1869.] GEOLOGY AND MINERALOGY. 233 



oceanic waters, whether influenced by accumulations of organic 

 matter or otherwise. It would be a simple matter to explain the 

 structure of the Gold Streak, on the supposition that organic 

 matter determined the deposition of the metal, in belts or zones, 

 for it is easy to conceive accumulations of stranded organisms 

 on subaqueous beaches, in a shallow sea, in the form of long, nar- 

 row bands. Organic matter determines the deposition of most 

 metals from solutions, and whatever intermediate combinations 

 and decompositions took place, accumulations of organic matter 

 may have been the proximate cause which determined the distri- 

 bution of the gold in zones or belts. According to this view the 

 direction of Gold Streak will probably differ slightly in each lead, 

 but there will be a general parallelism in a considerable number 

 of adjacent leads, and the direction of one zone will be a clue to 

 several. 



" But other and more important deductions may be drawn when 

 attention is given to one particular lead. The course of the 

 Gold Streak being once known, it can be traced through all the 

 deviations produced by anticlinals, synclinals, dislocations, and in 

 general almost all varieties of disturbance. 



" From Mr. Burkner's table, on page 36, it appears that the 

 average yield of the Tudor Lead, between the depths of 55 feet 

 and 100 feet from the surface, was as follows, from east to 

 west : — 



" Breadth of Zone, 55 feet. 



Mean yield on areas 165, 164, 163 450 feet. 22 dwts. 



area 162 150 " 36 " 



161 

 And one-third of 160 

 Mean yield of two-thirds of area 160 .... 100 " 3f " 



" The falling off in the west 100 feet of area, 160 is not only 

 sudden but extreme. But it must be remembered that on this 

 area the work was stopped at a depth of 110 feet. It is worth 

 while to consider what probabilities exist of discovering the rich 

 zone at a greater depth. 



" An inspection of the section showing the form of the east and 

 west anticlinal, points out the remarkable coincidence that in area 

 160 (or more properly area 201, where Mr. Burkner's shafts are 

 really situated, as shown on the large plan, in the Mines' Depart- 

 ment), the strata dip suddenly to the west at an angle of about 



YoL. lY. Q ifo. 2, 



I 200 " 24 



