abandoned mines and quarries
  BT:  human impacts
  RT:  industrial pollution
  SN:  Mines and quarries that have been abandoned and may expose harmful chemicals to the environment.
  TNR: 1725
absorption
  USE: sorption
abstracts
  USE: reports
Ac
  USE: actinium
accessing USGS data and products
  USE: USGS information services
acid deposition
  BT:  atmospheric deposition (chemical & particulate)
  RT:  atmospheric sciences
       human impacts
  UF:  acid precipitation
       acid rain
       acid snow
       acidic deposition
  SN:  The process by which emissions, chiefly sulfur and nitrogen compounds, either react with the atmosphere when deposited on earth by precipitation of snow, rain, or fog with a pH of 5.5 or below, or settle out as acidic particles or gases.
  TNR: 6
acidic deposition
  USE: acid deposition
acid precipitation
  USE: acid deposition
acid rain
  USE: acid deposition
acid snow
  USE: acid deposition
acoustic doppler current profiler
  USE: acoustic doppler current profiling
acoustic doppler current profiling
  BT:  acoustic methods
  RT:  stream-gage measurement
  UF:  ADCP
       hydroacoustics
       acoustic doppler current profiler
  SN:  Field monitoring of water currents using the doppler effect with acoustic instruments.
  TNR: 1726
acoustic methods
  BT:  field inventory and monitoring
  NT:  sonar methods
       acoustic doppler current profiling
  SN:  Study methods based on techniques of transmitting and receiving sound waves as well as measuring the properties of sound, such as pitch, absorption, frequency, intensity, or velocity.
  TNR: 10
actinide series elements
  BT:  rare earth elements
  RT:  actinium
       thorium
       protactinium
       uranium
       neptunium
       plutonium
       americium
       curium
       berkelium
       californium
       einsteinium
       fermium
       mendelevium
       nobelium
       lawrencium
  TNR: 1384
actinium
  BT:  chemical elements
  RT:  actinide series elements
  UF:  Ac
  SN:  Rare earth (actinide series) element with symbol Ac and atomic number 89 <http://periodic.lanl.gov/elements/89.html>
  TNR: 1385
ADCP
  USE: acoustic doppler current profiling
administrative and political boundaries
  BT:  culture and demographics
  RT:  cadastral and legal land descriptions
       geography
  UF:  borders
       geographic boundaries
       governmental units
       political boundaries
  SN:  Lines drawn on maps or described in documents which encompass territory controlled by a government or organizational unit that may or may not align with geographic or cultural barriers. Use for datasets containing boundary representations for political/administrative units and related information.
  TNR: 12
adsorption
  USE: sorption
Advanced Very High Resolution Radiometer (AVHRR)
  USE: AVHRR
aerial photographs
  US+: aerial photography
       image collections
aerial photography
  BT:  photography
  RT:  remote sensing
  UF:  aerial photographs
       aerial photos
       air photos
       orthoimagery
       orthophotographs
  SN:  The process of taking pictures with a camera mounted in an aircraft. Use for both the process of photography from the air and the images produced by the process.
  TNR: 15
aerial photos
  US+: aerial photography
       image collections
aeromagnetic maps
  US+: maps and atlases
       aeromagnetic surveying
aeromagnetic surveying
  BT:  remote sensing
  RT:  electromagnetic surveying
       geography
  UF:  aeromagnetic maps
       magnetic surveying
  SN:  Mapping of the earth's magnetic field with the use of airborne electronic magnetometers.
  TNR: 18
aeroradiometric surveying
  BT:  remote sensing
  RT:  geography
  UF:  gamma-ray spectrometric surveying
  SN:  Mapping of gamma radiation from the earth's surface with airborne scintillation meters or gamma-ray spectrometers.
  TNR: 19
Ag
  USE: silver
age dating (fission-track)
  USE: fission-track dating
age dating (radiometric)
  USE: radiometric dating
age dating (tree ring)
  USE: tree ring analysis
age estimation methods
  BT:  laboratory methods
  NT:  fission-track dating
       luminescence dating
       tephrochronology
       sclerochronology
  RT:  radiometric dating
       tree ring analysis
  UF:  dating methods
  SN:  Methods used to determine the age of earth materials, typically by laboratory analysis of properties of those materials.
