THE DIFFERENT METHODS OF MINING GOLD-PLACERS.
alluvions occur in many different forms : in river channels, in basins
and on flats, as surface deposits of sand and gravel, or as
accumulations of detritus (consisting of clay, sand, gravel, pebbles,
and boulders of all sizes) covered with varying thicknesses of lava and
other volcanic products.
Miners' Classification of Deposits.—Miners
classify the deposits in various ways, according to their mode of
occurrence and topographical position, and according to the mining
systems employed in working them. The term " shallow placers" is
applied to deposits whose depth varies from a few inches to several
feet, to distinguish them from " deep placers," which often cover
large areas and have a depth varying from one hundred to several
Hill Claims," or deposits of gravel on hills ; " Bench Claims," or
placers occurring in bench form on declivities and above the level of
existing rivers ; " Gulch Diggings," found in gulches and ravines;
"Flat Deposits," on small plains or flats ; " Bar Claims," or bars of
sand and gravel on the sides of streams, generally above the
water-level ; and " Beach Sands," or the auriferous sands of the
sea-shore, are terms in common use, as well as the names " sluice," "
drift," and " hydraulic " diggings.
Classification of Mining Operations.—The mining methods in common use may be divided into two general classes—viz., Surface-Mining and Deep-Mining.