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plug [drill]

plug [drill] . n. A watertight or gastight seal, such as an interval of cement or a bridge plug, installed in a borehole or well to prevent movement of fluids. v. To set a plug in a borehole; to fill in or seal off fractures, cavities, or other pores in the walls of a borehole.

peak-ring crater

peak-ring crater . A complex impact crater with a central mountainous ring, instead of a central peak, surrounding its center. Peak-ring craters are generally larger than central-peak craters on a given planet or satellite. The radial profile of the ring is roughly symmetric, as opposed to that of a multi-ring crater.

azonal soil

azonal soil . In the 1938 soil-classification system, one of the three soil orders. Azonal soils lack distinct genetic horizons and resemble the parent material (USDA, 1938). Not used in current U.S. system of soil taxonomy. Cf: intrazonal soil; zonal soil; Entisols. Syn: immature soil.

underconsolidation

underconsolidation (un''-der-con-sol''-i-da'-tion). Consolidation (of sedimentary material) less than that normal for the existing overburden; e.g. consolidation resulting from deposition that is too rapid to give time for complete settling. Ant: overconsolidation.

geologic age

geologic age . (a) The age of a fossil organism or of a particular geologic event or feature referred to the geologic time scale and expressed in terms either of years or centuries ( absolute age ) or of comparison with the immediate surroundings ( relative age ); an age datable by geologic methods. (b) The term is also used to emphasize the long-past periods of time in geologic history, as distinct from present-day or historic times. Cf: age [geochron].

glance pitch

glance pitch . A variety of asphaltite with a brilliant conchoidal fracture, sometimes called manjak. It is similar to gilsonite, but has a higher specific gravity and fixed-carbon content. It fuses between 230°F and 250°F.

parataxon

parataxon (par-a-tax'-on). An informal designation for those fossilized remains, esp. of animals, that are only part of the whole individual and that usually occur widely separated from other parts; e.g. a particular conodont element. Cf: form genus. See also: taxon.

flood lavas

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.

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