GeoWord of the Day

The GeoWord of the Day is a free service of the American Geosciences Institute. All of the terms and definitions are from the Glossary of Geology, 5th Edition Revised.

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minipermeametry . Measurement of permeability of flat rock faces at the millimeter scale (Goggin, 1993).

auto-biotope . The total of all environments which one and the same taxonomic unit characteristically inhabits (van Morkhoven, 1966, p.306).

upper plane bed . A bed configuration under a unidirectional current that is characterized by a flat, almost featureless surface over which sediment transport is intense, both in suspension and on the bed. Some authors report very low, downstream migrating bed forms as being characteristic of this bed configuration (e.g., Best and Bridge, 1992). Current lineations are common on upper plane bed surfaces. Syn: upper flow regime plane bed; upper stage plane bed.

Tuttle lamellae (Tut'-tle). Planes of inclusions in quartz, oriented randomly rather than with reference to the enclosing crystal. Cf: Boehm lamellae.

strontianite (stron'-ti-an-ite''). A pale green, white, gray, or yellowish orthorhombic mineral of the aragonite group: SrCO3 .

catenary ripple . "A ripple is described as catenary if the trace of its crestline has the pattern of a chain of catenary waves, such that the more pointed segments of the crestline face downcurrent" (Allen, 1968, p.62-63). It differs from a lunate ripple in having lesser curvature of the crestline. Catenary ripples may be in or out of phase with the ripples immediately upstream or downstream.

Milazzian (Mi-laz'-zi-an). Obs. European stage: Upper Pleistocene (above Sicilian, below Tyrrhenian). See: Ionian .

banco (ban'-co). A term applied in Texas to the part of a stream channel or floodplain cut off and left dry by a change in the stream course; an oxbow lake. Etymol: Spanish, "sandbank, shoal, bench".

kësterite (kes'-ter-ite). A metallic greenish-black tetragonal mineral: Cu2(Zn,Fe)SnS4 . It is the zinc analogue of ferrokesterite. Also spelled: kesterite. Syn: isostannite.

character [seis] . A recognizable aspect of a sequence of seismic events (or waveforms) that distinguishes it from others. It is usually a frequency or phasing effect, and is often not defined precisely and hence is dependent on subjective judgment.

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