Baixe Dictionary of Geology e outras Notas de estudo em PDF para Geologia, somente na Docsity! DICTIONARY OF E GroLogy & k y MORE THAN 9,000 ESSENTIAL TERMAS COVERS EVERY DISCIPLINE OF GEOLOGT & MINERALOGY McGraw-Hill Dictionary of Geology and Mineralogy Second Edition McGraw-Hill New York Chicago San Francisco Lisbon London Madrid Mexico City Milan New Delhi San Juan Seoul Singapore Sydney Toronto Downloaded from : iDATA.ws How to Use the Dictionary ALPHABETIZATION. The terms in the McGraw-Hill Dictionary of Geology and Mineralogy, Second Edition, are alphabetized on a letter-by-letter basis; word spacing, hyphen, comma, solidus, and apostrophe in a term are ignored in the sequencing. For example, an ordering of terms would be: abnormal fold acre-yield a-b plane Agassiz orogeny ACF diagram Age of Fishes FORMAT. The basic format for a defining entry provides the term in boldface, the field is small capitals, and the single definition in lightface: term [FIELD] Definition. A field may be followed by multiple definitions, each introduced by a bold- face number: term [FIELD] 1. Definition. 2. Definition. 3. Definition. A simple cross-reference entry appears as: term See another term. A cross reference may also appear in combination with definitions: term [FIELD] 1. Definition. 2. See another term. CROSS REFERENCING. A cross-reference entry directs the user to the defining entry. For example, the user looking up “abyssal” finds: abyssal See plutonic. The user then turns to the “P” terms for the definition. Cross references are also made from variant spellings, acronyms, abbreviations, and symbols. aenigmatite See enigmatite. aggradation See accretion. barkhan See barchan. ALSO KNOWN AS . . . , etc. A definition may conclude with a mention of a synonym of the term, a variant spelling, an abbreviation for the term, or other such information, introduced by “Also known as . . . ,” “Also spelled . . . ,” “Abbreviated . . . ,” “Symbolized . . . ,” “Derived from . . . .” When a term has vii Downloaded from : iDATA.ws more than one definition, the positioning of any of these phrases conveys the extent of applicability. For example: term [FIELD] 1. Definition. Also known as synonym. 2. Definition. Symbolized T. In the above arrangement, “Also known as . . .” applies only to the first defini- tion; “Symbolized . . .” applies only to the second definition. term [FIELD] Also known as synonym. 1. Definition. 2. Definition. In the above arrangement, “Also known as . . .” applies to both definitions. MINERAL FORMULAS. Mineral definitions may include a formula indicat- ing the composition. viii Downloaded from : iDATA.ws Fields and Their Scope [GEOCHEM] geochemistry—The field that encompasses the investigation of the chemical composition of the earth, other planets, and the solar system and universe as a whole, as well as the chemical processes that occur within them. [GEOL] geology—The study or science of earth, its history, and its life as recorded in the rocks; includes the study of the geologic features of an area, such as the geometry of rock formations, weathering and erosion, and sedimentation. [GEOPHYS] geophysics—The branch of geology in which the principles and practices of physics are used to study the earth and its environment, that is, earth, air, and (by extension) space. [MINERAL] mineralogy—The study of naturally occurring inorganic sub- stances, called minerals, whether of terrestrial or extraterrestrial origin. [PALEOBOT] paleobotany—The study of fossil plants and vegetation of the geologic past. [PALEON] paleontology—The study of life in the geologic past as recorded by fossil remains. [PETR] petrology—The branch of geology dealing with the origin, occurrence, structure, and history of rocks, especially igneous and metamorphic rocks. ix Downloaded from : iDATA.ws Contents Preface ................................................................................................................. v Staff ...................................................................................................................... vi How to Use the Dictionary ........................................................................... vii Fields and Their Scope .................................................................................. ix Pronunciation Key ............................................................................................ x Dictionary .................................................................................................... 1-404 Appendix .................................................................................................. 405-421 Equivalents of commonly used units for the U.S. Customary System and the metric system .................................... 407 Conversion factors for the U.S. Customary System, metric system, and International System ...................................... 408 Periodic table ......................................................................................... 412 Principal regions of a standard earth model ..................................... 413 Physical properties of some common rocks ...................................... 413 Approximate concentration of ore elements in earth’s crust and in ores ............................................................................... 414 Elemental composition of earth’s crust based on igneous and sedimentary rock ........................................................ 414 Some historical volcanic eruptions ..................................................... 415 Compositions of important rock types in the earth’s crust and the average continental crust ........................................ 416 Dental formulas of some mammals ................................................... 417 Geologic column and scale of time .................................................... 418 Types of volcanic structure ................................................................... 419 Mohs scale ............................................................................................. 419 Hardness, specific gravity, and refractive indices of gem materials ............................................................................... 420 Downloaded from : iDATA.ws A aa channel [GEOL] A narrow, sinuous channel in which a lava river moves down and away from a central vent to feed an aa lava flow. { ää chanəl } aa lava See block lava. { ää lävə } Aalenian [GEOL] Lowermost Middle or uppermost Lower Jurassic geologic time. { ȯlēnēən } a axis [GEOL] The direction of movement or transport in a tectonite. { ā aksis } abandoned channel See oxbow. { əbandənd chanəl } ABC system [GEOPHYS] A procedure in seismic surveying to determine the effect of irregular weathering thickness. { ābēsē sistəm } ablation [GEOL] The wearing away of rocks, as by erosion or weathering. { əblāshən } ablation moraine [GEOL] 1. A layer of rock particles overlying ice in the ablation of a glacier. 2. Drift deposited from a superglacial position through the melting of underlying stagnant ice. { əblāshən mərān } abnormal anticlinorium [GEOL] An anticlinorium with axial planes of subsidiary folds diverging upward. { abnȯrməl ¦antəklinȯrēəm } abnormal fold [GEOL] An anticlinorium in which there is an upward convergence of the axial surfaces of the subsidiary folds. { abnȯrməl fōld } abnormal magnetic variation [GEOPHYS] The anomalous value in magnetic compass readings made in some local areas containing unknown sources that deflect the compass needle from the magnetic meridian. { abnȯrməl magnedik verēā shən } abnormal synclinorium [GEOL] A synclinorium with axial planes of subsidiary folds converging downward. { abnȯrməl ¦sinklinȯrēəm } a-b plane [GEOL] The surface along which differential movement takes place. { ā¦bē plān } abrade [GEOL] To wear away by abrasion or friction. { əbrād } abrasion [GEOL] Wearing away of sedimentary rock chiefly by currents of water laden with sand and other rock debris and by glaciers. { əbrāzhən } abrasion platform [GEOL] An uplifted marine peneplain or plain, according to the smoothness of the surface produced by wave erosion, which is of large area. { əbrā zhən platfȯrm } abrasive [GEOL] A small, hard, sharp-cornered rock fragment, used by natural agents in abrading rock material or land surfaces. Also known as abrasive ground. { əbrāsəv } absarokite [PETR] An alkalic basalt of about equal portions of olivine, augite, labrador- ite, and sanidine with accessory biotite, apatite, and opaque oxides; leucite is occa- sionally present in small amounts. { absärəkı̄t } absolute age [GEOL] The geologic age of a fossil, or a geologic event or structure expressed in units of time, usually years. Also known as actual age. { absəlüt āj } absolute geopotential topography See geopotential topography. { absəlüt jēō pətenshəl təpägrəfē } absolute time [GEOL] Geologic time measured in years, as determined by radioactive decay of elements. { absəlüt tı̄m } Abukuma-type facies [PETR] A type of dynathermal regional metamorphism character- ized by low pressure. { abəkümə tı̄p fāshēz } Downloaded from : iDATA.ws abundance abundance [GEOCHEM] The relative amount of a given element among other elements. { əbəndəns } abyssal See plutonic. { əbisəl } abyssal cave See submarine fan. { əbisəl kāv } abyssal fan See submarine fan. { əbisəl fan } abyssal floor [GEOL] The ocean floor, or bottom of the abyssal zone. { əbisəl flȯr } abyssal gap [GEOL] A gap in a sill, ridge, or rise that lies between two abyssal plains. { əbisəl gap } abyssal hill [GEOL] A hill 2000 to 3000 feet (600 to 900 meters) high and a few miles wide within the deep ocean. { əbisəl hil } abyssal injection [GEOL] The process of driving magmas, originating at considerable depths, up through deep-seated contraction fissures in the earth’s crust. { əbisəl injekshən } abyssal plain [GEOL] A flat, almost level area occupying the deepest parts of many of the ocean basins. { əbisəl plān } abyssal rock [GEOL] Plutonic, or deep-seated, igneous rocks. { əbisəl räk } abyssal theory [GEOL] A theory of the origin of ores involving the separation of ore silicates from the liquid stage during the cooling of the earth. { əbisəl thēərē } abyssolith [GEOL] A molten mass of eruptive material passing up without a break from the zone of permanently molten rock within the earth. { əbisōlith } Acadian orogeny [GEOL] The period of formation accompanied by igneous intrusion that took place during the Middle and Late Devonian in the Appalachian Mountains. { əkādēən ȯräjənē } acanthite [MINERAL] Ag2S A blackish to lead-gray silver sulfide mineral, crystallizing in the orthorhombic system. { əkanthı̄t } Acanthodes [PALEON] A genus of Carboniferous and Lower Permian eellike acanthod- ian fishes of the family Acanthodidae. { əkanthōdēz } Acanthodidae [PALEON] A family of extinct acanthodian fishes in the order Acanthodi- formes. { əkanthōdədē } Acanthodiformes [PALEON] An order of extinct fishes in the class Acanthodii having scales of acellular bone and dentine, one dorsal fin, and no teeth. { əkanthō dəfȯrmēz } Acanthodii [PALEON] A class of extinct fusiform fishes, the first jaw-bearing vertebrates in the fossil record. { əkanthōdēı̄ } acanthopore [PALEON] A tubular spine in some fossil bryozoans. { əkanthəpȯr } acaustobiolith [PETR] A noncombustible organic rock, or one formed by organic accu- mulation of minerals. { ¦ākȯstəbı̄əlith } acaustophytolith [PETR] An acaustobiolith resulting from plant activity, such as a pelagic ooze that contains diatoms. { ¦ākȯstəfı̄dəlith } accelerated erosion [GEOL] Soil erosion that occurs more rapidly than soil horizons can form from the parent regolith. { akselərādəd irōzhən } acceptable risk [GEOPHYS] In seismology, that level of earthquake effects which is judged to be of sufficiently low social and economic consequence, and which is useful for determining design requirements in structures or for taking certain actions. { ak¦septəbəl risk } accessory ejecta [GEOL] Pyroclastic material formed from solidified volcanic rocks that are from the same volcano as the ejecta. { aksesərē ijektə } accessory element See trace element. { aksesərē eləmənt } accessory mineral [MINERAL] A minor mineral in an igneous rock that does not affect its general character. { aksesərē minrəl } accidental ejecta [GEOL] Pyroclastic rock formed from preexisting nonvolcanic rocks or from volcanic rocks unrelated to the erupting volcano. { ¦aksə¦dentəl ijektə } accidental inclusion See xenolith. { ¦aksə¦dentəl inklüzhən } accident block [GEOL] A solid chip of rock broken off from the subvolcanic basement and ejected from a volcano. { aksədent bläk } acclivity [GEOL] A slope that is ascending from a reference point. { əklivədē } 2 Downloaded from : iDATA.ws aerosiderite yellow, or light green orthorhombic mineral consisting of a basic arsenate of calcium and magnesium; usually occurs in massive form. { adəlı̄t } ader wax See ozocerite. { ädər waks } adiagnostic [PETR] Pertaining to a rock texture in which identification of individual components is not possible macroscopically or microscopically; applied especially to igneous rock. { ¦ādı̄əgnästik } adinole [GEOL] An argillaceous sediment that has undergone albitization at the margin of a basic intrusion. { adənōl } adipocerite See hatchettite. { adəpäsərı̄t } adipocire See hatchettite. { adəpäsir } admixture [GEOL] One of the lesser or subordinate grades of sediment. { ¦ad¦miks chər } adobe [GEOL] Heavy-textured clay soil found in the southwestern United States and in Mexico. { ədōbē } adobe flats [GEOL] Broad flats that are floored with sandy clay and have been formed from sheet floods. { ədōbē flats } adolescence [GEOL] Stage in the cycle of erosion following youth and preceding matu- rity. { adəlesəns } adolescent coast [GEOL] A type of shoreline characterized by low but nearly continuous sea cliffs. { adəlesənt kōst } adularia [MINERAL] A weakly triclinic form of the mineral orthoclase occurring in trans- parent, colorless to milky-white pseudo-orthorhombic crystals. { ajəlarēə } adularization [GEOL] Replacement by or introduction of the mineral adularia. { əjül ərəzāshən } advance [GEOL] 1. A continuing movement of a shoreline toward the sea. 2. A net movement over a specified period of time of a shoreline toward the sea. { ədvans } adventive cone [GEOL] A volcanic cone that is on the flank of and subsidiary to a larger volcano. Also known as lateral cone; parasitic cone. { adventiv kōn } adventive crater [GEOL] A crater opened on the flank of a large volcanic cone. { adventiv krātər } Aechminidae [PALEON] A family of extinct ostracodes in the order Paleocopa in which the hollow central spine is larger than the valve. { ēkminədē } Aeduellidae [PALEON] A family of Lower Permian palaeoniscoid fishes in the order Palaeonisciformes. { ēdüelədı̄ } aegirine [MINERAL] NaFe(SiO3)2 A brown or green clinopyroxene occurring in alkali- rich igneous rocks. Also known as aegirite. { āgərēn } aegirite See aegirine. { āgərı̄t } Aegyptopithecus [PALEON] A primitive primate that is thought to represent the com- mon ancestor of both the human and ape families. { əjiptōpithekəs } aenigmatite See enigmatite. { ənigmətı̄t } Aepyornis [PALEON] A genus of extinct ratite birds representing the family Aepyornithi- dae. { ēpēȯrnəs } Aepyornithidae [PALEON] The single family of the extinct avian order Aepyornithi- formes. { ēpēȯrnithədē } Aepyornithiformes [PALEON] The elephant birds, an extinct order of ratite birds in the superorder Neognathae. { ēpēȯrnithəfȯrmēz } aerogeology [GEOL] The geologic study of earth features by means of aerial observa- tions and aerial photography. { erōjēäləjē } aerohydrous mineral [MINERAL] A mineral containing water in small cavities. { ¦e rō¦hı̄drəs minrəl } aerolite See stony meteorite. { erōlı̄t } aeromagnetic surveying [GEOPHYS] The mapping of the magnetic field of the earth through the use of electronic magnetometers suspended from aircraft. { erō magnedik sərvāiŋ } aeropalynology [PALEOBOT] A branch of palynology that focuses on the study of pollen grains and spores that are dispersed into the atmosphere. { erōpalənäləjē } aerosiderite [GEOL] A meteorite composed principally of iron. { erōsı̄dərı̄t } 5 Downloaded from : iDATA.ws affine deformation affine deformation [GEOL] A type of deformation in which very thin layers slip against each other so that each moves equally with respect to its neighbors; generally does not result in folding. { əfı̄n dēfȯrmāshən } affine strain [GEOPHYS] A strain in the earth that does not differ from place to place. { əfı̄n strān } African superplume [GEOPHYS] A large, discrete, slowly rising plume of heated material in the earth’s mantle, beneath southern Africa, believed by some to contribute to the movement of tectonic plates. { ¦afrikən süpərplüm } aftershock [GEOPHYS] A small earthquake following a larger earthquake and originating at or near the larger earthquake’s epicenter. { aftərshäk } Aftonian interglacial [GEOL] Post-Nebraska interglacial geologic time. { aftonēən intərglāshəl } afwillite [MINERAL] Ca3Si2O4(OH)6 A colorless mineral consisting of a hydrous calcium silicate and occurring in monoclinic crystals; specific gravity is 2.6. { afwəlı̄t } agalite [MINERAL] A mineral with the same composition as talc but with a less soapy feel; used as a filler in writing paper. { agəlı̄t } agalmatolite [GEOL] A soft, waxy, gray, green, yellow, or brown mineral or stone, such as pinite and steatite; used by the Chinese for carving images. Also known as figure stone; lardite; pagodite. { agəlmadəlı̄t } agaric mineral See rock milk. { əgarik minrəl } Agassiz orogeny [GEOL] A phase of diastrophism confined to North America Cordillera occurring at the boundary between the Middle and Late Jurassic. { agəsē ȯräj ənē } Agassiz Valleys [GEOL] Undersea valleys in the Gulf of Mexico between Cuba and Key West. { agəsē valēz } agate [MINERAL] SiO2 A fine-grained, fibrous variety of chalcedony with color banding or irregular clouding. { agət } agate jasper [MINERAL] An impure variety of quartz consisting of jasper and agate. Also known as jaspagate. { agət jaspər } agatized wood See silicified wood. { agətı̄zd wu̇d } age [GEOL] 1. Any one of the named epochs in the history of the earth marked by specific phases of physical conditions or organic evolution, such as the Age of Mammals. 2. One of the smaller subdivisions of the epoch as geologic time, corres- ponding to the stage or the formation, such as the Lockport Age in the Niagara Epoch. { āj } aged [GEOL] Of a ground configuration, having been reduced to base level. { ājəd } age determination [GEOL] Identification of the geologic age of a biological or geologi- cal specimen by using the methods of dendrochronology or radiometric dating. { āj ditərmənāshən } aged shore [GEOL] A shore long established at a constant level and adjusted to the waves and currents of the sea. { ājəd shȯr } Age of Fishes [GEOL] An informal designation of the Silurian and Devonian periods of geologic time. { āj əv fishəz } Age of Mammals [GEOL] An informal designation of the Cenozoic era of geologic time. { āj əv maməlz } Age of Man [GEOL] An informal designation of the Quaternary period of geologic time. { āj əv man } age ratio [GEOL] The ratio of the amount of daughter to parent isotope in a mineral being dated radiometrically. { āj rāshō } agglomerate [GEOL] A pyroclastic rock composed of angular rock fragments in a matrix of volcanic ash; typically occurs in volcanic vents. { əglämərət } agglutinate cone See spatter cone. { əglütənāt kōn } aggradation See accretion. { agrədāshən } aggradation recrystallization [GEOL] Recrystallization resulting in the enlargement of crystals. { agrədāshən rēkristələzāshən } aggraded valley floor [GEOL] The surface of a flat deposit of alluvium which is thicker 6 Downloaded from : iDATA.ws Aistopoda than the stream channel’s depth and is formed where a stream has aggraded its valley. { əgrādəd valē flȯr } aggraded valley plain See alluvial plain. { əgrādəd valē plān } aggregate [GEOL] A collection of soil grains or particles gathered into a mass. { ag rəgət } aggregate structure [GEOL] A mass composed of separate small crystals, scales, and grains that, under a microscope, extinguish at different intervals during the rotation of the stage. { agrəgət strəkchər } aggressive magma [GEOL] A magma that forces itself into place. { əgresiv mag mə } Aglaspida [PALEON] An order of Cambrian and Ordovician merostome arthropods in the subclass Xiphosurida characterized by a phosphatic exoskeleton and vaguely trilobed body form. { əglaspədə } agmatite [PETR] 1. A migmatite that contains xenoliths. 2. Fragmental plutonic rock with granitic cement. { agmətı̄t } agonic line [GEOPHYS] The imaginary line through all points on the earth’s surface at which the magnetic declination is zero; that is, the locus of all points at which magnetic north and true north coincide. { āgänik lı̄n } agravic [GEOPHYS] Of or pertaining to a condition of no gravitation. { āgravik } agpaite [PETR] A group of igneous rocks containing feldspathoids; includes naujaite, lujavrite, and kakortokite. { agpəı̄t } agricere [GEOL] A waxy or resinous organic coating on soil particles. { agrəsir } agricolite See eulytite. { əgrikəlı̄t } agricultural geology [GEOL] A branch of geology that deals with the nature and distri- bution of soils, the occurrence of mineral fertilizers, and the behavior of underground water. { ¦agrə¦kəlchərəl jēäləjē } Agriochoeridae [PALEON] A family of extinct tylopod ruminants in the superfamily Merycoidodontoidea. { agrēōkirədē } aguilarite [MINERAL] Ag4SeS An iron-black mineral associated with argentite and silver in Mexico. { ägəlärı̄t } ahlfeldite [MINERAL] (Ni,Co)SeO32H2O A triclinic mineral identified as green to yellow crystals with a reddish-brown coating, consisting of a hydrous selenite of nickel. { älfeldı̄t } aiguille [GEOL] The needle-top of the summit of certain glaciated mountains, such as near Mont Blanc. { āgwēl } aikinite [MINERAL] PbCuBiS3 A mineral crystallizing in the orthorhombic system and occurring massive and in gray needle-shaped crystals; hardness is 2 on Mohs scale, and specific gravity is 7.07. Also known as needle ore. { ākənı̄t } ailsyte [PETR] An alkalic microgranite containing a considerable amount of riebeckite. Also known as paisanite. { ālsı̄t } air current [GEOPHYS] See air-earth conduction current. { er kərənt } air gap See wind gap. { er gap } air heave [GEOL] Deformation of plastic sediments on a tidal flat as a result of the growth of air pockets in them; the growth occurs by accretion of smaller air bubbles oozing through the sediment. { er hēv } air sac See vesicle. { er sak } air shooting [GEOPHYS] In seismic prospecting, the technique of applying a seismic pulse to the earth by detonating a charge or charges in the air. { er shüdiŋ } air volcano [GEOL] An eruptive opening in the earth from which large volumes of gas emanate, in addition to mud and stones; a variety of mud volcano. { ¦er väl¦kānō } Airy isostasy [GEOPHYS] A theory of hydrostatic equilibrium of the earth’s surface which contends that mountains are floating on a fluid lava of higher density, and that higher mountains have a greater mass and deeper roots. { ¦erē isästəsē } Aistopoda [PALEON] An order of Upper Carboniferous amphibians in the subclass Lepospondyli characterized by reduced or absent limbs and an elongate, snakelike body. { āəstäpədə } 7 Downloaded from : iDATA.ws alkali flat feldspar, such as orthoclase, microcline, albite, and anorthoclase; all are considered alkali-rich. { alkəlı̄ feldspar } alkali flat [GEOL] A level lakelike plain formed by the evaporation of water in a depres- sion and deposition of its fine sediment and dissolved minerals. { alkəlı̄ flat } alkali-lime index [PETR] The percentage by weight of silica in a sequence of igneous rocks on a variation diagram where the weight percentages of CaO and of K2O and Na2O are equal. { alkəlı̄ lı̄m indeks } alkaline soil [GEOL] Soil containing soluble salts of magnesium, sodium, or the like, and having a pH value between 7.3 and 8.5. { alkəlı̄n sȯil } alkali soil [GEOL] A soil, with salts injurious to plant life, having a pH value of 8.5 or higher. { alkəlı̄ sȯil } alkenones [GEOL] Long-chain (37–39 carbon atoms) di-, tri-, and tetraunsaturated methyl and ethyl ketones produced by certain phytoplankton (coccolithophorids), which biosynthetically control the degree of unsaturation (number of carbon-carbon double bonds) in response to the water temperature; the survival of this temperature signal in marine sediment sequences provides a temporal record