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Mineral01-Mineralogy and Crystallography
01A-General mineralogy
01B-Mineralogy of silicates
01C-Mineralogy of non-silicates

physical, optical, and chemical properties of naturally occurring inorganic minerals and related synthetic minerals, mineral crystallography, including crystal structure, determination of lattice parameters and unit cells, the bonding of atoms and molecules, crystal form and symmetry, collecting minerals, as well as non-mineral gems such as amber and jet

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02A-General geochemistry
02C-Geochemistry of rocks, soils, and sediments
02D-Isotope geochemistry

abundance of elements, organic materials, water, trace elements, isotopes, geochemical processes and properties, geochemical cycles, geochemical surveys analytical methods such as chemical, spectroscopic, thermal, and X-ray and electron microscopy instruments used for analysis
Related topics in other fields:
Field 05--petrology, fluid inclusions, geologic thermometry and barometry, meteorites
Field 03--geochronology
Field 06--clay mineralogy
Field 12--paleoclimatology
Fields 26 & 28--geochemical prospecting

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Tree rings03-Geochronology

determination by absolute age methods, including radiometric and radiogenic dating; establishing the chronology of events by methods such as lichenometry, racemization, tree rings, hydration of glass, varves, paleomagnetism, tephrochronology, thermoluminescence, radiation damage, fission-track dating and particle-track dating

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Surface04-Extraterrestrial geology

of the planets, asteroids, the Moon and moons of other planets, planetary composition, evolution, surface features, structure, motions 
Exclusions: astrophysics and extraterrestrial physics
Related topics in other fields:
Field 05-meteorites and tektites


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Lava05-Petrology, igneous and metamorphic
05A-Igneous and metamorphic petrology
05B-Petrology of meteorites and tektites


igneous rocks, metamorphic rocks, metasomatism metamorphism, phase equilibria, magmas, lava, intrusions, inclusions, ancient volcanology
Related topics in other fields:
Field 17-phase transitions
Field 23-volcanic features
Field 24-modern volcanology

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Pebbles06-Petrology, sedimentary
06A-Sedimentary petrology
06B-Petrology of coal


sedimentary rocks, sediments, sedimentation, diagenesis, sedimentary structures, genesis of peat, lignite and coal, clay mineralogy, chemical properties of clay minerals
Related topics in other fields:
Field 07-marine sedimentation
Field 24-Quaternary sediments
Field 29-economic studies of peat, lignite and coal

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Island07-Marine geology and oceanography



continental shelf, continental slope, ocean floors, ocean waves (sediment transport), ocean circulation (sediment transport), reefs (modern) 
patterns of ocean circulation
marine biology
wave propagation
Related topics in other fields:
Field 02-geochemistry of sea water
Field 18-ocean basin evolution
Field 21-estuarine studies
Field 24-Quaternary sediments and Recent lake and sea-level changes

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Fossil08-Paleontology, general studies
of both fossil plants and animals


Archaea, Bacteria, life origin, paleontological textbooks, paleontological glossaries, fossil collecting, problematic fossils, ichnofossils (if not related to a specific fossil group)
Related topics in other fields:
Field 09-fossil plants
Field 10-invertebrates
Field 11-vertebrates
Field 12-biostratigraphy

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Fossil Plant09-Paleontology, paleobotany



algae, Angiospermae, Bryophyta, Cyanobacteria, Fungi, Gymnospermae, Hepaticae, lichens, nannofossils, palynomorphs, Plantae, Pteridophyta
Related topics in other fields:
Field 12-biostratigraphy, paleoenvironmental interpretation
Field 24-Quaternary palynology

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Fossils10-Paleontology, invertebrate



Annelida, Archaeocyatha, Arthropoda, Brachiopoda, Bryozoa, Cnidaria (Coelenterata), ebridians, Echinodermata, Foraminifera, Graptolithina, Hemichordata, Insecta, Mollusca, Ostracoda, Porifera, Radiolaria, scolecodonts, Silicoflagellata, Thecamoeba, Tintinnida, Trilobita
Related topics in other fields: 
Field 12-biostratigraphy, paleoenvironmental interpretation
Field 24-Quaternary biostratigraphy, paleoenvironmental interpretation

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Fossil Fish11-Paleontology, vertebrate



Acanthodii, Agnatha, Amphibia, Aves, Chondrichthyes, Chordata, Conodonta, fish, fossil man, Heterostraci, Mammalia, Osteichthyes, Osteostraci, Placodermi, Reptilia, Tetrapoda
Related topics in other fields:
Field 12-biostratigraphy, paleoenvironmental interpretation
Field 24-Quaternary archaeology and artifacts

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Outcrop12-Stratigraphy, historical geology and paleoecology



lithostratigraphy (age relationships of rock strata), biostratigraphy, evolution of land masses (continental drift), paleomagnetism, paleogeography, biogeography, paleoclimatology
Related topics in other fields:
Field 06-reefs and sedimentation
Fields 08-11-paleontology
Field 22-Recent ecology
Field 24-Quaternary

