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.

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postabdomen (post-ab'-do-men). (a) The slender, attenuated posterior part of the abdomen of a scorpion, composed of five segments and a telson modified as a poison gland; the narrow posterior part of the abdomen of a merostome. (b) The telson of a crustacean. (c) A joint succeeding the third segment (abdomen) of the shell of a nassellarian radiolarian.

anthill (ant'-hill). A common term for termitarium.

clastic 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.

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

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.


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