a. Scot. Inward; toward the workings; the workman's right to enter the
pit.
b. The live or productive part of a lode. Arkell
c. A mountain peak; a word occurring chiefly in the names of many of the
highest summits of the mountains of Scotland, as Ben Nevis.
a. A terrace on the side of a river or lake having at one time formed its
bank. See also:bench gravel
b. In an underground mine, a long horizontal face or ledge of ore in a
stope or working place. CTD
c. A layer of coal; either a coal seam separated from nearby seams by an
intervening noncoaly bed, or one of several layers within a coal seam that
may be mined separately from the others. AGI
d. One of two or more divisions of a coal seam, separated by slate, etc.,
or simply separated by the process of cutting the coal, one bench or layer
being cut before the adjacent one.
e. The horizontal step or floor along which coal, ore, stone, or
overburden is worked or quarried. See also:benching; opencast.
Nelson
f. A stratum of coal forming a portion of the seam; also, a flat place on
a hillside indicating the outcrop of a coal seam. BCI g. In tunnel excavation, where a top heading is driven, the bench is the
mass of rock left, extending from about the spring line to the bottom of
the tunnel. Stauffer
h. A part of the face of a large excavation that is advanced not as part
of the round but as a separate operation. BS, 12
i. A ledge that, in open-pit mine and quarries, forms a single level of
operation above which minerals or waste materials are excavated from a
contiguous bank or bench face. The mineral or waste is removed in
successive layers, each of which is a bench, several of which may be in
operation simultaneously in different parts of, and at different
elevations in, an open-pit mine or quarry. CF:berm
j. See:siege
Ark. That plan of mining coal in a room that requires the blasting of the
two benches of coal alternately, each a little beyond the other.
Syn:bench working
A mining system used either underground or in surface pits whereby a thick
ore or waste zone is removed by blasting a series of successive horizontal
layers called benches.
A placer claim located on a bench above the present level of a stream.
Hess
A coal seam cut in benches or layers. Tomkeieff
a. In vertical shaft sinking, blasting of drill holes so as to keep one
end of a rectangular opening deep (leading), thus facilitating drainage
and removal of blasted rock. Pryor, 3
b. Benches in tunnel driving are often drilled from the top with
jackhammers. The vertical shotholes are generally spaced 4 ft (1.2 m)
apart in both directions, fired by electric delay detonators, one row at a
time. When bench shotholes are drilled horizontally with the drifter
drills mounted on a bar, the charges are fired in rotation, starting from
the upper center. In some cases, a bench may be drilled both vertically
and horizontally, particularly where the benches are exceptionally high or
when the headroom above the bench is inadequate for handling drill steels
long enough to bottom the shotholes to grade. The lifters are drilled by
machines mounted on a bar across the bottom of the tunnel, in which case
the upper vertical holes will all be fired before the horizontal charges.
Hammond
River placers not subject to overflows.
Foundation excavated on a sloping stratum of rock, which is cut in steps
so that it cannot slide when under load. Syn:stepped foundation
Hammond
A name applied to ledges of all kinds of rock that are shaped like steps
or terraces. They may be developed either naturally in the ordinary
processes of land degradation, faulting, and the like; or by artificial
excavation in mines and quarries.
See:bank
A conduit on a bench, cut on sloping ground. Seelye, 1
A term applied in Alaska and the Yukon Territory to gravel beds on the
side of a valley above the present stream bottom, which represent part of
the stream bed when it was at a higher level. See also:bench;
bench placer. AGI
The vertical distance from the top of a bench to the floor or to the top
of the next lower bench.
a. A method of working small quarries or opencast pits in steps or
benches, in which rows of blasting holes are drilled parallel to the free
face. The benching method has certain dangers since the quarrymen must
work on ledges at some height. It is possible to work benches up to 30 ft
(9.1 m) high using tripod or wagon drills. See also:bottom benching;
top benching. Nelson
b. The breaking up of a bottom layer of coal with steel wedges in cases
where holing is done above the floor. Nelson
c. Ches. The lower portion of the rock salt bed worked in one operation.
Fay
d. See:bench
An item of surveying equipment, comprising a triangular steel plate with
pointed studs at the corners. These studs are driven into the ground in
the desired position. The plate is used either as a temporary bench mark
or as a change point in running a line of levels. Hammond
a. A relatively permanent metal tablet or other mark firmly embedded in a
fixed and enduring natural or artificial object, indicating a precisely
determined elevation above or below a standard datum (usually sea level);
it bears identifying information and is used as a reference in topographic
surveys and tidal observations. It is often an embossed and stamped disk
of bronze or aluminum alloy, about 3.75 in (9.5 cm) in diameter, with an
attached shank about 3 in (7.6 cm) in length, and may be cemented in
natural bedrock, in a massive concrete post set flush with the ground, or
in the masonry of a substantial building. Abbrev: BM. AGI
b. A well-defined, permanently fixed point in space, used as a reference
from which measurements of any sort (such as of elevation) may be made.
AGI
A term used to describe the header when it is complete with legs.
Syn:set
A bench gravel that is mined as a placer. Syn:bench gravel;
river-bar placer; terrace placer. AGI
The scrap mica resulting from rifting and trimming hand-cobbed mica.
Skow
See:bank slope