RFG 2018 Conference

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.

Subscribe via EMail to the GeoWord of the Day.

infiltration vein . An interstitial mineral deposit formed by the action of percolating waters. Cf: segregated vein.

culvert (cul'-vert). Any covered structure, not classified as a bridge, that constitutes a transverse drain, waterway, or other opening under a road, railroad, canal, or similar structure.

horse [struc geol] . A displaced block of rock that is bounded on all sides by faults.

tideland (tide'-land). (a) The coastal area that is alternately covered and uncovered by the ordinary daily tides; land that is covered by tidewater during a flood tide. (b) Land that underlies the ocean beyond the low-water mark, but within the territorial waters of a nation. The term is often used in the plural.

coombsite . A vitreous brown rhombohedral mineral: K(Mn2+,Fe2+,Mg)13(Si,Al)18O42(OH)14. It is an isotype of zussmannite.

compaction [soil] . (a) Any process, such as burial or desiccation, by which a soil mass loses pore space and becomes denser. (b) The densification of a soil by mechanical means, accomplished by rolling, tamping, or vibrating, usually at controlled water content. Cf: consolidation [eng].

aerosol (aer'-o-sol). A sol in which the dispersion medium is a gas (usually air) and the dispersed or colloidal phase consists of solid particles or liquid droplets; e.g. mist, haze, most smoke, and some fog.

division [sed] . A portion of a bed [geomorph] that is distinguished from other parts of the bed by the presence of a specific type of sedimentary structure (Blatt et al., 1980).

Rosiwal analysis (Ro'-si-wal). In petrography, a quantitative method of estimating the volume percentages of the minerals in a rock. Thin sections of a rock are examined with a microscope fitted with a micrometer which is used to measure the linear intercepts of each mineral along a particular set of lines. This method "is based on the assumption that the area of a mineral on an exposed surface is proportional to its volume in the rock mass" (Nelson and Nelson, 1967, p.320).

Rg wave . A slow, short-period Rayleigh wave that travels only along a nonoceanic path. The "g" refers to the granitic layer. Cf: Lg wave.


Subscribe to GeoWord of the Day