of sea surface temperatures that reflect past climates. { alkənōnz } allactite [MINERAL] Mn7(AsO4)2(OH)8 A brownish-red mineral consisting of a basic man- ganese arsenate. { əlaktı̄t } allalinite [PETR] An altered gabbro with original texture and euhedral pseudomorphs. { əlalənı̄t } allanite [MINERAL] (Ca,Ce,La,Y)2(Al,Fe)3Si3O12(OH) Monoclinic mineral distinguished from all other members of the epidote group of silicates by a relatively high content of rare earths. Also known as bucklandite; cerine; orthite; treanorite. { alənı̄t } allcharite [MINERAL] A lead gray mineral, supposed to be a lead arsenic sulfide and known only crystallographically as orthorhombic crystals. { ȯlkərı̄t } alleghanyite [MINERAL] Mn5(SiO4)2(OH)2 A pink mineral consisting of basic manganese silicate. { ¦alə¦gānēı̄t } Alleghenian [GEOL] Lower Middle Pennsylvanian geologic time. { ¦alə¦gānēən } Alleghenian orogeny [GEOL] Pennsylvanian and Early Permian orogenic episode which deformed the rocks of the Appalachian Valley and the Ridge and Plateau provinces. { ¦alə¦gānēən ȯräjənē } allemontite [MINERAL] AsSb Rhombohedric, gray or reddish, native antimony aresenide occurring in reniform masses. Also known as arsenical antimony. { aləmäntı̄t } Allende meteorite [GEOL] A meteorite that fell in Mexico in 1969 and contains inclu- sions that have been radiometrically dated at 4.56 109 years, the oldest found so far, presumably indicating the time of formation of the first solid bodies in the solar system. { ai¦yende mēdēərı̄t } allevardite See rectorite. { aləvärdı̄t } allivalite [PETR] A form of gabbro composed of anorthite and olivine; accessories are augite, apatite, and opaque iron oxides. { aləvəlı̄t } allochem [GEOL] Sediment formed by chemical or biochemical precipitation within a depositional basin; includes intraclasts, oolites, fossils, and pellets. { alōkem } allochemical metamorphism [PETR] Metamorphism accompanied by addition or removal of material so that the bulk chemical composition of the rock is changed. { alōkeməkəl medəmȯrfizəm } allochetite [PETR] A porphyritic igneous rock composed of phenocrysts of labradorite, orthoclase, titanaugite, nepheline, magnetite, and apatite in a groundmass of augite, biotite, magnetite, hornblende, nepheline, and orthoclase. { aləkedı̄t } allochthon [GEOL] A rock that was transported a great distance from its original deposi- tion by some tectonic process, generally related to overthrusting, recumbent folding, or gravity sliding. { əläkthən } allochthonous [PETR] Of rocks whose primary constituents have not been formed in situ. { əläkthənəs } allochthonous coal [GEOL] A type of coal arising from accumulations of plant debris moved from their place of growth and deposited elsewhere. { əläkthənəs kōl } 10 Downloaded from : iDATA.ws alluvion allogene [GEOL] A mineral or rock that has been moved to the site of deposition. Also known as allothigene; allothogene. { aləjēn } allogenic See allothogenic. { ¦alə¦jenik } allomorphism See paramorphism. { aləmȯrfizəm } allomorphite [MINERAL] A mineral consisting of barite that is pseudomorphous after anhydrite. { aləmȯrfı̄t } allophane [GEOL] Al2O3SiO2nH2O A clay mineral composed of hydrated aluminosili- cate gel of variable composition; P2O5 may be present in appreciable quantity. { aləfān } Allosaurus [PALEON] A carnivorous therapod dinosaur, 40 feet (12 meters) long, and weighing 1.5 tons, from the Late Jurassic Period that had muscular hindlimbs, small forelimbs (with three-fingered hands), and sharp teeth; similar to but smaller than Tyrannosaurus. { aləsȯrəs } Allotheria [PALEON] A subclass of Mammalia that appeared in the Upper Jurassic and became extinct in the Cenozoic. { alōthirēə } allothigene See allogene. { əläthəjēn } allothimorph [GEOL] A metamorphic rock constituent which retains its original crystal outlines in the new rock. { əläthəmȯrf } allothogene See allogene. { əläthəjēn } allothogenic [GEOL] Formed from preexisting rocks which have been transported from another location. Also known as allogenic. { ə¦läthə¦jenik } allotrioblast See xenoblast. { alətrēəblast } allotriomorphic [MINERAL] Of minerals in igneous rock not bounded by their own crystal faces but having their outlines impressed on them by the adjacent minerals. Also known as anhedral; xenomorphic. { ə¦lätrēə¦mȯrfik } alluvial [GEOL] 1. Of a placer, or its associated valuable mineral, formed by the action of running water. 2. Pertaining to or consisting of alluvium, or deposited by running water. { əlüvēəl } alluvial cone [GEOL] An alluvial fan with steep slopes formed of loose material washed down the slopes of mountains by ephemeral streams and deposited as a conical mass of low slope at the mouth of a gorge. Also known as cone delta; cone of dejection; cone of detritus; debris cone; dry delta; hemicone; wash. { əlüvēəl kōn } alluvial dam [GEOL] A sedimentary deposit which is built by an overloaded stream and dams its channel; especially characteristic of distributaries on alluvial fans. { əlüvēəl dam } alluvial deposit See alluvium. { əlüvēəl dipäzət } alluvial fan [GEOL] A fan-shaped deposit formed by a stream either where it issues from a narrow moutain valley onto a plain or broad valley, or where a tributary stream joins a main stream. { əlüvēəl fan } alluvial flat [GEOL] A small alluvial plain having a slope of about 5 to 20 feet per mile (1.5 to 6 meters per 1600 meters) and built of fine sandy clay or adobe deposited during flood. { əlüvēəl flat } alluvial ore deposit [GEOL] A deposit in which the valuable mineral particles have been transported and left by a stream. { əlüvēəl ¦ȯr di¦päzət } alluvial plain [GEOL] A plain formed from the deposition of alluvium usually adjacent to a river that periodically overflows. Also known as aggraded valley plain; river plain; wash plain; waste plain. { əlüvēəl plān } alluvial slope [GEOL] A surface of alluvium which slopes down from mountainsides and merges with the plain or broad valley floor. { əlüvēəl slōp } alluvial soil [GEOL] A soil deposit developed on floodplain and delta deposits. { əlüv ēəl sȯil } alluvial terrace [GEOL] A terraced embankment of loose material adjacent to the sides of a river valley. Also known as built terrace; drift terrace; fill terrace; stream-built terrace; wave-built platform; wave-built terrace. { əlüvēəl terəs } alluvial valley [GEOL] A valley filled with a stream deposit. { əlüvēəl valē } alluviation [GEOL] The deposition of sediment by a river. { əlüvēāshən } alluvion See alluvium. { əlüvēən } 11 Downloaded from : iDATA.ws alluvium alluvium [GEOL] The detrital materials that are eroded, transported, and deposited by streams; an important constituent of shelf deposits. Also known as alluvial deposit; alluvion. { əlüvēəm } almandine [MINERAL] Fe3Al2(SiO4)3 A variety of garnet, deep red to brownish red, found in igneous and metamorphic rocks in many parts of world; used as a gemstone and an abrasive. Also known as almandite. { alməndēn } almandite See almandine. { alməndı̄t } almeriite See natroalunite. { almərēı̄t } alnoite [PETR] A variety of biotite lamprophyres characterized by lepidomelane pheno- crysts; it is feldspar-free but contains melitite, perovskite, olivine, and carbonate in the matrix. { alnəwit } aloisite [MINERAL] A brown to violet mineral consisting of a hydrous subsilicate of calcium, iron, magnesium, and sodium, and occurring in amorphous masses. { a ləwisēı̄t } Alpides [GEOL] Great east-west structural belt including the Alps of Europe and the Himalayas and related mountains of Asia; mostly folded in Tertiary times. { al pədēz } alpine [GEOL] Similar to or characteristic of a lofty mountain or mountain system. { alpı̄n } Alpine orogeny [GEOL] Jurassic through Tertiary orogeny which affected the Alpides. { alpı̄n ȯräjənē } alpine-type facies [PETR] High-pressure, low-temperature (150–400C) dynamother- mal metamorphism characterized by the presence of the pumpellyite and glauco- phane schist facies. { ¦alpı̄n¦tı̄p fāshez } alpinotype tectonics [GEOL] Tectonics of the alpine-type geosynclinal mountain belts characterized by deep-seated plastic folding, plutonism, and lateral thrusting. { alpēnōtı̄p tektäniks } alsbachite [PETR] A plutonic rock of sodic plagioclase, quartz, and subordinate ortho- clase and accessory garnet, biotite, and muscovite; a variety of porphyritic granodio- rite. { ȯlzbäkı̄t } alstonite See bromlite. { ȯlztənı̄t } Altaid orogeny [GEOL] Mountain building in Central Europe and Asia that occurred from the late Carboniferous to the Permian. { ¦altād ȯräjənē } altaite [MINERAL] PbTe A tin-white lead-tellurium mineral occurring as isometric crys- tals with tin ores in central Asia. { altāı̄t } alteration [PETR] A change in a rock’s mineral composition. { ȯltərāshən } altiplanation [GEOL] A phase of solifluction that may be seen as terracelike forms, flattened summits, and passes that are mainly accumulations of loose rock. { al təplānāshən } altiplanation surface [GEOL] A flat area fronted by scarps a few to hundreds of feet in height; the area ranges from several square rods to hundreds of acres. Also known as altiplanation terrace. { altəplānāshən sərfəs } altiplanation terrace See altiplanation surface. { altəplānāshən terəs } altithermal [GEOPHYS] Period of high temperature, particularly the postglacial thermal optimum. { ¦altə¦thərməl } Altithermal [GEOL] A dry postglacial interval centered about 5500 years ago during which temperatures were warmer than at present. Also known as Hypsithermal. { ¦altə¦thərməl } altithermal soil [GEOL] Soil recording a period of rising or high temperature. { ¦al tə¦thərməl sȯil } alum [MINERAL] KAl(SO4)212H2O A colorless, white, astringent-tasting evaporite min- eral. { aləm } alum coal [GEOL] Argillaceous brown coal rich in pyrite in which alum is formed on weathering. { aləm kōl } aluminite [MINERAL] Al2(SO4)(OH)47H2O Native monoclinic hydrous aluminum sul- fate; used in tanning, papermaking, and water purification. Also known as webster- ite. { əlümənı̄t } 12 Downloaded from : iDATA.ws Anaspida Amphitheriidae [PALEON] A family of Jurassic therian mammals in the infraclass Pan- totheria. { amfəthərı̄ədē } amphoterite [GEOL] A stony meteorite containing bronzite and olivine with some oligo- clase and nickel-rich iron. { amfädərı̄t } amygdaloid [GEOL] Lava rock containing amygdules. Also known as amygdaloidal lava. { əmigdəlȯid } amygdaloidal lava See amygdaloid. { əmigdəlȯidəllävə } amygdule [GEOL] 1. A mineral filling formed in vesicles (cavities) of lava flows; it may be chalcedony, opal, calcite, chlorite, or prehnite. 2. An agate pebble. { əmigdyül } Amynodontidae [PALEON] A family of extinct hippopotamuslike perissodactyl mam- mals in the superfamily Rhinoceratoidea. { amənədäntədē } anabohitsite [PETR] A variety of olivine-pyroxenite containing hornblende and hyper- sthene and a high proportion (about 30%) of magnetite and ilmenite. { anə bōhitsı̄t } anaclinal [GEOL] Having a downward inclination opposite to that of a stratum. { ¦an ə¦klı̄nəl } anaerobic sediment [GEOL] A highly organic sediment formed in the absence or near absence of oxygen in water that is rich in hydrogen sulfide. { ¦anə¦rōbik sed əmənt } analbite [MINERAL] A triclinic albite which is not stable and becomes monoclinic at about 700C. { ənalbı̄t } analcime [MINERAL] NaAlSi2O6H2O A white or slightly colored isometric zeolite found in diabase and in alkali-rich basalts. Also known as analcite. { ənalsēm } analcimite [PETR] An extrusive or hypabyssal rock that consists primarily of pyroxene and analcime. { ənalsəmı̄t } analcimization [GEOL] The replacement in igneous rock of feldspars or feldspathoids by analcime. { ə¦nalsəmə¦zāshən } analcite See analcime. { ənalsı̄t } analytical geomorphology See dynamic geomorphology. { anəlidəkəl jēōmȯrfäl əjē } anamigmatism [GEOL] A process of high-temperature, high-pressure remelting of sedi- ment to yield magma. { anəmigmətizəm } anamorphic zone [GEOL] The zone of rock flow, as indicated by reactions that may involve decarbonation, dehydration, and deoxidation; silicates are built up, and the formation of denser minerals and of compact crystalline structure takes place. { ¦an ə¦mȯrfik zōn } anamorphism [GEOL] A kind of metamorphism at considerable depth in the earth’s crust and under great pressure, resulting in the formation of complex minerals from simple ones. { anəmȯrfizəm } Anancinae [PALEON] A subfamily of extinct proboscidean placental mammals in the family Gomphotheriidae. { ənansənē } anapaite [MINERAL] Ca2Fe(PO4)24H2O A pale-green or greenish-white triclinic mineral consisting of a ferrous iron hydrous phosphate and occurring in crystals and massive forms; hardness is 3–4 on Mohs scale, and specific gravity is 3.81. { ənapəı̄t } anapeirean See Pacific suite. { anəpirēən } Anaplotheriidae [PALEON] A family of extinct tylopod ruminants in the superfamily Anaplotherioidea. { anəpläthərı̄ədē } Anaplotherioidea [PALEON] A superfamily of extinct ruminant artiodactyls in the infraorder Tylopoda. { anəpläthərēȯidēə } Anasca [PALEON] A suborder of extinct bryozoans in the order Cheilostomata. { ənaskə } anaseism [GEOPHYS] Movement of the earth in a direction away from the focus of an earthquake. { ¦anə¦sı̄zəm } Anaspida [PALEON] An order of extinct fresh- or brackish-water vertebrates in the class Agnatha. { ənaspədə } 15 Downloaded from : iDATA.ws anatase anatase [MINERAL] The brown, dark-blue, or black tetragonal crystalline form of tita- nium dioxide, TiO2; used to make a white pigment. Also known as octahedrite. { anətās } anatexis [GEOL] A high-temperature process of metamorphosis by which plutonic rock in the lowest levels of the crust is melted and regenerated as a magma. { an əteksəs } anathermal [GEOL] A period of time between the age of other strata or units of reference in which the temperature is increasing. { anəthərməl } anauxite [MINERAL] Al2(SiO7)(OH)4 A clay mineral that is a mixture of kaolinite and quartz. Also known as ionite. { ənȯksı̄t } anchieutectic [GEOL] A type of magma which is incapable of undergoing further nota- ble main-stage differentiation because its mineral composition is practically in eutec- tic proportions. { ¦aŋkēyü¦tektik } anchimonomineralic [PETR] Of rock composed mostly of one kind of mineral. { ¦aŋ kēmänōminə¦ralik } anchored dune [GEOL] A sand dune stabilized by growth of vegetation. { aŋkərd dün } anchorite [PETR] A variety of diorite having nodules of mafic minerals and veins of felsic minerals. { aŋkərı̄t } anchor stone [GEOL] A rock or pebble that has marine plants attached to it. { aŋ kər stōn } ancylite [MINERAL] SrCe(CO3)2(OH)H2O A mineral consisting of hydrous basic carbon- ate of cerium and strontium. { ansəlı̄t } ancylopoda [PALEON] A suborder of extinct herbivorous mammals in the order Perisso- dactyla. { ansəläpədə } andalusite [MINERAL] Al2SiO5 A brown, yellow, green, red, or gray neosilicate mineral crystallizing in the orthorhombic system, usually found in metamorphic rocks. { ¦andəlüsı̄t } Andean-type continental margin [GEOL] A continental margin, as along the Pacific coast of South America, where oceanic lithosphere descends beneath an adjacent continent producing andesitic continental margin volcanism. { andēən tı̄p känt ənentəl märjən } Andept [GEOL] A suborder of the soil order Inceptisol, formed chiefly in volcanic ash or in regoliths with high components of ash. { ¦an¦dept } andersonite [MINERAL] Na2Ca(UO2)(CO3)36H2O Bright yellow-green secondary min- eral consisting of a hydrous sodium calcium uranium carbonate. { andərsənı̄t } andesine [MINERAL] A plagioclase feldspar with a composition ranging from Ab70An30 to Ab50An50, where Ab NaAlSi3O8 and An CaAl2Si2O8; it is a primary constituent of intermediate igneous rocks, such as andesites. { andəzēn } andesite [PETR] Very finely crystalline extrusive rock of volcanic origin composed largely of plagioclase feldspar (oligoclase or andesine) with smaller amounts of dark- colored mineral (hornblende, biotite, or pyroxene), the extrusive equivalent of diorite. { andəzı̄t } andesite line [GEOL] The postulated geographic and petrographic boundary between the andesite-dacite-rhyolite rock association of the margin of the Pacific Ocean and the olivine-basalt-trachyte rock association of the Pacific Ocean basin. { an dəzı̄t lı̄n } andesitic glass [GEOL] A natural glass that is chemically equivalent to andesite. { an dəzı̄tik glas } andorite [MINERAL] AgPbSb3S6 A dark-gray or black orthorhombic mineral. Also known as sundtite. { andərı̄t } andradite [MINERAL] The calcium-iron end member of the garnet group. { andrädı̄t } andrewsite [MINERAL] (Cu,Fe2+)Fe33+(PO4)3(OH)2 A bluish-green mineral consisting of a basic phosphate of iron and copper. { andrüzı̄t } andrite [GEOL] A meteorite composed principally of augite with some olivine and troilite. { andrı̄t } 16 Downloaded from : iDATA.ws annual magnetic change anemoclast [GEOL] A clastic rock that was fragmented and rounded by wind. { ¦a nəmō¦klast } anemoclastic [GEOL] Referring to rock that was broken by wind erosion and rounded by wind action. { ¦anəmō¦klastik } angaralite [MINERAL] Mg2(Al,Fe)10Si6O29 A mineral of the chlorite group, occurring in thin black plates. { angarəlı̄t } Angara Shield [GEOL] A shield area of crystalline rock in Siberia. { äŋgərä shēld } angle of dip See dip. { aŋgəl əv dip } angle of shear [GEOL] The angle between the planes of maximum shear which is bisected by the axis of greatest compression. { aŋgəl əv shēr } anglesite [MINERAL] PbSO4 A mineral occurring in white or gray, tabular or prismatic orthorhombic crystals or compact masses. Also known as lead spar; lead vitriol. { aŋgləsı̄t } Angoumian [GEOL] Upper middle Upper Cretaceous (Upper Turonian) geologic time. { ängümēən } angrite [GEOL] An achondrite stony meteorite composed principally of augite with a little olivine and troilite. { aŋgrı̄t } anguclast [GEOL] An angular phenoclast. { aŋgyu̇klast } angular unconformity [GEOL] An unconformity in which the older strata dip at a differ- ent angle (usually steeper) than the younger strata. { aŋgyələr ənkənfȯrmədē } anhedral See allotriomorphic. { anhēdrəl } anhedron [PETR] Rock that has the organized internal structure of a crystal without the external geometric form of a crystal. { anhēdrən } anhydrite [MINERAL] CaSO4 A mineral that represents gypsum without its water of crystallization, occurring commonly in white and grayish granular to compact masses; the hardness is 3–3.5 on Mohs scale, and specific gravity is 2.90–2.99. Also known as cube spar. { anhı̄drı̄t } anhydrite evaporite [PETR] CuSO4 A sedimentary rock composed chiefly of copper sulfate in compact granular form deposited by evaporation of water; resembles marble and differs from gypsum in lack of water of hydration and hardness. { anhı̄drı̄t ivap ərı̄t } anhydrock [PETR] A sedimentary rock chiefly made of anhydrite. { anhidräk } Animikean [GEOL] The middle subdivision of Proterozoic geologic time. Also known as Penokean; Upper Huronian. { ə¦nimə¦kēən } animikite [GEOL] An ore of silver, composed of a mixture of sulfides, arsenides, and antimonides, and containing nickel and lead; occurs in white or gray granular masses. { əniməkı̄t } Anisian [GEOL] Lower Middle Triassic geologic time. { ənisēən } anisodesmic [MINERAL] Pertaining to crystals or compounds in which the ionic bonds are unequal in strength. { ¦anisədezmik } ankaramite [PETR] A mafic olivine basalt primarily composed of pyroxene with smaller amounts of olivine and plagioclase and accessory biotite, apatite, and opaque oxides. { aŋkərämı̄t } ankaratrite See olivine nephelinite. { aŋkərätrı̄t } ankerite [MINERAL] Ca(Fe,Mg,Mn)(CO3)2 A white, red, or gray iron-rich carbonate min- eral associated with iron ores and found in thin veins in coal seams; specific gravity is 2.95–3.1. Also known as cleat spar. { aŋkərı̄t } Ankylosauria [PALEON] A suborder of Cretaceous dinosaurs in the reptilian order Ornithischia characterized by short legs and flattened, heavily armored bodies. { ¦aŋ kələsȯrēə } annabergite [MINERAL] (Ni,Co)3(AsO4)28H2O A monoclinic mineral usually found as apple-green incrustations as an alteration product of nickel arsenides; it is isomor- phous with erythrite. Also known as nickel bloom; nickel ocher. { anəbərgı̄t } annual layer [GEOL] 1. A sedimentary layer deposited, or presumed to have been deposited, during the course of a year; for example, a glacial varve. 2. A dark layer in a stratified salt deposit containing disseminated anhydrite. { anyəwəl lāər } annual magnetic change See magnetic annual change. { anyəwəl magnedik chānj } 17 Downloaded from : iDATA.ws antlerite high shearing stress, and hence are not found in highly deformed rocks. { ¦an tē¦stres minərəl } antlerite [MINERAL] Cu3SO4(OH)4 Emerald- to blackish-green mineral occurring in aggregates of needlelike crystals; an ore of copper. Also known as vernadskite. { antlərı̄t } Antler orogeny [GEOL] Late Devonian and Early Mississippian orogeny in Nevada, resulting in the structural emplacement of eugeosynclinal rocks over microgeosyncli- nal rocks. { antlər ȯräjənē } Ao horizon [GEOL] That portion of the A horizon of a soil profile which is composed of pure humus. { ¦ā¦ō hərı̄zən } Aoo horizon [GEOL] Uppermost portion of the A horizon of a soil profile which consists of undecomposed vegetable litter. { ¦ā¦ō¦ō hərı̄zən } Apatemyidae [PALEON] A family of extinct rodentlike insectivorous mammals belong- ing to the Proteutheria. { əpadəmı̄ədē } apachite [PETR] A phonolite consisting of enigmatite and hornblende in about the same quantity as the pyroxene, but of a later crystallization phase. { əpachı̄t } Apathornithidae [PALEON] A family of Cretaceous birds, with two species, belonging to the order Ichthyornithiformes. { apəthȯrnithədē } apatite [MINERAL] A group of phosphate minerals that includes 10 mineral species and has the general formula X5(YO4)3Z, where X is usually Ca 2+ or Pb3+, Y is P5+ or As5+, and Z is F, Cl, or OH. { apətı̄t } Apatosaurus [PALEON] A herbivorous sauropod dinosaur, approximately 70 feet (21 meters) long and weighing 30 tons, from the Jurassic Period that had much longer hindlimbs than forelimbs. Also known as Brontosaurus. { əpadəsȯrəs } apex [GEOL] The part of a mineral vein nearest the surface of the earth. { āpeks } aphaniphyric [PETR] Denoting a texture of porphyritic rocks with microaphanitic groundmasses. Also known as felsophyric. { afənəfı̄rik } aphanite [PETR] 1. A general term applied to dense, homogeneous rocks whose constit- uents are too small to be distinguished by the unaided eye. 2. A rock having aphanitic texture. { afənı̄t } aphanitic [PETR] Referring to the texture of an igneous rock in which the crystalline components are not distinguishable by the unaided eye. { afənidik } Aphrosalpingoidea [PALEON] A group of middle Paleozoic invertebrates classified with the calcareous sponges. { ¦afrōsalpiŋgȯidēə } aphrosiderite See ripidolite. { afrōsidərı̄t } aphthitalite [MINERAL] (K,Na)3Na(SO4)2 A white mineral crystallizing in the rhombohe- dral system and occurring massively or in crystals. { afthidəlı̄t } aphyric [PETR] Of the texture of fine-grained igneous rocks, showing two generations of the same mineral but without phenocrysts. { āfirik } apjohnite [MINERAL] MnAl2(SO4)422H2O A white, rose-green, or yellow mineral con- taining water and occurring in crusts, fibrous masses, or efflorescences. { apjänı̄t } aplite [PETR] Fine-grained granitic dike rock made up of light-colored mineral constit- uents, mostly quartz and feldspar; used to manufacture glass and enamel. { aplı̄t } apophyllite [MINERAL] A hydrous calcium potassium silicate containing fluorine and occurring as a secondary mineral with zeolites with geodes and other igneous rocks; the composition is variable but approximates KFCa4(Si2O5)48H2O. Also known as fish-eye stone. { əpäfəlı̄t } Appalachia [GEOL] Proposed borderland along the southeastern side of North America, seaward of the Appalachian geosyncline in Paleozoic time. { ¦apə¦lāchə } Appalachian orogeny [GEOL] An obsolete term referring to Late Paleozoic diastro- phism beginning perhaps in the Late Devonian and continuing until the end of the Permian; now replaced by Alleghenian orogeny. { ¦apə¦lāchən ȯräjənē } apparent cohesion [GEOL] In soil mechanics, the resistance of particles to being pulled apart due to the surface tension of the moisture film surrounding each particle. Also known as film cohesion. { əparənt kōhēzhən } apparent dip [GEOL] Dip of a rock layer as it is exposed in any section not at a right angle to the strike. { əparənt dip } 20 Downloaded from : iDATA.ws Aquox apparent movement of faults [GEOL] The apparent motion