Physical Features of the Australian Alps. 107 



boulders and auriferous gravels. Ultimately the Livingstone 

 Creek (instead of wearing a passage through the centre of 

 the area so filled in) eroded a channel along its margin, 

 leaving the deposited gravels, with their underlying false 

 bottom of igneous boulders, literally high and dry above 

 the present bed of the latter stream. At Dry Gully, 

 near Omeo (a section of which I give), these auriferous 

 gravels have been worked profitably; by sluicing operations, 

 for gold during the past twenty years, and are now profitably 

 worked. 



A recent discovery of rich quartz reefs on the hills in 

 situ is likely to prove deeply interesting, both from a 

 mining and geological point of view. The character of the 

 rocks in which these reefs exist may be briefly described as 

 intercalated bands of gneissose, micaceous, and quartzitic 

 schists (strike, 70° N.W.; dip, 80° S.W.), intersected by hard 

 blue igneous dykes and bands of brownish quartz porphyry 

 (the latter apparently not descending more than 200 feet 

 below the surface). 



The reefs run in a general northerly direction, varying 

 from 20° N.E. to 10° N.W., with a dip of about 60° to 8.W * 

 An interesting problem that is likely to be opened out by 

 the working of these reefs (independently of the rich field 

 for observation in a study of the interrelations of these 

 altered rock masses) consists in the question whether 

 these auriferous reefs existed as such in the Silurian strata 

 prior to its metamorphism into crystalline schists, as the 

 result of aqueous solution, or whether they are derived by 

 gaseous sublimation from the rock masses during the process 

 of metamorphism, whether by hydro-plutonic causes or 

 otherwise. As I find, by observation, these metamorphic 

 schists are here corrugated parallel to the line of strike, it 

 seems feasible that reefs, if existing prior to the action of the 

 forces producing the corrugations, would be exceedingly 

 twisted and contorted along their line of strike. However, 

 these are questions outside the limits of this paper, and 

 which properly come within the scope of an inquiry into the 

 geological structure of the area. 



Returning to Mount Sisters, at the margin of the Omeo 

 Plains, we note a low rolling ridge of pasture hills, separating 



* Since writing the above, a number of claims have been opened out, 

 showing a dip of 60° to E ; strike still northerly. 



