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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glimmerite (glim'-mer-ite). biotite rock.

ice 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.

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

zero-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.

delta 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).

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

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

trabecula [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.

independent variable . The situation in regression analysis and similar procedures where a variable y is treated as a function of other variables xi plus a random error The xi variables are independent and the y variable is the dependent variable. Cf: dependent variable.

saltation load . The part of the bed load that is bouncing along the stream bed or is moved, directly or indirectly, by the impact of bouncing particles.


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