observed to have occurred in any chance section across a fault. { əparənt ¦müvmənt əv ¦fȯlts } apparent plunge [GEOL] Inclination of a normal projection of lineation in the plane of a vertical cross section. { əparənt plənj } apparent precession See apparent wander. { əparənt priseshən } apparent vertical [GEOPHYS] The direction of the resultant of gravitational and all other accelerations. Also known as dynamic vertical. { əparənt verdəkəl } apparent wander [GEOPHYS] Apparent change in the direction of the axis of rotation of a spinning body, such as a gyroscope, due to rotation of the earth. Also known as apparent precession; wander. { əparənt wändər } appinite [PETR] Hornblende-rich plutonic rock with high feldspar content. { apənı̄t } apple coal [GEOL] Easily mined soft coal that breaks into small pieces the size of apples. { apəl kōl } apposition beach [GEOL] One of a series of parallel beaches formed on the seaward side of an older beach. { apəzishən bēch } apposition fabric [PETR] A primary orientation of the elements of a sedimentary rock that is developed or formed at time of deposition of the material; fabrics of most sedimentary rocks belong to this type. Also known as primary fabric. { apəzish ən fabrik } apron See outwash plain. { āprən } Aptian [GEOL] Lower Cretaceous geologic time, between Barremian and Albian. Also known as Vectian. { aptēən } aquagene tuff See hyaloclastite. { akwəjēn təf } aqualf [GEOL] A suborder of the soil order Alfisol, seasonally wet and marked by gray or mottled colors; occurs in depressions or on wide flats in local landscapes. { akwəlf } aquamarine [MINERAL] A pale-blue or greenish-blue transparent gem variety of the mineral beryl. { akwəmərēn } Aquent [GEOL] A suborder of the soil order Entisol, bluish gray or greenish gray in color; under water until very recent times; located at the margins of oceans, lakes, or seas. { ākwənt } aqueous lava [GEOL] Mud lava produced by the mixing of volcanic ash with condensing volcanic vapor or other water. { ākwēəs lävə } aqueous rock [PETR] A sedimentary rock deposited by or in water. Also known as hydrogenic rock. { ākwēəs räk } Aquept [GEOL] A suborder of the soil order Inceptisol, wet or drained, which lacks silicate clay accumulation in the soil profiles; surface horizon varies in thickness. { akwəpt } aquiclude [GEOL] A porous formation that absorbs water slowly but will not transmit it fast enough to furnish an appreciable supply for a well or spring. { akwəklüd } aquifer [GEOL] A permeable body of rock capable of yielding quantities of groundwater to wells and springs. { akwəfər } aquifuge [GEOL] An impermeable body of rock which contains no interconnected open- ings or interstices and therefore neither absorbs nor transmits water. { akwəfyüj } Aquitanian [GEOL] Lower lower Miocene or uppermost Oligocene geologic time. { akwətānēən } aquitard [GEOL] A bed of low permeability adjacent to an aquifer; may serve as a storage unit for groundwater, although it does not yield water readily. { akwətärd } Aquod [GEOL] A suborder of the soil order Spodosol, with a black or dark brown horizon just below the surface horizon; seasonally wet, it occupies depressions or wide flats from which water cannot escape easily. { akwəd } Aquoll [GEOL] A suborder of the soil order Mollisol, with thick surface horizons; formed under wet conditions, it may be under water at times, but is seasonally rather than continually wet. { akwȯl } Aquox [GEOL] A suborder of the soil order Oxisol, seasonally wet, found chiefly in shallow depressions; deeper soil profiles are predominantly gray, sometimes mottled, and contain nodules or sheets of iron and aluminum oxides. { akwəks } 21 Downloaded from : iDATA.ws Aquult Aquult [GEOL] A suborder of the soil order Ultisol; seasonally wet, it is saturated with water a significant part of the year unless drained; surface horizon of the soil profile is dark and varies in thickness, grading to gray in the deeper portions; it occurs in depressions or on wide upland flats from which water drains very slowly. { akwəlt } Araeoscelidia [PALEON] A provisional order of extinct reptiles in the subclass Euryap- sida. { ə¦rēəsəlidēə } aragonite [MINERAL] CaCO3 A white, yellowish, or gray orthorhombic mineral species of calcium carbonate but with a crystal structure different from those of vaterite and calcite, the other two polymorphs of the same composition. Also known as Aragon spar. { ərägənı̄t } Aragon spar See aragonite. { arəgän spär } aramayoite [MINERAL] Ag(Sb,Bi)S2 An iron-black mineral consisting of silver antimony bismuth sulfide. { arəmı̄əwı̄t } arapahite [PETR] A dark-colored, porous, fine-grained basic basalt consisting of magne- tite, bytownite, and augite. { ərapəhı̄t } Arbuckle orogeny [GEOL] Mid-Pennsylvanian episode of diastrophism in the Wichita and Arbuckle Mountains of Oklahoma. { ärbəkəl ȯräjənē } arc [GEOL] A geologic or topographic feature that is repeated along a curved line on the surface of the earth. { ärk } arcanite [MINERAL] K2SO4 A colorless, vitreous orthorhombic sulfate mineral. Also known as glaserite. { ärkənı̄t } Archaeoceti [PALEON] The zeuglodonts, a suborder of aquatic Eocene mammals in the order Cetacea; the oldest known cetaceans. { ärkēəsētı̄ } Archaeocidaridae [PALEON] A family of Carboniferous echinoderms in the order Cidar- oida characterized by a flexible test and more than two columns of interambulacral plates. { ärkēəsədarədē } Archaeocopida [PALEON] An order of Cambrian crustaceans in the subclass Ostracoda characterized by only slight calcification of the carapace. { ärkēəkäpədə } Archaeopteridales [PALEOBOT] An order of Upper Devonian sporebearing plants in the class Polypodiopsida characterized by woody trunks and simple leaves. { ärkēäp tərı̄dəlēz } Archaeopteris [PALEOBOT] A genus of fossil plants in the order Archaeopteridales; used sometimes as an index fossil of the Upper Devonian. { ärkēäptərəs } Archaeopterygiformes [PALEON] The single order of the extinct avian subclass Archae- ornithes. { ärkēäptərijəfȯrmēz } Archaeopteryx [PALEON] The earliest known bird; a genus of fossil birds in the order Archaeopterygiformes characterized by flight feathers like those of modern birds. { ärkēäptəriks } Archaeornithes [PALEON] A subclass of Upper Jurassic birds comprising the oldest fossil birds. { ärkēȯrnəthēz } Archanthropinae [PALEON] A subfamily of the Hominidae, set up by F. Weidenreich, which is no longer used. { ärkənthräpənē } Archean [GEOL] A term, meaning ancient, which has been applied to the oldest rocks of the Precambrian; as more physical measurements of geologic time are made, the usage is changing; the term Early Precambrian is preferred. { ärkēən } archeomagnetic dating [GEOPHYS] An absolute dating method based on the earth’s shifting magnetic poles. When clays and other rock and soil materials are fired to approximately 1300F (700C) and allowed to cool in the earth’s magnetic field, they retain a weak magnetism which is aligned with the position of the poles at the time of firing. This allows for dating, for example, of when a fire pit was used, based on the reconstruction of pole position for earlier times. { ¦ärkēōmag¦nedik dādiŋ } Archeozoic [GEOL] 1. The era during which, or during the latter part of which, the oldest system of rocks was made. 2. The last of three subdivisions of Archean time, when the lowest forms of life probably existed; as more physical measurements of geologic time are made, the usage is changing; it is now considered part of the Early Precambrian. { ¦ärkēə¦zōik } 22 Downloaded from : iDATA.ws arteritic migmatite armangite [MINERAL] Mn3(AsO3)2 A black mineral crystallizing in the rhombohedral system and consisting of manganese arsenite. { ärmangı̄t } armenite [MINERAL] BaCa2Al6Si8O282H2O Mineral composed of a hydrous calcium bar- ium aluminosilicate. { ärmēnı̄t } armored mud ball [GEOL] A large (0.4–20 inches or 1–50 centimeters in diameter) subspherical mass of silt or clay coated with coarse sand and fine gravel. Also known as pudding ball. { ärmərd məd bȯl } Armorican orogeny [GEOL] Little-used term, now replaced by Hercynian or Variscan orogeny. { ärmȯrəkən ȯräjənē } arnimite [MINERAL] Cu5(SO4)2(OH)63H2O Mineral consisting of a hydrous copper sul- fate. { ärnəmı̄t } arquerite [MINERAL] A mineral consisting of a soft, malleable, silver-rich variety of amalgam, containing about 87% silver and 13% mercury. { ärkērı̄t } arrested decay [GEOL] A stage in coal formation where biochemical action ceases. { ərestəd dikā } arrhenite [MINERAL] A variety of fergusonite. { ərānı̄t } arris See arête. { arəs } arrival time [GEOPHYS] In seismological measurements, the time at which a given wave phase is detected by a seismic recorder. { ərı̄vəl tı̄m } arrojadite [MINERAL] Na2(Fe,Mn)5(PO4)4 Dark-green mineral crystallizing in the mono- clinic system, being isostructural with dickinsonite and occurring in masses. { arəjädı̄t } arroyo [GEOL] Small, deep gully produced by flash flooding in arid and semiarid regions of the southwestern United State. { ərȯiō } arsenic [MINERAL] A brittle, steel-gray hexagonal mineral, the native form of the ele- ment. { ärsənik } arsenical antimony See allemontite. { arsenəkəl antəmōnē } arsenical nickel See niccolite. { arsenəkəl nikəl } arsenic bloom See arsenolite. { ärsənik blüm } arseniopleite [MINERAL] A reddish-brown mineral consisting of a basic arsenate of manganese, calcium, iron, lead, and magnesium and occurring in cleavable masses. { är¦sēnēōplēı̄t } arseniosiderite [MINERAL] Ca3Fe4(AsO4)4(OH)4 4H2O A yellowish-brown mineral con- sisting of a basic iron calcium arsenate and occurring as concretions. { är¦sēnē ōsidərı̄t } arsenobismite [MINERAL] Bi2(AsO4)(OH)3 A yellowish-green mineral consisting of a basic bismuth arsenate and occurring in aggregates. { ärsənōbizmı̄t } arsenoclasite [MINERAL] Mn5(AsO4)2(OH)4 A red mineral consisting of a basic manga- nese arsenate. Also spelled arsenoklasite. { ärsənōklāsı̄t } arsenoklasite See arsenoclasite. { ärsənōklāsı̄t } arsenolamprite [MINERAL] FeAsS A lead gray mineral consisting of nearly pure arsenic; occurs in masses with a fibrous foliated structure. { ärsənōlamprı̄t } arsenolite [MINERAL] As2O3 A mineral crystallizing in the isometric system and usually occurring as a white bloom or crust. Also known as arsenic bloom. { ärsenəlı̄t } arsenopyrite [MINERAL] FeAsS A white to steel-gray mineral crystallizing in the mono- clinic system with pseudo-orthorhombic symmetry because of twinning; occurs in crystalline rock and is the principal ore of arsenic. Also known as mispickel. { ärs ənōpı̄rı̄t } arsoite [PETR] An olivine-bearing diopside trachyte. { ärsōı̄t } arterite [PETR] 1. A migmatite produced as a result of regional contact metamorphism during which residual magmas were injected into the host rock. 2. Gneisses charac- terized by veins formed from the solution given off by deep-seated intrusions of molten granite. 3. A veined gneiss in which the vein material was injected from a magma. { ärtirı̄t } arteritic migmatite [GEOL] Injection gneiss supposedly produced by introduction of pegmatite, granite, or aplite into schist parallel to the foliation. { ¦ardə¦ridik migmətı̄t } 25 Downloaded from : iDATA.ws Arthrodira Arthrodira [PALEON] The joint-necked fishes, an Upper Silurian and Devonian order of the Placodermi. { ärthrōdı̄rə } articulite See itacolumite. { ärtikyəlı̄t } artinite [MINERAL] Mg2CO3(OH)23H2O A snow-white mineral crystallizing in the ortho- rhombic system and occurring in crystals or fibrous aggregates. { ärtēnı̄t } Artinskian [GEOL] A European stage of geologic time including Lower Permian (above Sakmarian, below Kungurian). { ärtinskēən } arzrunite [MINERAL] A bluish-green mineral consisting of a basic copper sulfate with copper chloride and lead, and occurring as incrustations. { ärzrünı̄t } asar See esker. { asər } asbestos [MINERAL] A general name for the useful, fibrous varieties of a number of rock-forming silicate minerals that are heat-resistant and chemically inert; two varie- ties exist: amphibole asbestos, the best grade of which approaches the composition Ca2Mg5(OH)2Si8O22 (tremolite), and serpentine asbestos, usually chrysotile, Mg3Si2- (OH)4O5. { asbestəs } asbolane See asbolite. { azbəlān } asbolite [MINERAL] A black, earthy mineral aggregate containing hydrated oxides of manganese and cobalt. Also known as asbolane; black cobalt; earthy cobalt. { azbəlı̄t } aschistic [GEOL] Pertaining to rocks of minor igneous intrusions that have not been differentiated into light and dark portions but that have essentially the same composi- tion as the larger intrusions with which they are associated. { āskistik } aseismic [GEOPHYS] Not subject to the occurrence or destructive effects of earthquakes. { āsı̄zmik } ash [GEOL] Volcanic dust and particles less than 4 millimeters in diameter. { ash } Ashby [GEOL] A North American stage of Middle Ordovician geologic time, forming the upper subdivision of Chazyan, and lying above Marmor and below Porterfield. { ashbē } ash cone [GEOL] A volcanic cone built primarily of unconsolidated ash and generally shaped somewhat like a saucer, with a rim in the form of a wide circle and a broad central depression often nearly at the same elevation as the surrounding country. { ash kōn } ash fall [GEOL] 1. A fall of airborne volcanic ash from an eruption cloud; characteristic of Vulcanian eruptions. Also known as ash shower. 2. Volcanic ash resulting from an ash fall and lying on the ground surface. { ash fȯl } ash field [GEOL] A thick, extensive deposit of volcanic ash. Also known as ash plain. { ash fēld } ash flow [GEOL] 1. An avalanche of volcanic ash, generally a highly heated mixture of volcanic gases and ash, traveling down the flanks of a volcano or along the surface of the ground. Also known as glowing avalanche; incandescent tuff flow. 2. A deposit of volcanic ash and other debris resulting from such a flow and lying on the surface of the ground. { ash flō } ash-flow tuff See ignimbrite. { ashflō təf } ash fusibility [GEOL] The gradual softening and melting of coal ash that takes place with increase in temperature as a result of the melting of the constituents and chemical reactions. { ash fyüzəbilədē } Ashgillian [GEOL] A European stage of geologic time in the Upper Orodovician (above Upper Caradocian, below Llandoverian of Silurian). { ashgilyən } ash plain See ash field. { ash plān } ash rock [GEOL] The material of arenaceous texture produced by volcanic explosions. { ash räk } ash shower See ash fall. { ash shau̇ər } ashstone [PETR] A rock composed of fine volcanic ash; particles are less than 0.06 millimeter in diameter. { ashstōn } ashtonite See mordenite. { ashtənı̄t } ash viscosity [GEOL] The ratio of shearing stress to velocity gradient of molten ash; 26 Downloaded from : iDATA.ws Astian indicates the suitability of a coal ash for use in a slag-tap-type boiler furnace. { ash viskäsədē } ashy grit [GEOL] 1. Pyroclastic material of sand and smaller size. 2. Mixture of ordinary sand and volcanic ash. { ashē grit } asiderite See stony meteorite. { əsı̄dərı̄t } Aso lava [GEOL] A type of indurated pyroclastic deposit produced during the explosive eruptions that formed the Aso Caldera of Kyushu, Japan. { äsō lävə } asparagolite See asparagus stone. { aspəragəlı̄t } asparagus stone [MINERAL] A yellow-green variety of apatite occurring in crystals. Also known as asparagolite. { əsparəgəs stōn } aspect [GEOL] 1. The general appearance of a specific geologic entity or fossil assem- blage as considered more or less apart from relations in time and space. 2. The direction toward which a valley side or slope faces with respect to the compass or rays of the sun. { aspekt } aspect angle [GEOL] The angle between the aspect of a slope and the geographic south (Northern Hemisphere) or the geographic north (Southern Hemisphere). { aspekt aŋgəl } asperity [GEOL] A type of surface roughness appearing along the interface of two faults. { asperədē } asphaltic sand [GEOL] Deposits of sand grains cemented together with soft, natural asphalt. { asfȯltik sand } asphaltite [GEOL] Any of the dark-colored, solid, naturally occurring bitumens that are insoluble in water, but more or less completely soluble in carbon disulfide, benzol, and so on, with melting points between 250 and 600F (121 and 316C); examples are gilsonite and grahamite. { asfȯltı̄t } asphaltite coal See albertite. { asfȯltı̄t kōl } asphalt rock [GEOL] Natural asphalt-containing sandstone or dolomite. Also known as asphalt stone; bituminous rock; rock asphalt. { asfȯlt räk } asphalt stone See asphalt rock. { asfȯlt stōn } Aspidorhynchidae [PALEON] The single family of the Aspidorhynchiformes, an extinct order of holostean fishes. { ¦aspədōriŋkədē } Aspidorhynchiformes [PALEON] A small, extinct order of specialized holostean fishes. { ¦aspədōriŋkəfȯrmēz } Aspinothoracida [PALEON] The equivalent name for Brachythoraci. { aspı̄nō thərasədə } aspite [GEOL] A cratered volcano with the base wide in relation to the height; for example, Mauna Loa. { aspı̄t } assemblage [GEOL] 1. A group of fossils that, appearing together, characterize a partic- ular stratum. 2. A group of minerals that compose a rock. [PALEON] A group of fossils occurring together at one stratigraphic level. { əsemblij } assemblage zone [PALEON] A biotstratigraphic unit defined and identified by a group of associated fossils rather than by a single index fossil. { əsemblij zōn } assimilation [GEOL] Incorporation of solid or fluid material that was originally in the rock wall into a magma. { əsiməlāshən } assyntite [PETR] A plutonic rock consisting largely of orthoclase and pyroxene, lesser amounts of sodalite and nepheline, and accessory biotite, sphene, apatite, and opaque oxides. { əsintı̄t } Astartian See Sequanian. { əstärshən } asthenolith [GEOL] A body of magma locally melted at any time within any solid portion of the earth. { asthenəlith } asthenosphere [GEOL] That portion of the upper mantle beneath the rigid lithosphere which is plastic enough for rock flowage to occur; extends from a depth of 30–60 miles (50–100 kilometers) to about 240 miles (400 kilometers) and is seismically equivalent to the low velocity zone. { asthenəsfir } Astian [GEOL] A European stage of geologic time: upper Pliocene, above Plaisancian, below the Pleistocene stage known as Villafranchian, Calabrian, or Günz. { as tēən } 27 Downloaded from : iDATA.ws augitophyre glassy groundmass containing microlites of nepheline and plagioclase, with accessory biotite, apatite, and opaque oxides. { ȯjətı̄t } augitophyre [PETR] A porphyritic rock in which the phenocrysts are augite and the groundmass is potash feldspar. { ȯjidəfı̄ər } aulacogen [GEOL] A major fault-bounded trough considered to be one part of a three- rayed fault system on the domes above mantle hot spots; the other two rays open as proto-ocean basins. { au̇läkəjən } Aulolepidae [PALEON] A family of marine fossil teleostean fishes in the order Cten- othrissiformes. { ȯləlepədē } Auloporidae [PALEON] A family of Paleozoic corals in the order Tabulata. { ȯl əpȯrədē } aureole [GEOL] A ring-shaped contact zone surrounding an igneous intrusion. Also known as contact aureole; contact zone; exomorphic zone; metamorphic aureole; metamorphic zone; thermal aureole. { ȯrēōl } aurichalcite [MINERAL] (Zn,Cu)5(CO3)2(OH)6 Pale-green or pale-blue mineral consisting of a basic copper zinc carbonate and occurring in crystalline incrustations. Also known as brass ore. { ȯrəkalsı̄t } auriferous [GEOL] Of a substance, especially a mineral deposit, bearing gold. { ȯrif ərəs } aurora [GEOPHYS] The most intense of the several lights emitted by the earth’s upper atmosphere, seen most often along the outer realms of the Arctic and Antarctic, where it is called the aurora borealis and aurora australis, respectively; excited by charged particles from space. { ərȯrə } aurosmiridium [MINERAL] A brittle, silver-white, isometric mineral consisting of a solid solution of gold and osmium in iridium. { ¦ȯrōsməridēəm } austinite [MINERAL] CaZnAsO4(OH) A colorless or yellowish mineral crystallizing in the orthorhombic system; consists of a basic calcium zinc arsenate; hardness is 4.5 on Mohs scale, and specific gravity is 4.13. { ȯstənı̄t } austral axis pole [GEOPHYS] The southern intersection of the geomagnetic axis with the earth’s surface. { ȯstrəl ¦aksəs pōl } australite [GEOL] A tektite found in southern Australia, occurring as glass balls and spheroidal dumbbell forms of green and black, similar to obsidian and probably of cosmic origin. { ȯstrəlı̄t } Australopithecinae [PALEON] The near-men, a subfamily of the family Hominidae com- posed of the single genus Australopithecus. { ȯstrālōpithəsı̄nē } Australopithecus [PALEON] A genus of near-men in the subfamily Australopithecinae representing a side branch of human evolution. { ȯstrālōpithəkəs } Austrian orogeny [GEOL] A short-lived orogeny during the end of the Early Cretaceous. { ȯstrēən ȯräjənē } autallotriomorphic [PETR] Pertaining to an aplitic texture in which all mineral constit- uents crystallized simultaneously, preventing the development of euhedral crystals. { ¦audə¦lätrēə¦mȯrfik } authigene [MINERAL] A mineral which has not been transported but has been formed in place. Also known as authigenic mineral. { ȯthəjēn } authigenic [GEOL] Of constituents that came into existence with or after the formation of the rock of which they constitute a part; for example, the primary and secondary minerals of igneous rocks. { ¦ȯthə¦jenik } authigenic mineral See authigene. { ¦ȯthə¦jenik minrəl } authigenic sediment [GEOL] Sediment occurring in the place where it was originally formed. { ¦ȯthə¦jenik sedəmənt } autobrecciation [GEOL] The process whereby portions of the first consolidated crust of a lava flow are incorporated into the still-fluid portion. { ¦ȯdōbrechēāshən } autochthon [GEOL] A succession of rock beds that have been moved comparatively little from their original site of formation, although they may be folded and faulted extensively. [PALEON] A fossil occurring where the organism once lived. { ȯtäk thən } 30 Downloaded from : iDATA.ws aventurine autochthonous [GEOL] Having been formed or occurring in the place where found. { ȯtäkthənas } autochthonous coal [GEOL] Coal believed to have originated from accumulations of plant debris at the place where the plants grew. Also known as indigenous coal. { ȯtäkthənas kōl } autochthonous sediment [GEOL] A residual soil deposit formed in place through decomposition. { ȯtäkthənas sedəmənt } autoclastic [GEOL] Of rock, fragmented in place by folding due to orogenic forces when the rock is not so heavily loaded as to render it plastic. { ¦ȯdō¦klastik } autoclastic schist [GEOL] Schist formed in place from massive rocks by crushing and squeezing. { ¦ȯdō¦klastik shist } autogenetic topography [GEOL] Conformation of land due to the physical action of rain and streams. { ¦ȯdōjə¦nedik təpägrəfē } autogeosyncline [GEOL] A parageosyncline that subsides as an elliptical basin or trough nearly without associated highlands. Also known as intracratonic basin. { ¦ȯdō¦jēōsinklı̄n } autoinjection See autointrusion. { ¦ȯdōinjekshən } autointrusion [GEOL] A process wherein the residual liquid of a differentiating magma is drawn into rifts formed in the crystal mesh at a late stage by deformation of unspecified origin. Also known as autoinjection. { ¦ȯdōintrüzhən } autolith [PETR] 1. A fragment of igneous rock enclosed in another igneous rock of later consolidation, each being regarded as a derivative from a common parent magma. 