equivalent freefalling diameter
See:equivalent particle diameter
In textural classification, refers to the arithmetic mean size.
AGI
The resistance of a mine airway obstruction, duct or pipe elbow, valve,
damper, orifice, bend, fitting, or other obstruction to flow, expressed in
the number of feet of straight airway, duct, or pipe of the same cross
section that would have the same resistance. Strock, 2
A term that compares the resistance of air of a mine to the resistance of
a circular opening in a thin plate through which the same quantity of air
flows under the same pressure as in the mine.
A concept used in evaluating the size of fine particles by a sedimentation
process; it is defined as the diameter of a sphere that has the same
density and the same freefalling velocity in any given fluid as the
particle in question. CF:particle size
Syn:equivalent freefalling diameter
a. The radius of a spherical particle of density 2.65 (the density of
quartz) which would have the same rate of settling as the given particle.
AGI
b. A measure of particle size, equal to the computed radius of a
hypothetical sphere of specific gravity 2.65 (quartz) having the same
settling velocity and same density as those calculated for a given
sedimentary particle in the same fluid; one half of the equivalent
diameter. AGI
A composite of mean radiant temperature and air temperature; also defined
as the mean temperature of the environment effective in controlling the
rate of sensible heat loss from a black body in still air when the surface
temperature and size of the black body are comparable to those of the
human body. Where the enclosure surface (mean radiant temperature) and air
temperatures are equal, this temperature is also the British equivalent
temperature; when not equal, the British equivalent temperature is that
temperature at which a body with an 80 degrees F (26.7 degrees C) surface
temperature will lose sensible heat at the same rate as in the given
environment. Syn:British equivalent temperature
See:distortional wave; S wave; transverse wave.
The formal geochronologic unit next in order of magnitude below an eon,
during which the rocks of the corresponding erathem were formed; e.g., the
Paleozoic Era, the Mesozoic Era, and the Cenozoic Era. Each of these
includes two or more periods, during each of which a system of rocks was
formed. Long-recognized Precambrian Eras are the Archeozoic (older) and
Proterozoic (younger). AGI
Former spelling of jeremejevite, also spelled eremeevite.
An orthorhombic mineral, (Fe,Mg,Mn)3 B7 O13 Cl ;
forms a series with boracite; dimorphous with congolite; Mohs hardness of
7 to 7-1/2; forms pseudocubes in halite-anhydrite deposits in the Harz
Mountains, Germany.
A U.S. trademark name for a yellowish-green synthetic spinel.
A casein plastic used for molding many common objects and possibly for
inferior gem imitations; sp gr, about 1.33; refractive index, 1.53 to
1.54.
An orthorhombic mineral, CuCl2 .2H2 O ; forms a sublimate of
soft bluish-green woollike aggregates on the sides of fumaroles.
Syn:antofagasite; erythrocalcite.
The group of physical and chemical processes by which earth or rock
material is loosened or dissolved and removed from any part of the Earth's
surface. It includes the processes of weathering, solution, corrosion, and
transportation. The mechanical wear and transportation are effected by
rain, running water, waves, moving ice, or winds, which use rock fragments
to pound or to grind other rocks to powder or sand.
An unconformity that separates older rocks that have been subjected to
erosion from younger sediments that cover them; specif. disconformity.
AGI
a. A land surface shaped and subdued by the action of erosion, esp. by
running water. The term is generally applied to a level or nearly level
surface. AGI
b. An area that has been flattened by subaerial or marine erosion to form
an area of relatively low relief at an elevation close to the base level
(sea level) existing at the time of its formation. Relics of such surfaces
may now be found far above sea level owing to the falling base level,
below the present ocean surface. Hunt
A thrust fault along which the hanging wall moved across an erosion
surface.
A rock fragment carried by glacial ice or by floating ice, deposited at
some distance from the outcrop from which it was derived, and generally
though not necessarily resting on bedrock of different lithology. Size
ranges from a pebble to a house-size block. AGI
A partition curve drawn to defined conventional scales with the portion
showing recoveries over 50% reversed to enclose an error area.
Syn:tromp error curve