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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GeoWord of the Dayclastic dike . A sedimentary dike consisting of a variety of clastic materials derived from underlying or overlying beds; esp. a sandstone dike or a pebble dike.

GeoWord of the Daysyngenite (syn'-ge-nite). A colorless, white, or pale yellow monoclinic mineral: K2Ca(SO4)2•H2O . It is the K analogue of koktaite.

GeoWord of the Dayglimmerite (glim'-mer-ite). biotite rock.

GeoWord of the Dayice cliff . Any vertical wall of ice; e.g. a very steep surface bounding a glacier or a mass of shelf ice. Less recommended syn: ice front; ice wall. Syn: ice face.

GeoWord of the Dayeurygeographic (eu''-ry-ge''-o-graph'-ic). Said of plant or animal species with wide geographic ranges. Cf: stenogeographic.

GeoWord of the Dayzero-order basin . An unchannelized upland valley that serves as a sediment storage site and may be important for debris-flow initiation. Cf: hollow; stream order.

GeoWord of the Daydelta diversity . The change in taxon diversity from geographic region to geographic region, arising from biotic provinciality. It is typically calculated as the ratio of epsilon to gamma diversity (Whittaker, 1972).

GeoWord of the Daybarrier [ecol] . A condition, such as a topographic feature or physical quality, that tends to prevent the free movement and mixing of populations or individuals.

GeoWord of the Daylikely (like'-ly). Said of a rock, lode, or belt of ground that gives indications of containing valuable minerals. Syn: kindly. Ant: hungry.

GeoWord of the Daytrabecula [paleont] . (a) A rod or pillar of radiating calcareous fibers forming a skeletal element in the structure of the septum and related components of a coral. See also: simple trabecula; compound trabecula. (b) A branch separating the fenestrae in reteporiform cheilostome bryozoans. (c) One of the individual anastomosing filaments of a hexactinellid sponge, which form a web in which the flagellated chambers are suspended and constitute the pinacoderm. Also, any rodlike or beamlike skeletal element of a sponge other than a ray or branch of a single spicule; esp. such a structure of sclerosome. (d) A tiny rodlike structure, smaller and less regular than a pillar, connecting layers of sclerite in holothurians. Pl: trabeculae.