THE KLONDIKE GOLD DISTRICT. -S5 



igneous rocks miiigied almost eveiywhere with some local aqueous 

 deposits. The name Keewatin (pronounced Keewajiiin) was given to 

 this division, while the name Huronian is retained for the upper and 

 greater part of the system, which is made up principally of a variety 

 of sedimentary rocks that are more or less altered in some districts. A 

 part of the Laurentian series was supposed by some geologists to be 

 represented in a few places in the Rocky Mountain region. One of 

 these is near the Klondike district. If this supposition be con*ect, then 

 the Keewatin and Huronian are probably there as well. The above 

 short description of our oldest rocks is intended to prepare the way for 

 some remarks on the position of the Klondike auriferous series, since 

 the geological age of i^icli gold-bearing rocks is one of the most 

 interesting points in connection with the whole matter. 



Rocks of the Klondike Gold District. 



The Klondike gold district lies in the angle between the east side 

 of the Yukon and the south side of the Klondike River, and measures 

 about 40 miles from north-west to south-east by about 25 miles at 

 right angles to this direction. The gold-bearing series within this 

 area embraces a variety of ciystalline schists and other rocks, which 

 are here mentioned in the approximate order of their abundance: 

 Foliated quai-tz, porphyiy, silicious sericite, quartz-mica schists, imper- 

 fect g-neisses, sheared greenstones, chloritic, and graphitic schists, 

 rhyolites, andesites, and diabase, the last-mentioned passing in places 

 into serpentine. The schists of this group have been mostly derived 

 from massive rocks by pressure and shearing, but some of them are 

 altei-ed sediments. Silicious limestone occurs in a few places 

 associated with silicious and argillaceous schists. Epidotic and 

 actinolitic schists occur in a few instances. Nearly all these rocks 

 contain many small and souie larger veins of white quartz, which in 

 the aggregate make up a proportion of the whole mass worth noting. 

 Small quantities of accessory minerals of various species have been 

 found in this gi'oup of mstamoq^hic rocks. More recent intrusions of 

 Ucassive rocks of several groups and ages, penetrating through the 

 old schists and gray granite, like that which forms the great coast 

 range, have been observed cutting schists of sedimentary origin. 

 Throughout the district the strike of the bedding and that of the 

 cleavage or schistosity generally coincide, and they haA'^e a prevailing 

 nortli-west and south-east course, and dip at rather low angles to the 

 south-west, but, on the large scale, these lines sweep round through 

 the district in flattened parallel concentric curves belonging to three 

 sets or centres. 



Huronian Age of the Klondike Rocks. 



The following are some of the reasons for classifying the gold- 

 bearing rocks of the Klondike with the Huronian system: — No 

 crystalline rocks of later age than the Huronian are known to occur 

 elsewdiere in this part of the Dominion, and there is no reason to 

 assume that the Klondike series is exceptional in this respect. In 

 the Rocky Mountains and other chains formed by profound upheaval 

 through an immense thickness of strata, the oldest rocks are found 

 in the central portions. Considerable areas, for 200 miles along the 

 Yukon Valley, have been provisionally coloured as Laurentian by the 