  TNR: 1680
agricultural water use
  BT:  offstream water use
  NT:  irrigation
  RT:  hydraulic engineering
       hydrology
  UF:  livestock water use
       rural water use
  SN:  Water used for soil cultivation, crop production and livestock rearing.
  TNR: 23
agriculture
  BT:  topics
  NT:  aquaculture
  RT:  soil chemistry
  UF:  farming
       horticulture
       livestock husbandry
  SN:  The science and business of soil cultivation to raise crops and of animal husbandry to raise domesticated animals.
  TNR: 24
airborne imaging
  USE: remote sensing
airborne visible infrared imaging spectrometer
  USE: AVIRIS
air photos
  US+: image collections
       aerial photography
air pollution
  US+: contamination and pollution
       atmospheric composition
air temperature
  BT:  atmospheric properties
  RT:  atmospheric sciences
  UF:  temperature (air)
  TNR: 27
air transportation
  USE: transportation
Al
  USE: aluminum
algae
  BT:  organisms
  NT:  calcareous nannoplankton
       diatoms
       dinoflagellates
  RT:  algal blooms
       bacteria
       phycology
       protists
       periphyton
  SN:  Chlorophyll-bearing primarily aquatic nonvascular species that have no true roots, stems, or leaves; most algae are microscopic, but some species can be as large as vascular plants.
  TNR: 29
algal blooms
  BT:  ecological processes
  RT:  algae
       hazards
       phycology
       population dynamics
  UF:  brown tides
       harmful algal blooms
       red tides
  SN:  Exceptional growth of algae and cyanobacteria in lakes, rivers or oceans due to excessive nutrients or climatic conditions.
  TNR: 30
algology
  USE: phycology
alien species
  USE: nonindigenous species
alkali metal elements
  BT:  chemical element groups
  RT:  hydrogen
       lithium
       sodium
       potassium
       rubidium
       cesium
       francium
  TNR: 1388
alkaline earth elements
  BT:  chemical element groups
  RT:  beryllium
       magnesium
       calcium
       strontium
       barium
       radium
  TNR: 1389
alluvial sedimentation
  USE: sedimentation
alluvial transport
  USE: sediment transport
alluvium
  USE: unconsolidated deposits
altimetry measurement
  BT:  geolocation measurement
  RT:  geography
  UF:  satellite altimetry
  SN:  The measurement of altitude, or height above mean sea level, using instruments such as aneroid barometers and radar altimeters.
  TNR: 36
aluminum
  BT:  chemical elements
  RT:  metal elements
  UF:  Al
  SN:  Metalloid element with symbol Al and atomic number 13 <http://periodic.lanl.gov/elements/13.html>
  TNR: 1390
Am
  USE: americium
americium
  BT:  chemical elements
  RT:  actinide series elements
  UF:  Am
  SN:  Rare earth (actinide series) element with symbol Am and atomic number 95 <http://periodic.lanl.gov/elements/95.html>
  TNR: 1392
amphibians
  BT:  vertebrates
  RT:  herpetology
  SN:  Vertebrates of the class Amphibia including frogs and toads (Anura), salamanders (Urodela), caecilians (Apoda) and extinct forms which are cold-blooded and have life stages in water as eggs and larval forms (tadpoles)until they metamorphose as adults.
  TNR: 37
anadromous fish
  US+: migratory species
       fish
anatomy and physiology
  BT:  life sciences
  NT:  endocrinology
       histology
       immunology
  RT:  plant and animal testing
       therapeutic methods
  UF:  physiology
  SN:  Study of the body structures (anatomy) and life functions and activities (physiology)of plants and animals.
  TNR: 39
animal and plant census
  BT:  field inventory and monitoring
  UF:  census
  SN:  Inventory of macroscopic animals and plants by observation in the field. Used to estimate population and distribution.
  TNR: 1353
animal behavior
  BT:  population and community ecology
  RT:  ecology
       migration (organisms)
       migratory species
  SN:  The way animals act or react to conditions in the environment and to other organisms, including life patterns such as migration, hibernation, and nocturnal living.
