An instrument used in measuring the depth of water by the time required
for a sound wave to travel from surface to bottom and for its echo to be
returned. It may also be used for measuring the rise and fall of the tides
in offshore localities. Hunt
The weakening or failure of a material after many repetitions of a stress
that of itself is not strong enough to cause failure. AGI
The maximum stress below which a material can presumably endure an
infinite number of stress cycles.
A deterioration in the crystalline structure and strength of metals due to
repeated stresses above a certain critical value. See also:annealing
Nelson
The ratio of the fatigue limit for cycles of reversed flexural stress to
the tensile strength.
Stone with fracture surfaces having a greasy luster. Syn:nepheline
A yellowish amber resembling goose fat; not as opaque as cloudy amber.
Syn:flohmig amber
Having the brilliancy of a freshly oiled reflecting surface;
characteristic of slightly transparent minerals, e.g., serpentine and
sulfur. Syn:greasy luster
An earlier percussive boring method used largely in Europe for
exploration, etc. The cutting tool is given a rapid but very short stroke,
and the hole is flushed by water passing down through the hollow rods. No
beam is used, but the rope to which the boring tools are suspended has an
up-and-down motion imparted to it by an eccentric. The arrangement gives
up to 250 strokes/min with a stroke length as low as 3-1/4 in (8.3 cm).
Nelson
The tymp arch or working arch of a furnace. Fay
Catches in a mine shaft to facilitate the stopping of the cage at
intermediate coal seams. CTD
a. A fracture or a fracture zone in crustal rocks along which there has
been displacement of the two sides relative to one another parallel to the
fracture. The displacement may be a few inches or many miles long.
b. A break in the continuity of a body of rock. It is accompanied by a
movement on one side of the break or the other so that what were once
parts of one continuous rock stratum or vein are now separated. The amount
of displacement of the parts may range from a few inches to thousands of
feet. Various descriptive names have been given to different kinds of
faults, including closed fault; dip fault; dip-slip fault; distributive
fault; flaw fault; gravity fault; heave fault; hinge fault; horizontal
fault; longitudinal fault; normal fault; oblique fault; oblique slip
fault; open fault; overthrust fault; parallel displacement fault; pivotal
fault; reverse fault; rotary fault; step fault; strike fault; strike-slip
fault; thrust fault; transcurrent fault; translatory fault; underthrust;
vertical fault; want.
c. In coal mining, a sudden thinning or disappearance of a coal seam. Also
known as a want or pinchout. Kentucky
A region depressed relative to the surrounding region and separated from
it by bordering faults.
A small fault terrace. AGI
a. A mass bounded on at least two opposite sides by faults. It may be
elevated or depressed relative to the adjoining region, or it may be
elevated relative to the region on one side and depressed relative to that
on the other side. AGI
b. A body of rock bounded by one or more faults. AGI
c. The displaced mass of rocks on either side of a fault plane.
See also:footwall; hanging wall. Nelson
See:block mountain
a. The assemblage of angular fragments resulting from the crushing,
shattering, or shearing of rocks during movement on a fault; a friction
breccia. It is distinguished by its cross-cutting relations, by the
presence of fault gouge, and by blocks with slickensides. AGI
b. Angular to subangular fragments of crushed rock, up to several meters
in size, filling a fault. Syn:fault stuff
A layer of hardened clay lining the fault plane and often showing
groovings and striae due to the rock movement along the fault plane.
See also:fault gouge
An intricate system of interconnecting and intersecting faults of the same
or different ages.
See:block mountain
A depressed region in a fault zone or between two faults, invaded by the
sea. The Red Sea and Tomales Bay on the San Andreas fault in California
are examples.