2. A round, oval, or elongated accumulation of iron-magnesium minerals of uncertain origin in granitoid rock. { ȯdōlith } autolysis [GEOCHEM] Return of a substance to solution, as of phosphate removed from seawater by plankton and returned when these organisms die and decay. { ȯtäl əsəs } autometamorphism [PETR] Metamorphism of an igneous rock by the action of its own volatile fluids. Also known as autometasomatism. { ¦ȯdōmedəmȯrfizəm } autometasomatism See autometamorphism. { ¦ȯdōmedəsōmətizəm } automorphic [PETR] Of minerals in igneous rock bounded by their own crystal faces. Also known as euhedral; idiomorphic. { ¦ȯdō¦mȯrfik } automorphosis [PETR] Metamorphosis of solidified igneous rock by solutions from its heated interior. { ȯdəmȯrfəsəs } autophytograph [GEOL] An imprint on a rock surface made by chemical activity of a plant or plant part. { ȯdəfı̄dəgraf } autopneumatolysis [GEOL] The occurrence of metamorphic changes at the pneumato- lytic stage of a cooling magma when temperatures are approximately 400–600C. { ¦ȯdōnümətäləsəs } Autunian [GEOL] A European stage of Lower Permian geologic time, above the Stephanian of the Carboniferous and below the Saxonian. { ōtünēən } autunite [MINERAL] Ca(UO2)2(PO4)210H2O A common fluorescent mineral that occurs as yellow tetragonal plates in uranium deposits; minor ore of uranium. { ōtənı̄t } Auversian See Ledian. { ōvərzhən } auxiliary fault [GEOL] A branch fault; a minor fault ending against a major one. { ȯgzilyərē fȯlt } auxiliary mineral [MINERAL] A light-colored, relatively rare or unimportant mineral in an igneous rock; examples are apatite, muscovite, corundrum, fluorite, and topaz. { ȯgzilyərē minrəl } auxiliary plane [GEOL] A plane at right angles to the net slip on a fault plane as determined from analysis of seismic data for an earthquake. { ȯgzilyərē plān } available relief [GEOL] The vertical distance after uplift between the altitude of the original surface and the level at which grade is first attained. { əvāləbəl rilēf } aven See pothole. { avən } aventurine [MINERAL] 1. A glass or mineral containing sparkling gold-colored particles, usually copper or chromic oxide. 2. A shiny red or green translucent quartz having 31 Downloaded from : iDATA.ws average igneous rock small, but microscopically visible, exsolved hematite or included mica particles. { əvenchərēn } average igneous rock [PETR] A hypothetical rock whose composition is thought to be similar to the average chemical composition of the outermost 10-mile (16-kilome- ter) shell of the earth. { avrij ignēəs räk } aviolite [PETR] A mica-cordierite-hornfels. { āvı̄əlı̄t } avogadrite [MINERAL] (K,Cs)BF4 An orthorhombic fluoborate mineral occurring in small crystals on Vesuvian lava. { avəgädrı̄t } Avonian See Dinantian. { əvōnēən } awaruite [MINERAL] Native nickel-iron alloy containing 57.7% nickel. { awärüı̄t } axial compression [GEOL] A compression applied parallel with the cylinder axis in experimental work involving rock cylinders. { aksēəl kəmpreshən } axial culmination [GEOL] Distortion of the fold axis upward in a form similar to an anticline. { aksēəl kəlmənāshən } axial dipole field [GEOPHYS] A postulated magnetic field for the earth, consisting of a dipolar field centered at the earth’s center, with its axis coincident with the earth’s rotational axis. { aksēəl dipōl fēld } axial plane [GEOL] A plane that intersects the crest or trough in such a manner that the limbs or sides of the fold are more or less symmetrically arranged with reference to it. Also known as axial surface. { aksēəl plān } axial-plane cleavage [GEOL] Rock cleavage essentially parallel to the axial plane of a fold. { aksēəl ¦plān klēvij } axial-plane foliation [GEOL] Foliation developed in rocks parallel to the axial plane of a fold and perpendicular to the chief deformational pressure. { aksēəl ¦plān fō lēāshən } axial-plane schistosity [GEOL] Schistosity developed parallel to the axial planes of folds. { aksēəl ¦plān shistäsədē } axial-plane separation [GEOL] The distance between axial planes of adjacent anticline and syncline. { aksēəl ¦plān sepərāshən } axial surface See axial plane. { aksēəl sərfəs } axial trace [GEOL] The intersection of the axial plane of a fold with the surface of the earth or any other specified surface; sometimes such a line is loosely and incorrectly called the axis. { aksēəl trās } axial trough [GEOL] Distortion of a fold axis downward into a form similar to a syncline. { aksēəl trȯf } axinite [MINERAL] H2(Ca,Fe,Mn)4(BO)Al2(SiO4)5 Brown, blue, green, gray, or purplish gem mineral that commonly forms glassy triclinic crystals. Also known as glass schorl. { aksənı̄t } axinitization [GEOL] The replacement of rocks by axinite, as in the border zones of some granites. { akzinətəzāshən } axiolite [MINERAL] A variety of elongated spherulite in which there is an aggregation of minute acicular crystals arranged at right angles to a central axis. { aksēəlı̄t } axis [GEOL] 1. A line where a folded bed has maximum curvature. 2. The central portion of a mountain chain. { aksəs } Azoic [GEOL] That portion of the earlier Precambrian time in which there is no trace of life. { āzōik } azonal soil [GEOL] Any group of soils without well-developed profile characteristics, owing to their youth, conditions of parent material, or relief that prevents develop- ment of normal soil-profile characteristics. Also known as immature soil. { āzōn əl sȯil } azulite [MINERAL] A translucent pale-blue variety of smithsonite found in large masses in Arizona and Greece. { azhəlı̄t } azurite [MINERAL] Cu3(CO3)2(OH)2 A blue monoclinic mineral consisting of a basic carbonate of copper; an ore of copper. Also known as blue copper ore; blue mala- chite; chessylite. { azhərı̄t } azurmalachite [MINERAL] A mixture of azurite and malachite, usually occurring massive with concentric banding; used as an ornamental stone. { ¦azhərmaləkı̄t } 32 Downloaded from : iDATA.ws Barremian bandylite [MINERAL] CuB2O4CuCl24H2O A tetragonal mineral that is deep blue with greenish lights and consists of a hydrated copper borate-chloride. { bandəlı̄t } bank [GEOL] 1. The edge of a waterway. 2. The rising ground bordering a body of water. 3. A steep slope or face, generally consisting of unconsolidated material. { baŋk } bank deposit [GEOL] Mounds, ridges, and terraces of sediment rising above and about the surrounding sea bottom. { ¦baŋk dipäzət } banket [GEOL] A conglomerate containing valuable metal to be exploited. { baŋket } bank-inset reef [GEOL] A coral reef situated on island or continental shelves well inside the outer edges. { baŋk inset rēf } bank reef [GEOL] A reef which rises at a distance back from the outer margin of rimless shoals. { baŋk rēf } bank-run gravel [GEOL] A natural deposit comprising gravel or sand. { baŋk rən gravəl } bank sand [GEOL] Deposits occurring in banks or pits and containing a low percentage of clay; used in core making. { baŋk sand } bar [GEOL] 1. Any of the various submerged or partially submerged ridges, banks, or mounds of sand, gravel, or other unconsolidated sediment built up by waves or currents within stream channels, at estuary mouths, and along coasts. 2. Any band of hard rock, for example, a vein or dike, that extends across a lode. { bär } baraboo [GEOL] A monadnock buried by a series of strata and then reexposed by the partial erosion of these younger strata. { bärəbü } bararite [MINERAL] (NH4)2SiF6 A white, hexagonal mineral consisting of ammonium silicon fluoride; occurs in tabular, arborescent, and mammillary forms. { bərärı̄t } Barbados earth [GEOL] A deposit of fossil radiolarians. { barbādəs ərth } bar beach [GEOL] A straight beach of offshore bars that are separated by shallow bodies of water from the mainland. { bär bēch } barbertonite [MINERAL] Mg6Cr2(OH)16CO34H2O A lilac to rose pink, hexagonal mineral consisting of a hydrated carbonate-hydroxide of magnesium and chromium; occurs in massive form or in masses of fibers or plates. { bärbərtənı̄t } barbierite [MINERAL] NaAlSi3IO8 A hypothetical soda feldspar thought to be isomor- phous with orthoclase. { barbirı̄t } barchan [GEOL] A crescent-shaped dune or drift of windblown sand or snow, the arms of which point downwind; formed by winds of almost constant direction and of moderate speeds. Also known as barchane; barkhan; crescentic dune. { bärkän } barchane See barchan. { bärkän } bar finger sand [GEOL] An elongated lenticular sand body that lies beneath a distribu- tory in a birdfoot delta. { bär ¦fiŋgər sand } baring See overburden. { bariŋ } barite [MINERAL] BaSO4 A white, yellow, or colorless orthorhombic mineral occurring in tabular crystals, granules, or compact masses; specific gravity is 4.5; used in paints and drilling muds and as a source of barium chemicals; the principal ore of barium. Also known as baryte; barytine; cawk; heavy spar. { barı̄t } barite dollar [MINERAL] Barite in the form of rounded disk-shaped masses; formed in a sandstone or sandy shale. { barı̄t dälər } barkevikite [MINERAL] A brown or black member of the amphibole mineral group; looks like basaltic hornblende but differs from it in its iron concentration. { bärkəvikı̄t } barkhan See barchan. { bärkän } bar plain [GEOL] A plain formed by a stream without a low-water channel or an alluvial cover. { bär plān } barranca [GEOL] A hole or deep break made by heavy rain; a ravine. { bəraŋkə } barred basin See restricted basin. { ¦bärd ¦bāsən } barred beach sequence [GEOL] A sequence comprising longshore bars, barrier beaches, and lagoons that develop when, under low-energy conditions, waves cross a broad continental shelf before impinging on a shoreline where sand-sized sediments are abundant. { ¦bärd bēch sēkwəns } Barremian [GEOL] Lower Cretaceous geologic age, between Hauterivian and Aptian. { bərāmēən } 35 Downloaded from : iDATA.ws barrier bar barrier bar [GEOL] Ridges whose crests are parallel to the shore and which are usually made up of water-worn gravel put down by currents in shallow water at some distance from the shore. { barēər bär } barrier basin [GEOL] A basin formed by natural damming, for example, by landslides or moraines. { barēər bāsən } barrier beach [GEOL] A single, long, narrow ridge of sand which rises slightly above the level of high tide and lies parallel to the shore, from which it is separated by a lagoon. Also known as offshore beach. { barēər bēch } barrier chain [GEOL] A series of barrier spits, barrier islands, and barrier beaches extending along a coastline. { barēər chān } barrier flat [GEOL] An area which is relatively flat and frequently occupied by pools of water that separate the seaward edge of the barrier from a lagoon on the landward side. { barēər flat } barrier island [GEOL] An elongate accumulation of sediment formed in the shallow coastal zone and separated from the mainland by some combination of coastal bays and their associated marshes and tidal flats; barrier islands are typically several times longer than their width and are interrupted by tidal inlets. { barēər ı̄lənd } barrier reef [GEOL] A coral reef that runs parallel to the coast of an island or continent, from which it is separated by a lagoon. { barēər rēf } barrier spit [GEOL] A barrier of sand joined at one of its ends to the mainland. { bar ēər spit } Barrovian metamorphism [GEOL] A regional metamorphism that can be zoned into facies that are metamorphic. { bərōvēən medəmȯrfizəm } Barstovian [GEOL] Upper Miocene geologic time. { bärstōvēən } bar theory [GEOL] A theory that accounts for thick deposits of salt, gypsum, and other evaporites in terms of increased salinity of a solution in a lagoon caused by evaporation. { bär thēərē } Bartonian [GEOL] A European stage: Eocene geologic time above Auversian, below Ludian. Also known as Marinesian. { bärtōnēən } Barychilinidae [PALEON] A family of Paleozoic crustaceans in the suborder Platycopa. { barəkəlinədē } Barylambdidae [PALEON] A family of late Paleocene and early Eocene aquatic mam- mals in the order Pantodonta. { barəlamdədē } barysphere See centrosphere. { barəsfir } baryta feldspar See hyalophane. { bərı̄də felspär } baryte See barite. { barı̄t } Barytheriidae [PALEON] A family of extinct proboscidean mammals in the suborder Barytherioidea. { barəthərı̄ədē } Barytherioidea [PALEON] A suborder of extinct mammals of the order Proboscidea, in some systems of classification. { barəthirēȯidēə } barytine See barite. { barətēn } barytocalcite [MINERAL] CaBa(CO3)2 A colorless to white, grayish, greenish, or yellow- ish monoclinic mineral consisting of calcium and barium carbonate. { bərı̄d əkalsı̄t } basal arkose [PETR] Partially reworked feldspathic residuum in the lower section of a sandstone that overlies granitic rock. { bāsəl ärkōs } basal complex See basement. { bāsəl kämpleks } basal conglomerate [GEOL] A coarse gravelly sandstone or conglomerate forming the lowest member of a series of related strata which lie unconformably on older rocks; records the encroachment of the seabeach on dry land. { bāsəl kənglämərət } basalt [PETR] An aphanitic crystalline rock of volcanic origin, composed largely of plagioclase feldspar (labradorite or bytownite) and dark minerals such as pyroxene and olivine; the extrusive equivalent of gabbro. { bəsȯlt } basalt glass See tachylite. { bəsȯlt glas } basaltic dome See shield volcano. { bəsȯltik dōm } basaltic hornblende [PETR] A black or brown variety of hornblende rich in ferric iron 36 Downloaded from : iDATA.ws basining and occurring in basalts and other iron-rich basic igneous rocks. Also known as basaltine; lamprobolite; oxyhornblende. { bəsȯltik hȯrnblend } basaltic lava [PETR] A volcanic fluid rock of basaltic composition. { bəsȯltik lavə } basaltic magma [GEOL] Mobile rock material of basaltic composition. { bəsȯltik magmə } basaltic rock [PETR] Igneous rock that is fine-grained and contains basalt, diabase, and dolerite; if andesite is included the rock is dark in color. { bəsȯltik räk } basaltic shell [GEOL] The lower crystal layer of basalt underlying the oceans and beneath the sialic layer of continents. { bəsȯltik shel } basaltiform [GEOL] Similar to basalt in form. { bəsȯltəfȯrm } basaltine See basaltic hornblende. { bəsȯltēn } basalt obsidian See tachylite. { bəsȯlt əbsidēən } basaluminite [MINERAL] Al4(SO4)(OH)105H2O A white mineral consisting of hydrated basic aluminum sulfate; occurs in compact masses. { ¦bāsəlümənı̄t } basanite [PETR] A basaltic extrusive rock closely allied to chert, jasper, or flint. Also known as Lydian stone; lydite. { basənı̄t } basculating fault See wrench fault. { baskyəlādiŋ fȯlt } base exchange [GEOCHEM] Replacement of certain ions by others in clay. { bās ikschānj } base level [GEOL] That critical plane of erosion and deposition represented by river level on continents and by wave or current base in the sea. { bās levəl } base-leveled plain [GEOL] Any land surface changed almost to a plain by subaerial erosion. Also known as peneplain. { bās levəld plān } base-leveling epoch See gradation period. { bās levəliŋ epək } basement [GEOL] 1. A complex, usually of igneous and metamorphic rocks, that is overlain unconformably by sedimentary strata. Also known as basement rock. 2. A crustal layer beneath a sedimentary one and above the Mohorovičić discontinuity. 3. The ancient continental igneous rock base that lies beneath Precambrian rocks. Also known as basal complex; basement complex. { bāsmənt } basement complex See basement. { bāsmənt kämpleks } basement rock See basement. { bāsmənt räk } basic [PETR] Of igneous rocks, having low silica content (generally less than 54%) and usually being rich in iron, magnesium, or calcium. { bāsik } basic front [GEOL] An advancing zone of granitization enriched in calcium, magnesium, and iron. { bāsik ¦frənt } basic hornfels [PETR] A type of hornfels derived from a basic igneous rock. { bā sik hȯrnfelz } basic rock [PETR] An igneous rock with a relatively low silica content, and rich in iron, magnesium, or calcium. { bāsik räk } basic schist [PETR] A schistose rock that forms from the metamorphism of a basic igneous rock. { bāsik shist } basification [GEOL] Development of a more basic rock, usually with more hornblende, biotite, and oligoclase, by contamination of a granitic magma in the assimilation of country rock. { bāsəfəkāshən } basimesostasis [GEOL] A process of the partial or entire enclosure of plagioclase crystals in a diabase by augite. { ¦bāzēmezəstāsəs } basin [GEOL] 1. A low-lying area, wholly or largely surrounded by higher land, that varies from a small, nearly enclosed valley to an extensive, mountain-rimmed depres- sion. 2. An entire area drained by a given stream and its tributaries. 3. An area in which the rock strata are inclined downward from all sides toward the center. 4. An area in which sediments accumulate. { bāsən } basin-and-range structure [GEOL] Regional structure dominated by fault-block moun- tains separated by basins filled with sediment. { bāsən ən ranj strəkchər } basin fold [GEOL] Synclinal and anticlinal folds in structural basins. { bāsən fōld } basining [GEOL] A settlement of earth in the form of basins due to the solution and transportation of underground deposits of salt and gypsum. { bāsəniŋ } 37 Downloaded from : iDATA.ws beckerite beckerite [MINERAL] A brown variety of the fossil resin retinite with a very high oxygen content. { bekərı̄t } becquerelite [MINERAL] CaU6O1911H2O An orthorhombic mineral consisting of a hydrated oxide of uranium; occurs in tabular, elongated, striated, and massive form. { bekrelı̄t } bed [GEOL] 1. The smallest division of a stratified rock series, marked by a well-defined divisional plane from its neighbors above and below. 2. An ore deposit, parallel to the stratification, constituting a regular member of the series of formations; not an intrusion. { bed } bedded [GEOL] Pertaining to rocks exhibiting depositional layering or bedding formed from consolidated sediments. { bedəd } bedded chert [PETR] Chert of brittle, close-jointed, rhythmically layered character found over large areas in thick deposits, the usually even-bedded layers separated by partings of dark siliceous shale or by siderite layers. { bedəd chərt } bedded vein [GEOL] A lode occupying the position of a bed that is parallel with the enclosing rock stratification. { bedəd vān } bedding [GEOL] Condition where planes divide sedimentary rocks of the same or different lithology. { bediŋ } bedding cleavage [GEOL] Cleavage parallel to the rock bedding. { bediŋ klēvij } bedding fault [GEOL] A fault whose fault surface is parallel to the bedding plane of the constituent rocks. Also known as bedding-plane fault. { bediŋ fȯlt } bedding fissility [GEOL] Primary foliation parallel to the bedding of sedimentary rocks. { bediŋ fisilədē } bedding joint [GEOL] A joint parallel to the rock bedding. { bediŋ jȯint } bedding plane [GEOL] Any of the division planes which separate the individual strata or beds in sedimentary or stratified rock. { bediŋ plān } bedding-plane fault See bedding fault. { bediŋ plān fȯlt } bedding-plane slip See flexural slip. { bediŋ plān slip } bedding schistosity [GEOL] Schistosity that is parallel to the rock bedding. { bed iŋ shistäsədē } bedding thrust [GEOL] A thrust fault parallel to bedding. { bediŋ thrəst } bedding void [GEOL] A void formed between successive batches of lava that are dis- charged in a single short activity of a volcano, as well as between flows made a long time apart. { bediŋ vȯid } Bedford limestone See spergenite. { bedfərd lı̄mstōn } bediasite [GEOL] A black to brown tektite found in Texas. { bēdı̄əzı̄t } bed load [GEOL] Particles of sand, gravel, or soil carried by the natural flow of a stream on or immediately above its bed. Also known as bottom load. { bed lōd } Bedoulian [GEOL] Lower Cretaceous (lower Aptian) geologic time in Switzerland. { bədülēən } bedrock [GEOL] General term applied to the solid rock underlying soil or any other unconsolidated surficial cover. { bedräk } beegerite [MINERAL] Pb6Bi2S9 A light to dark gray mineral consisting of lead bismuth sulfide; usually occurs in granular to dense massive form. { begərı̄t } beekite [MINERAL] 1. A concretionary form of calcite or silica that occurs in small rings on the surface of a fossil shell which has weathered out of its matrix. 2. White, opaque accretions of silica found on silicified fossils or along joint surfaces as a replacement of organic matter. { bēkı̄t } beerbachite [PETR] A hornfels with large poikiloblastic crystals of olivine. { bir bəkı̄t } beetle stone See septarium. { bēdəl stōn } beidellite [MINERAL] A clay mineral of the montmorillonite group in which Si4+ has been replaced by Al3+ and in which there is virtual absence of Mg or Fe replacing Al. { bı̄delı̄t } Belemnoidea [PALEON] An order of extinct dibranchiate mollusks in the class Cephalo- poda. { bələmnȯidēə } 40 Downloaded from : iDATA.ws berg till Belinuracea [PALEON] An extinct group of horseshoe crabs; arthropods belonging to the Limulida. { belənu̇rāsēə } belite See larnite. { bēlı̄t } Bellerophontacea [PALEON] A superfamily of extinct gastropod mollusks in the order Aspidobranchia. { bəlerəfäntāsēə } bellingerite [MINERAL] 3Cu(IO3)22H2O A light green triclinic mineral consisting of hydrated copper iodate. { bəliŋərı̄t } bell-metal ore See stannite. { bel medəl ȯr } belonite [GEOL] A rod- or club-shaped microscopic embryonic crystal in a glassy rock. { belənı̄t } belted plain [GEOL] A plain whose surface has been slowly worn down and sculptured into bands or belts of different levels. { beltəd ¦plān } belteroporic [GEOL] Of crystals in rocks whose growth was determined by the direction of easiest growth. { bel¦terəpȯrik } belt of cementation See zone of cementation. { ¦belt əv simentāshən } belt of soil moisture See belt of soil water. { ¦belt əv sȯil mȯischər } belt of soil water [GEOL] The upper subdivision of the zone of aeration limited above by the land surface and below by the intermediate belt; this zone contains plant roots and water available for plant growth. Also known as belt of soil moisture; discrete film zone; soil-water belt; soil-water zone; zone of soil water. { ¦belt əv sȯil wȯdər } bench [GEOL] A terrace of level earth or rock that is raised and narrow and that breaks the continuity of a declivity. { bench } bench gravel [GEOL] Gravel beds found on the sides of valleys above the present stream bottoms, representing parts of the bed of the stream when it was at a higher level. { bench gravəl } bench lava [GEOL] Semiconsolidated, crusted basaltic lava forming raised platforms and crags about the edges of lava lakes. Also known as bench magma. { bench lavə } bench magma See bench lava. { bench magmə } bench placer [GEOL] A placer in ancient stream deposits from 50 to 300 feet (15 to 90 meters) above present streams. { bench plāsər } bend [GEOL] 1. A curve or turn occurring in a stream course, bed, or channel which has not yet become a meander. 2. The land area partly encircled by a bend or meander. { bend } Benioff zone [GEOPHYS] A zone of earthquake hypocenters distributed on well-defined planes that dips from a shallow depth into the earth’s mantle to depths as great as 420 miles (700 kilometers). Also known as Benioff-Wadati zone; Wadati-Benioff zone. { benēȯf zōn } Benioff-Wadati zone See Benioff zone. { ¦benēȯf wədätē zōn } benitoite [MINERAL] BaTi(SiO3)3 A blue to violet barium-titanium silicate mineral; at one time it was cut and sold as sapphire. { bənēdəwı̄t } benjaminite [MINERAL] Pb2(Cu,Ag)2Bi4S9 A gray mineral occurring in granular massive form. { benjəmənı̄t } Bennettitales [PALEOBOT] An equivalent name for the Cycadeoidales. { bəned ətālēz } Bennettitatae [PALEOBOT] A class of fossil gymnosperms in the order Cycadeoidales. { benedətādē } bentonite [GEOL] A clay formed from volcanic ash decomposition and largely com- posed of montmorillonite and beidellite. Also known as taylorite. { bentənı̄t } beraunite [MINERAL] Fe2+Fe3+(PO4)3(OH)53H2O A reddish-brown to blood red, mono- clinic mineral consisting of hydrated basic phosphate of ferric and ferrous iron. { bərau̇nı̄t } beresorite See phoenicochroite. { bəresərı̄t } berg crystal See rock crystal. { bərg kristəl } bergmehl See rock milk. { berkmel } berg till See floe till. { bərg til } 41 Downloaded from : iDATA.ws berkeyite berkeyite See lazulite. { bərkēı̄t } berlinite [MINERAL] Al(PO4) A colorless to gray or pale rose, hexagonal mineral con- sisting of aluminum orthophosphate; occurs in massive form. { bərlənı̄t } berm [GEOL] 1. A narrow terrace which originates from the interruption of an erosion cycle with rejuvenation of a stream in the mature stage of its development and renewed dissection. 