artesian basin . A terrane, often but not necessarily basin-shaped, including an artesian aquifer whose potentiometric surface typically is above the land surface in the topographically lower portion of the terrane. Examples range in size from areas a few hundred feet across to several hundred miles across. Cf: groundwater basin.
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.
mature [geomorph] (ma-ture'). Pertaining to the hypothetical stage of maturity of the cycle of erosion; esp. said of a topography or region and of its landforms (such as a plain or plateau) that have undergone maximum development and accentuation of form; also, of a stream (and its valley) with a fully developed profile of equilibrium; or of a coast that is relatively stable.
corner frequency . (a) The frequency at which a graph of the logarithm of the amplitude of the frequency response has an abrupt change of slope. Syn: break frequency . (b) For a seismic wave generated from an earthquake, the frequency at which the spectral field begins to decrease. It is related theoretically to the dimensions or other properties of the source.
trapping temperature . In fluid inclusion geothermometry, the actual temperature at which a fluid inclusion was trapped in a mineral. Rarely determined directly; most commonly inferred by a pressure correction on the homogenization temperature using salinity corrected isochores and assuming constant volume of the inclusion.
cyanolith . An oncoid, or microbial biscuit , formed by calcified cyanophytes (blue-green algae) or cyanobacteria. Also called cyanoids (Riding, 1983).
schlieren arch . A term introduced by Balk (1937, p.56) for an intrusive igneous body with flow layers along its borders but poorly developed or absent in its interior. Cf: schlieren dome. Obsolete.
coalescing pediment . One of a series of expanding pediments that join to produce a continuous pediment surrounding a mountain range or that merge over a broad region to ultimately reduce a desert mountain mass to an approximately continuous level; one of a number of pediments that make up a pediplain.
schoderite (scho'-der-ite). A yellow or orange-yellow monoclinic mineral: Al2(PO4)(VO4)•8H2O .
fleet . (a) A term used in England for a small, shallow inlet, estuary, creek, or arm of the sea. Also, a place where water flows; a small rapid stream. (b) A small, usually salty or brackish lagoon behind the coastline, separated from the open sea by a long bank of sand or shingle parallel to the coast (Monkhouse, 1965, p.125).
lower flow regime . The flow regime of a unidirectional current that is characterized by relatively low sediment transport rates (largely as bed load ) and bed forms that are out of phase with the water surface, including ripple, dune, and lower plane bed; flow Froude number is less than unity (Simons and Richardson, 1961).
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