GOLD MINING IN KLONDIKE. 233 



numerous adits penetrate the white gravel, and are marked by long 

 heaps of tailings which descend from them towards the creek. 



What little is known of the geology of the Klondike district can 

 be stated in a few words. The auriferous area is occupied by Palaeozoic 

 schists, which may be roughly distinguished as grey or green chlorite- 

 sehist and mica-schist, and a light colored or white sericite-schist. 

 These are bounded on the north — upon the right bank of the Klondike 

 Eiver — by a mass of diabase and serpentine, winch constitutes the 

 Moosehide Mountain; and on the south — on the left bank of the 

 Indian Eiver — by a series of quartzitic slates, schists and crystalline 

 limestones. 



The auriferous creeks are entirely situated in the micaceous schists, 

 which constitute the bed-rock everywhere. Mr. McConnel, the gov- 

 ernment geologist, regards these schists as having originated from 

 quartz-porphyry and other eruptive rocks, but they have been much 

 crushed and altered and entirely recrystallized from their original 

 condition. They are intersected by numerous bands and bosses of more 

 recent eruptive rocks — quartz-porphyry, rhyolite, augite-andesite, dio- 

 rite, basalt, etc. — and also by numerous quartz veins. In the north- 

 ern and northwestern portions of the area occupied by these Klondike 

 schists, are both broad and narrow bands of a black graphitic schist, 

 which can sometimes be traced across the valleys. 



The veins and stringers of quartz which are so frequent through- 

 out the district have for the most part a very barren appearance, but 

 they are sometimes mineralized to a small extent and contain a little 

 iron pyrites, argentiferous galena, and — very rarely — gold. 



Up to the present, however, the gold has been exclusively won 

 from the gravels in the valleys, and not from the quartz veins. 



The gravels are mainly of two sorts: — (1) those which constitute 

 the floors of the present valleys and have been laid down by the 

 present streams; (2) those which cover terraces upon the sides of 

 the valleys and represent old valley gravels which have been cut 

 through by the present streams. 



The gold mining was at first carried on entirely in the lower 

 gravels, and it was in them that the precious metal was first dis- 

 covered. These are sandy gravels consisting of pebbles of quartz and 

 schist — in fact, they are made up of the same materials as the bed-rock, 

 and contain nothing that might not have been derived from the break- 

 ing up of the rocks of the district. There is no reason to believe that 

 they were derived from any other source, and some of the pebbles are 

 so lightly rounded that they have clearly not traveled far. Among 

 the minerals which I have seen from these gravels are haematite, rutile, 

 pyrites, graphite, cyanite, garnet, cassiterite, epidote and tourmaline; 

 also barytes and mispickel. 



