relief well . A well used to relieve excess hydrostatic pressure, as to reduce waterlogging of soil or to prevent blowouts on the land side of levees or dams at times of high water. Cf: drainage well.
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.
thorium-230/protactinium-231 deficiency method . Calculation of an age in years for fossil coral, shell, or bone 10,000 to 250,000 years old, based on the growth of uranium daughter products from uranium isotopes that enter the carbonate or phosphate material shortly after its formation or burial. The age depends on measurement of the thorium-230/uranium-234 and protactinium-231/uranium-235 activity ratios, which vary with time. See also: uranium-series age method; ionium-deficiency method.
pseudolagoon (pseu''-do-la-goon'). The shallow pool of water encircled by a pseudoatoll. Syn: miniature lagoon.
ferruginous (fer-ru'-gi-nous). (a) Pertaining to or containing iron, e.g. a sandstone that is cemented with iron oxide. Cf: ferriferous; siderose. (b) Said of a rock having a red or rusty color due to the presence of ferric oxide (the quantity of which may be very small).
pseudomorphism (pseu-do-mor'-phism). The process of becoming, and the condition of being, a pseudomorph.
liandratite (li-an'-dra-tite). A yellow to yellowish-brown metamict mineral that converts to a rhombohedral form on heating: U6+(Nb,Ta)2O8 .
para-alumohydrocalcite (par''-a-a-lu''-mo-hy''-dro-cal'-cite). A white mineral: CaAl2(OH)4(CO3)2•6H2O. It is a higher hydrate of alumohydrocalcite.
lava-inflation cleft . A deep axial or star-shaped crack characteristic of tumulus , commonly invaded by squeeze-ups (Walker, 1991).
floating peat . Peat that is derived from floating plants.
nodal (nod'-al). A crinoid columnal that is generally larger than adjacent columnals and that commonly bears cirri.
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