  TNR: 40
animal distribution
  USE: biogeography
animals
  BT:  organisms
  NT:  invertebrates
       vertebrates
  RT:  wildlife
       zoology
  UF:  fauna
  SN:  Multi-celled organisms of the kingdom Animalia with eukaryotic cells (cells with distinct nuclei containing genetic material and bounded by thin membranes) that are heterotrophic (obtaining energy from organic substances produced by other organisms).
  TNR: 45
animal tagging
  USE: plant and animal tagging
animal testing
  USE: plant and animal testing
animal tracking
  BT:  field sampling
  RT:  telemetry
       wildlife biology
  UF:  tracking
  SN:  Method of studying animals by following spoor (footprints, droppings, scent, and other evidence) in an area to document the presence and movements of the animal and its interactions within the landscape.
  TNR: 44
animations
  BT:  product types
  SN:  Graphical representation of scientific data presented as a timed sequence of visual images, normally without sound.
  TNR: 1740
annelids
  USE: segmented worms
anoxia
  USE: oxygen content (water)
anthracite resources
  USE: coal resources
antimony
  BT:  chemical elements
  RT:  metal elements
  UF:  Sb
  SN:  Metalloid element with symbol Sb and atomic number 51 <http://periodic.lanl.gov/elements/51.html>
  TNR: 1393
aquaculture
  BT:  agriculture
  RT:  commercial fishery resources
       fishery resources
  UF:  fish farming
  SN:  The farming of organisms that live in water, such as fish, shellfish, and algae for human use.
  TNR: 52
aquatic biology
  BT:  life sciences
  RT:  aquatic ecosystems
       benthic ecosystems
       commercial fishery resources
       ecology
       estuarine ecosystems
       fishery resources
       freshwater ecosystems
       inland fishery resources
       macroinvertebrates
       marine biology
       marine ecosystems
       marine fishery resources
       migratory species
       plankton
       recreational fishery resources
       shellfish
       water quality
       wetland ecosystems
  SN:  The scientific study of organisms living in or near water.  This term is to be used for the science of 'aquatic biology' and for  biological studies in fresh and brackish water. For marine biological studies, use 'marine biology'.
  TNR: 53
aquatic ecosystems
  BT:  ecosystems
  NT:  benthic ecosystems
       estuarine ecosystems
       freshwater ecosystems
       marine ecosystems
  RT:  aquatic biology
       coastal ecosystems
       ecology
       limnology
       marine biology
  UF:  planktonic ecosystems
  SN:  Communities of interdependent organisms living primarily in or on water.
  TNR: 54
aquatic vegetation
  BT:  vegetation
  UF:  hydrophytes
       mangroves
       seagrass
       seaweeds
  SN:  Plants living primarily in or under water.
  TNR: 1705
aquifer-surface water interaction
  USE: ground-water and surface-water interaction
aquifer level
  USE: ground-water level
Ar
  USE: argon
arachnids
  BT:  arthropods
  RT:  entomology
       invertebrate zoology
  UF:  false scorpions
       mites
       spiders
       ticks
  SN:  Carnivorous arthropods, chiefly terrestrial, of the class Arachnida including spiders, scorpions, mites, ticks, false scorpions, palpigrades, solifugids, and harvestmen.
  TNR: 55
arboreal ecosystems
  USE: forest ecosystems
archaea
  BT:  organisms
  RT:  microbiology
  UF:  archaebacteria
  SN:  Microscopic organisms of the domain Archaea living on a diet of hydrogen and carbon dioxide, once thought to be bacteria, and often inhabiting extreme environments, such as thermal vents and hot springs, extremely alkaline and acidic waters, hypersaline water, and anoxic habitats.
  TNR: 56
archaean
  BT:  precambrian
  UF:  archean
  TNR: 1622
archaebacteria
  USE: archaea
archaeology
  USE: archeology
archean
  USE: archaean
archeology
  BT:  social sciences
  UF:  archaeology
  SN:  Study of human cultures through the recovery and analysis of their material relics.
