hydro  search
hydrobiotite  search
BTsilicates
 .sheet silicates
 ..hydrobiotite
RTaluminosilicates
 mica group
hydroboracite  search
BTborates
 .hydroboracite
hydrocarbon indicators  search
BTgeophysical methods
 .seismic methods
 ..hydrocarbon indicators
UFdirect hydrocarbon indicators
RTgeophysical surveys
 AVO methods
 petroleum exploration
 bottom-simulating reflectors
 indicators
 seismic stratigraphy
SNBefore 1993, also search bright spots. For surveys, also index geophysical surveys and specific method. Added to Thesaurus in 1993.
hydrocarbons  search
BTorganic compounds
 .hydrocarbons
NTaliphatic hydrocarbons
 aromatic hydrocarbons
 diasteranes
 diterpanes
 saturated hydrocarbons
 steranes
 terpanes
 triterpanes
RTsapropel
 geochemical anomalies
 solvents
 aromatization
 petroleum
 carbon
 chlorinated hydrocarbons
 halogenated hydrocarbons
 volatile organic compounds
 natural gas
 crude oil
 gasoline
 petroleum products
 isoprenoids
 Rock-Eval
SNFor economic deposits, see petroleum; natural gas; bitumens; asphalt; oil sands; oil shale. For discussion as pollutants, search (hydrocarbons OR petroleum) with pollution; also see petroleum products and oil spills. (Note modified 1995.)
hydrochemistry  search
UFhydrogeochemistry
RTdiffusion
 geochemistry
 ground water
 ions
 ion exchange
 aqueous solutions
 hydrogeology
 hydrology
 dechlorination
 brackish water
 brines
 desalinization
 chemical composition
 chemical dispersion
 fresh water
 diffusivity
 dissolved materials
 electro-osmosis
 lysimet
SNMay be used for chemistry of waters including sea water.
hydrochloric acid  search
BTinorganic acids
 .hydrochloric acid
UFmuriatic acid
RTgeochemistry
 acids
SNAdded to Thesaurus in 1985.
hydrodynamics  search
RTcatchment hydrodynamics
 critical flow
 Darcy's law
 deep aquifers
 eddy flow
 flowmeters
 fluid dynamics
 Green-Ampt model
 ground water
 hydraulics
 Kalman filters
 laminar flow
 multiphase flow
 pollutants
 preferential flow
 radial flow
 Rayleigh number
 Reynolds numb
SNUsed when discussing mathematical aspects of ground water movement. As of 1993, restricted to natural processes. For discussion of channels, engineering and practical applications, see hydraulics.
hydroelectric energy  search
UFhydropower
 water power
RTenergy
 water resources
 energy sources
 waterways
 geothermal energy
 power plants
 water harnessing
SNBefore 1993, also search hydroelectric power. Added to Thesaurus in 1993.
hydrofluoric acid  search
BTinorganic acids
 .hydrofluoric acid
UFhydrogen fluoride
RTgeochemistry
 acids
SNChemical formula is HF. Added to Thesaurus in 1989.
hydrogen  search
NTD/H
 deuterium
 tritium
RTchemical elements
 isotopes
 stable isotopes
hydrogen dioxide  search
USEhydrogen peroxide
hydrogen fluoride  search
USEhydrofluoric acid
hydrogen peroxide  search
UFhydrogen dioxide
 peroxide
RTcompounds
 corrosion
SNAn explosive, corrosive compound. Added to Thesaurus in 1989.
hydrogen sulfide  search
RTeutrophication
 gases
 lakes
 natural gas
 sulfides
hydrogeochemical prospecting  search
SNNot a valid GeoRef index term after 1970. See geochemical methods; hydrological methods; hydrochemistry. For economic geology, see exploration.
hydrogeochemistry  search
USEhydrochemistry
hydrogeologic  search
SNA valid term through 1977. After 1977, use hydrogeologic maps.
hydrogeologic maps  search
BTmaps
 .hydrogeologic maps
RThydrogeology
 potentiometric surface
SNBefore 1978, search hydrogeologic AND maps.
hydrogeological controls  search
RTcontrols
 hydrogeology
 mineral deposits, genesis
SNAs of 1993, restricted to economic studies.
hydrogeology  search
UFgeohydrology
RTground water
 aquifers
 hydrochemistry
 artesian waters
 hydrologic cycle
 hydrology
 hydrosphere
 imbibition
 hydrogeological controls
 flowmeters
 dolines
 dye tracers
 fluorimetry
 ground-water provinces
 hydrogeologic maps
 hydrological methods
 infiltrometers
 lysime
SNUsed for general studies. For the science that deals with subsurface waters and related geologic aspects of surface waters. To search for the hydrology of a particular river, search for the name of the river in combination with hydrology or hydrogeology.
