Amateur Geologist Structured Geological Glossary: General

Structured Geological Glossary: General

m.y.	Abbreviation for million years.
AFMAG	Audio Frequency Magnetic technique in which natural electromagnetic fields in the audio-frequency range are used to study lateral changes in earth resistivity.
albedo	The percentage of solar radiation reflected from the earth's surface. This percentage is higher for ice than for land or water and usually higher for land than for water.
amplitude	The maximum height of a wave crest or depth of a trough.
angstrom	A length of 10 to the minus tenth meter or one hundred millionth of a centimeter.
atmosphere (unit)	A unit of pressure equal to 101,325 newtons per square meter, or about 14.7 pounds per square inch.
bar	" A unit of pressure equal to 10 to the sixth dynes/square centimeter; approximately one atmosphere. "
beta-particle	An electron emitted with high energy and velocity from a nucleus undergoing radioactive decay.
bimodal distribution	A size or mass spectrum that has two peaks of concentration.
Brownian coagulation	The process by which a particle grows by the rapid condensation of gases and fine particles.
conduction	Transfer of heat from one place to another by molecular agitation and without movement of the medium.
continent	A large landmass covered with lighter (less dense) rocks. Since their rocks weigh less than the denser oceanic crust, continent float higher on the mantle and overide oceanic plate on colision.
convection	Rotational flow of a fluid resulting from imbalances in density. This often occurs because the fluid below is heated and becomes less dense than the fluid above or because the fluid above is cooled and becomes more dense than the fluid below.
CSAMT	Controled Source Audio-MagnetoTelluric method in which an artificial source generally a long cable is used to simulate the audio-frequency magnetotelluric fields.
Curie temperature	Temperature above which there is no spontaneous magnetization.
datum plane	An artificially established, well surveyed horizontal plane against which elevation, depths, tide, etc. are measured (for example mean sea-level).
density	The mass per unit volume of a substance commonly expressed in grams per cubic centimeter.
dilatancy	Inelastic volume increase caused by the occurrence of small cracks in rock or soil under stress.
di-polar	The arrangement of the hydrogen atom of a water molecule at 105 deg. across the oxygen results in a slight electrical charge to the molecule.
eccentricity	Measures how elliptical the earth-sun orbit is, with consequent effects on solar radiation received by the earth. If e is the eccentricity then (1 + e)/(1 - e) is the ratio of the farthest and closest earth-sun distance.
ecliptic	The plane that contains the Earth's orbit around the Sun.
electron	A negatively charged particle with negligible mass orbiting around the nucleus of an atom.
electronegativity	Relative measure (on a scale of 4) of an atom's attraction for the electron in its outer shell.
elliptical orbit	An orbit with the shape of a geometrical ellipse. All orbits are elliptical or hyperbolic, with the Sun occupying one focus.
evaporation	The change from a liquid into the form of a vapor or gas.
FEM	Frequency Electromagnetic Method, in which the primary field is sinusoidal in character.
galvanic interaction	Redox reaction between two mineral entities with different rest potential, where the mineral with lower rest potential acts as reductant and the mineral with the higher rest potential acts as oxidant/reductant in conveying electron to oxygen or some other suitable acceptor.
Gaussian coefficients	Coefficients of a spherical harmonic expansion of the potential function of the geomagnetic field.
geodetic	Pertaining to measurement of the shape and dimensions of the earth.
Hooke's Law	The principle that the stress within a solid is proportional to the strain. It holds only for strains of a few percent or less.
hill	A natural land elevation, usually less than 1000 feet above its surroundings, with a rounded outline. The distinction between hill and mountain depends on the locality.
hydration	A chemical reaction, usually in weathering, which adds water or OH to a mineral structure.
hydrous	Literally, with water. Refers to mineral or other materials which have water as a primary constituent.
induction	Process by which a body becomes magnetized or electrified by merely placing it in a magnetic or electric field. Also refers to the process under which electric currents are initiated in a conductor by merely placing it in an electromagnetic field.
infrared radiation	"Electromagnetic radiation lying in the wavelength interval from 0.7 microns to 1000 microns. Its lower limit is bounded by visible radiation and its upper limit is bounded by microwave radiation. Most of the energy emitted by the Earth and its atmosphere is at infrared wavelengths. Infrared radiation is generated almost entirely by large-scale intramolecular processes. The tri-atomic gases, such as water vapor, carbon dioxide, and ozone absorb infrared radiation and play important roles in the propagation of infrared radiation in the atmosphere. Abbreviated IR; also called longwave radiation."
island	A body of land surrounded on all sides by water.
kilobar	A unit of pressure equal to 1000 bar.
land-use	Present and historical uses of land, such as for agriculture, mining, recreation and grazing.
langley	The unit of solar energy relating to the amount which reaches a specific area of the earth's surface.
