[rYRRE LL] THE GOLD OF THE KLONDIKE 43 
on the bottom over the rock, and wears it down like a file, so that the 
bottoms of the streams, which are in this way deepening their channels, 
rarely, if ever, give evidence of the presence of a weathered layer of rock. 
In the Klondike district it is certain that the valleys, both during 
the Second and Third Cycles of Erosion, were cut down by this process 
of downward erosion as narrow V-shaped gorges through unweathered 
rock to base level. 
By the processes of erosion and transportation, the old Dome 
Peneplain has had deep and wide valleys cut in it, and most of the 
material derived from the cutting out of these valleys has been carried 
away beyond the limit of the district, either to the Ocean or to some 
lower-lying land. 
The lowest point in the Klondike area, which we are now consider- 
ing, may be taken as the bed of the Yukon river at the mouth of the 
Klondike river, opposite the city of Dawson. In 1898 this was cal- 
culated by the author to be at a level of 1,200 feet above the sea, the 
calculation being then based on the assumption that the Yukon river 
from Lake Bennett to its mouth flowed in a parabolic curve. Since 
that time no exact measurements of the height of Dawson have been 
made, but a number of approximate levellings would indicate that 
the height so calculated in 1898 is not far from correct. The highest 
point in the area is the Dome, with an elevation of 4,250 feet above the 
sea. 
Some years ago a contour map on the scale of two miles to the inch, 
with contour intervals every hundred feet, was prepared by Mr. 
R. G. McConnell and his associates of the Geological Survey of Canada. 
Some corrections were made to this map by the writer and then the area 
of each contour line was computed. Summing these areas together 
it was found that the district had a mean elevation of 2,600 feet above 
the sea. Assuming that the Dome Peneplain had a mean elevation of 
3,500 feet above the sea, which is the elevation of those remnants of it 
which can be clearly distinguished, the country has been reduced under 
the influence of atmospheric and water erosion from 3,500 to 2,600 feet 
above the sea. This computation may be not strictly correct, for the 
Dome Peneplain may have sloped off towards the surrounding valleys, 
so that portions of it may have been lower than its remnants which are 
now recognizable, but on the other hand parts of it may have been higher 
than those parts which remain, and therefore it is probable that an ele- 
vation of 3,500 feet is not far from correct. 
Taking a total area of 800 miles for the entire Klondike district 
and assuming that we are correct in our calculation that the country 
has been reduced 900 feet on an average, it would appear that 136 
cubic miles, or 1,600 billion tons, of rock have been removed from this 
