west, and also a production of gold and platinum from ocean-beach mining in California and Oregon.
Some
interesting notes on beach mining in California and Oregon, and on dry
placers in California, by Charles G. Yale, and on dry placers in
Arizona, Nevada, and New Mexico, by V. C. Heikes, were published in the
Survey report on gold and silver for 1912, copies of which can still be
had on application to the Director, United States Geological Survey,
Washington, D. C.
A
geologic investigation of the placer deposits of the United States is
now being made by James M. Hill, of the United States Geological
Survey, and cooperative work on the technology is being done by Charles
Janin, of the United States Bureau of Mines. The investigation will
require considerable field study as well as office work, and it is
hoped that operators will assist in furnishing the necessary data
requested, as well as the annual statistics for the Mineral Resources
reports, in order that publication of the results may not be unduly
delayed.
DREDGING.
The
production of gold by dredging in the United States and Alaska from the
commercial beginning of the industry in 1896 to the record output of
1914, inclusive, has amounted, according to best available data, to
$94,833,468, and the value will probably have passed the $100,000,000
mark by the middle of 1915.
Profitable
dredging for gold is first noted from Grasshopper Gulch in the Bannock
district, Beaverhead County, Mont., where a Bucyrus double-elevator
bucket dredge was operated as early as 1893-94. Before that time, and
only too frequently since, dredging operations had been attempted in
various regions only to fail because of insufficient knowledge of the
ground or of the engineering and financial features of the work.
Dredges of various types have been tried without permanent
success—clam-shell, suction, single bucket, spoon or scoop, and
pump—until finally has been evolved the modern bucket-elevator machine
of amazing capacity and endurance, fitted, according to the special
conditions involved, to overcome natural obstacles that have blocked
earlier attempts, operated in many cases by electric power, and
profitably treating material unprofitable under all other known or
attempted methods of operation. From the Bannock district dredging
extended to Alder Gulch, near Ruby, in Madison County, and operations
have been continuous in Montana since, with a total yield from this
source of more than $6,500,000. In Idaho, where the gravels of the
Boise Basin have been worked by this method, dredging has produced
nearly $3,000,000 and been continuous since 1897. In Colorado dredging
has been practiced in the Breckonridge district, Summit County, since
1901, and has produced over 82,700,000 in gold. In New Mexico, from
1902 to 1905, inclusive, a dredge was operated on Cimarron River, near
Elizabethtown, in Colfax County, and added materially at that time to
the gold output of the State. The gravels became finally too poor to
operate, according to report, and work came to an end. In Alaska
dredging has been continuous and of increasing importance since 1903
and is now an important factor in the production of gold—over
$10,000,000 to date. In Oregon dredging has not been always profitable,
but it has been almost continuous since 1904, and in 1914 it was
reported as notably
