32 ALASKAN MINEEAL RESOURCES IN 1906. 
large bowlders may be exceptional. In general, however, bowlders 
must be expected, since glaciation has been an active agent throughout 
this province. As a rule the placers of this part of Alaska have not 
been found to be as rich as those of the Yukon and Seward Peninsula. 
On the other hand, frost is not encountered in the region tributary to 
the Pacific except in the Copper River basin and possibly in the upper 
basin of the Susitna. Other and very important factors in favor of 
the southern province are its accessibility, relatively cheap fuel, and 
abundance of water power. In the Yukon and Seward Peninsula 
districts glaciation is, for the most part, absent and bowlders are 
relatively rare. The values also average much higher, though these 
vary, of course, locally. Of fundamental importance for considera- 
t ion in these fields is the large amount of frozen ground which can not 
be handled by a dredge- unless previously thawed. The laws which I 
govern the distribution of the ground ice are not known, so that each 
placer must be carefully tested on this point before a decision is 
reached. In general, however, it can be stated as an established fact 
that the river beds are not frozen, and also that any loose sand or 
gravel which is well drained is not frozen. The cost of fuel, transpor- 
tation, and other factors which have been mentioned, vary in differ- 
ent districts of this northern province, but in general are higher than 
along the Pacific coast. Water power, too, is much rarer than in the 
southern field. In a comparison of the two provinces it is obvious 
that the southern field is one where bowlders are to be expected, 
while in the north the presence of frozen ground may so increase the 
cost of exploitation as to make it prohibitive. | 
It may be of value to present some facts on the costs and methods 
of dredging frozen ground, as determined in the Klondike. The 
writer is indebted to Mr. Albert J. Beaudette, government mining 
engineer of the Yukon Territory, for the following statement: j 
The dredge now operating on Bonanza Creek was erected on creek claim No. 42 
below Discovery in the year 1901 and afterwards removed to where it is now, on Dis- 
covery claim, a distance of about 4 miles farther upstream. It is one of the old type of 
dredges manufactured in San Francisco, using steam as its motive power. This boat 
has a theoretical capacity of 1,200 cubic yards per twenty-four hours, but this year it 
has excavated on an average 700 cubic yards per twenty-four hours for a period of 
one hundred and twenty-seven days. The capacity of the buckets is 3| cubic feet, 
moving with a velocity of 14 to 16 buckets a minute. It requires 65 horsepower to run 
the dredge. 
The great drawback in dredging operations is the "frost," which must be overcome 
at any cost before the gravel can be excavated and washed. As the plant on the dredge 
is too small to furnish steam for both the dredge and the points used for thawing, the 
management had to erect another plant near by to furnish steam for the points. This 
plant consists of two boilers of 50 horsepower each, 60 points, and pipes to transmit 
the steam from the boilers to the points at a distance of 25 to 100 feet from the boilers. 
The points used are from 14 to 16 feet in length and they will thaw the material to the 
bed rock. 