  TNR: 1691
archives (USGS)
  USE: USGS libraries and archives
argon
  BT:  chemical elements
  RT:  noble gas elements
  UF:  Ar
  SN:  Noble gas element with symbol Ar and atomic number 18 <http://periodic.lanl.gov/elements/18.html>
  TNR: 1395
argon-argon dating
  USE: radiometric dating
arsenic
  BT:  chemical elements
  RT:  nonmetal elements
  UF:  As
  SN:  Nonmetal element with symbol As and atomic number 33 <http://periodic.lanl.gov/elements/33.html>
  TNR: 1396
arthropods
  BT:  invertebrates
  NT:  arachnids
       crustaceans
       horseshoe crabs
       insects
       trilobites
  RT:  invertebrate zoology
  SN:  Invertebrates belonging to the largest phylum of animals, Arthropoda, with an exoskeleton, segmented bodies, and jointed appendages, including many subphyla and classes, such as insects, crustaceans, horseshoe crabs, sea spiders, centipedes, millipedes, and the extinct trilobites.
  TNR: 58
articles (publications)
  USE: reports
artificial recharge
  USE: water resource management
As
  USE: arsenic
Ask-A services (USGS)
  USE: USGS expertise services
astatine
  BT:  chemical elements
  RT:  halogen elements
  UF:  At
  SN:  Halogen element with symbol At and atomic number 85 <http://periodic.lanl.gov/elements/85.html>
  TNR: 1398
asteroid impact
  USE: impact cratering
asthenosphere
  BT:  mantle (earth)
  RT:  tectonophysics
  SN:  A layer of the earth within the upper mantle and directly below the lithosphere. This layer has a semi-solid consistency that reaches to about 200 kilometers (124 miles) below the surface.
  TNR: 61
astronomy
  USE: planetary sciences
At
  USE: astatine
atlases
  USE: maps and atlases
atmosphere properties
  USE: atmospheric properties
atmospheric and climatic processes
  BT:  biological and physical processes
  NT:  evaporation
       atmospheric circulation
       atmospheric deposition (chemical & particulate)
       climate change
       droughts
       ocean-atmosphere interaction
       precipitation (atmospheric)
       storms
       wind
       greenhouse effect
  RT:  atmospheric properties
       atmospheric sciences
       meteorology
       snow and ice cover
  UF:  climate
       weather monitoring
       weather observations
       weather
       microclimate
  SN:  Phenomena affecting or occurring within the mass of gases that surrounds the earth, including its physics, chemistry, dynamics, and weather conditions.
  TNR: 63
atmospheric circulation
  BT:  atmospheric and climatic processes
  RT:  atmospheric sciences
       water circulation
  SN:  Movement of atmospheric gases around the earth.
  TNR: 64
atmospheric composition
  BT:  atmospheric properties
  NT:  greenhouse gases
       ozone layer
  RT:  atmospheric sciences
  UF:  air pollution
  SN:  Components of the mass of gases that surrounds a planet.  The earth's atmosphere consists of nitrogen, oxygen, and small portions of other gases.
  TNR: 65
atmospheric deposition (chemical & particulate)
  BT:  atmospheric and climatic processes
  NT:  acid deposition
  RT:  atmospheric sciences
       precipitation (atmospheric)
       sedimentation
  UF:  atmospheric deposition (chemical and particulate)
  SN:  The transfer of substances from the air to the surface of the earth, either in wet form (rain, fog, snow, dew, frost, hail) or in dry form (gases, aerosols, particles).
  TNR: 66
atmospheric deposition (chemical and particulate)
  USE: atmospheric deposition (chemical & particulate)
atmospheric properties
  BT:  earth characteristics
  NT:  air temperature
       atmospheric composition
  RT:  atmospheric and climatic processes
       atmospheric sciences
  UF:  atmosphere properties
  SN:  Characteristics of the mass of gases surrounding the earth  such as composition, temperature, pressure, and humidity.
  TNR: 67
atmospheric sciences
  BT:  earth sciences
  NT:  climatology
       meteorology
  RT:  acid deposition
       air temperature
       atmospheric and climatic processes
       atmospheric circulation
       atmospheric composition
       atmospheric deposition (chemical & particulate)
       atmospheric properties
       droughts
       fires
       global change
       global warming
       greenhouse gases
       ocean temperature
       ocean-atmosphere interaction
       ozone layer
       precipitation (atmospheric)
  SN:  Studies relating to composition, structure, physics, chemistry, and dynamics of the atmosphere.