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Rocks13-Areal geology, general



area studies dealing with several aspects of geology, entries that might be placed in three or more fields, guidebooks, road logs, bibliographies of geology of an area
Related topics in other fields:  
Field 14-geologic maps

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People Reading Maps14-Areal geology, maps and charts



separately published geologic maps, geologic maps with explanatory texts, separately published geologic charts, methodology of geologic mapping
Related topics in other fields:
specific types of maps are found under the specific field, e.g. geomorphologic maps are found in Field 23, Surficial geology, geomorphology

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People with computer15-Miscellaneous and mathematical geology



biography (if not related to a specific field)
bibliography (if not related to a specific field)
popular geology
elementary geology (textbooks)
general mathematical principles
annual reports of geologic surveys and associations
historical accounts
education-curricula, enrollments
directories to geology departments
geology as a profession-career opportunities
forensic geology-geology applied to crime solving
Related topics in other fields:
anything related to a specific field will be found in that field rather than here

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Outcrop with road16-Structural geology



classical tectonics (regional and local structures resulting from solid-rock movements), faults, fractures, folds, orogeny, geosynclines, deformation, structural analysis, epeirogeny, foliation, lineation
Related topics in other fields:
Field 18-plate tectonics, continental drift, sea-floor spreading

Before 1975 the following subjects were found in Structural geology; they are now found in other fields:
Field 05-batholiths, dikes, intrusions, stocks and volcanism
Field 06-breccia, sedimentary structures
Field 12-paleogeography, sea-level changes, unconformities
Field 18-crust, diapirs, geodesy, isostasy, Mohorovicic discontinuity
Field 22-nuclear explosions
Field 23-cratering, cryptoexplosion features
Field 24-glaciers

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Planet with field around it17-Geophysics, general
17A-General geophysics
17B-Geophysics of minerals and rocks


experimental and theoretical studies of physical properties of rocks, transition states of various compounds under elevated temperature and pressure (applied to core and mantle composition), magnetic and electrical properties of minerals and melts that relate to the Earth's magnetic field; history, development and education in geophysics (since 1981 in Field 18)
magnetic and gravity fields of the Earth (since 1981 in Field 18)
Exclusions: Meteorology, magnetosphere, astrophysics, aeronomy and solar physics
Related topics in other fields: 
Field 04-Extraterrestrial geology

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Map of Earth18-Geophysics, solid-Earth



worldwide structure of the Earth, plate tectonics, continental drift sea-floor spreading, paleomagnetism, structure of core, crust and mantle, Mohorovicic discontinuity
Related topics in other fields:
Field 16-Regional and local structure

Prior to 1975 the following subjects were found in Solid-Earth Geophysics; they are now found in other fields:
Field 20-Geophysical surveys
Field 19-Seismology

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Seismograph19-Geophysics, seismology



earthquakes and elastic waves, including seismograms, wave velocity, seismic sources, seismicity, microearthquakes, microseisms, mechanism of tsunamis and volcanic earthquakes
Related topics in other fields:
Field 18-velocity structure of Earth's interior
Field 22-geologic hazards, seismic risk
Field 30-earthquake engineering

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Satellite surveying planet20-Geophysics, applied



applied studies not related to a specific subject including: well-logging, remote sensing, magnetotelluric surveys, gravity surveys, electrical surveys, magnetic surveys, seismic surveys, electromagnetic surveys

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Lake21-Hydrogeology and hydrology



ground water-geochemistry, movement, resources, mathematical models
thermal waters, springs, geysers, fumaroles, soil-water regimes, surface water-chemistry, sediment transport, hydrologic cycle (from 1969 to 1974, fewer references to surface water were included)
Exclusions:   biology of surface water, hydraulics
Related topics in other fields:
Field 02-geochemistry of water
Field 22-pollution of water

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Oil barrels22-Environmental geology



climate change, ecology, geologic hazards-earthquakes, floods, land subsidence, landslides, debris flows, tsunamis, volcanoes, groundwater pollution conservation, land use, pollution of surface water (seldom covered) reclamation
* With the growth of the environmental sciences, inclusion of environmental topics has increased dramatically in recent years.
Related topics in other fields:
Field 21-Hydrogeology and hydrology
Field 30-Engineering geology

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Outcrop23-Surficial geology, geomorphology



genesis and evolution of features on the Earth's surface-meteor craters, cryptoexplosion features, eolian features, erosion features, fluvial features, frost action, lacustrine features, mass movements, shore features, solution features, and volcanic features
Related topics in other fields:
Field 24-Quaternary glacial features and modern volcanology

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Glacier24-Surficial geology, Quaternary geology



the last 2.6 million years of Earth's history, including:
archaeology, glacial geology, stratigraphy, palynology, modern volcanology, sea-level changes

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Soil25-Surficial geology, soils



soils-genesis, morphology, evolution, chemistry, erosion and classification
Exclusions: agricultural studies
Related topics in other fields:
Field 21-soil water regimes
Field 22-soil pollution
Field 23-erosion processes
Field 30-engineering properties of soils

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Open-pit mine26-Economic geology, general--geology of deposits
26A-General economic geology--geology of deposits
26B-General economic geology--economics


commodity studies-more than one type of commodity mining geology
Related topics in other fields:
Field 27-metals
Field 28-nonmetals
Field 29-energy sources