2. A horizontal portion of a beach or backshore formed by deposit of material as a result of wave action. Also known as backshore terrace; coastal berm. { bərm } bermanite [MINERAL] Mn2+Mn23+(PO4)2(OH)24H2O A reddish-brown, orthorhombic mineral consisting of a hydrated basic phosphate of manganese; occurs in crystal aggregates and as lamellar masses. { bərmənı̄t } berm crest [GEOL] The seaward limit and usually the highest spot on a coastal berm. Also known as berm edge. { bərm krest } berm edge See berm crest. { bərm ej } bernalite [MINERAL] Fe(OH)3 An iron hydroxide, yellow-green or dark green in color. { bərnəlı̄t } Berriasian [GEOL] Part of or the underlying stage of the Valanginian at the base of the Cretaceous. { berēāzhən } berthierite [MINERAL] FeSb2S4 A dark steel gray, orthorhombic mineral consisting of iron antimony sulfide. { bərthēərı̄t } berthonite See bournonite. { bərthənı̄t } bertrandite [MINERAL] Be4Si2O7(OH)2 A colorless or pale-yellow mineral consisting of a beryllium silicate occurring in prismatic crystals; hardness is 6–7 on Mohs scale, and specific gravity is 2.59–2.60. { bərtrəndı̄t } beryllonite [MINERAL] NaBe(PO4) A colorless or yellow mineral occurring in short, prismatic or tabular, monoclinic crystals with two good pinacoidal cleavages at right angles; hardness is 5.5–6 on Mohs scale, and specific gravity is 2.85. { bərilənı̄t } berzelianite [MINERAL] Cu2Se A silver-white mineral composed of copper selenide and found in igneous rock; specific gravity is 4.03. { bərzēlyənı̄t } beta chalcocite See chalcocite. { bādə chalkəsı̄t } betafite See ellsworthite. { bedəfı̄t } beta plane [GEOPHYS] The model, introduced by C.G. Rossby, of the spherical earth as a plane whose rate of rotation (corresponding to the Coriolis parameter) varies linearly with the north-south direction. { bādə plān } betrunked river [GEOL] A river that is shorn of its lower course as a result of submer- gence of the land margin by the sea. { bētrəŋkt rivər } betwixt mountains See median mass. { bətwikst mau̇ntənz } beudantite [MINERAL] PbFe3(AsO4)(SO4)(OH)6 A black, dark green, or brown, hexagonal mineral consisting of a basic sulfate-arsenate of lead and ferric iron; occurs as rhombohedral crystals. { byüdənı̄t } beveling [GEOL] Planing by erosion of the outcropping edges of strata. { bevəliŋ } beyerite [MINERAL] (Ca,Pb)Bi2(CO3)2O2 A bright yellow to lemon yellow, tetragonal mineral consisting of bismuth and calcium carbonate; occurs as thin plates and compact earthy masses. { bı̄ərı̄t } Beyrichacea [PALEON] A superfamily of extinct ostracodes in the suborder Beyrichicop- ina. { bı̄rəkāsēə } Beyrichicopina [PALEON] A suborder of extinct ostracodes in the order Paleocopa. { bı̄rəkəkōpı̄nə } Beyrichiidae [PALEON] A family of extinct ostracodes in the superfamily Beyrichacea. { bı̄rəkı̄ədē } B girdle [PETR] A circular pattern in petrofabric diagrams that indicates a B axis. { bē gərdəl } B horizon [GEOL] The zone of accumulation in soil below the A horizon (zone of leaching). Also known as illuvial horizon; subsoil; zone of accumulation; zone of illuviation. { bē hərı̄zən } bianchite [MINERAL] (Fe,Zn)SO46H2O A white, monoclinic mineral consisting of iron and zinc sulfate hexahydrate; occurs in crusts of indistinct crystals. { bēaŋkı̄t } 42 Downloaded from : iDATA.ws black cotton soil bipedal dinosaur [PALEON] A dinosaur having two long, stout hindlimbs for walking and two relatively short forelimbs. { bı̄pedəl dı̄nəsȯr } bird-hipped dinosaur [PALEON] Any member of the order Ornithischia, distinguished by the birdlike arrangement of their hipbones. { bərd hipt dı̄nəsȯr } bird’s-foot delta [GEOL] A delta with long, projecting distributary channels that branch outward like the toes or claws of a bird. { bərdz fu̇t deltə } birnessite [MINERAL] A manganese oxide mineral often found as a primary constituent of manganese nodules or crusts. { bərnesı̄t } bischofite [MINERAL] MgCl26H2O A colorless to white, monoclinic mineral consisting of magnesium chloride hexahydrate. { bishəfı̄t } bisilicate [MINERAL] See metasilicate. { bı̄siləkət } bismite [MINERAL] Bi2O3 A monoclinic mineral composed of bismuth trioxide; native bismuth ore, occurring as a yellow earth. Also known as bismuth ocher. { bizmı̄t } bismuth [MINERAL] The brittle, rhombohedral mineral form of the native element bis- muth. { bizməth } bismuth blende See eulytite. { bizməth ¦blend } bismuth glance See bismuthinite. { bizməth ¦glans } bismuthinite [MINERAL] Bi2S3 A mineral consisting of bismuth trisulfide, which has an orthorhombic structure and is usually found in fibrous or leafy masses that are lead gray with a yellowish tarnish and a metallic luster. Also known as bismuth glance. { bizməthənı̄t } bismuth ocher See bismite. { bizməth ōkər } bismuth spar See bismutite. { bizməth spär } bismutite [MINERAL] (BiO)2CO3 A dull-white, yellowish, or gray, earthy, amorphous mineral consisting of basic bismuth carbonate. Also known as bismuth spar. { bizmədı̄t } bismutotantalite [MINERAL] Bi(Ta,Nb)O4 A pitch black, orthorhombic mineral con- sisting of an oxide of bismuth and tantalum and occurring in crystals. { bizməd ətantəlı̄t } bitumenite See torbanite. { bı̄tümənı̄t } bituminization See coalification. { bı̄tümənəzāshən } bituminous [MINERAL] Of a mineral, having the odor of bitumen. { bı̄tümənəs } bituminous coal [GEOL] A dark brown to black coal that is high in carbonaceous matter and has 15–50% volatile matter. Also known as soft coal. { bı̄tümənəs kōl } bituminous lignite [GEOL] A brittle, lustrous bituminous coal. Also known as pitch coal. { bı̄tümənəs lignı̄t } bituminous rock See asphalt rock. { bı̄tümənəs räk } bituminous sand [GEOL] Sand containing bituminous-like material, such as the tar sands at Athabasca, Canada, from which oil is extracted commercially. { bı̄tümə nəs sand } bituminous sandstone [PETR] A sandstone containing bituminous matter. { bı̄tü mənəs sandstōn } bituminous shale [PETR] A shale containing bituminous material. { bı̄tümənəs shāl } bituminous wood [GEOL] A variety of brown coal having the fibrous structure of wood. Also known as board coal; wood coal; woody lignite; xyloid coal; xyloid lignite. { bı̄tümənəs wu̇d } bixbyite [MINERAL] (Mn,Fe)2O3 A manganese-iron oxide mineral; black cubic crystals found in cavities in rhyolite. Also known as partridgeite; sitaparite. { biksbēı̄t } black alkali [GEOL] A deposit of sodium carbonate that has formed on or near the surface in arid to semiarid areas. { ¦blak alkəlı̄ } black amber See jet coal. { ¦blak ambər } blackband [GEOL] An earthy carbonate of iron that is present with coal beds. { blakband } black coal See natural coke. { ¦blak kōl } black cobalt See asbolite. { ¦blak kōbȯlt } black cotton soil See regur. { ¦blak ¦katən sȯil } 45 Downloaded from : iDATA.ws black diamond black diamond See carbonado. { ¦blak dı̄mənd } black durain [GEOL] A durain that has high hydrogen content and volatile matter, many microspores, and some vitrain fragments. { ¦blak du̇rān } black granite See diorite. { ¦blak granət } black lead See graphite. { ¦blak led } black lignite [GEOL] A lignite with a fixed carbon content of 35–60% and a total carbon content of 73.6–76.2% that contains between 6300 and 8300 Btu per pound; higher in rank than brown lignite. Also known as lignite A. { blak lignı̄t } black mica See biotite. { ¦blak mı̄kə } black mud [GEOL] A mud formed where there is poor circulation or weak tides, such as in lagoons, sounds, or bays; the color is due to iron sulfides and organic matter. { ¦blak məd } black ocher See wad. { ¦blak ōkər } black opal [MINERAL] A variety of gem-quality opal displaying internal reflections against a dark background. { ¦blak ōpəl } black sand [GEOL] Heavy, dark, sandlike minerals found on beaches and in stream beds; usually magnetite and ilmenite and sometimes gold, platinum, and monazite are present. { ¦blak sand } black shale [PETR] Very thinly bedded shale rich in sulfides such as pyrite and organic material deposited under barred basin conditions so that there was an anaerobic accumulation. Also known as biopelite. { ¦blak shāl } black silver See stephanite. { ¦blak silvər } black tellurium See nagyagite. { blak talu̇rēəm } bladder See vesicle. { bladər } Blaine formation [GEOL] A Permian red bed formation containing red shale and gypsum beds of marine origin in Oklahoma, Texas, and Kansas. { blān fȯrmāshən } blairmorite [PETR] A porphyritic extrusive rock consisting mainly of analcite pheno- crysts in a groundmass of sanidine, analcite, and alkalic pyroxene, with accessory sphene, melanite, and nepheline. { blermərı̄t } blakeite [MINERAL] A deep reddish-brown to deep brown mineral consisting of anhy- drous ferric tellurite; occurs in massive form, as microcrystalline crusts. { blākı̄t } Blancan [GEOL] Upper Pliocene or lowermost Pleistocene geologic time. { bläŋkən } blanket deposit [GEOL] A flat deposit of ore; its length and width are relatively great compared with its thickness. { blaŋkət dipäzət } blanket sand [GEOL] A relatively thin body of sand or sandstone covering a large area. Also known as sheet sand. { blaŋkət sand } blastic deformation [GEOL] Rock deformation involving recrystallization in which space lattices are destroyed or replaced. { blastik dēfȯrmāshən } blasting [GEOL] Abrasion caused by movement of fine particles against a stationary fragment. { blastiŋ } blasto- [PETR] A prefix indicating the presence in a rock of residual structures somewhat modified by metamorphism. { blastō } blastogranitic rock [PETR] A metamorphic granitic rock which still has parts of the original granitic texture. { ¦blastōgrənidik räk } Blastoidea [PALEON] A class of extinct pelmatozoan echinoderms in the subphylum Crinozoa. { blastȯidēə } blastomylonite [PETR] Rock which has recrystallized after granulation. { blas təmı̄lənı̄t } blastopelitic [PETR] Descriptive of the structure of metamorphosed argillaceous rocks. { ¦blastōpəlidik } blastophitic [PETR] A metamorphosed rock which once contained lath-shaped crystals partly or wholly enclosed in augite and in which part of the original texture remains. { ¦blastōfidik } blastoporphyritic [PETR] Applied to the textures of metamorphic rocks that are derived from porphyritic rocks; the porphyritic character still remains as a relict feature. { ¦blastō¦pȯrfə¦ridik } 46 Downloaded from : iDATA.ws blue copper ore blastopsammite [GEOL] A relict fragment of sandstone that is contained in a metamor- phosed conglomerate. { blastäpsəmı̄t } blastopsephitic [GEOL] Descriptive of the structure of metamorphosed conglomerate or breccia. { bla¦stäpsə¦fidik } bleach spot [GEOL] A green or yellow area in red rocks formed by reduction of ferric oxide around an organic particle. Also known as deoxidation sphere. { blēch spät } bleb [PETR] A small, usually spherical inclusion in a rock mass. { bleb } blende See sphalerite. { blend } blended unconformity [GEOL] An unconformity that is not sharp because the original erosion surface was covered by a thick residual soil that graded downward into the underlying rock. { ¦blendəd ənkənfȯrmədē } blind [GEOL] Referring to a mineral deposit with no surface outcrop. { blı̄nd } blind coal See natural coke. { ¦blı̄nd ¦kōl } blind valley [GEOL] A valley that has been made by a spring from an underground channel which emerged to form a surface stream, and that is enclosed at the head of the stream by steep walls. { blı̄nd valē } blister [GEOL] A domelike protuberance caused by the buckling of the cooling crust of a molten lava before the flowing mass has stopped. { blistər } blister hypothesis [GEOL] A theory of the formation of compressional mountains by a process in which radiogenic heat expands and melts a portion of the earth’s crust and subcrust, causing a domed regional uplift (blister) on a foundation of molten material that has no permanent strength. { blistər hı̄päthəsəs } block clay See mélange. { bläk klā } block faulting [GEOL] A type of faulting in which fault blocks are displaced at different orientations and elevations. { bläk fȯltiŋ } block glide [GEOL] A translational landslide in which the slide mass moves outward and downward as an intact unit. { bläk glı̄d } block lava [GEOL] Lava flows which occur as a tumultuous assemblage of angular blocks. Also known as aa lava. { bläk lävə } block mountain [GEOL] A mountain formed by the combined processes of uplifting, faulting, and tilting. Also known as fault-block mountain. { bläk mau̇ntən } blödite See bloedite. { blōdı̄t } bloedite [MINERAL] MgSO4Na2SO44H2O A white or colorless monoclinic mineral con- sisting of magnessium sodium sulfate. Also spelled blödite. Also known as astra- kanite; astrochanite. { blōdı̄t } blomstrandine See priorite. { blȯmstrandēn } bloodstone [MINERAL] 1. A form of deep green chalcedony flecked with red jasper. Also known as heliotrope; oriental jasper. 2. See hematite. { bləd stōn } bloom See blossom; efflorescence. { blüm } blossom [GEOL] The oxidized or decomposed outcrop of a vein or coal bed. Also known as bloom. { bläsəm } blowhole [GEOL] A longitudinal tunnel opening in a sea cliff, on the upland side away from shore; columns of sea spray are thrown up through the opening, usually during storms. { blōhōl } blowing cave [GEOL] A cave with an alternating air movement. Also known as breath- ing cave. { ¦blōiŋ ¦kāv } blowout [GEOL] Any of the various trough-, saucer-, or cuplike hollows formed by wind erosion on a dune or other sand deposit. { blōau̇t } blowout dune See parabolic dune. { blōau̇t dün } blue asbestos See crocidolite. { ¦blü asbestəs } blue band [GEOL] 1. A layer of bubble-free, dense ice found in a glacier. 2. A bluish clay found as a thin, persistent bed near the base of No. 6 coal everywhere in the Illinois-Indiana coal basin. { ¦blü band } blue copper ore See azurite. { ¦blü ¦käpər ȯr } 47 Downloaded from : iDATA.ws borickite borickite [MINERAL] CaFe5(PO4)2(OH)113H2O Reddish-brown, isotropic mineral con- sisting of a hydrated basic phosphate of calcium and iron; occurs in compact reniform masses. { bȯrəkı̄t } bornhardt [GEOL] A large dome-shaped granite-gneiss outcrop having the characteris- tics of an inselberg. { bȯrnhärt } bornite [MINERAL] Cu5FeS4 A primary mineral in many copper ore deposits; specific gravity 5.07; the metallic and brassy color of a fresh surface rapidly tarnishes upon exposure to air to an iridescent purple. { bȯrnı̄t } boroarsenate [MINERAL] One of a group of borate minerals containing arsenic; cahnite is an example. { ¦bȯrōarsənāt } borolanite [PETR] A hypabyssal rock that is essentially orthoclase and melanite with subordinate nepheline, biotite, and pyroxene. { bərälənı̄t } Boroll [GEOL] A suborder of the soil order Mollisol, characterized by a mean annual soil temperature of less than 8C and by never being dry for 60 consecutive days during the 90-day period following the summer solstice. { bȯrȯl } boronatrocalcite See ulexite. { ¦bȯrō¦natrōkalsı̄t } borosilicate [MINERAL] A salt of boric and silicic acids which occurs in the natural minerals tourmaline, datolite, and dumortierite. { ¦bȯrōsilikət } bort [MINERAL] Imperfectly crystallized diamond material unsuitable for gems because of its shape, size, or color and because of flaws or inclusions; used for abrasive and cutting purposes. Also spelled boart. { bȯrt } Boryhaenid [PALEON] A carnivorous marsupial from the Miocene Epoch that resembled the wolf. { bȯrēhanəd } boss [GEOL] A large, irregular mass of crystalline igneous rock that formed some distance below the surface but is now exposed by denudation. { bȯs } bostonite [PETR] A rock with coarse trachytic texture formed almost wholly of albite and microcline and with accessory pyroxene. { bȯstənı̄t } botallackite [MINERAL] Cu2(OH)3Cl3H2O A pale bluish-green to green, orthorhombic mineral consisting of a basic copper chloride; occurs as crusts of crystals. { bətaləkı̄t } Bothriocidaroida [PALEON] An order of extinct echinoderms in the subclass Perischo- echinoidea in which the ambulacra consist of two columns of plates, the interambula- cra of one column, and the madreporite is placed radially. { bäthrēōsikərȯid ēə } botryogen [MINERAL] MgFe(SO4)2(OH)7H2O Orange-red, monoclinic mineral con- sisting of a hydrated basic sulfate of magnesium and trivalent iron. { bätrēəjen } botryoid [GEOL] 1. A mineral formation shaped like a bunch of grapes. 2. Specifically, such a formation of calcium carbonate occurring in a cave. Also known as clusterite. { bätrēȯid } bottom [GEOL] 1. The bed of a body of running or still water. 2. See root. { bädəm } bottomland [GEOL] A lowland formed by alluvial deposit about a lake basin or a stream. { bädəmland } bottom load See bed load. { bädəm lōd } bottom moraine See ground moraine. { bädəm mərān } bottomset beds [GEOL] Horizontal or gently inclined layers of finer material carried out and deposited on the bottom of a lake or sea in front of a delta. { bäd əmset bedz } bottom terrace [GEOL] A landform deposited by streams with moderate or small bot- tom loads of coarse sand and gravel, and characterized by a broad, sloping surface in the direction of flow and a steep escarpment facing downstream. { bädəm terəs } boudin [GEOL] One of a series of sausage-shaped segments found in a boudinage. { büdan } boudinage [GEOL] A structure in which beds set in a softer matrix are divided by cross fractures into segments resembling pillows. { ¦büdən¦äzh } Bouguer correction See Bouguer reduction. { bu̇ger kərekshən } Bouguer gravity anomaly [GEOPHYS] A value that corrects the observed gravity for 50 Downloaded from : iDATA.ws brackebuschite latitude and elevation variations, as in the free-air gravity anomaly, plus the mass of material above some datum (usually sea level) within the earth and topography. { bu̇ger gravədē ənäməlē } Bouguer reduction [GEOL] A correction made in gravity work to take account of the station’s altitude and the rock between the station and sea level. Also known as Bouguer correction. { bu̇ger ridəkshən } boulangerite [MINERAL] Pb5Sb4S11 A bluish-lead-gray, monoclinic mineral consisting of lead antimony sulfide. { bu̇lanjərı̄t } boulder [GEOL] A worn rock with a diameter exceeding 256 millimeters. Also spelled bowlder. { bōldər } boulder barricade [GEOL] An accumulation of large boulders that is visible along a coast between low and half tide. { bōldər barəkād } boulder belt [GEOL] A long, narrow accumulation of boulders elongately transverse to the direction of glacier movement. { bōldər belt } boulder clay See till. { bōldər klā } boulder pavement [GEOL] A surface of till with boulders; the till has been abraded to flatness by glacier movement. { bōldər pāvmənt } boulder train [GEOL] Glacial boulders derived from one locality and arranged in a right-angled line or lines leading off in the direction in which the drift agency operated. { bōldər trān } bounce cast [GEOL] A short ridge underneath a stratum fading out gradually in both directions. { bau̇ns kast } boundary [GEOL] A line between areas occupied by rocks or formations of different type and age. { bau̇ndrē } boundary wave [GEOPHYS] A seismic wave that propagates along a free surface or an interface between defined layers. { bau̇ndrē wāv } bournonite [MINERAL] PbCuSbS3 Steel-gray to black orthorhombic crystals; mined as an ore of copper, lead, and antimony. Also known as berthonite; cogwheel ore. { bürnənı̄t } boussingaultite [MINERAL] (NH4)2Mg(SO4)26H2O A colorless to yellowish-pink, mono- clinic mineral consisting of a hydrated sulfate of ammonium and magnesium; usually occurs in massive form, as crusts or stalactites. { büsəngȯltı̄t } Bowen reaction series [MINERAL] A series of minerals wherein any early-formed phase will react with the melt later in the differentiation to yield a new mineral further in the series. { bōən rēakshən sirēz } Bowie formula [GEOPHYS] A correction used for calculation of the local gravity anomaly on earth. { bōē fȯrmyələ } bowlder See boulder. { bōldər } bowlingite See saponite. { bōliŋgı̄t } box fold [GEOL] A fold in which the broad, flat top of an anticline or the broad, flat bottom of a syncline is bordered by steeply dipping limbs. { bäks fōld } Box Hole [GEOL] A meteorite crater in central Australia, 575 feet (175 meters) in diameter. { bäks hōl } boxwork [GEOL] Limonite and other minerals which formed at one time as blades or plates along cleavage or fracture planes, after which the intervening material dis- solved, leaving the intersecting blades or plates as a network. { bäkswərk } Brachiosaurus [PALEON] A herbivorous sauropod dinosaur, 90 feet (27 meters) long and weighing 85110 tons, from the Late Jurassic that had a very long neck. { brā kēəsȯrəs } brachypinacoid [GEOL] A pinacoid parallel to the vertical and the shorter lateral axis. { brakipinəkȯid } brachysyncline [GEOL] A broad, short syncline. { brakisinklı̄n } Brachythoraci [PALEON] An order of the joint-neckfishes, now extinct. { brakithȯr əsı̄ } brackebuschite [MINERAL] Pb4MnFe(VO4)42H2O Dark brown to black, monoclinic min- eral consisting of a hydrated vanadate of lead, manganese, and iron. { bra kəbu̇shı̄t } 51 Downloaded from : iDATA.ws Bradfordian Bradfordian [GEOL] Uppermost Devonian geologic time. { bradfȯrdēən } bradleyite [MINERAL] Na3Mg(PO4)(CO3) A light gray mineral consisting of a phosphate- carbonate of sodium and magnesium; occurs as fine-grained masses. { bradlēı̄t } Bradyodonti [PALEON] An order of Paleozoic cartilaginous fishes (Chondrichthyes), presumably derived from primitive sharks. { brādēōdäntı̄ } braggite [MINERAL] PtS A steel-gray platinum sulfide mineral with tetragonal crys- tals. { bragı̄t } brammalite [MINERAL] A mica-type clay mineral that is different from illite because it has soda instead of potash; it is the sodium analog of illite. Also known as sodium illite. { braməlı̄t } branchite See hartite. { branchı̄t } brandtite [MINERAL] Ca2Mn(AsO4)22H2O A colorless to white, monoclinic mineral con- sisting of a hydrated arsenate of calcium and manganese. { brantı̄t } brannerite [MINERAL] A complex, black, opaque titanite of uranium and other elements in which the weight of uranium exceeds the weight of titanium; monoclinic and possibly (U,Ca,Fe,Y,Th)3Ti5O6 { branərı̄t } brass [GEOL] A British term for sulfides of iron (pyrites) in coal. Also known as brasses. { bras } brasses See brass. { brasəz } brass ore See aurichalcite. { brasȯr } braunite [MINERAL] 3Mn2O3MnSiO3 Brittle mineral that forms tetragonal crystals; com- monly found as steel-gray or brown-black masses in the United States, Europe, and South America; it is an ore of manganese. { brau̇nı̄t } bravoite [MINERAL] (Ni,Fe)S2 A yellow sulfide ore of nickel containing iron. { brävōı̄t } brazilianite [MINERAL] NaAl3(PO4)2(OH)4 A chartreuse yellow to pale yellow, monoclinic mineral consisting of a basic phosphate of sodium and aluminum. { brəzilyənı̄t } breached anticline [GEOL] An anticline that has been more deeply eroded in the center. Also known as scalped anticline. { ¦brēcht antiklı̄n } breached cone [GEOL] A cinder cone in which lava has broken through the sides and broken material has been carried away. { brēcht kōn } breadcrust [GEOL] A surficial structure resembling a crust of bread, as the concretions formed by evaporation of salt water. { bredkrəst } breadcrust bomb [GEOL] A volcanic bomb with a cracked exterior. { bredkrəst bäm } break [GEOL] See knickpoint. { brāk } breaker terrace [GEOL] A type of shore found in lakes in glacial drift; the terrace is formed from stones deposited by waves. { brākər terəs } break thrust [GEOL] A thrust fault cutting across one limb of a fold. { brāk thrəst } breathing cave See blowing cave. { brēthiŋ kāv } breccia [PETR] A rock made up of very angular coarse fragments; may be sedimentary or may be formed by grinding or crushing along faults. { brechə } breccia dike [GEOL] A dike formed of breccia injected into the country rock. { brech ə dı̄k } breccia marble [PETR] Any marble containing angular fragments. { brechə mär bəl } breccia pipe See pipe. { brechə pı̄p } breithauptite [MINERAL] NiSb A light copper red mineral consisting of nickel antimon- ide; commonly occurs in association with silver minerals. { brı̄thau̇ptı̄t } Bretonian orogeny [GEOL] Post-Devonian diastrophism that is found in Nova Scotia. { bretōnēən ȯräjənē } Bretonian strata [GEOL] Upper Cambrian strata in Cape Breton, Nova Scotia. { bretōnēən stradə } breunnerite [MINERAL] (Mg,Fe,Mn)CO3 A carbonate mineral consisting of an isomor- phous system of the metallic components. { brȯinərı̄t } brewsterite [MINERAL] Sr(Al2Si6O18)5H2O A member of the zeolite family of minerals; crystallizes in the monoclinic system and usually contains some calcium. { brü stərı̄t } 52 Downloaded from : iDATA.ws bytownite burkeite [MINERAL] Na6(CO3)(SO4)2 A white to pale buff or gray mineral consisting of a carbonate-sulfate of sodium. { bərkı̄t } Bushveld Complex [GEOL] In South Africa, an enormous layered intrusion, containing over half the world’s platinum, chromium, vanadium, and refractory minerals. { ¦bu̇shveld kämpleks } bustite See aubrite. { bəstı̄t } butlerite [MINERAL] Fe(SO4)(OH)2H2O A deep orange, monoclinic mineral consisting of a hydrated basic ferric sulfate. Also known as parabutlerite. { bətlərı̄t } butter rock See halotrichite. { bədər räk } buttgenbachite [MINERAL] Cu19(NO3)2Cl4(OH)323H2O An azure blue, hexagonal min- eral consisting of a hydrated basic chloride-sulfate-nitrate of copper. { bət gənbakı̄t } buttress [PALEON] A ridge on the inner surface of a pelecypod valve which acts as a support for part of the hinge. { bətrəs } buttress sands [GEOL] Sandstone bodies deposited above an unconformity; the upper portion rests upon the surface of the unconformity. { bətrəs sanz } byerite [GEOL] Bituminous coal that does not crack in fire and melts and enlarges upon heating. { bı̄ərı̄t } byon [GEOL] Gem-bearing gravel, particularly that with brownish-yellow clay in which corundum, rubies, sapphires, and so forth occur. { bı̄än } bysmalith [GEOL] A body of igneous rock that is more or less vertical and cylindrical; it crosscuts adjacent sediments. { bizməlith } bytownite [MINERAL] A plagioclase feldspar with a composition ranging from Ab30An70 to Ab10An90, where Ab NaAlSi3O8 and An CaAl2Si2O8; occurs in basic and ultrabasic igneous rock. { bı̄tau̇nı̄t } 55 Downloaded from : iDATA.ws C cacoxenite [MINERAL] Fe4(PO4)3(OH)312H2O Yellow or brownish mineral consisting of a hydrous basic iron phosphate occurring in radiated tufts. { kəkäksənı̄t } cadmium blende See greenockite. { kadmēəm blend } cadmium ocher See greenockite. { kadmēəm ōkər } cadwaladerite [MINERAL] Al(OH)2Cl4H2O A mineral consisting of a hydrous basic alu- minum chloride. { kadwälədərı̄t } Caenolestidae [PALEON] A family of extinct insectivorous mammals in the order Marsu- pialia. { sēnəlestəde } cahnite [MINERAL] Ca2B(OH)4(AsO4) A tetragonal borate mineral occurring in white, sphenoidal crystals. { känı̄t } Cainotheriidae [PALEON] The single family of the extinct artiodactyl superfamily Caino- therioidea. { kānəthərı̄ədē } Cainotherioidea [PALEON] A superfamily of extinct, rabbit-sized tylopod ruminants in the mammalian order Artiodactyla. { kānətherēȯidēə } Cainozoic See Cenozoic. { kānəzōik } cairngorm See smoky quartz. { kerngȯrm } caking coal [GEOL] A type of coal which agglomerates and softens upon heating; after volatile material has been expelled at high temperature, a hard, gray cellular mass of coke remains. Also known as binding coal. { kākiŋ kōl } Calabrian [GEOL] Lower Pleistocene geologic time. { kəläbrēən } calaite See turquoise. { kəlāı̄t } calamine See hemimorphite; smithsonite. { kaləmı̄n } Calamitales [PALEOBOT] An extinct group of reedlike plants of the subphylum Sphenop- sida characterized by horizontal rhizomes and tall, upright, grooved, articulated stems. { kəlamətālēz } calaverite [MINERAL] AuTe2 A yellowish or tin-white, monoclinic mineral commonly containing gold telluride and minor amounts of silver. { kəlavərı̄t } calc-alkalic series [PETR] Series of igneous rocks in which the weight percentage of silica is 55–61. { ¦kalk alkalik sirēz } calcarenite [PETR] A type of limestone or dolomite composed of coral or shell sand or of sand formed by erosion of older limestones, with particle size ranging from 1/16 to 2 millimeters. { kalkərēnı̄t } calcareous crust See caliche. { kalkerēəs krəst } calcareous duricrust See caliche. { kalkerēəs du̇rikrəst } calcareous ooze [GEOL] A fine-grained pelagic sediment containing undissolved sand- or silt-sized calcareous skeletal remains of small marine organisms mixed with amorphous clay-sized material. { kalkerēəs üz } calcareous schist [PETR] A coarse-grained metamorphic rock derived from impure calcareous sediment. { kalkerēəs shist } calcareous sinter See tufa. { kalkerēəs sintər } calcareous soil [GEOL] A soil containing accumulations of calcium and magnesium carbonate. { kalkerēəs sȯil } calcareous tufa See tufa. { kalkerēəs tüfə } calciclastic [PETR] Pertaining to calcium carbonate-containing rock eroded from a Downloaded from : iDATA.ws calcification preexisting source, transported some distance, and then redeposited; for example, calciclastic limestone. { kalsəklastik } calcification [GEOCHEM] Any process of soil formation in which the soil colloids are saturated to a high degree with exchangeable calcium, thus rendering them relatively immobile and nearly neutral in reaction. { kalsəfəkāshən } calcilutite [PETR] 1. A dolomite or limestone formed of calcareous rock flour that is typically nonsiliceous. 2. A rock of calcium carbonate formed of grains or crystals with average diameter less than 1/16 millimeter. { kalsəlütı̄t } calciocarnotite See tyuyamunite. { ¦kalsēōkärnətı̄t } calcioferrite [MINERAL] Ca2Fe2(PO4)OH7H2O A yellow or green mineral consisting of a hydrous basic calcium iron phosphate and occurring in nodular masses. { ¦kal sēōferı̄t } calciovolborthite [MINERAL] CaCu(VO4)(OH) Green, yellow, or gray mineral consisting of a basic vanadate of calcium and copper. Also known as tangeite. { ¦kalsē ōvȯlbȯrthı̄t } calcirudite [PETR] Dolomite or limestone formed of worn or broken pieces of coral or shells or of limestone fragments coarser than sand; the interstices are filled with sand, calcite, or mud, the whole bound together with a calcareous cement. { kalsirədı̄t } calcite [MINERAL] CaCO3 One of the commonest minerals, the principal constituent of limestone; hexagonal-rhombohedral crystal structure, dimorphous with aragonite. Also known as calcspar. { kalsı̄t } calcite compensation depth [GEOL] The depth in the ocean (about 5000 meters) below which solution of calcium carbonate occurs at a faster rate than its deposition. Abbreviated CCD. { kalsı̄t kämpənsāshən depth } calcite dolomite [PETR] A carbonate rock with a composition of 10–50% calcite and 90–50% dolomite. { kalsı̄t doləmı̄t } calclacite [MINERAL] CaCl2Ca(C2H3O2)10H2O A white mineral consisting of a hydrated chloride-acetate of calcium; occurs as hairlike efflorescences. { kalkləsı̄t } Calclamnidae [PALEON] A family of Paleozoic echinoderms of the order Dendrochirot- ida. { kalklamnədē } calclithite [PETR] Limestone with 50% or more fragments of older limestone that was redeposited after being eroded from the land. { kalkləthı̄t } calcrete [GEOL] A conglomerate of surficial gravel and sand cemented by calcium carbonate. { ¦kal¦krēt } calc-silicate [GEOL] Referring to a metamorphic rock consisting mainly of calcite and calcium-bearing silicates. { kalk siləkət } calc-silicate hornfels [PETR] A metamorphic rock with a fine grain of calcium silicate minerals. { kalk siləkāt hȯrnfelz } calc-silicate marble [PETR] Marble having conspicuous calcium silicate or magnesium silicate minerals. { kalk siləkāt märbəl } calcspar See calcite. { kalkspär } calcsparite See sparry calcite. { kalkspärı̄t } caldera [GEOL] A large collapse depression at a volcano summit that is typically circular to slightly elongate in shape, with dimensions many times greater than any included vent. It ranges from a few miles to 37 miles (60 kilometers) in diameter. It may resemble a volcanic crater in form, but differs in that it is a collapse rather than a constructional feature. { kalderə } Caledonian orogeny [GEOL] Deformation of the crust of the earth by a series of dia- strophic movements beginning perhaps in Early Ordovician and continuing through Silurian, extending from Great Britain through Scandinavia. { ¦kalə¦dōnēən ȯräj ənē } Caledonides [GEOL] A mountain system formed in Late Silurian to Early Devonian time in Scotland, Ireland, and Scandinavia. { kalədänı̄dz } caledonite [MINERAL] Cu2Pb5(SO4)3CO3(OH)6 A mineral occurring as green, orthorhom- bic crystals composed of basic copper lead sulfate; found in copper-lead deposits. { kalədänı̄t } caliche [GEOL] 1. Conglomerate of gravel, rock, soil, or alluvium cemented with sodium 58 Downloaded from : iDATA.ws Carrara marble carbonatite [PETR] 1. Intrusive carbonate rock associated with alkaline igneous intru- sive activity. 2. A sedimentary rock that is composed of at least 80% calcium or magnesium. { kärbänətı̄t } carbon cycle [GEOCHEM] The cycle of carbon in the biosphere, in which plants convert carbon dioxide to organic compounds that are consumed by plants and animals, and the carbon is returned to the biosphere in the form of inorganic compounds by processes of respiration and decay. { kärbən sı̄kəl } carbon diamond See carbonado. { ¦kärbən dı̄mənd } Carboniferous [GEOL] A division of late Paleozoic rocks and geologic time including the Mississippian and Pennsylvanian periods. { kärbənifərəs } carbonification See coalification. { kärbänəfəkāshən } carbon isotope ratio [GEOL] Ratio of carbon-12 to either of the less common isotopes, carbon-13 or carbon-14, or the reciprocal of one of these ratios; if not specified, the ratio refers to carbon-12/carbon-13. Also known as carbon ratio. { ¦karbən is ətōp rāshō } carbonite See natural coke. { kärbənı̄t } carbonization [GEOCHEM] 1. In the coalification process, the accumulation of residual carbon by changes in organic material and their decomposition products. 2. Deposi- tion of a thin film of carbon by slow decay of organic matter underwater. 3. A process of converting a carbonaceous material to carbon by removal of other compo- nents. { kärbənəzāshən } carbon pool [GEOCHEM] A reservoir with the capacity to store and release carbon, such as soil, terrestrial vegetation, the ocean, and the atmosphere. { kärbən pül } carbon ratio [GEOL] 1. The ratio of fixed carbon to fixed carbon plus volatile hydro- carbons in a coal. 2. See carbon isotope ratio. { kärbən rāshō } carbon-ratio theory [GEOL] The theory that the gravity of oil in any area is inversely proportional to the carbon ratio of the coal. { kärbən rāshō thēərē } carbon sequestration [GEOCHEM] The uptake and storage of atmospheric carbon in, for example, soil and vegetation. { kärbən sēkwestrāshən } carbon sink [GEOCHEM] A reservoir that absorbs or takes up atmospheric carbon; for example, a forest or an ocean. { kärbən siŋk } carminite [MINERAL] PbFe2(AsO4I)2(OH)2 A carmine to tile-red mineral consisting of a basic arsenate of lead and iron. { kärmənı̄t } carnallite [MINERAL] KMgCl36H2O A milky-white or reddish mineral that crystallizes in the orthorhombic system and occurs in deliquescent masses; it is valuable as an ore of potassium. { kärnəlı̄t } carnegieite [MINERAL] NaAlSiO4 An artificial mineral similar to feldspar; it is triclinic at low temperatures, isometric at elevated temperatures. { kärnəgēı̄t } Carnian [GEOL] Lower Upper Triassic geologic time. Also spelled Karnian. { kärn ēən } Carnosauria [PALEON] A group of large, predacious saurischian dinosaurs in the subor- der Theropoda having short necks and large heads. { kärnəsȯrēə } carnotite [MINERAL] K(UO2)2(VO4)2nH2O A canary-yellow, fine-grained hydrous vana- date of potassium and uranium having monoclinic microcrystals; an ore of radium and uranium. { kärnətı̄t } carpholite [MINERAL] MnAl2Si2O6(OH)4 A straw-yellow fibrous mineral consisting of a hydrous aluminum manganese silicate occurring in tufts; specific gravity is 2.93. { kärfəlı̄t } carphosiderite [MINERAL] A yellow mineral consisting of a basic hydrous iron sulfate occurring in masses and crusts. { kärfōsı̄dərı̄t } Carpoidea [PALEON] Former designation for a class of extinct homalozoan echino- derms. { kärpȯidēə } carpoids [PALEON] An assemblage of three classes of enigmatic, rare Paleozoic echino- derms formerly grouped together as the class Carpoidea. { kärpȯidz } Carrara marble [PETR] All marble quarried near Carrara, Italy, having a prevailing white to bluish color, or white with blue veins. { kərärə märbəl } 61 Downloaded from : iDATA.ws caryinite caryinite [MINERAL] (Ca,Pb,Na)5(Mn,Mg)4(AsO4)5 A mineral consisting chiefly of a cal- cium manganese arsenate. { karēənı̄t } cascade [GEOL] A landform structure formed by gravity collapse, consisting of a bed that buckles into a series of folds as it slides down the flanks of an anticline. { kaskād } Cascadian orogeny [GEOL] Post-Tertiary deformation of the crust of the earth in west- ern North America. { kaskādēən ȯräjənē } case hardening [GEOL] Formation of a mineral coating on the surface of porous rock by evaporation of a mineral-bearing solution. { kās härdəniŋ } Cassadagan [GEOL] Middle Upper Devonian geologic time, above Chemungian. { kəsadəgən } Casselian See Chattian. { kaselyən } Cassiar orogeny [GEOL] Orogenic episode in the Canadian Cordillera during late Paleozoic time. { kasēər ȯräjənē } cassidyite [MINERAL] Ca2(Ni,Mg)(PO4)22H2O A mineral found in meteorites. { kəsidēı̄t } cassiterite [MINERAL] SnO2 A yellow, black, or brown mineral that crystallizes in the tetragonal system in prisms terminated by dipyramids; the most important ore of tin. Also known as tin stone. { kəsidərı̄t } cast [PALEON] A fossil reproduction of a natural object formed by infiltration of a mold of the object by waterborne minerals. { kast } castings See fecal pellets. { kastiŋz } castorite [MINERAL] A transparent variety of petalite occurring in crystals. { kas tərı̄t } catachosis [GEOL] Fracturing or crushing of rock during metamorphism. { kad əkōsəs } cataclasis [GEOL] Deformation of rock by fracture and rotation of aggregates or mineral grains. { kadəklāsəs } cataclasite See cataclastic rock. { kadəklāsı̄t } cataclastic metamorphism [PETR] Local metamorphism restricted to a region of faults and overthrusts involving purely mechanical forces resulting in cataclasis. { ¦kad ə¦klastik medəmȯrfizəm } cataclastic rock [PETR] Rock containing angular fragments formed by cataclasis. Also known as cataclasite. { ¦kadə¦klastik räk } cataclastic structure See mortar structure. { ¦kadə¦klastik strəkchər } catapleiite [MINERAL] (Na2,Ca)ZrSi3O92H2O A yellow or yellowish-brown mineral crys- tallizing in the hexagonal system, consisting of a hydrous silicate of sodium, calcium, and zirconium, and occurring in thin tabular crystals; hardness is 6 on Mohs scale, and specific gravity is 2.8. { kadəplı̄ı̄t } catastrophism [GEOL] The theory that most features in the earth were produced by the occurrence of sudden, short-lived, worldwide events. [PALEON] The theory that the differences between fossils in successive stratigraphic horizons resulted from a general catastrophe followed by creation of the different organisms found in the next-younger beds. { kətastrəfizəm } catazone [GEOL] The deepest zone of rock metamorphism where high temperatures and pressures prevail. { kadəzōn } catena [GEOL] A group of soils derived from uniform or similar parent material which nonetheless show variations in type because of differences in topography or drainage. { kətēnə } catoptrite [MINERAL] An iron black to jet black, monoclinic mineral consisting of a silicoantimonate of aluminum and divalent manganese. Also spelled katoptrite. { kətäptrı̄t } cauldron subsidence [GEOL] 1. A structure formed by the lowering along a steep ring fracture of a more or less cylindrical block, usually 1 to 10 miles (1.6 to 16 kilometers) in diameter, into a magma chamber. 2. The process of forming such a structure. { kȯldrən səbsı̄dəns } 62 Downloaded from : iDATA.ws cement rock caustobiolith [GEOL] Combustible organic rock formed by direct accumulation of plant materials; includes coal peat. { ¦kȯstōbı̄əlith } cave [GEOL] A natural, hollow chamber or series of chambers and galleries beneath the earth’s surface, or in the side of a mountain or hill, with an opening to the surface. { kāv } cave breccia [GEOL] Sharp fragments of limestone debris deposited on the floor of a cave. { ¦kāv brechə } cave formation See speleothem. { kāv fȯrmāshən } Cavellinidae [PALEON] A family of Paleozoic ostracodes in the suborder Platycopa. { kavəlinədē } cave pearl [GEOL] A small, smooth, rounded concretion of calcite or aragonite, formed by concentric precipitation about a nucleus and usually found in limestone caves. { kāv pərl } cavern [GEOL] An underground chamber or series of chambers of indefinite extent carved out by rock springs in limestone. { kavərn } cavernous [GEOL] 1. Having many caverns or cavities. 2. Producing caverns. 3. Of or pertaining to a cavern, that is, suggesting vastness. { kavərnəs } c axis [GEOL] The reference axis perpendicular to the plane of movement of rock or mineral strata. { sē aksəs } cay [GEOL] 1. A flat coral island. 2. A flat mound of sand built up on a reef slightly above high tide. 3. A small, low coastal islet or emergent reef composed largely of sand or coral. { kā } cay sandstone [GEOL] Firmly cemented or friable coral sand formed near the base of coral reef cays. { ¦kā sanstōn } Caytoniales [PALEOBOT] An order of Mesozoic plants. { kātänēālēz } Cayugan [GEOL] Upper Silurian geologic time. { kı̄yügən } Cazenovian [GEOL] Lower Middle Devonian geologic time. { kazənōvēən } CCD See calcite compensation depth. Cebochoeridae [PALEON] A family of extinct palaeodont artiodactyls in the superfamily Entelodontoidae. { ¦sebəkōerədē } cebollite [MINERAL] H2Ca4Al2Si3O16 A greenish to white mineral consisting of hydrous calcium aluminum silicate occurring in fibrous aggregates; hardness is 5 on Mohs scale, and specific gravity is 3. { sebəlı̄t } cecilite [PETR] A basaltic rock having few phenocrysts and consisting of at least 50% leucite with augite, melilite, nepheline, olivine, anorthite, magnetite, and apatite. { sesəlı̄t } cedricite [MINERAL] A variety of lamproite composed principally of diopside, leucite, and phlogopite and usually containing crystals of serpentine. { sedrəsı̄t } celadonite [MINERAL] A soft, green variety of mica having high iron content and con- taining silicates of magnesium and potassium. { selədənı̄t } celestine See celestite. { seləstēn } celestite [MINERAL] SrSO4 A colorless or sky-blue mineral occurring in orthorhombic, tabular crystals and in compact forms; fracture is uneven and luster is vitreous; principal ore of strontium. Also known as celestine. { seləstı̄t } cellular [PETR] Pertaining to igneous rock having a porous texture, usually with the cavities larger than pore size and smaller than caverns. { selyələr } cellular soil See polygonal ground. { selyələr sȯil } celsian [MINERAL] BaAl2Si2O8 Colorless, monoclinic mineral consisting of barium feldspar. { selsēan } cement [GEOL] Any chemically precipitated material, such as carbonates, gypsum, and barite, occurring in the interstices of clastic rocks. { siment } cementation [GEOL] The precipitation of a binding material around minerals or grains in rocks. { sēmentāshən } cement gravel [GEOL] Gravel consolidated by clay, silica, calcite, or other binding material. { siment gravəl } cement rock [PETR] An argillaceous limestone containing lime, silica, and alumina in 63 Downloaded from : iDATA.ws chamosite chamosite [MINERAL] A greenish-gray or black mineral consisting of silicate belonging to the chlorite group and having monoclinic crystals; found in many oolitic iron ores. { shaməzı̄t } Champlainian [GEOL] Middle Ordovician geologic time. { shamplānēən } champsosaur [PALEON] A large crocodile-like reptile that lived in freshwater ponds and swamps 55–65 million years ago. { champsəsȯr } Chandler motion See polar wandering. { chandlər mōshən } channel fill [GEOL] Accumulations of sand and detritus in a stream channel where the transporting capacity of the water is insufficient to remove the material as rapidly as it is delivered. { chanəl fil } channel frequency See stream frequency. { chanəl frēkwənsē } channel gradient ratio See stream gradient ratio. { chanəl grādēənt rāshō } channel-lag deposit [GEOL] Coarse residual material left as accumulations in the chan- nel in the normal processes of the stream. { chanəl lag dipäzət } channel morphology See river morphology. { chanəl mȯrfäləjē } channel-mouth bar [GEOL] A bar formed where moving water enters a body of still water, due to decreased velocity. { chanəl mau̇th bär } channel roughness [GEOL] A measure of the resistivity offered by the material consti- tuting stream channel margins to the flow of water. { chanəl rəfnəs } channel sand [GEOL] A sandstone or sand deposited in a stream bed or other channel eroded into the underlying bed. { chanəl sand } channel splay See floodplain splay. { chanəl splā } channel width [GEOL] The distance across a stream or channel as measured from bank to bank near bankful stage. { chanəl width } chapmanite [MINERAL] Fe2Sb(SiO4)2(OH) A mineral consisting of a silicate of iron and antimony. { chapmənı̄t } Charmouthian [GEOL] Middle Lower Jurassic geologic time. { chärmau̇thēən } charnockite [PETR] Any of various faintly foliated, nearly massive varieties of quartzo- feldspathic rocks containing hypersthene. { chärnəkı̄t } charnockite series [GEOL] A series of plutonic rocks compositionally similar to the granitic rock series but characterized by the presence of orthopyroxene. { chär nəkı̄t sirēz } chassignite [GEOL] An achondritic stony meteorite composed chiefly of olivine (95); resembles dunite. { shasənyı̄t } chatoyant [MINERAL] Of a mineral or gemstone, having a changeable luster or color marked by a band of light, resembling the eye of a cat in this respect. { shətȯiənt } chatter mark [GEOL] A scar on the surface of bedrock made by the abrasive action of drift carried at the base of a glacier. { chadər märk } Chattian [GEOL] Upper Oligocene geologic time. Also known as Casselian. { chad ēən } Chautauquan [GEOL] Upper Devonian geologic time, below Bradfordian. { shətäk wən } Chazyan [GEOL] Middle Ordovician geologic time. { chazēən } Cheiracanthidae [PALEON] A family of extinct acanthodian fishes in the order Acan- thodiformes. { kı̄rəkanthədē } chemical denudation [GEOL] Wasting of the land surface by water transport of soluble materials into the sea. { kemikəl dēnüdāshən } chemical fossils See biomarkers. { ¦kemikəl fäsəlz } chemical precipitates [GEOL] A sediment formed from precipitated materials as distin- guished from detrital particles that have been transported and deposited. { kem ikəl prisipətāts } chemical remanent magnetization [GEOPHYS] Permanent magnetization of rocks acquired when a magnetic material, such as hematite, is grown at low temperature through the oxidation of some other iron mineral, such as magnetite or goethite; the growing mineral becomes magnetized in the direction of any field which is present. Abbreviated CRM. { kemikəl remənənt magnətəzāshən } 66 Downloaded from : iDATA.ws chilled contact chemical reservoir [GEOL] An underground oil or gas trap formed in limestones or dolomites deposited in quiescent geologic environments. { kemikəl rezəvwär } chemical rock [PETR] A type of sedimentary rock comprising material deposited directly by precipitation from solution or colloidal suspension and frequently pos- sessing a crystalline texture. { kemikəl räk } chemical weathering [GEOCHEM] A weathering process whereby rocks and minerals are transformed into new, fairly stable chemical combinations by such chemical reactions as hydrolysis, oxidation, ion exchange, and solution. Also known as decay; decomposition. { kemikəl wethəriŋ } chemostratigraphy [GEOCHEM] The correlation and dating of marine sediments and sedimentary rocks through the use of trace-element concentrations, molecular fossils, and certain isotopic ratios that can be measured on components of the rocks. { kē mōstrətigrəfē } Chemungian [GEOL] Middle Upper Devonian geologic time, below Cassodagan. { kemənjēən } chenevixite [MINERAL] Cu2Fe2(AsO4)2(OH)4H2O A dark-green to greenish-yellow min- eral consisting of a hydrous copper iron arsenate occurring in masses. { ¦shen ə¦viksı̄t } chenier [GEOL] A continuous ridge of beach material built upon swampy deposits; often supports trees, such as pines or evergreen oaks. { shenyā } Chernozem [GEOL] One of the major groups of zonal soils, developed typically in temperate to cool, subhumid climate; the Chernozem soils in modern classification include Borolls, Ustolls, Udolls, and Xerolls. Also spelled Tchernozem. { ¦chər nəz¦yȯm } chert [PETR] A hard, dense, sedimentary rock composed of fine-grained silica, charac- terized by a semivitreous to dull luster and a splintery to conchoidal fracture; com- monly gray, black, reddish brown, or green. Also known as hornstone; phthanite. { chərt } chertification [GEOL] A process of replacement by silica in limestone in the form of fine-grained quartz or chalcedony. { chərdəfəkashən } chessylite See azurite. { shesəlı̄t } Chesterian [GEOL] Upper Mississippian geologic time. { chestirēən } chestnut coal [GEOL] Anthracite coal small enough to pass through a round mesh of 1 5/8 inches (3.1 centimeters) but too large to pass through a round mesh of 1 13/16 inches (1.7 centimeters). { chesnət kōl } Chestnut soil [GEOL] One of the major groups of zonal soils, developed typically in temperate to cool, subhumid to semiarid climate; the Chestnut soils in modern classification include Ustolls, Borolls, and Xerolls. { chesnət ¦sȯil } chevkinite [MINERAL] (Fe,Ca)(Ce,La)2(Si,Ti)2O8 A mineral consisting of silicotitanate of iron, calcium, and rare-earth elements. { chefkənı̄t } chevron fold [GEOL] An accordionlike fold with limbs of equal length. { shevrən fōld } chiastolite [MINERAL] A variety of andalusite whose crystals have a cross-shaped appearance in cross section due to the arrangement of carbonaceous impurities. Also known as macle. { kı̄astəlı̄t } Chideruan [GEOL] Uppermost Permian geologic time. { chiderəwən } childrenite [MINERAL] (Fe,Mn)AlPO4(OH)2H2O A pale-yellowish to dark-brown ortho- rhombic mineral consisting of a hydrous basic iron aluminum phosphate occurring as translucent crystals; it is isomorphous with eosphorite; hardness is 4.5–5 on Mohs scale, and specific gravity is 3.18–3.24. { childrənı̄t } Chile niter See Chile saltpeter. { ¦chilē nı̄dər } Chile saltpeter [MINERAL] Also known as Chile niter. 