  TNR: 68
atomic absorption analysis
  BT:  chemical analysis
  RT:  biochemistry
       geochemistry
  SN:  Technique used to identify chemicals based on the measurement of the spectra produced by atoms and molecules with absorption of electromagnetic radiation.
  TNR: 69
atomic emission spectroscopy
  BT:  chemical analysis
  UF:  ICP-AES
       inductively coupled plasma-atomic emission spectrometry
  SN:  Chemical detection of element concentration by examining the intensity and wavelength of light emitted from the sample when gaseous sample is ionized and maintained in a plasma state.
  TNR: 1342
Au
  USE: gold
audio recordings
  USE: sound recordings
autumn
  BT:  seasons
  UF:  fall (season)
  TNR: 1624
avalanches
  USE: landslides
AVHRR
  BT:  infrared imaging
  RT:  geography
       sea surface temperature
  UF:  AVHRR images
       Advanced Very High Resolution Radiometer (AVHRR)
  SN:  Advanced Very High Resolution Radiometer or broad-band, four or five channel scanner, sensing in the visible, near-infrared, and thermal infrared portions of the electromagnetic spectrum. This information is used to estimate characteristics of the land and sea surface such as temperature and overall health of vegetation.
  TNR: 74
AVHRR images
  US+: image collections
       AVHRR
avian flu
  USE: avian influenza
avian influenza
  BT:  health and disease
  UF:  avian flu
       bird flu
       HPAI
       H5N1
  SN:  A virulent disease of poultry and wild birds that has spread throughout a large geographic area in Asia and Eastern Europe since it was first documented in 1997 in Asia.
  TNR: 1732
aviation
  USE: transportation
aviation safety
  BT:  hazard preparedness
  RT:  volcanic activity
  SN:  Effects on air transportation of natural hazards such as volcanic activity (ash plumes and volcanic clouds).
  TNR: 1694
AVIRIS
  BT:  infrared imaging
  UF:  airborne visible infrared imaging spectrometer
  TNR: 1379
B
  USE: boron
Ba
  USE: barium
bacteria
  BT:  organisms
  RT:  algae
       microbiology
  SN:  Single celled microorganisms, beneficial or pathogenic, without a nuclear membrane.
  TNR: 76
bacteriology
  BT:  microbiology
  RT:  culturing (specimens)
       health and disease
  SN:  Study of the single celled microorganisms known as bacteria.
  TNR: 77
banding
  USE: plant and animal tagging
bankfull stage
  USE: floods
barium
  BT:  chemical elements
  RT:  alkaline earth elements
  UF:  Ba
  SN:  Alkaline earth element with symbol Ba and atomic number 56 <http://periodic.lanl.gov/elements/56.html>
  TNR: 1403
baseline characterization
  USE: field inventory and monitoring
basement maps
  US+: maps and atlases
       bedrock geologic units
bathymetry
  BT:  topography
  RT:  geomorphology
       limnology
       ocean sciences
       sea-floor characteristics
  UF:  bathymetry data
       sea floor topography
       underwater contours
  SN:  The topography of a body of water, especially the ocean, determined by measurements of depth.
  TNR: 80
bathymetry data
  USE: bathymetry
bathymetry measurement
  BT:  geolocation measurement
  RT:  geography
       sonar methods
  SN:  Means of determining the depth to the floor of a body of water, especially the ocean.
  TNR: 82
bats
  BT:  mammals
  SN:  Small flying mammals of the order Chiroptera.
  TNR: 1747
Be
  USE: beryllium
bears
  BT:  mammals
  UF:  polar bears
       grizzly bears
       black bears
  SN:  Large wild mammals of the family Ursidae.  Includes black and brown (grizzly) bears and polar bears.
  TNR: 1746
bed forms
  USE: bedforms
bedforms
  BT:  sedimentary rocks
  RT:  sedimentology
  UF:  bed forms
  SN:  Fluctuations from horizontal layers in sediments or sedimentary rocks made by flow on the beds of alluvial channels.
