38 ALASKAN MINERAL RESOURCES IN 1904. [bull. 259. 
imply great age and erosion subsequent to any deposition beneath sea 
level. Topographic conditions exercise a remarkable control over the 
methods which can profitably be employed in gravel mining, and the 
prospective miner neglects a vital part of his preparation if he does 
not study the topographic features of a given district in detail before 
entering upon operations. In California and Australia the geologic 
and topographic conditions favor the placer miner. In other coun- 
tries, notably in Siberia, Alaska, and the Yukon territory, they are 
inimical to his success. In Alaska, as a rule, alluvial gold is almost 
entirely lacking where timber and water are plenty, grades steep, and 
the ground unfrozen. Where gold is distributed in paying quantity 
water supply is inadequate, timber is poor or altogether lacking, and 
the miner must provide grade for his boxes and dump for his tailings 
by artificial means and meet the formidable condition of solidly frozen 
alluvium. Bench deposits, where gravel can be moved on natural 
grade, occur in both the Forty mile and Rampart districts of interior 
Alaska, and have been made to produce a small amount of gold by the 
hydraulic method. Although it is not impossible that extensive and 
valuable bench deposits may }^et be found, no deposit comparing either 
in extent or in richness with the famous u white channel" of the 
Klondike has been discovered. 
In that portion of the Alaska interior lying between Circle, on the 
Yukon, and Fairbanks, on the Tanana, the mountains rise to heights of 
from 1,500 to 2,000 feet above the level of the streams, have rounded 
tops, and slope to the intervening valleys at angles which do not exceed 
20 degrees, and often are not greater than 10 degrees. The streams 
and valleys are on a gently descending plain, the grade of which does 
not exceed 3 per cent, except in the upper one-half mile, and frequently 
is not over 1 per cent. The mountains are referred to by the inhabi- 
tants as " domes," and the word fairly well describes them. They 
present what corresponds most nearly to the upper segment of a great 
ellipsoid except in the cases where the erosion has not been sufficient 
to accomplish the obliteration of a still more ancient topography. 
This ancient surface, remnants of which are visible on the tops of the 
highest mountains, was evidently a base-leveled plain which was 
approximately 2,500 feet above the present drainage plain. Although 
the base-leveling is apparent to the eye it is not evidenced by the 
presence of rounded gravel on its surface. The lack of gravel is 
accounted for by the fact that the second denudation has progressed 
for a great period, and the comparatively small amount or vertical 
section of gravel which existed subsequent to the elevation has been 
worn away. 
In the Klondike recent streams have cut the old Pleistocene chan- 
nels and have reconcentrated the gold." The gold is about equally 
«See McConnell, R. G., Preliminary report on the Klondike gold fields: Geol. Survey Canada, 1900. 
