[TYRRELL] THE GOLD OF THE KLONDIKE 47 
It may also be interesting to point out that the law above annun- 
ciated, namely, that the pay-streak marks the bottom of the old V- 
shaped valley, should be of interest to all students of Physical Geo- 
graphy, since, wherever it can be found, it furnishes a datum line from 
which the growth of the valley outwards can be followed and studied. 
Even where a pay-streak carrying gold is not present in a valley, a band 
of heavy minerals or coarse rock fragments might be detected which 
would indicate the original position of the bottom of the V. 
It is not improbable that gold may have a tendency to settle down 
through gravels and to collect on the bed-rock below them; but this 
tendency exerts a minor influence in the formation of workable placers. 
In McConnell’s Report, pages 9 and 10, the gold values per cubic 
yard of two columns of gravel are given, taken from the hills beside 
Bonanza and Last Chance creeks, one 159 feet high and the other 90 
feet high. These columns were unfortunately taken over the pay- 
streaks in which the gold existed before the gravel was deposited over 
it; but omitting the lowest 6 feet in each column which appear to con- 
tain the pay-streak, the rest shows an increase in value downwards, 
in the one case from .6 cent to the cubic yard to 18 cents a cubic yard, 
and in the other from .7 cent to the cubic yard to 11.4 cents to the cubic 
yard. 
In the first column the total amount of gold contained in the upper 
51 yards is $1-27, while the lowest 2 yards contained $8-26. In the 
other column the upper 28 yards contained $1-07, while the lowest 2 
yards contained $4-40. 
These values may give some indication of the relative amount of 
gold which was concentrated into the valleys, first, in the earlier stages 
of erosion when the pay-streak was formed, and the lighter material 
was carried away, and secondly, in the more mature stages of erosion, 
when the pebbles of quartz and other rocks were deposited with the gold. 
The upper gravels probably contain almost all the gold that was 
eroded out of the rocks of the surrounding country while these gravels 
were being deposited, and if we knew the relative sizes of the particles of 
gold in the gravels and in the pay-streak, we might be able to form some 
idea of the percentage of the gold which had been worn out of the rock of 
the country and had been collected in the pay-streak; but unfortunately 
this information is not available at the present time. However, it is 
quite certain that the gold in the gravel is, on the average, much finer 
than in the pay-streak, and as the gravel gold doubtless represents 
closely the general character of that contained in the country rocks, 
we must assume that in the pay-streak much of the finer gold has been 
carried away, and that the coarser particles are all that have been left. 