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Metal ore27-Economic geology of metal ore deposits
27A-Geology of metal ore deposits
27B-Economics of metal ores


metal ores-genesis, resources, economics, exploration, production and utilization (includes uranium)
Related topics in other fields: 
Field 26-general and mining geology

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Nonmetal deposit28-Economic geology of nonmetal deposits
28A-Geology of nonmetal deposits
28B-Economics of nonmetal deposits


nonmetal deposits-genesis, resources, economics, exploration, production, and utilization
Related topics in other fields: 
Field 26-general and mining geology

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Oil rig29-Economic geology of energy sources
29A-Geology of energy sources
29B-Economics of energy sources


petroleum, natural gas, coal deposits (economic studies), oil shale geothermal energy, oil sands
Related topics in other fields:
Field 06-genesis of coal, peat, and lignite
Field 26-general and mining geology
Field 27-uranium ores

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Dam30-Engineering geology



waste disposal, reclamation, structures-dams, foundations, highways, marine installations, nuclear facilities, reservoirs, tunnels, underground installations and waterways when geologic subjects such as rock and soil properties are discussed
Related topics in other fields:
Field 22-Environmental geology

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List A - GeoRef Categories/Subjects Covered

Subjects Covered (back to top)

General notes
These thesaurus lists, lists A-R, are used by GeoRef indexers for selecting index terms and by searchers for additional information on the hierarchies not necessarily found in individual term records in the body of the Thesaurus. In most cases, an hierarchical list is given. In some cases, an alphabetical or other list is provided.

The notes under Searching attempt to guide the searcher in the use of the list. Searchers might also read the notes on Indexing for further clues but should be aware that these notes reflect current practice which in some cases differs from past practice. Further notes on specific terms are in the body of the Thesaurus and additional notes on searching are in the GeoRef Thesaurus, 11th edition Introduction beginning on page x. Information specific to searching and the individual list topics is included, e.g. a section on subject categories begins on page x.

Under Indexing current indexing practice is given. These notes should be read along with the instructions under the individual terms in the body of the Thesaurus.

Subject categories
All references included in the GeoRef database are assigned one or occasionally several specific categories. The list of Subjects Covered shows the categories, lettered subcategories, and major topics as well as related topics in other fields, exclusions, and notes on changes in scope.

Generally one major code is selected with the intention of targeting the article to a particular audience. Similar topics are sometimes found under different codes, such as reclamation under both environmental geology and engineering geology. The indexer generally chooses one over the other and rarely may choose to include the article under both topics.

Beginning in 1981, the specific letter-coded categories are used. The categories may be used in searching both as words (phrases) or codes.

Single words from the codes are often included in the default subject search field. Thus a search for earthquake engineering can be accomplished by combining variant forms of "earthquake" which may be found in the Basic Index available on a searching platform, with "engineering" (either searched in the category field or the default subject search field).

Categories may also be used to eliminate unwanted aspects from a search. A search on magmas, for example, could be restricted to Earth-bound processes by using the Boolean Not with "extraterrestrial". To distinguish papers on commodities, the user may restrict the category to economic geology, e.g. copper AND economic in category. For geochemical papers, one might want to exclude economic in the category.

When searching categories, keep in mind that certain categories are not used with Quaternary geology 24. Therefore if the searcher wants to include those articles, the search could include the topic as an index term with Quaternary geology as the category, or with Quaternary as an index term, e.g.: igneous rocks and 05* in category; OR igneous rocks and Quaternary in category.

For specific field identifiers, see the documentation for the individual retrieval system. For more information regarding the application of each category code, see Subjects Covered above.

• In some categories, such as Geochemistry 02, Paleontology 08-11, and Economic Geology 26-29, there is a general category which is used for articles on the discipline or technique, or when more than one of the topics are included in the same article, e.g. when both hydrochemistry 02B and soils 02C are included, then 02A would be selected as the geochemistry category.

• Seismology applied to hazards engineering is used with Engineering geology 30, otherwise, seismology is usually placed under geologic hazards in Environmental geology 22, or in Geophysics, seismology 19.

• Quaternary geology is placed in category 24 rather than petrology (05, 06), paleontology 08-11, stratigraphy 12, structural geology 16, solid-Earth geophysics 18, geomorphology 23, or soils 25.

• Extraterrestrial geology 04 is used alone. If an Earth process or meteorites are discussed in the same record, other categories such as 02 Geochemistry may be used as well.

• Areal geology 13 is used where the article deals with three or more separate topics and is concerned with an area.

• Areal geology, maps and charts 14 is used for discussions of mapping and maps larger than a standard manuscript page.

• General geophysics 17B is used where geophysics of rocks and minerals are related to the Earth's core or mantle.

• Geomorphology 23 papers on landforms use many of the common feature names, such as deltas. Other topics are indexed using environment or sedimentation terms.

• Economic geology 26-29 papers which focus on economics rather than geology of the commodity are designated with a B code, e.g. 26B-29B. Articles with a commodity economics focus are rarely covered unless they occur with another topic of interest.