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triangular facet

triangular facet . As a physiographic feature, a triangular face having a broad base and an apex pointing upward; specif. the face on the end of a faceted spur, usually a remnant of a fault plane at the base of a block mountain. A triangular facet may also form by wave erosion of a mountain front or by glacial truncation of a spur. Syn: spur-end facet.

accordant

accordant (ac-cord'-ant). Said of topographic features that have the same or nearly the same elevation; e.g. an accordant valley whose stream enters the main stream at the same elevation as that of the main stream. Ant: discordant [geomorph].

Alluvial

Alluvial (Al-lu'-vi-al). A name, now obsolete, applied by Jameson (1808) from the teachings of A.G. Werner in the 1790's to the group or series of rocks consisting of unconsolidated or poorly consolidated gravels, sands, clays, and peat that were believed to have been formed after the withdrawal of the ocean from the continents. It constituted the fourth (following the Floetz ) of the divisions in which Werner placed the rocks of the geologic column. Syn: Tertiary.

gyrocone

gyrocone (gy'-ro-cone). A loosely coiled cephalopod shell in which the successive whorls are not in contact with each other, or in which only a single whorl is approximately completed. Also called: gyroceracone.

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.

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