124 REPORT — 1891. 



groups of rock-bands contain auriferous-quartz reefs, while in 

 others the reefs are poor or barren, and that the alluvial 

 deposits, whether deep or shallow, are rich or poor accord- 

 ing to their position with respect to such zones ; and I believe 

 that the same phenomena have been noticed in other parts 

 of the world. 



Here, then, are two main lines of investigation : First, with 

 respect to alluvial-gold deposits, to observe the strikes of the 

 auriferous and non-auriferous belts where the rocks are ob- 

 servable at the surface, to learn from such observations the 

 probable trends of these zones in their extensions beneath 

 overlying deposits, and to reason thence as to where the latter, 

 and also the quartz reefs contained in the concealed bed- 

 rock, are most likely to prove auriferous. That this is no 

 chimerical view can be shown by means of numerous practical 

 illustrations wherein actual results have demonstrated its 

 correctness. 



The second line of investigation involves research of a 

 -deeper and more exhaustive character, and applies specially 

 to the zones themselves and the contained gold -matrices. 

 Although in a general way the rich and poor groups of rock- 

 bands can be respectively indicated with tolerable clearness 

 from actual past results, there is as yet no other recognised 

 mode of distinguishing between them. Take, for instance, the 

 .Sandhurst and Ballarat goldfields, where we find strips of 

 country, many miles in length and three or four miles wide, 

 running in the direction of strike of the Silurian rocks, and 

 within which the alluvial deposits, deep or shallow, have 

 nearly everywhere been rich, and numerous lines of auri- 

 ferous-quartz reefs have been proved. 



On either side of these strips may be observed apparently 

 the same class of coinitry, the same description of Silurian 

 rocks, and numerous lines of quartz reef, often large and per- 

 sistent ; yet little or no gold can be found. 



Exceptions are to be met with in both classes, as within 

 the auriferous belts are many reefs which have not yet proved 

 gold-bearing, while within the poor zones are occasional 

 occurrences of gold in both alluvial and quartz, indicating 

 possibly some minor auriferous groups of bands. 



Again, there are, along the known rich lines of reef, intervals 

 where the quartz is barren. The conclusion arising out of all 

 these observations appears to be that, apart from the study of 

 the lodes, reefs, or veins themselves, the mining geologist has 

 a vast field of study before him in the containing rocks, and 

 that the latter are perhaps the more important, and most likely 

 to yield to the student valuable scientific results, which will 

 enable him with far greater accuracy and confidence than at 

 present to guide and assist the miner. 



