gas chromatography . A process for separating gases or vapors from one another by passing them over a solid ( gas-solid chromatography ) or liquid ( gas-liquid chromatography ) phase. The gases are repeatedly adsorbed and released at differential rates resulting in separation of their components. Abbrev: GC. See also: liquid chromatography; chromatography.
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.
kostovite (kos'-tov-ite). A metallic creamy-white orthorhombic mineral: CuAuTe4 .
retention (re-ten'-tion). The amount of water from precipitation that has not escaped as runoff or through evapotranspiration; "the difference between total precipitation and total runoff on a drainage area" (Nelson and Nelson, 1967).
matteuccite (mat-te-uc'-cite). A white monoclinic mineral: NaHSO4•H2O .
wineglass valley (wine'-glass). A valley resembling in plan view a goblet or champagne glass. It flares broadly open at its upper end, where it has a cup-shaped or funnel-shaped head; narrows sharply to form a constricted lower section; and flares open again on a spreading alluvial fan. The valley commonly forms at right angles to a fault scarp in an arid region. Syn: goblet valley; hourglass valley.
biocorrelation (bi''-o-cor''-re-la'-tion). Biostratigraphic correlation. Demonstration of similarity of fossil content and biostratigraphic position between geologic units (NACSN, 1983, p.851). Cf: lithologic correlation; chronocorrelation.
Geodimeter (Ge-o-dim'-e-ter). Trade name of an electronic-optical device that measures ground distances precisely by electronic timing and phase comparison of modulated light waves that travel from a master unit to a reflector and return to a light-sensitive tube where an electric current is set up. It is normally used at night and is effective with first-order accuracy up to distances of 5-40 km (3-25 miles). Etymol: acronym for geo detic- di stance meter.
debris cone [geomorph] . (a) alluvial cone. (b) A conical mound of tightly packed, fine-grained debris piled at the angle of repose atop certain boulders moved by a landslide.
stenoplastic (sten-o-plas'-tic). Having limited capacity for modification and adaptation to new environmental conditions; incapable of major evolutionary differentiation. Cf: euryplastic.
vastitas (vas'-ti-tas). A term established by the International Astronomical Union for an extensive plain on Mars (USGS, 2003). Used as part of a formal name for a Martian landform, such as Vastitas Borealis (Mutch, et al., 1976, p.57). Etymol: Latin "vastus", empty, immense. Pl: vastitates.
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