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.


interradial [paleont] (in-ter-ra'-di-al). adj. Situated midway between the axes of adjacent rays of an echinoderm; e.g. an "interradial suture" representing a common line or division between adjacent radial plates of a blastoid. n. (a) A plate in the interradial area; e.g. a crinoid plate above a basal. (b) interray.

complex valley . A valley of which part may be parallel and part transverse to the general structure of the underlying strata. Term introduced by Powell (1874, p.50). Cf: simple valley; compound valley.

hexagonal-trapezohedral class (hex-ag'-o-nal-tra-pe''-zo-he'-dral). That crystal class in the hexagonal system having symmetry 622.

subcontinent (sub-con'-ti-nent). (a) A division or part of a continent having characteristics that distinguish it from the rest of the continent, e.g. the Indian subcontinent. This subdivision is typically based on geologic or geomorphic characteristics. (b) A large land mass, such as Greenland or Antarctica, that is smaller than any of the seven recognized continents.

high-frequency magnetics . Magnetic anomalies of shallow sedimentary origin, often <1 nT, seen in areas of deep magnetic basement. Possible sources include detrital magnetite, diagenetic magnetite, or other minerals possibly related to hydrocarbon microseepage, salt or anhydrite diamagnetism, or fault mineralization. Abbrev: HFMAG.

level trier . An apparatus for use in measuring the angular value of the divisions of a spirit level.

sadanagaite (sa-da-na'-ga-ite). A dark brown to black monoclinic member of the amphibole group: NaCa2(Fe2+3Fe3+2)(Si5Al3)O22(OH)2.

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marsh creek . A drainage channel developed on a salt marsh.

marsh creek . A drainage channel developed on a salt marsh.

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