THE MINING INDUSTRY IN 1906. 33 
The claims upon which the dredge is being operated have all been worked by the 
placer method, and it has been found that a great portion of the ground is already 
thawed and only places where the muck has not been removed arc required to be 
thawed by steam. In the spring the thawing begins fully a month before the dredge 
is put into operation, and in that way there is always enough ground (hawed ahead 
of the dredge to keep it in operation. The ground is 15 feet to bed rook, consisting 
nowhere of more than 4 feet of muck and the remainder gravel. The character of 
the bed rock changes many times in one cross section of the creek from very soil: to' 
very hard and slabby, which will affect the duty of the point. The amount of ground 
that can be thawed by each point A^aries from 5 to 8 cubic yards in twenty-four hours, 
according to the amount of muck and the depth to bed rock, the lowest average 
being 3 feet square of bed rock for a depth of 15 feet to each point. 
I here give you concise data about the operations, together with the costs: 
Wood used per twenty-four hours cords . . h\ 
Cost of wood per cord $13. 50 
Labor, 2 shifts, 3 men each shift $40. 00 
Cubic yards thawed per twenty-four hours 400 
Cost per cubic yard for thawing cents . . 28. 5 
The above is the expenditure for thawing alone, for which the plant cost about 
$4,000. 
The figures above given are in a general way applicable to the 
inland placer districts of Alaska. Costs will, of course, vary accord- 
ing to locality. On Seward Peninsula the operating expenses, as 
well as the cost of installment of the plant, should be less than these 
figures. 
The question of water supply for hydraulic-mining purposes is still 
of supreme importance in all the placer districts. At Nome and in 
other parts of Seward Peninsula the rapid extension of ditches will 
very soon drain all the streams available for use in hydraulic min- 
ing, and then placer-mining operations will cease to expand in this 
direction. With the cheaper fuel which is likely to come with the 
utilizing of water powers, other than hydraulic methods will 
undoubtedly be introduced. In the Yukon camps but little ditch 
building has taken place, and most of the mining work has been in 
rich ground, where hydraulic methods are not necessary for profit- 
able exploitation. The deep-lying gravels of the Fairbanks district 
must always be mined by underground methods, and the only hope 
of material reduction in costs appears to be in lessening the expense 
of transportation. 
PLACER MINING, BY DISTRICTS. 
It is here proposed to summarize the mining developments in the 
regions which are not more fully treated in other parts of the report. 
As the following notes are only in part based on the observations of 
members of the Geological Survey, they must of necessity be ill 
balanced. 
Bull. 314—07 3 
