Geology Reference
In-Depth Information
Crossing point method
A method in which the rates at which the temperatures of a sample and a
reference increase are compared. The point at which the temperature of the
sample equals that of the reference, the crossing point, is considered an
indicator of the sample
'
s tendency to self-heat.
Cryogenic
Extremely cold freezing process, using liquid nitrogen or carbon dioxide,
any process carried out at very low temperature, such as
-
50 °C.
Dip
The angle at which a stratum or any horizontal feature is inclined to the
horizontal.
Excavation
(loading out, daylighting, dig and quench, stripping) A fuel-removal
method, involves physically removing the burning material and cooling it
to extinguish the fire.
Exothermic
A chemical reaction producing heat.
Fire barrier
A natural feature or excavated structure which breaks the continuity of the
coal and carbonaceous shales intended to limit the spread of a subsurface fire.
Flooding
A method of fire control in which a constructed dam is used to raise the
natural water level above the fire zone. Rarely used because of the diffi-
culties in remote installation of a dam, the necessity that the surrounding
down dip rock must be unfractured, and the risk of catastrophic failure.
Flushed barrier
Designed to fill the voids in an underground fires zone with fine, noncombus-
tible solids which cover the burning material and fill the interstices in adjacent
rock, limiting the amount of oxygen in the system and adsorbing heat.
Gob
The space left by the extraction of a coal seam into which waste is packed
or the immediate roof caves.
Ground-penetrating radar
A method that uses radar pulses to image the subsurface; detects objects,
changes in material, voids and cracks in rock, soil, ice, fresh water, pave-
ments, and structures.
Heat capacity
The amount of heat it takes to raise the temperature of one gram of a material
1°Celsius, a property of a material denoting its ability to adsorb heat.
Heat of vaporization
The heat required per unit mass to change a unit mass of the substance at its
boiling point from liquid to gas or vapor.
Inactive mine
Under SMCRA, a coal mining and reclamation operation for which recla-
mation has been completed or the reclamation bonds have been forfeited.
Inundation
Methods that involve the underground use of water to lower the tempera-
ture of the burning material (heat removal) and stop the combustion reac-
tion by oxygen exclusion.
Magnetic susceptibility
A measure of the degree to which a substance is attracted to a magnet; the
ratio of the intensity of magnetization to the magnetic field strength.
ppm
Parts per million, a unit of concentration, mg/kg for solids or mg/L for
liquids and gases.
Proton precession magnetometer
An instrument used to measure the strength and/or direction of the mag-
netic field in the vicinity of the instrument. A direct current creates a strong
magnetic field around a hydrogen-rich fluid, causing protons to align
themselves with the magnetic field. The current is then interrupted, and
as protons are realigned with earth
s magnetic field the direction of axial
rotation changes at a specific frequency. This produces a weak alternating
magnetic field. The precession frequency depends only on atomic constants
and the strength of the external magnetic field.
'
Remnant magnetization
Part of the magnetization of a body that does not disappear when the
external magnetic field disappears.
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