1. Soda niter found in large quantities in caliche in arid regions of northern Chile. 2. Deposits of sodium nitrate. { ¦chilē sȯltpēdər } chilled contact [PETR] The finer-grained portion of an igneous rock found near its contact with older rock. { child käntakt } 67 Downloaded from : iDATA.ws Chilobolbinidae Chilobolbinidae [PALEON] A family of extinct ostracods in the superfamily Hollinacea showing dimorphism of the velar structure. { kı̄ləbälbı̄nədē } chimney [GEOL] See pipe; spouting horn. { chimnē } chimney rock [GEOL] 1. A chimney-shaped remnant of a rock cliff whose sides have been cut into and carried away by waves and the gravel beach. 2. A rock column rising above its surroundings. { chimnē räk } chiolite [MINERAL] Na5Al3F14 A snow white mineral resembling cryolite. Also known as arksutite. { kı̄əlı̄t } Chirodidae [PALEON] A family of extinct chondrostean fishes in the suborder Platyso- moidei. { kı̄rädədē } Chirognathidae [PALEON] A family of conodonts in the suborder Neurodontiformes. { kı̄rəgnäthədē } Chitinozoa [PALEON] An extinct group of unicellular microfossils of the kingdom Pro- tista. { ¦kı̄tənə¦zōə } chiviatite [MINERAL] Pb2Bi6S11 A lead-gray mineral consisting of a lead bismuth sulfide occurring in foliated masses. { chivēätı̄t } chloanthite [MINERAL] NiAs23 A white or gray mineral with metallic luster forming crystals in the isometric system; it is isomorphous with nickel-skutterudite. { klōanthı̄t } chloraluminite [MINERAL] AlCl36H2O A mineral consisting of hydrous aluminum chlo- ride. { ¦klȯrə¦lümənı̄t } chlorapatite [MINERAL] Ca5(PO4)3Cl An apatite mineral containing chlorine. { klȯrapətı̄t } chlorargyrite See cerargyrite. { klȯrarjərı̄t } chlorastrolite [MINERAL] A mottled, green variety of pumpellyite occurring as grains or small nodules of a stellate structure in basic igneous rock in the Lake Superior region; used as a semiprecious stone. { klȯrastrəlı̄t } chlorite [MINERAL] Any of a group of greenish, platyhydrous monoclinic silicates of aluminum, ferrous iron, and magnesium which are closely associated with and resemble the micas. { klȯrı̄t } chlorite schist [PETR] A metamorphic rock whose composition is dominated by mem- bers of the chlorite group. { klȯrı̄t shist } chlorite-sericite schist [PETR] A low-grade, fine-grained variety of mica schist without biotite. { klȯrı̄t serəsı̄t shist } chloritoid [MINERAL] FeAl4Si2O10(OH)4 A micaceous mineral related to the brittle mica group; has both monoclinic and triclinic modifications, a gray to green color, and weakly pleochroic crystals. { klȯrətoid } chloritoid schist [PETR] A variety of mica schist whose composition is dominated by chloritoid. { klȯrətoid shist } chlormanganokalite [MINERAL] K4MnCl6 A wine yellow to lemon or canary yellow, hex- agonal mineral consisting of potassium and manganese chloride; occurs as rhombo- hedrons. { klȯr¦maŋgənōkālı̄t } chlorocalcite [MINERAL] KCaCl3 A white mineral consisting of a chloride of potassium and calcium. Also known as hydrophilite. { ¦klȯrōkalsı̄t } chloromagnesite [MINERAL] MgCl2 A mineral consisting of anhydrous magnesium chlo- ride, found on the volcano Vesuvius. { ¦klȯrōmagnəsı̄t } chloropal See nontronite. { klȯrəpal } chlorophoenicite [MINERAL] (Mn,An)5(AsO4)(OH)7 Gray-green monoclinic mineral con- sisting of a basic arsenate of manganese and zinc occurring in crystals. { klȯr ōfēnəsı̄t } chlorothionite [MINERAL] K2Cu(SO4)Cl2 Bright-blue secondary mineral consisting of potassium copper sulfate chloride, found on the volcano Vesuvius. { klȯrəthı̄ ənı̄t } chloroxiphite [MINERAL] Pb3CuCl2(OH)2O2 A dull-olive or pistachio-green mineral con- sisting of a basic chloride of lead and copper, found in the Mendip Hills of England. { kləräksəfı̄t } 68 Downloaded from : iDATA.ws clay Claibornian [GEOL] Middle Eocene geologic time. { klerbȯrnēən } clairite See enargite. { klerı̄t } clan [PETR] A category of igneous rocks defined in terms of similarities in mineralogical or chemical composition. { klan } clarain [GEOL] A coal lithotype appearing as stratifications parallel to the bedding plane and usually having a silky luster and scattered or diffuse reflection. Also known as clarite. { klarān } Clarendonian [GEOL] Lower Pliocene or upper Miocene geologic time. { klarəndōn ēən } clarinite [MINERAL] A heterogeneous, generally translucent material making up the major micropetrological ingredient of clarain. { klarənı̄t } clarite See clarain. { kları̄t } clarke [GEOCHEM] A unit of the average abundance of an element in the earth’s crust, expressed as a percentage. Also known as crustal abundance. { klärk } Clarkecarididae [PALEON] A family of extinct crustaceans in the order Anaspidacea. { klärkəridədē } clarkeite [MINERAL] (Na,Ca,Pb)2U2(O,OH)7 A dark reddish-brown or dark brown mineral consisting of a hydrous or hydrated uranium oxide. { klärkı̄t } clarodurain [GEOL] A transitional lithotype of coal composed of vitrinite and other macerals, principally micrinite and exinite. { ¦klarōdu̇rān } clarofusain [GEOL] A transitional lithotype of coal composed of fusinite and vitrinite and other macerals. { ¦klarōfyüzān } clarovitrain [GEOL] A transitional lithotype of coal rock composed primarily of the maceral vitrinite, with lesser amounts of other macerals. { ¦klarōvitrān } clast [GEOL] An individual grain, fragment, or constituent of detrital sediment or sedi- mentary rock produced by physical breakdown of a larger mass. { klast } clastation See weathering. { klastāshən } clastic [GEOL] Rock or sediment composed of clasts which have been transported from their place of origin, as sandstone and shale. { klastik } clastic dike [GEOL] A tabular-shaped sedimentary dike composed of clastic material and transecting the bedding of a sedimentary formation; represents invasion by extraneous material along a crack of the containing formation. { klastik dı̄k } clastic pipe [GEOL] A cylindrical body of clastic material having an irregular columnar or pillarlike shape, standing approximately vertically through enclosing formations (usually limestone), and measuring a few centimeters to 50 meters (165 feet) in diameter and 1 to 60 meters (3 to 200 feet) in height. { klastik pı̄p } clastic ratio [GEOL] The ratio of the percentage of clastic rocks to that of nonclastic rocks in a geologic section. Also known as detrital ratio. { klastik rāshō } clastic reservoir [GEOL] An underground oil or gas trap formed in clastic limestone. { klastik rezəvwär } clastic sediment [GEOL] Deposits of clastic materials transported by mechanical agents. Also known as mechanical sediment. { klastik sedəmənt } clastic wedge [GEOL] The sediments of the exogeosyncline, derived from the tectonic landmasses of the adjoining orthogeosyncline. { klastik wej } clathrate [GEOCHEM] See gas hydrate. [PETR] Pertaining to a condition, chiefly in leucite rock, in which clear leucite crystals are surrounded by tangential leucite crystals to give the rock an appearance of a net or a section of sponge. Also known as enclosure compound. { klathrāt } clathrate hydrate See gas hydrate. { ¦klathrāt hı̄drāt } claudetite [MINERAL] As2O3 A mineral containing arsenic that is dimorphous with arse- nolite; crystallizes in the monoclinic system. { klȯdətı̄t } clausthalite [MINERAL] PbSe A mineral consisting of lead selenide and resembling galena; specific gravity is 7.6–8.8. { klau̇stəlı̄t } Clavatoraceae [PALEOBOT] A group of middle Mesozoic algae belonging to the Charo- phyta. { klavədərāsēē } clay [GEOL] 1. A natural, earthy, fine-grained material which develops plasticity when mixed with a limited amount of water; composed primarily of silica, alumina, and 71 Downloaded from : iDATA.ws Clay Belt water, often with iron, alkalies, and alkaline earths. 2. The fraction of an earthy material containing the smallest particles, that is, finer than 3 micrometers. { klā } Clay Belt [GEOL] A lowland area bordering on the western and southern portions of Hudson and James bays in Canada, composed of clays and silts recently deposited in large glacial lakes during the withdrawal of the continental glaciers. { klā belt } clay gall [GEOL] A dry, curled clay shaving derived from dried, cracked mud and embed- ded and flattened in a sand stratum. { klā gȯl } clay ironstone [PETR] 1. A clayey rock containing large quantities of iron oxide, usually limonite. 2. A clayey-looking stone occurring among carboniferous and other rocks; contains 20–30% iron. { klā ı̄ərnstōn } clay loam [GEOL] Soil containing 27–40% clay, 20–45% sand, and the remaining portion silt. { ¦klā lōm } clay marl [GEOL] A chalky clay, whitish with a smooth texture. { ¦klā märl } clay mineral [MINERAL] One of a group of finely crystalline, hydrous silicates with a two-or three-layer crystal structure; the major components of clay materials; the most common minerals belong to the kaolinite, montmorillonite, attapulgite, and illite groups. { ¦klā ¦minrəl } claypan [GEOL] A stratum of compact, stiff, relatively impervious noncemented clay; can be worked into a soft, plastic mass if immersed in water. { klāpan } clay plug [GEOL] Sediment, with a great deal of organic muck, deposited in a cutoff river meander. { ¦klā ¦pləg } clay shale [GEOL] 1. Shale composed wholly or chiefly of clayey material which becomes clay again on weathering. 2. Consolidated sediment composed of up to 10% sand and having a silt to clay ratio of less than 1:2. { ¦klā ¦shāl } clay soil [GEOL] A fine-grained inorganic soil which forms hard lumps when dry and becomes sticky when wet. { ¦klā ¦sȯil } claystone [GEOL] Indurated clay, consisting predominantly of fine material of which a major proportion is clay mineral. { klāstōn } clay vein [GEOL] A body of clay which is similar to an ore vein in form and fills a crevice in a coal seam. Also known as dirt slip. { klā vān } cleat [GEOL] Vertical breakage planes found in coal. Also spelled cleet. { klēt } cleat spar See ankerite. { klēt spär } cleavage [GEOL] Splitting, or the tendency to split, along parallel, closely positioned planes in rock. { klēvij } cleavage banding [GEOL] A compositional banding, usually formed from incompetent material such as argillaceous rocks, that is parallel to the cleavage rather than the bedding. { klēvij bandiŋ } cleavelandite [MINERAL] A white, lamellar variety of albite that is almost pure NaAl- Si3O8 and has a tabular habit, with individuals often showing mosaic developments and tending to occur in fan-shaped aggregates. { klēvləndı̄t } cleet See cleat. { klēt } cliachite [MINERAL] A group of brownish, colloidal aluminum hydroxides that consti- tutes most bauxite. { klı̄əkı̄t } cliff of displacement See fault scarp. { klif əv displāsmənt } Cliftonian [GEOL] Middle Middle Silurian geologic time. { kliftänēən } Climatiidae [PALEON] A family of archaic tooth-bearing fishes in the suborder Climati- oidei. { klı̄mətı̄ədē } Climatiiformes [PALEON] An order of extinct fishes in the class Acanthodii having two dorsal fins and large plates on the head and ventral shoulder. { klı̄mətı̄əfȯrmēz } Climatioidei [PALEON] A suborder of extinct fishes in the order Climatiiformes. { klı̄ mətı̄ȯidēı̄ } climatochronology [GEOL] The absolute age dating of recent geologic events by using the oxygen isotope ratios in ice, shells, and so on. { klı̄¦madōkrənäləjē } climbing dune [GEOL] A dune that develops on the windward side of mountains or hills. { klı̄miŋ dün } clinker [GEOL] Burnt or vitrified stony material, as ejected by a volcano or formed in a furnace. { kliŋkər } 72 Downloaded from : iDATA.ws coalification clinoamphibole [MINERAL] A group of amphiboles which crystallize in the monoclinic system. { ¦klı̄nōamfəbōl } clinochlore [MINERAL] (Mg,Fe,Al)3(Si,Al)2O5(OH)4 Green mineral of the chlorite group, occurring in monoclinic crystals, in folia or scales, or massive. { klı̄nəklȯr } clinoclase [MINERAL] Cu3(AsO4)(OH)3 A dark-green mineral consisting of basic copper arsenate occurring in translucent prismatic crystals or massive. Also known as clinoclasite. { klı̄nəklās } clinoclasite See clinoclase. { ¦klı̄nə¦klāsı̄t } clinoenstatite [MINERAL] Mg2(Si2O6) A monoclinic pyroxene consisting principally of magnesium silicate; occurs frequently in stony meteorites, but is rare in terrestrial environments. { ¦klı̄nōenztətı̄t } clinoferrosilite [MINERAL] Fe2(Si2O6) A monoclinic pyroxene consisting of iron silicate. { ¦klı̄nōferōsı̄lı̄t } clinoform [GEOL] A subaqueous landform, such as the continental slope of the ocean or the foreset bed of a delta. { klı̄nəfȯrm } clinohedrite [MINERAL] CaZnSiO3(OH)2 A colorless, white, or purplish monoclinic min- eral consisting of a calcium zinc silicate occurring in crystals; hardness is 5.5 on Mohs scale, and specific gravity is 3.33. { ¦klı̄nō¦hēdrı̄t } clinohumite [MINERAL] Mg9(SiO4)4(F,OH2) A monoclinic mineral of the humite group. { ¦klı̄nōhyümı̄t } clinoptilolite [MINERAL] (Na,K,Ca)23Al3(Al,Si)2Si13O3612H2O A zeolite mineral that is considered to be a potassium-rich variety of heulandite. { klinəptiləlı̄t } clinopyroxene [MINERAL] The general term for any of those pyroxenes that crystallize in the monoclinic system; on occasion, these pyroxenes have large amounts of calcium with or without aluminum and the alkalies. Also known as monopyroxene clinoaugite. { ¦klı̄nəpəräksēn } clinozoisite [MINERAL] Ca2Al3(SiO4)3(OH) A grayish-white, pink, or green monoclinic mineral of the epidote group. { ¦klı̄nəzōisı̄t } clint [GEOL] A hard or flinty rock, such as a projecting rock or ledge. { klint } Clintonian [GEOL] Lower Middle Silurian geologic time. { klintōnēən } clintonite [MINERAL] Ca(Mg,Al)3(Al,Si)O10(OH)2 A reddish-brown, copper-red, or yellow- ish monoclinic mineral of the brittle mica group occurring in crystals or foliated masses. Also known as seybertite; xanthophyllite. { klintənı̄t } closed fold [GEOL] A fold whose limbs have been compressed until they are parallel, and whose structure contour lines form a closed loop. Also known as tight fold. { ¦klōzd ¦fōld } close-joints cleavage See slip cleavage. { ¦klōs ¦jȯins klēvij } close sand See tight sand. { ¦klōs ¦sand } closure [GEOL] The vertical distance between the highest and lowest point on an anticline which is enclosed by contour lines. { klōzhər } cluse [GEOL] A narrow gorge, trench, or water gap with steep sides that cuts trans- versely through an otherwise continuous ridge. { klüz } clusterite See botryoid. { kləstərı̄t } Coahuilan [GEOL] A North American provincial series in Lower Cretaceous geologic time, above the Upper Jurassic and below the Comanchean. { kōəwēlən } coal [GEOL] The natural, rocklike, brown to black derivative of forest-type plant mate- rial, usually accumulated in peat beds and progressively compressed and indurated until it is finally altered into graphite or graphite-like material. { kōl } coal ball [GEOL] A subspherical mass containing mineral matter embedded with plant material, found in coal seams and overlying beds of the late Paleozoic. { kōl bȯl } coal bed [GEOL] A seam or stratum of coal parallel to the rock stratification. Also known as coal rake; coal seam. { kōl bed } coal breccia [GEOL] Angular fragments of coal within a coal bed. { kōl brechə } coal clay See underclay. { kōl klā } coalification [GEOL] Formation of coal from plant material by the processes of diagen- esis and metamorphism. Also known as bituminization; carbonification; incarbon- ization; incoalation. { kōləfəkāshən } 73 Downloaded from : iDATA.ws collinite collinite [GEOL] The maceral, of collain consistency, of jellified plant material precipi- tated from solution and hardened; a variety of euvitrinite. { kälənı̄t } collinsite [MINERAL] Ca2(Mg,Fe)(PO4)2 A phosphate mineral occurring in concentric layers in phosphoric nodules; found in meteorites. { kälənzı̄t } colloform [GEOL] Pertaining to the rounded, globular texture of mineral formed by colloidal precipitation. { käləfȯrm } collophane [MINERAL] A massive, cryptocrystalline, carbonate-containing variety of apatite and a principal source of phosphates for fertilizers. Also known as collophan- ite. { käləfān } collophanite See collophane. { kəläfənı̄t } colluvium [GEOL] Loose, incoherent deposits at the foot of a slope or cliff, brought there principally by gravity. { kəlüvēəm } Collyritidae [PALEON] A family of extinct, small, ovoid, exocyclic Euechinoidea with fascioles or a plastron. { käləridədē } Coloradoan [GEOL] Middle Upper Cretaceous geologic time. { käləradəwən } coloradoite [MINERAL] HgTe A grayish-black, isometric telluride mineral with a metallic luster; specific gravity is 8.6. { käləradəwı̄t } columbite [MINERAL] (Fe,Mn)(Cb,Ta)2O6 An iron-black mineral with a submetallic luster that crystallizes in the orthorhombic system; the chief ore mineral of niobium (colum- bium); hardness is 6 on Mohs scale, and specific gravity is 5.4–6.5. Also known as dianite; greenlandite; niobite. { kələmbı̄t } column [GEOL] See geologic column; stalacto-stalagmite. { käləm } columnar jointing [GEOL] Parallel, prismatic columns that are formed as a result of contraction during cooling in basaltic flow and other extrusive and intrusive rocks. Also known as columnar structure; prismatic jointing; prismatic structure. { kələm nər jȯintiŋ } columnar section [GEOL] A vertical strip or scale drawing of the strip taken from a given area or locality showing the sequence of the rock units and their stratigraphic relationship, and indicating the thickness, lithology, age, classification, and fossil content of the rock units. Also known as section. { kələmnər sekshən } columnar structure [GEOL] See columnar jointing. [MINERAL] Mineral structure con- sisting of parallel columns of slender prismatic crystals. [PETR] A primary sedimen- tary structure consisting of columns arranged perpendicular to the bedding. { kələmnər strəkchər } colusite [MINERAL] Cu3(As,Sn,V,Fe,Te)S4 A bronze-colored mineral consisting of a sul- fide of copper and arsenic with vanadium, iron, and telluride substituting for arsenic; usually occurs in massive form. { kəlüsı̄t } comagmatic province See petrographic province. { ¦kōmagmadik prävəns } Comanchean [GEOL] A North American provincial series in Lower and Upper Creta- ceous geologic time, above Coahuilan and below Gulfian. { kəmanchēən } combination trap [GEOL] Underground reservoir structure closure, deformation, or fault where reservoir rock covers only part of the structure. { kämbənāshən ¦trap } combined water [GEOCHEM] Water attached to soil minerals by means of chemical bonds. { kəmbı̄nd wȯdər } combustible shale See tasmanite. { kəmbəstəbəl shāl } comendite [GEOL] A white, sodic rhyolite containing alkalic amphibole or pyroxene. { kəmendı̄t } Comleyan [GEOL] Lower Cambrian geologic time. { kämlāən } common feldspar See orthoclase. { ¦kämən feldspär } common mica See muscovite. { ¦kämən mı̄kə } common pyrite See pyrite. { ¦kämən pı̄rı̄t } common salt See halite. { ¦kämən sȯlt } compaction [GEOL] Process by which soil and sediment mass loses pore space in response to the increasing weight of overlying material. { kəmpakshən } competence [GEOL] The ability of the wind to transport solid particles either by rolling, suspension, or saltation (intermittent rolling and suspension); usually expressed in terms of the weight of a single particle. { kämpədəns } 76 Downloaded from : iDATA.ws concentric weathering competent beds [GEOL] Beds or strata capable of withstanding the pressures of folding without flowing or changing in original thickness. { ¦kämpədənt ¦bedz } complementary rocks [GEOL] Rocks which are differentiated from the same magma, and whose average composition is the same as the parent magma. { kämpləmen trē räks } complex [GEOL] An assemblage of rocks that has been folded together, intricately mixed, involved, or otherwise complicated. [MINERAL] Composed of many ingredi- ents. { kämpleks } complex dune [GEOL] A dune of varying forms, often very large, and produced by variable, shifting winds and the merging of various dune types. { kämpleks dün } complex fold [GEOL] A fold whose axial line is also folded. { kämpleks fōld } complex tombolo [GEOL] A system resulting when several islands and the mainland are interconnected by a complex series of tombolos. Also known as tombolo cluster; tombolo series. { kämpleks tämbəlō } composite cone [GEOL] A large volcanic cone constructed of lava and pyroclastic material in alternating layers. { kəmpäzət kōn } composite dike [GEOL] A dike consisting of several intrusions differing in chemical and mineralogical composition. { kəmpäzət dı̄k } composite fold [GEOL] A fold having smaller folds on its limbs. { kəmpäzət fōld } composite gneiss [PETR] A banded rock formed by intimate penetration of magma into country rocks. { kəmpäzət nı̄s } composite grain [GEOL] A sedimentary clast formed of two or more original particles. { kəmpäzət grān } composite sequence [GEOL] An ideal sequence of cyclic sediments containing all the lithological types in their proper order. { kəmpäzət sēkwəns } composite sill [GEOL] A sill consisting of several intrusions differing in chemical and mineralogical compositions. { kəmpäzət sil } composite topography [GEOL] A topography whose features have developed in two or more erosion cycles. { kəmpäzət təpägrəfē } composite unconformity [GEOL] An unconformity that has resulted from more than one episode of nondeposition and possible erosion. { kəmpäzət ənkənfȯr mədē } composite vein [GEOL] A large fracture zone composed of parallel ore-filled fissures and converging diagonals, whose walls and intervening country rock have been replaced to a certain degree. { kəmpäzət vān } composite volcano See stratovolcano. { kəmpäzət välkānō } compositional maturity [GEOL] Concept of a type of maturity in sedimentary rocks in which a sediment approaches the compositional end product to which formative processes drive it. { kämpəzishənəl məchu̇rədē } compound alluvial fan [GEOL] Structure formed by the lateral growth and merger of fans made by neighboring streams. { kämpau̇nd ə¦lüvēəl ¦fan } compound fault [GEOL] A zone or series of essentially parallel faults, closely spaced. { kämpau̇nd fȯlt } compound ripple marks [GEOL] Complex ripple marks of great diversity which origi- nate by simultaneous interference of wave oscillation with current action. { käm pau̇nd ripəl märks } compound volcano [GEOL] 1. A volcano consisting of a complex of two or more cones. 2. A volcano with an associated volcanic dome. { kämpau̇nd välkānō } compression [GEOL] A system of forces which tend to decrease the volume or shorten rocks. { kəmpreshən } concentric faults [GEOL] Faults that are arranged concentrically. { kənsentrik fȯlts } concentric fold [GEOL] A fold in which the original thickness of the strata is unchanged during deformation. Also known as parallel fold. { kənsentrik fōld } concentric fractures [GEOL] A system of fractures concentrically arranged about a center. { kənsentrik frakchərz } concentric weathering See spheroidal weathering. { kənsentrik wethəriŋ } 77 Downloaded from : iDATA.ws conchoidal conchoidal [GEOL] Having a smoothly curved surface; used especially to describe the fracture surface of a mineral or rock. { käŋkȯidəl } concordant body [GEOL] An intrusive igneous body whose contacts are parallel to the bedding of the country rock. Also known as concordant injection; concordant pluton. { kən kȯrdənt ¦bädē } concordant coastline [GEOL] A coastline parallel to the land structures which form the margin of an ocean basin. { kənkȯrdənt kōstlı̄n } concordant injection See concordant body. { kənkȯrdənt injekshən } concordant pluton See concordant body. { kənkȯrdənt plütän } concretion [GEOL] A hard, compact mass of mineral matter in the pores of sedimentary or fragmental volcanic rock; represents a concentration of a minor constituent of the enclosing rock or of cementing material. { känkrēshən } concretionary [GEOL] Tending to grow together, forming concretions. { kənkrē shənerē } concretioning [GEOL] The process of forming concretions. { kənkrēshəniŋ } concussion fracture [GEOL] Radiating system of fractures in a shock-metamorphosed rock. { kənkəshən frakchər } condensate field [GEOL] A petroleum field developed in predominantly gas-bearing reservoir rocks, but within which condensation of gas to oil commonly occurs with decreases in field pressure. { kändənsāt fēld } conductivity See permeability. { kändəktivədē } conduit [GEOL] A water-filled underground passage that is always under hydrostatic pressure. { kändəwət } Condylarthra [PALEON] A mammalian order of extinct, primitive, hoofed herbivores with five-toed plantigrade to semidigitigrade feet. { kändəlärthrə } cone [GEOL] A mountain, hill, or other landform having relatively steep slopes and a pointed top. { kōn } cone delta See alluvial cone. { kōn deltə } cone dike See cone sheet. { kōn dı̄k } cone-in-cone structure [GEOL] The structure of a concretion characterized by the devel- opment of a succession of cones one within another. { kōn in kōn strəkchər } cone karst [GEOL] A type of karst, typical of tropical regions, characterized by a pattern of steep, convex sides and slightly concave floors. Also known as cockpit karst; Kegel karst. { kōn kärst } Conemaughian [GEOL] Upper Middle Pennsylvanian geologic time. { känəmȯgē ən } cone of dejection See alluvial cone. { kōn əv dijekshən } cone of detritus See alluvial cone. { kōn əv ditrı̄dəs } cone sheet [GEOL] An accurate dike forming part of a concentric set that dips inward toward the center of the arc. Also known as cone dike. { kōn shēt } Conewangoan [GEOL] Upper Upper Devonian geologic time. { känəwaŋgəwən } confining bed [GEOL] An impermeable bed adjacent to an aquifer. { kənfı̄niŋ bed } confining pressure [GEOL] An equal, all-sided pressure, such as lithostatic pressure produced by overlying rocks in the crust of the earth. { kənfı̄niŋ preshər } conformable [GEOL] 1. Pertaining to the contact of an intrusive body when it is aligned with the internal structures of the intrusion. 