[TYRRELL] THE GOLD OF THE KLONDIKE 53 
now flowing in valleys in which the deposits of the Third Cycle are the 
only ones recognizable. For example, on the upper portions of Domin- 
ion creek, the gravel, both of the benches, and of the flood plain in the 
bottom of the valley, belong to the Third Cycle. In the upper portions 
of Gold Run valley any gravels of the Second Cycle that may have once 
existed have either been washed away or have been reassorted, and 
those that remain clearly belong to the Third Cycle. 
On Quartz creek, the conditions are somewhat more complicated. 
The present stream has cut down into the gravels of the Second Cycle 
almost to, or into, bed-rock. In some places terraces may exist com- 
posed entirely of gravel of the Second Cycle, while the adjoining valley 
may be underlain by gravel of the Third Cycle. In other places the 
stream has cut sufficiently deep into bed-rock to leave the bed-rock 
terrace on which the gravel of the Second Cycle rests almost exactly 
at the same height as the surface of the flood-plain composed of gravel 
deposited during the Third (or last) Cycle of Erosion. 
As with the terrace gravels, these streams gravels are usually well 
rounded, and the pebbles are composed of quartz and all the other rocks 
that occur above them in the valleys. 
In most places these gravels are covered by a considerable thick- 
ness of frozen muck and moss, in which are often more or less extensive 
horizontal beds of ice or chrystosphenes, formed by the freezing of water 
that has risen through unfrozen channels in the frozen ground beneath. 
Gravels in the bottoms of the small lateral gullies, or V-shaped 
valleys, are particularly interesting, as they are the prototypes of the pay- 
streaks which underlie portions of the flood plains of the wider valleys. 
They are composed of large and small particles of gold associated with 
more or less rounded pebbles or masses of such rocks as the country is 
composed of, but as these loose fragments of rock are near the localities 
from which they have been derived they are not as well rounded as 
those in the flood plains of the wider valleys. The gravel is also 
generally quite shallow, and in most cases it is being moved down the 
gulch intermittently by the stream. 
In some of the gulches in the Klondike district, however, active 
erosion has ceased for the present, and they have been filled by muck 
and moss which has either grown in the valley itself or has slidden into 
it from the sides. In parts of Lovett Gulch this covering of muck is as 
much as 100 feet in depth, and the present stream flows with a fairly 
swift current on the top of it. As such gulches have formed embay- 
ments where erosion has not lately been active, and where the growth 
of moss and vegetable material has been particularly rank, they have 
provided favourable places for the preservation of bones of animals, 
many of them now extinct, that lived and died in the valleys. The 
