[TYRRELL] THE GOLD OF THE KLONDIKE 49 
a variety of characteristics, according to the manner of growth of the 
valley in which it has been formed.! 
From these considerations it may be seen that continuous and 
regular formation of a valley will tend to the existence of a regular pay- 
streak, while discontinuous and irregular growth of a valley will form 
an irregular and disjointed pay-streak with many lateral apophyses. 
In some cases it may happen that the rejuvenated stream will 
abandon the old valley altogether and in this way be removed from the 
influence of the old pay-streak. An example of this condition occurs 
on the lower portion of Bonanza creek, where, at about claim 80 below 
Discovery, the new valley leaves the old one, the stream having turned 
Westward to cut out an independent channel through the country rock. 
As the creek during this later stage of its existence gathered but little 
gold from the rocks of the surrounding country, but rather depended 
for the richness of its placers upon that which had already been collected 
into the pay-streak of the White Channel period, and as in leaving the 
old valley it had here left this old pay-streak entirely, the gold which oc- 
curs on this lower portion of Bonanza Creek has either been carried 
down the Creek itself from the higher parts of its valley, or has been 
brought into it by the stream flowing from Lovett Gulch which taps the 
White Channel pay-streak. The pay-streak is consequently not as 
rich here as it 1s farther up Bonanza creek, where it is directly beneath 
the former position of the old White Channel pay-streak, and contains 
much of the gold which that pay-streak formerly contained. 
When we recognize that a pay-streak was formed in the bottom 
of a V-shaped valley at a time when that valley was being actively 
deepened, and when the bottom of the channel of the stream was com- 
posed of the hard unweathered rock of the country, we can readily ap- 
preciate the influence that the character of the rock would have on its 
richness or poverty. 
If the rock were hard and smooth the gradient of the stream would 
in that case continue higher that the average until base level had been 
reached throughout, the current would consequently be stronger, and 
the gold and coarse gravel would tend to be carried down to a more 
favourable location for settlement. 
If, on the contrary, the rock were soft and fissile the gradient would 
be lower than over hard rock, the current of the stream would be slacker 
and the gold would have a better opportunity to settle down into the 
fissures and joints that form riffles to collect it. 

1 See paper by the same author on The Law of the Pay-streak, with illustrations, 
in Trans. Inst. Mining and Metallurgy, Vol. X XI (1912) pp. 593-605. 
