ALASKA AND ITS MINERAL RESOURCES 167 



ing rocks. Such conglomerates have been observed in both the 

 Mission creek and Kenai series of beds, and if future study shows 

 them to have been formed under favorable conditions they may 

 prove to be an important source of gold. According to Mr Spurr's 

 observation, the modern placers of Napoleon creek in the Forty- 

 mile district, have been enriched by gold derived from the basal 

 conglomerate of the Mission creek series, which is made up of 

 materials derived from the Birch creek, Fortymile, and Ram- 

 part series. 



PROBABLE EXTENT OF GOLD-BEARING DEPOSITS 



In a new country gold is first sought in the stream gravels, and 

 thence traced up to its source. Very fine gold may be carried 

 long distances by river waters ; hence it is only when it becomes 

 relatively coarse, or at any rate carries coarse particles, that the 

 source may be considered necessarity near at hand. Fine gold 

 is found in almost all the rivers of Alaska, even the silts of the 

 Yukon yield it in places. Gold has been found along the whole 

 length of the Lewes, the Teslin, the Big Salmon, the Pelly, the 

 Stewart, and the Selwyn, and on the Yukon river almost con- 

 tinuously from the junction of the Lewes and Pelly downward. 

 Still further east, Frances and Dease rivers, the main branches 

 of Liard river, which flows into the Mackenzie, carry gold. In 

 the Cassiar district, on the Dease river, gold was discovered as 

 early as 1861. The district was astively worked as a placer camp 

 from 1873 to 1887, during which time it yielded about five mil- 

 lion dollars' worth of gold dust. These upper regions are dis- 

 tant about 1,000 miles in a straight line from the known outcrops 

 of gold-bearing rocks in the Rampart mountains on the Lower 

 Yukon, and are within areas either in which exposures of the 

 gold-bearing rocks as defined above are actually known to exist 

 or in which the similar litbological character of rocks described 

 renders it probable that in some part of the area they may be 

 exposed. 



There is also some evidence of the extension of rocks of the 

 gold-bearing series to the northwest of the Lower Yukon, though 

 it is as yet impossible to determine whether the primitive gold- 

 bearing rocks of the Birch creek and Fortymile series there come 

 to the surface, or whether it is simply the fossil placers or gold- 

 bearing conglomerates of -later formations, where made up of 

 fragments of these older rocks, that have furnished the gold of 

 modern streams. 



