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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smaragdite (sma-rag'-dite). A fibrous or thinly foliated green amphibole (near actinolite) pseudomorphous after pyroxene (such as omphacite) in rocks such as eclogite.

flood lavas . A term applied to the very large scale lava flows in flood basalt fields; also to extensive trachyte and phonolite flows described from the East African rift system (Cas and Wright, 1987). Cf: flood basalt.

tectonosphere (tec-ton'-o-sphere). The zone or layer of the Earth above the level of isostatic equilibrium, in which crustal or tectonic movements originate. Rarely used. Cf: crust [interior Earth].

edge water . The water around the margins of an oil pool or a gas pool. Cf: bottom water [petroleum]. Also spelled: edgewater.

sai . A term used in central Asia for a gravelly talus, a river bed filled with stones, and a dry wash (Stone, 1967, p.258); also for a piedmont plain covered with pebbles showing desert varnish (Termier and Termier, 1963, p.413).

Waipipian (Wai-pi-pi'-an). South Pacific stage: lower middle Pliocene (above Opoitian, below Mangapanian).

graphic [ign] (graph'-ic). Said of the texture of an igneous rock characterized by regular poikilitic intergrowth of triangular or linear-angular quartz grains within larger alkali feldspar grains. Similar intergrowths of other minerals, e.g. ilmenite-pyroxene, are less common. Syn: runic.

paleopedology . The study of paleosols or buried soils.

outwash drift . A deposit of outwash.

cat coal . Coal that contains pyrite.

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