1902.] on Gold Mining in Klondike. 75 



zoic schists, which may be roughly distinguished as grey or green 

 chlorite-schist and mica-schist, and a light-coloured 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, which con- 

 stitutes the Moosehide mountain ; and on the south — on the left bank 

 of the Indian River — 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 government geologist, regards these schists as having originated 

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

 much crushed and altered and entirely re-crystallised from their 

 original condition. They are intersected by numerous bands and 

 bosses of more recent eruptive rocks — quartz-porphyry, rhyolite, 

 augite-andesite, diorite, basalt, etc. — and also by numerous quartz 

 veins. In the northern and north-western portions of the area occu- 

 pied 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 mineralised 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 thai, might not have been derived from 

 the breaking 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 travelled 

 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. 



The gold is very unevenly distributed in the gravel. The richest 

 patches of pay-gravel seem to occur about half-way down the valley. 

 In the wider portions of the valleys the pay-streak may be some- 

 times on one side and sometimes on the other, following no doubt 

 the former course of the stream. 



The valley gravel is generally from 10 to 30 feet thick, and is 

 overlaid by from 5 to 16 feet of frozen bog, locally known as " muck." 