  TNR: 83
bedload
  USE: sediment transport
bed load
  USE: sediment transport
bedrock geologic units
  BT:  stratigraphic sections
  RT:  stratigraphy
  UF:  basement maps
       geologic formations
  SN:  Units of consolidated (solid) rock that underlie soils or other unconsolidated materials.
  TNR: 84
bees
  USE: bees and wasps
bees and wasps
  BT:  insects
  UF:  wasps
       bees
  TNR: 1737
benchmarks
  USE: field monitoring stations
benthic ecosystems
  BT:  aquatic ecosystems
  RT:  aquatic biology
       ecology
       limnology
       marine biology
  SN:  Biologic communities and habitats at the bottom of lakes, streams, or oceans.
  TNR: 85
benthos
  BT:  organism groupings (non-taxonomic)
  SN:  Animals that live on the bottom of water bodies.
  TNR: 1345
berkelium
  BT:  chemical elements
  RT:  actinide series elements
  UF:  Bk
  SN:  Rare earth (actinide series) element with symbol Bk and atomic number 97 <http://periodic.lanl.gov/elements/97.html>
  TNR: 1405
beryllium
  BT:  chemical elements
  RT:  alkaline earth elements
  UF:  Be
  SN:  Alkaline earth element with symbol Be and atomic number 4 <http://periodic.lanl.gov/elements/4.html>
  TNR: 1406
beryllium isotope analysis
  BT:  light stable isotope analysis
  SN:  Method of age determination based on measurement of the activity of beryllium-10, used in dating deep-sea sediments, and in determining sedimentation rates.
  TNR: 86
Bh
  USE: bohrium
Bi
  USE: bismuth
bibliographies
  BT:  catalogs and indexes
  RT:  reports
  SN:  List of publications on a given topic, by an author or group, or published in a specific time period. Limited here to lists primarily of paper documents.
  TNR: 87
biking
  USE: recreation
bioaccumulation
  BT:  ecological processes
  RT:  ecology
       ecotoxicology
  UF:  bioconcentration
  SN:  The biological sequestering of a substance at a higher concentration than that at which it occurs in the surrounding environment or medium.  Also, the process whereby a substance enters an organism through the gills, epithelial tissues, dietary, or other sources.
  TNR: 88
biochemistry
  BT:  life sciences
  RT:  atomic absorption analysis
       biogeochemical cycling
       carbon cycling
       carbon isotope analysis
       chemical analysis
       chromatography
       DNA sequencing
       electrophoresis
       flow cytometry
       food web
       gas chromatography
       isotopic analysis
       light stable isotope analysis
       liquid chromatography
       mass spectroscopy
       mercury contamination
       neutron activation analysis
       nutrient cycling
       oxygen isotope analysis
       particle-beam spectroscopy
       pesticide and herbicide contamination
       polymerase chain reaction
       tritium analysis
  UF:  biogeochemistry
       chemistry (life sciences)
       environmental chemistry
  SN:  Study of chemical processes that occur within or are mediated by living organisms.
  TNR: 89
biocide contamination
  USE: pesticide and herbicide contamination
bioconcentration
  USE: bioaccumulation
biodegradation
  BT:  geochemical processes
  UF:  natural attenuation (harmful chemicals)
  SN:  Reduction in the concentration of harmful chemicals by the action of animals and plants.
  TNR: 1346
biodiversity
  BT:  population and community ecology
  NT:  ecosystem diversity
       genetic diversity
       species diversity
  RT:  biogeography
       ecological competition
       ecology
       endangered species
       endemic species
       invasive species
       life sciences
       native species
       nonindigenous species
  UF:  biological diversity
       diversity (biological)
  SN:  The variety in form, genetics, and ecological roles of organisms within a specific geographic area.
  TNR: 92
bioenergetic processes
  USE: biological and physical processes
biogeochemical cycling
  BT:  ecological processes
  NT:  carbon cycling
       nutrient cycling
  RT:  biochemistry
       decomposers
       ecology
       geochemistry
       geochemical processes
  UF:  biogeochemical functioning
       biogeochemical processes
       decomposition (organic)
       organic decomposition
  SN:  The cycling of chemical constituents through a biological system.
