of the North Gippslancl 

 Mountains. 



The examinations made by Mr. Reginald Murray and 

 myself, of which the results have been published in the 

 Reports of Progress of the Geological Survey of Victoria, 

 show that during Miocene times the vast tableland which I 

 have indicated still existed. Terrestrial conditions which 

 have been continuous until now have sculptured the surface 

 of that plateau as we now find it — a land of deep valleys 

 and corresponding mountains. The volcanic portions of 

 these highlands have been deeply excavated and lessened in 

 extent, and during that vast period the surrounding higher 

 points have been reduced in altitude. Thus the tableland 

 has become separated into isolated parts of greater or less 

 extent, and for long distances so entirely removed that a 

 simple ridge is all that remains now, forming the Great 

 Dividing Range. 



It is evident that during these terrestrial conditions our 

 existing alluvial gold workings of Gippsland were mainly 

 accumulated, and that while some alluviums of age contem- 

 poraneous with or earlier than the Miocene period were 

 sealed up in their valleys by flows of basalt, other auriferous 

 deposits of such age suffered continuous rearrangement up 

 to recent times as the streams gradually deepened their 

 valleys with greater or less rapidity in accordance with the 

 varying oscillations of the land. 



The gold-bearing quartz veins in the Silurian formations, 

 in the metamorphic schists, and, as I shall show, in the 

 metamorphosed rocks in contact with intrusive quartz 



