92 



by veinlets of chalcopyrite though in many cases the two 

 minerals appear to have been contemporaneous. 



The values so far have not greatly decreased with depth, 

 though this is not apparent in the production since more 

 lower grade ore can now be mined than formerly because 

 of reduced smelting charges. The evidence though not 

 conclusive, is strongly in favour of almost the entire 

 deposition being due to ascending solutions, though possibly 

 at two or more periods. In the first period, the dyking 

 and faulting phenomena accompanying the formation of 

 the lodes formed barriers which afforded favourable condi- 

 tions for the precipitation of copper and gold. A favourable 

 area for deposition appears to be the underside of dykes. 

 In the second period, ascending solutions of different com- 

 position may have deposited new minerals in the ores or 

 concentrated at successively higher levels, the values of the 

 ore minerals formerly deposited. 



If a zone of true secondary enrichment ever existed, it 

 was swept away during the heavy erosion accomplished 

 by the Cordilleran ice sheets. 



The success that has attended the vigorous development 

 policy of the operating companies, gives no indication that 

 the productivity of the lodes is near the end, nor even on 

 the wane, but on the other hand, gives every encouragement 

 to the view that ore bodies will be found at much greater 

 depths than the levels now being exploited. 



GEOLOGY OF THE REGION BETWEEN 

 CASTLEGAR AND REVELSTOKE. 



THE ARROW LAKES. 



Between West Robson and Arrowhead there are two 

 pronounced expansions of the Columbia river known as 

 Upper and Lower Arrow lakes, which with the river 

 connections have a total length of about 107 miles (172 km.). 

 The junction of Lower Arrow lake and the Columbia 

 river is about 10 miles (16 km.) west of Castlegar. The 

 lake, whose shape is that of a slightly bent bow with the 

 convex side to the west, has a length of about 51 miles 

 (82 km.) with an average width of about one mile (i -6 km.) 

 tapering at both ends. The low water level is about 



