a. The relatively free falling or precipitous movement of a newly detached
segment of bedrock (usually massive, homogeneous, or jointed) of any size
from a cliff or other very steep slope; it is the fastest form of mass
movement and is most frequent in mountain areas and during spring when
there is repeated freezing and thawing of water in cracks in the rock.
Movement may be straight down, or in a series of leaps and bounds down the
slope; it is not guided by an underlying slip surface. AGI
b. The mass of rock moving in or moved by a rockfall; a mass of fallen
rocks. Also spelled rock fall. AGI
Eng. A replacement of a coal seam over a greater or lesser area by some
other rock, usually sandstone. See also:horse; washout. Fay
An earth dam built of any broken rock or similar material that may be
available. Hammond
a. Waste rock, used to fill up worked-out stopes to support the roof.
Weed, 2
b. See:overhand stoping
a. Powdered rock material formed by the grinding-up of rocks beneath a
glacier, either deposited as part of the till or washed or blown away and
deposited elsewhere as stratified drift or loess. Also called glacier
meal. Syn:rock meal
b. Fault gouge.
a. The movement of solid rock when it is in a plastic state.
Leet, 1
b. The term given to a slope failure when there is a general breakdown of
the rock mass. When such a rock mass is subjected to shear stresses
sufficient to break down the cement or to cause crushing of the
angularities and points of the rock blocks, the blocks will move as
individuals and the mass will flow down the slope, or will slump into a
more stable slope position. Woodruff
See:formation
A mineral that is common and abundant in the Earth's crust; one making up
large masses of rock. From 20 to 30 minerals are usually considered as
being the most important. Stokes
A foundation that is carried down to the solid rock. The rock is cut and
dressed level, loose and decayed portions are removed, and holes filled
with concrete. The crushing strength of the rock can be ascertained by
tests and the bearing pressure should not exceed one-eighth of the value.
Nelson
When rock is broken by crushing or impact, the resulting fragments can be
divided into two components: (1) the complement, comprising a wide size
distribution in accordance with a probability law, and (2) the residue of
large incompletely broken pieces. The relative proportions of complement
and residue depend upon the mode of fracture. If the rock is completely
crushed, only complement is formed, but if the rock is fractured by the
impact of a point or wedge, there may be more residue than complement.
Syn:complement
An ice-cored mass of angular rock waste, usually heading in a cirque or
other steep-walled amphitheater and in many cases grading into a true
glacier.
Obsidian or other volcanic glass.
A massive, coarsely crystalline to finely granular, sedimentary rock of
the mineral gypsum with bedding commonly disturbed by expansion during
hydration of parent anhydrite. Syn:gyprock
The resistance of the rock to the intrusion of a foreign body.
Stoces
a. The upper surface of bedrock.
b. The boundary between superficial deposits (or drift) and the underlying
solid rock. BS, 11
c. See:bedrock
A short staple shaft driven from a lower to a higher coal seam and used
for the gravity transfer of coal to the haulage road in the lower seam.
See also:roofing hole
An amateur mineralogist or collector.
a. The process of separating ores by washing on an incline trough.
See also:rocker
b. Pushing a resistant object repeatedly, and backing or rolling back
between pushes to allow it to reach or cross its original position.
Nichols, 1
See:walking beam
Short sluice, hand-oscillated; used in gold prospecting and fossicking.
See also:rocker
A beam to give the reciprocal motion in hand boring. Nelson