A mineral, Al4 (SO4 )(OH)10 .5H2 O ; in
veinlets lining crevices in ironstone. CF:felsoebanyaite
a. An extrusive rock composed of calcic plagioclase, augite, olivine, and
a feldspathoid (nepheline, leucite, or analcime); essentially, a
feldspathoidal olivine basalt. Some basanites have been the source of
sapphires or rubies. AGI
b. A touchstone consisting of flinty jasper or finely crystalline
quartzite. Syn:touchstone; Lydian stone. AGI
c. A black variety of jasper. AGI
a. As used by drillers, a line of stakes set by an engineer or drill
foreman to be used as a guide to line up and point the drill in a specific
compass direction. A line in a survey which, being accurately determined
in length and position, serves as the origin for computing the distances
and relative positions of remote points and objects by triangulation.
See also:base line
b. A compound, e.g., lime, ammonia, or caustic alkali, or an alkaloid,
capable of reacting with an acid to form a salt either with or without
elimination of water.
c. Foundation or supporting structure on which a drill is mounted.
Long
d. See:basal pinacoid; base course.
A unit of quantity in the tin plate trade consisting of 112 sheets
measuring 14 in by 20 in (35.6 cm by 50.8 cm) or the equivalent in area;
consequently 31,360 in2 (20.2 m2 ) of tin plate.
Crude lead containing recoverable silver, with or without gold.
See also:work lead
a. The main explosive charge in the base of a detonator. Meyer
b. The charge loaded into the bottom of vertical holes in quarrying,
usually applicable to 3-in (7.62-cm) diameter holes and larger.
Nelson
c. The detonating component in a detonator, initiated by the priming
charge. BS, 12
a. A layer of specified or selected material of planned thickness
constructed on the subgrade or subbase to serve one or more functions,
such as distributing load, providing drainage, minimizing frost action,
etc. ASCE
b. See:base
a. The clay particle with its cations may be regarded as a kind of salt in
which the colloidal clay particle is the anion. Certain cations may
replace others, making the clay more flocculent. The cation replacement is
known as the base exchange. Syn:ion exchange; cation exchange.
AGI
b. The physicochemical process by which one species of ions adsorbed on
soil particles is replaced by another species.
See also:zeolite process
See:slope failure
Water entering drainage system from underground sources. Pryor, 3
In quarrying, used to describe the condition of the base after a blast. It
may be a good or bad base fracture. Streefkerk
a. The lowest level to which a land surface can be eroded by running
water. Mather
b. To reduce by erosion to or toward a baselevel. Standard, 2
A baseleveled surface is any land surface, however small, that has been
brought approx. to a baselevel, either general or local, by the process of
gradation. When such a surface has considerable extent, it becomes a
baselevel plain. Syn:peneplain
A flat, comparatively featureless area or lowland, the elevation of which
cannot be materially reduced by the erosive force of running water.
AGI
a. A line taken as the foundation of operations in trigonometrical and
geological surveys. See also:base
b. A surveyed line established with more than usual care, that serves as a
reference to which surveys are coordinated and correlated.
See also:base
c. The initial measurement in triangulation, being an accurately measured
distance constituting one side of one of a series of connected triangles,
and used, together with measured angles, in computing the lengths of the
other sides. AGI
d. One of a pair of coordinate axes (the other being the principal
meridian) used in the U.S. Public Land Survey system. It consists of a
line extending east and west along the true parallel of latitude passing
through the initial point, along which standard township, section, and
quarter-section corners are established. AGI
e. An aeromagnetic profile flown at least twice in opposite directions and
at the same level, in order to establish a line of reference of magnetic
intensities on which to base an aeromagnetic survey. AGI
f. The center line of location of a railway or highway; the reference line
for the construction of a bridge or other engineering structure. Sometimes
spelled: baseline. AGI
a. A map on which information may be placed for purposes of comparison or
geographical correlation. Base map was at one time applied to a class of
maps now known as outline maps. It may be applied to topographic maps,
also termed "mother maps," that are used in the construction of many types
of maps by the addition of particular data. AGI
b. A map of any kind showing essential outlines necessary for adequate
geographic reference, on which additional or specialized information is
plotted for a particular purpose; esp. a topographic map on which geologic
information is recorded. AGI
In geology, an underlying complex that behaves as a unit mass and does not
deform by folding. AIME, 1
A series of rocks generally with complex structure beneath the dominantly
sedimentary rocks. In many places, these are igneous and metamorphic rocks
of either Early or Late Precambrian, but in some places these may be much
younger, as Paleozoic, Mesozoic, or even Cenozoic. See also:complex
Syn:fundamental complex
a. A name commonly applied to metamorphic or igneous rocks underlying the
sedimentary sequence. AGI
b. Metamorphic and igneous Precambrian rocks. AGI
a. Any of the more common and more chemically active metals, e.g., lead,
copper. AGI
b. The principal metal of an alloy, e.g., the copper in brass.
CF:noble metal
c. In plural form, a classification of metals usually considered to be of
low value and higher chemical activity when compared with the noble metals
(gold, silver, platinum, etc.). This nonspecific term generally refers to
the high-volume, low-value metals copper, lead, tin, and zinc.
d. The metal base to which a coating or plating is applied.
e. The chief constituent of a metal alloy; e.g., brass is a copper-base
alloy.
Ore in which gold is associated with sulfides, as contrasted to
free-milling ores, in which the sulfides have been removed by leaching.
Newton, 1