50 THE ROYAL SOCIETY OF CANADA 
The conditions would be similar to those in a sluice-box. If the 
water flowed over a smooth bottom the gold would be carried away, and 
if it flowed over a rough and broken bottom with many openings in it, 
the gold would settle down in these openings. 
As the stream cuts down into the bottom of its valley it will not 
under ordinary conditions, again pick up this gold that has settled into 
the fissures, except in cases where the supply of gold becomes too great 
for the natural riffles to hold, but rather as the surface of the rock is 
gradually worn down by the stream, the gold will be allowed to settle 
deeper and deeper below its original point of sedimentation. For in- 
stance, if gold particles have settled in fissures in a schistose rock these 
particles will continue to sink vertically for hundreds of feet if the fissures 
continue to persist, as long as the stream continues to deepen its channel 
on the same course. 
Local Characteristics.—The placers of the Klondike which have all 
been formed by fairly continuous erosion and sedimentation in the 
bottoms of valleys, divide themselves naturally up into two sub-divisions 
namely, the gravels of the “ White Channel Period” or “Second Cycle 
of Erosion” and the gravels of “The Recent Period” or “Third Cycle 
of Erosion.” 
Gravels of “ Second Cycle of Erosion.’’—These gravels have been 
well described by Mr. R. G. McConnell, and we cannot do better than 
quote his description of them:— 
“The White Channel gravels differ somewhat from the ordinary 
type of stream deposit. They are very compact as a rule and in some 
of the hydraulic cuts stand up in almost vertical cliffs, even when the 
face is unfrozen. The white or light grey coloration from which the 
deposit derives its name is very conspicuous in most of the sections but 
is not universal, as red, yellow and dark grey beds frequently occur. 
The deposit is highly siliceous, the principal constituent consisting of 
rounded pebbles and rounded and sub-angular boulders of vein quartz. 
Flat schist pebbles and boulders, usually in a more or less advanced 
stage of decomposition, occur with the quartz, and also occasional peb- 
bles derived from the various dikes and stocks outcropping along the 
valleys. No material foreign to the district occurs in the deposit. The 
pebbles and boulders are usually small, seldom exceeding eighteen inches 
in diameter, and are embedded in a compact matrix consisting essentially 
of small sericite plates and fine angular quartz grains. A few large 
angular blocks from three to four feet in diameter are occasionally met 
with but are rare and usually occur on or near bedrock. 
“The uniformity of the deposit in composition and general character 
throughout sections a hundred feet or more in thickness is very striking. 
