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ground control

a. Maintaining rock mass stability by controlling the movement of
excavations in the ground, which can be either rock or soil.
SME, 1
b. Accurate data on the horizontal and/or vertical positions of
identifiable ground points so that they may be recognized on aerial
photographs. AGI

grounded circuit

Electrical system earthed at key points to ensure a common potential and
eliminate danger to personnel. Pryor, 3

grounded power conductor

An insulated or bare cable that constitutes one side of a power circuit
and normally is connected to ground. It differs from a ground wire in that
a grounded power conductor normally carries the load current while the
equipment it serves is in operation.

ground fault

An electrical contact between part of the blasting circuit and earth.
Atlas

ground geophysical anomaly

A geophysical anomaly that is mapped instrumentally at the surface of the
ground. Hawkes, 2

grounding transformer

See:zigzag transformer

ground log

A device for determining the course and speed made good over the ground in
shallow water, consisting of a lead or weight attached to a line. The lead
is thrown overboard and allowed to rest on the bottom. The course being
made good is indicated by the direction the line tends, and the speed by
the amount of line paid out in unit time. Hunt

ground magnetometer

A magnetometer primarily suitable for making observations of magnetic
field intensity on the surface of the Earth. AGI

groundmass

a. The material between the phenocrysts of a porphyritic igneous rock. It
is relatively finer grained than the phenocrysts and may be crystalline,
glassy, or both. CF:mesostasis
b. A term sometimes used for the matrix of a sedimentary rock. AGI

ground movement

a. Subsidence due to the caving or collapse of underground workings.
Pryor, 3
b. Displacement of ground along a fault, bedding plane, or joint caused by
mining-induced stress.

ground noise

Seismic disturbance of the ground not caused by the shot.
Schieferdecker

ground plate

a. A bedplate supporting railroad sleepers or ties. Standard, 2
b. In electricity, a metal plate in the ground forming the earth
connection of a metallic circuit. Standard, 2

ground pressure

a. The pressure to which a rock formation is subjected by the weight of
the superimposed rock and rock material or by diastrophic forces created
by movements in the rocks forming the Earth's crust. Such pressures may be
great enough to cause rocks having a low compressional strength to deform
and be squeezed into and close a borehole or other underground opening not
adequately strengthened by an artificial support, such as casing or
timber. Also called rock pressure. CF:bottom-hole pressure
Long
b. The weight of a machine divided by the area in square inches of the
ground directly supporting it. Nichols, 1

ground prop

The puncheon between the lowest frame and a foot block in a timbered
excavation, used to support the weight of the timbering. Hammond

ground roll

a. Low-frequency, low-velocity interface waves encountered in seismic
prospecting commonly arising from the ground-air interface, in which case
they are known as Rayleigh waves. Ground roll can completely mask desired
signals, and means to minimize it commonly must be used. AGI
b. Seismic surface wave generated by the shot. See also:ground waves
Schieferdecker

ground sluice

a. A channel or trough in the ground through which auriferous earth is
sluiced for placer mining. Webster 3rd
b. To wash down a bank of earth with a stream of water.

ground sluicing

To strip ground downslope by means of a directed stream of water to
excavate placer material and transport it to a riffled trough in which the
valuable mineral is recovered. CF:hydraulicking

ground spears

Wooden rods (one on each side of the pump) by which a sinking pump is
suspended.

ground vibrations

See:blasting vibrations

ground water

a. That part of the subsurface water that is in the zone of saturation,
including underground streams. AGI
b. Loosely, all subsurface water as distinct from surface water. Also
spelled: groundwater; ground-water. Syn:subterranean water;
underground water. AGI

ground-water discharge

The return of ground water to the surface.