330 



PEOCEEDIN'GS OF THE GEOLOGICAL SOCIETY. 



[June 9, 



apparently a number of branches entering the country (fig*. 4). From 

 this vein likewise the reef has not suflfered any displacement or 

 change. On being sunk through, the granite was observed to have, 



Fig. 4. — Section of Reef, showing second Granite-vein. 



in a line with the smooth eastern wall of the reef, a distinct joint 

 or crack, filled with black clayey matter. This feature was so de- 

 ceptive that the miners believed the vein really terminated right at 

 the eastern wall ; and as a similar joint, though not so marked, was 

 observed on the western wall also, the belief generally gained 

 ground, and it was at last positively asserted, that this second gra- 

 nite-vein did not penetrate into the country, but formed, so to 

 speak, an intrinsic portion of the reef. However, through a late 

 break in the mine, causing a great portion of the reef and country 

 to cave in at the surface, the fallacy of this assertion is clearly 

 proved, since the branches into which the vein divides can plainly 

 be seen entering the country. The sinking through this granite 

 vein, in the Speculation Company's ground, led principally to the 

 proper understanding of the nature of the previously mentioned 

 " horse," and, in consequence, to the discovery of the easterly vein 

 of the reef. Not knowing that the "horse" expands, and thus 

 causes the easterly vein to disappear towards the surface, the com- 

 pany worked down the westerly vein and penetrated through the 

 granite. But on finding the reef beneath of a far greater width, 

 save a thin parting of metamorphic sandstone in the centre, and 

 also striking the smooth eastern wall, that had not been observed 

 above the granite, it was at once rightly supposed that what had 

 been thus far considered the country was in reality the " horse," 

 which suddenly contracted beneath the granite vein, thereby causing 

 the eastern and western quartz-veins to join. A cross cut and a 

 rise through the granite up the eastern wall were, as already men- 



