The Gold Deposits of Mount Morgan, Queensland. 



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alumina, manganese and gold were held in solution, to 

 be deposited when the bulk of the water from time to 

 time withdrew into the pipe or the subterranean reservoirs 

 with which the pipe communicated. The overflow of the 



ejected fluid left a siliceous, aluminous 

 and ferruginous deposit on the slope 

 of the hillside, but the gold does not 



appear to have been deposited to any 

 extent beyond the limit of the basin. 

 It may be remarked that " prospects " 

 of gold have been obtained in a few 



localities in the overflow deposit. In 

 such cases it may be a question 

 whether the gold was carried down 

 the overflow or whether it emanated 

 from some subsidiary springs, which, 

 in such cases as our experience of 

 active geysers lias shown, are pretty 

 sure to break out in the vicinity of the 

 main overflow. " Ca Han's Knob," for 

 instance, is suggestive of one of these 

 smaller springs. 



The accompanying diagramatie sec- 

 tion (Figure II.) represents my idea of 

 what would take place in the case 

 of a geyser remaining in activity for 

 a, geologically speaking, lengthened 

 period. The original form of the 

 ground may be taken to have been the 

 line (a a). At the end of an out- 

 burst the sides of the hill would be 

 Covered with a deposit of precipitated 

 material (b b), while on the recession 

 of the water from the cup. a film 



or layer of solid material (c c) would be deposited on its 

 sides and bottom. If we suppose the cup to be a necessity 