Hydrogeology (category)  search
SNHydrogeology, GeoRef category code 21, is one of thirty categories used to classify documents in GeoRef. Each reference in GeoRef is assigned one or more categories. Categories can be used, in addition to Terms, to refine searches (See List A.).
hydrogoethite  search
BToxides
 .hydrogoethite
RTiron ores
 limonite
hydrographic maps  search
BTmaps
 .hydrographic maps
RTwaterways
SNAdded to Thesaurus in 1985.
hydrographs  search
RThydraulics
 hydrology
hydrogrossular  search
BTsilicates
 .orthosilicates
 ..nesosilicates
 ...garnet group
 ....hydrogrossular
UFhibschite
RTgrossular
hydrolog  search
hydrologic budget  search
USEwater balance
hydrologic cycle  search
UFwater cycle
RTmeteorology
 ground water
 water
 hydrogeology
 recharge
 atmospheric precipitation
 cycles
 evapotranspiration
 hydrology
 surface water
 hydrosphere
 discharge
 MODFLOW
 water balance
 DRAINMOD
 lysimeters
SNBefore 1983, also search cycles AND hydrology.
hydrologic maps  search
BTmaps
 .hydrologic maps
RThydrology
SNBefore 1978, search maps AND hydrologic.
hydrological methods  search
RThydrogeology
 hydrology
 methods
 mineral exploration
 water
hydrology  search
RTatmosphere
 atmospheric precipitation
 basin management
 bedforms
 cascades
 catchment hydrodynamics
 channel geometry
 constructed wetlands
 critical flow
 discharge
 DRAINMOD
 drought
 dye tracers
 ecology
 eddy flow
 engineering geology
 environmental geology
 eutrophi
SNUsed for continental surface water. In cases where the interchange between ground and surface water is intimate, this term may be used with hydrologic cycle. (Before 1983, cycles was used this way.) To search for the hydrology of a particular river, searc
hydrolysis  search
RTgeochemistry
 oxidation
 processes
 weathering
hydromagnesite  search
BTcarbonates
 .hydromagnesite
hydrometallurgy  search
RTmetallurgy
SNAdded to Thesaurus in 1981.
hydromica  search
BTsilicates
 .sheet silicates
 ..hydromica
RTclay minerals
 mica group
 illite
hydromica schist  search
SNNot a valid term for GeoRef. Use schists and hydromica.
Hydromorphic soils  search
BTsoils
 .Hydromorphic soils
RTsoil group
 Bog soils
 Histosols
 Intrazonal soils
 constructed wetlands
hydromuscovite  search
BTsilicates
 .sheet silicates
 ..hydromuscovite
RTclay minerals
 mica group
 muscovite
hydrophobic materials  search
UFwater repellants
RTmaterials
 absorption
 adsorption
 wettability
 organic compounds
 properties
 water
 anthracene
 transport
SNAdded to Thesaurus in 1998.
hydrophones  search
RTacoustical methods
 geophones
 instruments
 marine methods
 ocean bottom seismographs
 pressuremeters
 seismic methods
 streamers
SNAdded to Thesaurus in 1985.
hydropower  search
USEhydroelectric energy
hydrosodalite  search
BTsilicates
 .framework silicates
 ..sodalite group
 ...hydrosodalite
RTaluminosilicates
SNArtificial mineral.
hydrosphere  search
RTatmosphere
 biosphere
 Earth
 glaciers
 ground water
 hydrogeology
 hydrologic cycle
 hydrology
 ice
 lakes
 rain
 rivers
 rivers and streams
 snow
 streams
 surface water
 tectonosphere
 water
hydrostatic pressure  search
RTelevation
 geopressure
 hydraulic head
 hydraulics
 hydrology
 overpressure
 pressure
 underpressure
hydrostratigraphy  search
SNNot a valid term for GeoRef. As of 1998, see hydrogeology or aquifers.
hydrotalcite  search
BTcarbonates
 .hydrotalcite
RTpyroaurite
hydrothermal  search
SNA valid term through 1977. See hydrothermal conditions; ore-forming fluids; hydrothermal alteration; hydrothermal processes.
hydrothermal alteration  search
BTmetasomatism
 .hydrothermal alteration
UFhydrothermal processes
RTprocesses
 ground water
 autometamorphism
 mineral deposits, genesis
 alteration
 carbonatization
 leakage anomalies
 hydrothermal conditions
 epithermal processes
 hot springs
 greisenization
 ore-forming fluids
 propylitization
 pyritization
 pyrometasomatism
 sericit
hydrothermal chimneys  search
USEhydrothermal vents
hydrothermal conditions  search
RTblack smokers
 boiling
 hydrothermal alteration
 hydrothermal vents
 metasomatism
 phase equilibria
 thermophilic taxa
hydrothermal fluids  search
SNNot a valid term for GeoRef. As of 1981, use ore-forming fluids if applicable. Before 1981, hydrothermal solutions was used for this term.
hydrothermal plumes  search
USEplumes
hydrothermal processes  search
USEhydrothermal alteration
hydrothermal solutions  search
SNAs of 1981, no longer a valid term for GeoRef. Use ore-forming fluids or thermal waters if applicable.
hydrothermal systems  search
USEgeothermal systems
hydrothermal vent  search
hydrothermal vents  search
NTblack smokers
UFhydrothermal chimneys
RTbottom features
 ocean floors
 thermophilic taxa
 hydrothermal conditions
 chimneys
 vents
 plumes
SNBefore 1993, also search vents or chimneys in conjunction with hydrothermal conditions. Also index ocean floors. Added to Thesaurus in 1993.
hydroxides  search
BToxides
 .hydroxides
NTiron hydroxides
 oxyhydroxides
hydroxyapatite  search
USEhydroxylapatite
hydroxyl ion  search
RTgeochemistry
 ions
 sodium hydroxide
SNAdded to Thesaurus in 1985.
hydroxylapatite  search
BTphosphates
 .hydroxylapatite
UFhydroxyapatite
RTapatite
Hydrozoa  search
BTInvertebrata
 .Coelenterata
 ..Hydrozoa