latitude	The location of a point north or south of the equator. Latitude is shown on a map or globe as east-west lines parallel to the equator.
layer	A bed or stratum of rock.
longitude	The location of a point east or west of the prime meridian. Longitude is shown on a map or globe as north-south lines left and right of the prime meridian, which passes through Greenwich, England.
magnetic field lines	Mathematical construction: a family of curves in space giving at each point the direction (by the tangent of the line) and the strength (by the local density of lines) of a magnetic field.
mass spectrometer	An instrument for separating ion of different mass but equal charge (mainly isotope in geology) and measuring their relative quantities.
mountain	" A steep-sided topographic elevation larger than a hill; also a single prominence forming part of a ridge or mountain range. "
neutron	An electrically neutral elementary particle in the atomic nucleus having the mass of one proton.
neutron-activation analysis	A method of identifying isotope of an element by bombarding them with neutron and observing the characteristic radioactive decay products emitted.
period, wave	The time between two successive wave crests.
ppm	Abbreviation for parts per million.
radiative transfer	One mechanism for the movement of heat, in which it takes the form of long-wavelength infrared radiation.
reflectivity	The ratio of the energy carried by a wave that is reflected from a surface to the energy of a wave incident on the surface.
residual enrichment	Increase in the enrichment factor of a relatively immobile element by virtue of hydrochemical leaching of mobile species.
reservoir	Any natural or artificial holding area used to store, regulate, or control a substance.
ring current	Electrical current at about three earth radii from the center of the earth. The current results from charged particles trapped in the geomagnetic field.
rupture strength	The greatest stress that a material can sustain without fracturing at one atmosphere pressure.
seiche	A free or standing wave oscillation of the surface of water in an enclosed basin that is initiated by local atmospheric changes, tidal current or earthquake. Similar to water sloshing in a bathtub.
skin depth	Measure of the effective depth of penetration of electromagnetic fields. It is defined as the depth at which the amplitude of an electromagnetic field drops to 37% of its surface value.
Soret effect (thermal diffusivity)	Solute flux due to a temperature gradient.
speleology	The exploration and study of cave.
spontaneous magnetization	Magnetization resulting from cooperative behavior of unpaired spins within a crystal lattice, creating a magnetic moment that is independent of the external field.
stochastic inversion	Method for computing Gaussian coefficients (or equivalent parameters) that is based on a priori estimates of parameter and noise covariances.
submicroscopic	Not resolvable in a microscope.
subsolidus convection	Convection via solid-state deformational processes.
supersaturation	The unstable state of a solution that contains more solute than its solubility allows.
stress probing	Measurement of in situ stresses in a dedicated small-diamter hole drilled ahead of the primary drill bit.
telluric currents	Natural electric currents that flow in the ground.
TEM	Transient Electromagnetic Method in which the primary energizing field is a repetitive pulse.
thermal conductivity	A measure of a rock's capacity for heat conduction.
thermal expansion	The property of increasing in volume as a result of an increase in internal temperature.
thermonuclear reaction	" A reaction in which atomic nuclei fuse into new elements with a large release of heat; especially a reaction that is self-sustaining. Occasionally used to include fission reactions as well. "
transition element	Elements of atomic number 21 to 29, 38 to 46, and 71 to 78, whose second outermost electron shell is only partially filled.
turam	Electromagnetic survey method in which the energizing source is a long, grounded, insulated cable or a large, rectangular, horizontal loop excited by one or more frequencies in the range of 100-1000 Hz.
van der Waals bond	A bond much weaker than the ionic or covalent, which bonds atom by small electrostatic attraction.
valence electron	" An electron of the outermost shell of an atom; one of those most active in bonding. "
vector	A mathematical element that has a direction and magnitude, but no fixed position. Examples are force and gravity.
vertical exaggeration	The ratio of the horizontal scale (for example, 100,000
viscosity	A measure of resistance to flow in a liquid (molasses in January has high viscosity while molasses in August has lower viscosity).
wave	A regular movement on a surface or within a material when energy travels through it. On the surface of an ocean or body of water, it is usually in the form of a curving swell or ridge.
wavelength	The distance between two successive peaks, or between troughs, of a cyclic propagating disturbance.
wave steepness	The maximum height or amplitude of a wave divided by its wavelength.
weights of evidence modeling	Estimation of posterior probability that a hypothesis holds true from its prior probability and a combination of weights associated with presence or absence of features supporting the hypothesis.
El Nino	El Nino is the warm phase of an extensive cycle of atmospheric and oceanic conditions called the El Nino/Southern Oscillation (ENSO) cycle. El Nino is marked by a warming of the upper ocean off the coast of Peru every three to seven years.
La Nina	La Nina is the cold phase of an extensive cycle of atmospheric and oceanic conditions called the El Nino/Southern Oscillation (ENSO) cycle. La Nina is marked by cold currents off Peru.