120 MR. W. S. JEVONS : REMARKS 



The lead was here contained in a deep, well-marked 

 channel in the schistose bottom rocks, now filled up by a 

 most peculiar alluvium, consisting of quartz gravel, fine 

 black clay, and an abundance of lignite or blackened fossil 

 wood, — complete trunks of trees, indeed, being sometimes 

 encountered by the miners. The gold dust lay most 

 thickly in the very lowest part of the channel, where it 

 was not difficult to detect the shining grains and pick 

 them out with the fingers ; they were partly entangled in 

 the crevices and joints of the bottom rock, but smaller 

 quantities of gold dust lay on the sides of the channel, or 

 were disseminated through the alluvium. 



We need only see such a mine as this to be con- 

 vinced that these singular leads of gold lie in the water- 

 courses, or river-beds of a former age, where streamlets 

 and rivers ran down from hills now washed away. The 

 history of alluvial gold can here be read as plainly as 

 in a book ; great masses, perhaps mountains, of schistose 

 rock have in the course of ages become disintegrated ; the 

 quartz reefs which the hills contained were then broken 

 down and filled the river bed with smoothly worn gravel, 

 while the particles or nuggets of gold thus liberated from 

 their quartzose matrix sought, by means of their high 

 specific gravity, the lowest possible position, and there 

 accumulated. Nature has in this way for many ages been 

 performing the self same operations to which the gold 

 miner has recourse in extracting and separating his gold. 



A large space of time indeed must have elapsed since 

 the lower parts of the alluvium and the large quantity of 

 gold which they contain were deposited, because we find 

 them covered by two or three hundred feet depth of other 

 alluvium since accumulated, not to speak of the basaltic 

 layer, which proves that extensive volcanic eruptions have 

 both commenced and become quiescent in the intervening 

 period. 



