ON THE AUSTRALIAN GOLD FIELDS, 123 



are now chiefly worked, a small quantity of soft whitish 

 rock occurs, containing leaders or thin veins of quartz; 

 but I am not sure whether this is to be considered Silurian 

 schist rock. Even if it prove that there are here the re- 

 mains of Silurian strata, formerly existing in much larger 

 mass but now carried away by pluvial action to supply the 

 alluvial drift of the surrounding country, it is still true 

 that in another part of the mount the close conjunction of 

 quartz reefs, hornblendic rock and granite is clearly estab- 

 lished. 



Adelong Creek is in New South Wales, not far from 

 the borders of Victoria, and is remarkable for the most 

 splendid single quartz reef yet opened, I believe, in Aus- 

 tralia. The reef traverses bold steep ranges of a granitoid 

 rock for a distance of a mile, and probably much further, 

 in a line very nearly straight and not diverging more 

 than two or three degrees of azimuth from the true meri- 

 dional direction, as I ascertained by means of a prismatic 

 compass. 



This great reef is one continuous wall of quartz, crop- 

 ping out at the surface and inclining, as it descends, ten 

 or fifteen degrees from the perpendicular towards the west. 

 The thickness of the quartz varies from almost nothing to 

 six feet or more, " making " or " dying out," as the miners 

 say {i.e. becoming thicker or thinner), in a most capricious 

 manner. But the most instructive circumstance to the 

 geologist is that a variety of igneous rocks occur close along- 

 side the wall of quartz, appearing to support it, or at least 

 to form bands parallel to it. The accompanying specimens 

 will best show the nature of these rocks; they comprise 

 felspar in a state of purity, and a series of hornblendic 

 rocks containing successively larger proportions of white 

 quartz. Hornblende was evidently a predominant mineral 

 .in the neighbourhood ; but so various were the rocks 

 which the miners had encountered, and so difficult was it 