2. Referring to strata in which layers are formed above one another in an unbroken, parallel order. { kənfȯrməbəl } conformity [GEOL] The shared and undisturbed correspondence between adjacent sed- imentary strata that have been deposited in orderly sequence with little or no indication of time lapses. { kənfōrmədē } congelifluction See gelifluction. { kənjeləfləkshən } congelifraction [GEOL] The splitting or disintegration of rocks as the result of the freezing of the water contained. Also known as frost bursting; frost riving; frost shattering; frost splitting; frost weathering; frost wedging; gelifraction; gelivation. { kən¦jelə¦frakshən } congeliturbate [GEOL] Soil or unconsolidated earth which has been moved or dis- turbed by frost action. { kənjelətərbət } 78 Downloaded from : iDATA.ws cooperite bottom; generally consists of the continental borderland, shelf, slope, and rise. { ¦käntən¦entəl märjən } continental nucleus [GEOL] A large area of basement rock consisting of basaltic and more mafic oceanic crust and periodotitic mantle from which it is postulated that continents have grown. Also known as continental shield; cratogene; shield. { ¦käntən¦entəl nüklēəs } continental plate [GEOL] Thick continental crust. { ¦käntən¦entəl plāt } continental platform See continental shelf. { ¦käntən¦entəl platfȯrm } continental rise [GEOL] A transitional part of the continental margin; a gentle slope with a generally smooth surface, built up by the shedding of sediments from the continental block, and located between the continental slope and the abyssal plain. { ¦käntən¦entəl rı̄z } continental shelf [GEOL] The zone around a continent, that part of the continental margin extending from the shoreline and the continental slope; composes with the continental slope the continental terrace. Also known as continental platform; shelf. { ¦käntən¦entəl shelf } continental shield See shield. { ¦käntən¦entəl shēld } continental slope [GEOL] The part of the continental margin consisting of the declivity from the edge of the continental shelf extending down to the continental rise. { ¦käntən¦entəl slōp } continental shield See shield. { ¦käntən¦entəl shēld } continental terrace [GEOL] The continental shelf and slope together. { ¦käntən¦ent əl terəs } continent formation [GEOL] A series of six or seven major episodes, resulting from the buildup of radioactive heat and then the melting or partial melting of the earth’s interior; the molten rock melt rises to the surface, differentiating into less primitive lavas; the continent then nucleates, differentiates, and grows from oceanic crust and mantle. { ¦käntən¦entəl fərmāshən } continuous permafrost zone [GEOL] Regional zone predominantly underlain by per- manently frozen subsoil that is not interrupted by pockets of unfrozen ground. { kən¦tinyəwəs pərməfrȯst zōn } continuous profiling [GEOL] A method of shooting in seismic exploration in which uniformly placed seismometer stations along a line are shot from holes spaced along the same line so that each hole records seismic ray paths geometrically identical with those from adjacent holes. { kən¦tinyəwəs prōfı̄liŋ } continuous reaction series [MINERAL] A branch of Bowen’s reaction series comprising the plagioclase mineral group in which reaction of early-formed crystals with water takes place continuously, without abrupt changes in crystal structure. { kən¦tinyə wəs rēakshən sirēz } contraction hypothesis [GEOL] Theory that shrinking of the earth is the cause of compression folding and thrusting. { kəntrakshən hı̄päthəsəs } Conularida [PALEON] A small group of extinct invertebrates showing a narrow, four- sided, pyramidal-shaped test. { känəlarədə } Conulidae [PALEON] A family of Cretaceous exocyclic Euechinoidea characterized by a flattened oral surface. { kənülədē } convection current [GEOPHYS] Mass movement of subcrustal or mantle material as the result of temperature variations. { kənvekshən kərənt } convergence [GEOL] Diminution of the interval between geologic horizons. { kənvərjəns } convolute bedding [GEOL] The extremely contorted laminae usually confined to a single layer of sediment, resulting from subaqueous slumping. { känvəlüt bediŋ } convolution [GEOL] 1. The process of developing convolute bedding. 2. A structure resulting from a convolution process, such as a small-scale but intricate fold. { kän vəlüshən } cooperite [MINERAL] (Pt,Pd)S A steel-gray tetragonal mineral of metallic luster con- sisting of a sulfide of platinum, occurring in irregular grains in igneous rock. { küpərı̄t } 81 Downloaded from : iDATA.ws coorongite coorongite [GEOL] A boghead coal in the peat stage. { kōärənjı̄t } copiapite [MINERAL] 1. Fe5(SO4)6(OH)220H2O A yellow mineral occurring in granular or scalar aggregates. Also known as ihleite; knoxvillite; yellow copperas. 2. A group of minerals containing hydrous iron sulfates. { kōpēəpı̄t } Copodontidae [PALEON] An obscure family of Paleozoic fishes in the order Bradyo- donti. { kōpədäntədē } copper glance See chalcocite. { käpər glans } copperite [MINERAL] An important platinum mineral, composed of platinum sulfide. { käpərı̄t } copper mica See chalcophyllite. { käpər mı̄kə } copper nickel See niccolite. { käpər nikəl } copper ore [GEOL] Rock containing copper minerals. { käpər ȯr } copper pyrite See chalcopyrite. { käpər pı̄rı̄t } copper uranite See torbernite. { käpər yu̇rənı̄t } coprolite [GEOL] Petrified excrement. { käprəlı̄t } coquimbite [MINERAL] Fe2(SO4)39H2O A white mineral that crystallizes in the hexago- nal system; it is dimorphous with paracoquimbite. { kōkimbı̄t } coquina [PETR] A coarse-grained, porous, easily crumbled variety of limestone com- posed principally of mollusk shell and coral fragments cemented together as rock. { kōkēnə } coquinoid [PETR] 1. Of or pertaining to coquina. 2. Lithified coquina. 3. An autoch- thonous deposit of limestone made up of more or less whole mollusk shells. { kōkənȯid } coracite See uraninite. { kȯrəsı̄t } coral head [GEOL] A small reef patch of coralline material. Also known as coral knoll. { kärəl ¦hed } coral knoll See coral head. { kärəl ¦nōl } coral mud [GEOL] Fine-grade deposits of coral fragments formed around coral islands and coasts bordered by coral reefs. { kärəl məd } coral pinnacle [GEOL] A sharply upward-projecting growth of coral rising from the floor of an atoll lagoon. { kärəl pinəkəl } coral reef [GEOL] A ridge or mass of limestone built up of detrital material deposited around a framework of skeletal remains of mollusks, colonial coral, and massive calcareous algae. { kärəl rēf } coral-reef shoreline [GEOL] A shoreline formed by reefs composed of coral polyps. Also known as coral shoreline. { kärəl rēf shȯrlı̄n } coral rock See reef limestone. { kärəl räk } coral sand [GEOL] Coarse-grade deposits of coral fragments formed around coral islands and coasts bordered by coral reefs. { kärəl sand } coral shoreline See coral-reef shoreline. { kärəl shȯrlı̄n } Cordaitaceae [PALEOBOT] A family of fossil plants belonging to the Cordaitales. { kȯrdāı̄tāsēē } Cordaitales [PALEOBOT] An extensive natural grouping of forest trees of the late Paleo- zoic. { kȯrdāı̄tālēz } cordierite [MINERAL] Mg2(Al4Si5O18) A blue, orthorhombic magnesium aluminosilicate mineral frequently occurring associated with thermally metamorphosed rocks derived from argillaceous sediments. { kȯrdēərı̄t } cordilleran geosyncline [GEOL] The Devonian geosynclinal region of western North America. { kȯrdəlerən jēōsinklı̄n } cordylite [MINERAL] (Ce,La)2Ba(CO3)3F2 A colorless to wax-yellow mineral consisting of a carbonate and fluoride of cerium, lanthanum, and barium. { kȯrdəlı̄t } core [GEOL] 1. Center of the earth, beginning at a depth of 2900 kilometers. Also known as earth core. 2. A vertical, cylindrical boring of the earth from which composi- tion and stratification may be determined; in oil or gas well exploration the presence of hydrocarbons or water are items of interest. { kȯr } core analysis [GEOL] The use of core samples taken from the borehole during drilling 82 Downloaded from : iDATA.ws Coryphodontoidea to give information on strata age, composition, and porosity, and the presence of hydrocarbons or water along the length of the borehole. { kȯr ənaləsəs } core intersection [GEOL] 1. The point in a borehole where an ore vein or body is encountered as shown by the core. 2. The width or thickness of the ore body, as shown by the core. Also known as core interval. { kȯr ¦intərsekshən } core interval See core intersection. { kȯr ¦intərvəl } core logging [GEOL] The analysis of the strata through which a borehole passes by the taking of core samples at predetermined depth intervals as the well is drilled. { kȯr lägiŋ } core sample [GEOL] A sample of rock, soil, snow, or ice obtained by driving a hollow tube into the undisturbed medium and withdrawing it with its contained sample or core. { kȯr sampəl } corestone [GEOL] A rounded or broadly rectangular joint block of granite formed as a result of subsurface weathering in a manner similar to a tor but entirely separated from the bedrock. { kȯrstōn } corneite [GEOL] A biotite-hornfels formed during deformation of shale by folding. { kȯrnēı̄t } cornetite [MINERAL] Cu3(PO4)(OH)3 A peacock-blue mineral consisting of basic copper phosphate. { kȯrnətı̄t } cornwallite [MINERAL] Cu5(AsO4)2(OH)4H2O A verdigris green to blackish-green min- eral consisting of a hydrated basic arsenate of copper; occurs as small botryoidal crusts. { kȯrnwȯlı̄t } corona [GEOL] A mineral zone that is usually radial about another mineral or at the area between two minerals. Also known as kelyphite. [MINERAL] An annular zone of minerals that is disposed either around another mineral or at the contact between two minerals. { kərōnə } coronadite [MINERAL] Pb(Mn2+,Mn4+)8O16 A black mineral consisting of a lead and manganese oxide, occurring in massive form with fibrous structure; an important constituent of manganese ore. { kȯrənädı̄t } corrasion [GEOL] Mechanical wearing away of rock and soil by the action of solid materials moved along by wind, waves, running water, glaciers, or gravity. Also known as mechanical erosion. { kərāzhən } correlation [GEOL] 1. The determination of the equivalence or contemporaneity of geologic events in separated areas. 2. As a step in seismic study, the selecting of corresponding phases, taken from two or more separated seismometer spreads, of seismic events seemingly developing at the same geologic formation boundary. { kärəlāshən } corrie See cirque. { kȯrē } corrosion [GEOCHEM] Chemical erosion by motionless or moving agents. { kərō zhən } corrosion border See corrosion rim. { kərōzhən bȯrdər } corrosion rim [MINERAL] A modification of the outlines of a porphyritic crystal due to the corrosive action of a magma on previously stable minerals. Also known as corrosion border. { kərōzhən rim } corsite [PETR] A spheroidal variety of gabbro. Also known as miagite; napoleonite. { kȯrsı̄t } cortlandite [PETR] A peridotite consisting of large crystals of hornblende with poikilit- ically included crystals of olivine. Also known as hudsonite. { kȯrtləndı̄t } corundum [MINERAL] Al2O3 A hard mineral occurring in various colors and crystallizing in the hexagonal system; crystals are usually prismatic or in rounded barrel shapes; gem varieties are ruby and sapphire. { kərəndəm } corvusite [MINERAL] V2O46V2O5nH2O A blue-black to brown mineral consisting of a hydrous oxide of vanadium; occurs in massive form. { kȯrvəsı̄t } Coryphodontidae [PALEON] The single family of the Coryphodontoidea, an extinct superfamily of mammals. { kȯrəfədäntədē } Coryphodontoidea [PALEON] A superfamily of extinct mammals in the order Panto- donta. { kȯrəfədäntȯidēə } 83 Downloaded from : iDATA.ws cross section cross section [GEOL] 1. A diagram or drawing that shows the downward projection of surficial geology along a vertical plane, for example, a portion of a stream bed drawn at right angles to the mean direction of the flow of the stream. 2. An actual exposure or cut which reveals geological features. { krȯs sekshən } cross-stone See harmotome; staurolite. { krȯs stōn } cross-stratification See cross-bedding. { krȯs stradəfəkāshən } cross valley See transverse valley. { krȯs valē } croute calcaire See caliche. { krüt kalker } crude oil [GEOL] A comparatively volatile liquid bitumen composed principally of hydrocarbon, with traces of sulfur, nitrogen, or oxygen compounds; can be removed from the earth in a liquid state. { ¦krüd ȯil } crumb structure [GEOL] A soil condition in which the particles are crumblike aggre- gates; suitable for agriculture. { krəm strəkchər } crush breccia [GEOL] A breccia formed in place by mechanical fragmentation of rock during movements of the earth’s crust. { krəsh brechə } crush conglomerate [GEOL] Beds similar to a fault breccia, except that the fragments are rounded by attrition. Also known as tectonic conglomerate. { krəsh kəngläm ərət } crush fold [GEOL] A fold of large dimensions that may involve considerable minor folding and faulting such as would produce a mountain chain or an oceanic deep. { krəsh fōld } crush zone [GEOL] A zone of fault breccia on fault gouge. { krəsh zōn } crust [GEOL] The outermost solid layer of the earth, mostly consisting of crystalline rock and extending no more than a few miles from the surface to the Mohorovičić discontinuity. Also known as earth crust. { krəst } crustal motion [GEOL] Movement of the earth’s crust. { ¦krəstəl mōshən } crustal plate See tectonic plate. { krəstəl plāt } cryoconite [GEOL] A dark, powdery dust transported by wind and deposited on the surface of snow or ice; found, however, mainly in cryoconite holes. [MINERAL] A mixture of garnet, sillimanite, zircon, pyroxene, quartz, and various other minerals. { krı̄äkənı̄t } cryoconite hole [GEOL] A cylindrical dust well filled with cryoconite; absorbs solar radiation, causing melting of glacier ice around and below it. { krı̄äkənı̄t hōl } cryogenic period [GEOL] A time period in geologic history during which large bodies of ice appeared at or near the poles and climate favored the formation of continental glaciers. { krı̄əjenik ¦pirēəd } cryolaccolith See hydrolaccolith. { ¦krı̄ōlakəlith } cryolite [MINERAL] Na3AlF6 A white or colorless mineral that crystallizes in the mono- clinic system but has a pseudocubic aspect; found in masses of waxy luster; hardness is 2.5 on Mohs scale, and specific gravity is 2.95–3.0; used chiefly as a flux in producing aluminum from bauxite and for making salts of sodium and aluminum and porcelaneous glass. Also known as Greenland spar; ice stone. { krı̄əlı̄t } cryolithionite [MINERAL] Na3Li3Al2F12 A colorless mineral that crystallizes in the isomet- ric system; found in the Ural Mountains. { krı̄ōlithēənı̄t } cryomorphology [GEOL] The branch of geomorphology that treats the processes and topographic features of regions where the ground is permanently frozen. { ¦krı̄ō mȯrfäləjē } cryopedology [GEOL] A branch of geology that deals with the study of intensive frost action and permanently frozen ground. { ¦krı̄ōpədäləjē } cryoplanation [GEOL] Land erosion at high latitudes or elevations due to processes of intensive frost action. { ¦krı̄ōplənāshən } cryosphere [GEOL] That region of the earth in which the surface is perennially frozen. { krı̄əsfir } cryostatic pressure [GEOL] Hydrostatic pressure exerted on soil and rocks when soil water freezes. { krı̄əstadik preshər } cryoturbation See congeliturbation. { ¦krı̄ōtərbāshən } 86 Downloaded from : iDATA.ws Ctenothrissidae cryptoclastic [GEOL] Composed of extremely fine, almost submicroscopic, broken or fragmental particles. { ¦kriptə¦klastik } cryptocrystalline [GEOL] Having a crystalline structure but of such a fine grain that individual components are not visible with a magnifying lens. { ¦kriptōkristələn } cryptohalite [MINERAL] (NH4)2SiF6 A colorless to white or gray, isometric mineral con- sisting of ammonium silicon fluoride; occurs in massive and arborescent forms. { ¦kriptōhalı̄t } cryptolite See monazite. { kriptəlı̄t } cryptomelane [MINERAL] KMn8O16H2O A usually massive mineral, common in manga- nese ores; contains an oxide of manganese and potassium and crystallizes in the monoclinic system. { ¦kriptōməlān } cryptoperthite [MINERAL] A fine-grained, submicroscopic variety of perthite consisting of an intergrowth of potassic and sodic feldspar, detectable only by means of x-rays or with the aid of an electron microscope. { ¦kriptōpərthı̄t } Cryptostomata [PALEON] An order of extinct bryozoans in the class Gymnolaemata. { kriptəstōmədə } cryptovolcanic [GEOL] A small, nearly circular area of highly disturbed strata in which there is no evidence of volcanic materials to confirm the origin as being volcanic. { ¦kriptōvälkanik } cryptozoon [PALEOBOT] A hemispherical or cabbagelike reef-forming fossil algae, prob- ably from the Cambrian and Ordovician. { ¦kriptōzōən } crystal See rock crystal. { kristəl } crystalline-granular texture [PETR] A primary texture of an igneous rock due to crystalli- zation from a fluid medium. { ¦kristələn ¦granyələr tekschər } crystalline porosity [GEOL] Porosity in crystalline limestone and dolomite, making possible underground oil reservoirs. { kristələn pəräsədē } crystalline rock [PETR] 1. Rock made up of minerals in a clearly crystalline state. 2. Igneous and metamorphic rock, as opposed to sedimentary rock. { kristələn räk } crystallinity [PETR] Degree of crystallization exhibited by igneous rock. { kristəlin ədē } crystallite [GEOL] A small, rudimentary form of crystal which is of unknown mineralogic composition and which does not polarize light. { kristəlı̄t } crystallization differentiation See fractional crystallization. { kristələzāshən dif ərenchēāshən } crystalloblast [MINERAL] A mineral crystal produced by metamorphic processes. { kristəlōblast } crystalloblastic series [GEOL] A series of metamorphic minerals ordered according to decreasing formation energy, so crystals of a listed mineral have a tendency to form idioblastic outlines at surfaces of contact with simultaneously developed crystals of all minerals in lower positions. { kristələblastik sirēz } crystalloblastic texture [GEOL] A crystalline texture resulting from metamorphic recrystallization under conditions of high viscosity and directed pressure. { kris tələblastik tekschər } crystallographic texture [MINERAL] A texture of replacement or exsolution mineral deposits, with the distribution and form of the inclusions controlled by the host- mineral crystallography. { ¦kristəlō¦grafik tekschər } crystal sandstone [GEOL] Siliceous sandstone in which deposited silica is precipitated upon the quartz grains in crystalline position. { ¦kristəl sandstōn } crystal settling [GEOL] Sinking of crystals in magma from the liquid in which they formed, by the action of gravity. { ¦kristəl ¦setliŋ } crystal tuff [GEOL] Consolidated volcanic ash in which crystals and crystal fragments predominate. { ¦kristəl təf } crystal-vitric tuff [GEOL] Consolidated volcanic ash composed of 50–75% crystal frag- ments and 25–50% glass fragments. { ¦kristəl ¦vitrik təf } Ctenothrissidae [PALEON] A family of extinct teleostean fishes in the order Ctenothris- siformes. { tenəthrisədē } 87 Downloaded from : iDATA.ws Ctenothrissiformes Ctenothrissiformes [PALEON] A small order of extinct teleostean fishes; important as a group on the evolutionary line leading from the soft-rayed to the spiny-rayed fishes. { tenəthrisəfȯrmēz } cubanite [MINERAL] CuFe2S3 Bronze-yellow mineral that crystallizes in the orthorhom- bic system. Also known as chalmersite. { kyübənı̄t } cube ore See pharmacosiderite. { kyüb ȯr } cube spar See anhydrite. { kyüb spär } culmination [GEOL] A high point on the axis of a fold. { kəlmənāshən } cumberlandite [PETR] A coarse-grained, ultramafic, ultrabasic rock composed princi- pally of olivine crystals in a ground mass of magnetite and ilmenite with minor plagioclase. { kəmbərləndı̄t } cumbraite [PETR] A variety of dacite or rhyodacite containing very calcic plagioclase and pyroxene in a glassy groundmass. { kyümbrāı̄t } cumengite [MINERAL] Pb4Cu4Cl8(OH)8H2O A deep-blue or light-indigo-blue tetragonal mineral consisting of a basic lead-copper chloride occurring in crystals. { kyümenjı̄t } cummingtonite [MINERAL] (Fe,Mg)7Si8O22(OH)2 A brownish mineral that crystallizes in the monoclinic system; usually occurs as lamellae or fibers in metamorphic rocks. { kəmiŋtənı̄t } cumulate [PETR] Any igneous rock formed by the accumulation of crystals settling out of a magma. { kyümyəlāt } cumulus [GEOCHEM] The accumulation of minerals which have precipitated from a liquid without having been modified by later crystallization. { kyümyələs } cup-and-ball joint [GEOL] A dish-shaped transverse fracture which divides a basalt column into segments. Also known as ball-and-socket joint. { kəp ən bȯl jȯint } cupola [GEOL] An isolated, upward-projecting body of plutonic rock that lies near a larger body; both bodies are presumed to unite at depth. { kyüpələ } cupped pebble [GEOL] A pebble fragment that has become hollow after being sub- jected to solution. { kəpt ¦pebəl } cuprite [MINERAL] Cu2O A red mineral that crystallizes in the isometric system and is found in crystals and fine-grained aggregates or is massive; a widespread supergene copper ore. Also known as octahedral copper ore; red copper ore; ruby copper ore. { kyüprı̄t } cuprocopiapite [MINERAL] CuFe4(SO4)6(OH)220H2O A sulfur yellow to orange-yellow, triclinic mineral consisting of a hydrated basic sulfate of copper and iron. { ¦kyü prōkōpēəpı̄t } cuprodescloizite See mottramite. { ¦kyüprōdesklōəzı̄t } cuprotungstite [MINERAL] Cu2(WO4)(OH)2 A green mineral that forms compact masses; soluble in acids; the crystal system is not known. { ¦kyüprōtəŋstı̄t } cuprouranite See torbernite. { ¦kyüprōyu̇rənı̄t } curite [MINERAL] Pb2U5O174H2O An orange-red radioactive mineral, occurring in acicu- lar crystals, an alteration product of uraninite. { kyu̇rı̄t } current-bedding [GEOL] Cross-bedding resulting from water or air currents. { kər ənt bediŋ } current lineation See parting lineation. { kərənt linēāshən } current mark [GEOL] Any structure formed by direct or indirect action of a water current on a sedimentary surface. { kərənt märk } current ripple [GEOL] A type of ripple mark having a long, gentle slope toward the direction from which the current flows, and a shorter, steeper slope on the lee side. { kərənt ripəl } curtain [GEOL] 1. A thin sheet of dripstone that hangs or projects from a cave wall. 2. A rock formation connecting two adjacent bastions. { kərtən } cusp [GEOL] One of a series of low, crescent-shaped mounds of beach material sepa- rated by smoothly curved, shallow troughs spaced at more or less regular intervals along and generally perpendicular to the beach face. Also known as beach cusp. [GEOPHYS] Any of the funnel-shaped regions in the magnetosphere extending from 88 Downloaded from : iDATA.ws