Surface Geology of the Yukon Territory. — Nordcuskjold. 297 
are often to be found in the early summer in the upper forks 
of the larger valleys veritable though small local glaciers just 
like those described by Spurr from the Forty Mile district. 
Occasionally, moreover, a blue clay containing angular stones 
is to be found in the larger valleys; this may be due to a sort of 
moraine attendant on the local glaciers. Otherwise all moraine 
accumulations are wanting. 
In the beds of these valleys it is that the gold is lodged. In 
another place''' I have given an account of its occurrence and 
confine myself here to the mere mention of the fact that the 
greatest part of it lies in the lowest layer of the river gravel 
and in the top 5-8 feet of the disintegrated and partly decayed 
bed-rock. Along with the gold there are found numerou? 
mammoth remains, — among others whole tusks which 
can scarcely have been secondarily washed out of the older lay- 
ers. Seeing the whole mass is frozen hard all the year round 
and that the gold is only found in small quantities in the recent 
river gravel, we are bound to assume that the main body of 
the gold was washed clear and deposited during a time when 
the mammoth was still in existence in these regions, presuma- 
bly during the Pliocene or Pleistocene epoch. As in most of 
the valleys no foreign blocks are to be found at all, the metal 
must come from the circumjacent rock, which is a schist dis- 
tinguished for its very muscovite-like mica. In the whole 
territory where this rock is found the rivers are exceedingly 
rich in gold. The rock contains continuous veins as well as 
short, irregular, contorted and shredded lenticular bodies of 
quartz ; and seeing the larger quartz boulders practically never 
contain gold in a free state it seems most probable that the gold 
.originates from the smaller bodies, perhaps enriched in shear 
zones. Practically no free gold has yet been discovered in the 
rich district in the surrounding rock. 
Actual plateaus do not occur in this region though rounded 
ridges are common; they are as a rule of almost the same hight 
above the sea, — nearly 3,000 feet. On the top of these I never 
saw any gravel that showed evidence of rolling; and it is an 
open question as to whether these ridges form the surviving 
remains of a "pene-plain" or of a plateau originating from ma- 
*In a paper sent to the editors of the "Zeitschrift fiir praktische Ge- 
ologic," Berlin. 