  TNR: 93
biogeochemical functioning
  USE: biogeochemical cycling
biogeochemical processes
  USE: biogeochemical cycling
biogeochemistry
  USE: biochemistry
biogeography
  BT:  population and community ecology
  RT:  biodiversity
       ecology
       ecosystem monitoring
       migration (organisms)
       migratory species
       population dynamics
       wildlife population management
  UF:  animal distribution
       distribution of animals
       distribution of plants
       distribution of species
       flyways
       plant distribution
       species distribution maps
       species distribution
       species geographic range
  SN:  The study of the geographic distributions of plants and animals.
  TNR: 96
biographies
  USE: reports
bioinformatics
  USE: biological informatics
biological and physical processes
  BT:  topics
  NT:  atmospheric and climatic processes
       ecological processes
       fires
       geologic processes
       geochemical processes
       ocean processes
       physiological processes
       hydrologic processes
       evolution
       impact cratering
  UF:  bioenergetic processes
  SN:  All continuing activities, functions, and phenomena associated with organisms and non-living matter.
  TNR: 101
biological diversity
  USE: biodiversity
biological informatics
  BT:  information sciences
  RT:  life sciences
  UF:  bioinformatics
  SN:  Development and use of computer, statistical, and other tools in the collection, organization, dissemination, and use of information to solve problems in the life sciences.
  TNR: 103
biological invasions
  US+: migration (organisms)
       invasive species
biological oceanography
  USE: marine biology
biological organisms
  USE: organisms
biological population management
  BT:  natural resource management
  NT:  fishery management
       reintroduction (organisms)
       wildlife population management
       pest control
  RT:  ecosystem monitoring
       population and community ecology
  UF:  conservation genetics
  SN:  Judicious means of controlling or directing numbers and life conditions of organisms living in a specific locality to achieve a selected goal.
  TNR: 107
biological productivity
  BT:  ecological processes
  RT:  ecology
       life sciences
  SN:  The rate at which primary producers in the ecosystem utilize solar energy to produce food for consumption by other organisms. Do not use this term for "productivity" of organisms related to studies of the reproduction rates of a species.
  TNR: 108
biological remediation
  USE: bioremediation
biological sciences
  USE: life sciences
biology
  USE: life sciences
bioluminescence
  BT:  physiological processes
  SN:  Emission of light by organisms.
  TNR: 1348
bionomics
  USE: ecology
bioremediation
  BT:  remediation
  RT:  ecology
       ecosystem monitoring
  UF:  biological remediation
       revegetation
  SN:  Use of biological methods, usually involving microorganisms, to break down or neutralize contaminants in soil, water, and wastes.
  TNR: 113
biosphere
  USE: ecosystems
biostratigraphy
  BT:  geologic history
  RT:  fossils
       ichnofossils
       paleontology
       stratigraphy
  SN:  Branch of geology concerned with the separation and differentiation of rock units based on the fossils they contain.
  TNR: 115
biota
  BT:  organism groupings (non-taxonomic)
  RT:  life sciences
  SN:  All living organisms in an area.
  TNR: 116
biotelemetry
  USE: telemetry
bird banding
  USE: plant and animal tagging
bird flu
  USE: avian influenza
birds
  BT:  vertebrates
  RT:  ornithology
  UF:  shorebirds
       water birds
       waterfowl
  SN:  Land vertebrates belonging to the class Aves with warm blood, feathers, wings, and reproduction characterized by egg laying.
  TNR: 119
bird watching
  USE: recreation
bismuth
  BT:  chemical elements
  RT:  metal elements
  UF:  Bi
  SN:  Metalloid element with symbol Bi and atomic number 83 <http://periodic.lanl.gov/elements/83.html>
  TNR: 1409
bituminous coal resources
  USE: coal resources
Bk
  USE: berkelium
black bears
  USE: bears
blizzards
  BT:  storms
  SN:  Severe snowstorms with intense winds.
  TNR: 121
boating
  USE: recreation
bohrium
  BT:  chemical elements
  RT:  metal elements
  UF:  Bh
  SN:  Metal element with symbol Bh and atomic number 107 <http://periodic.lanl.gov/elements/107.html>
  TNR: 1411
bolide impact
  USE: impact cratering
bolides
  USE: meteorites
books and book chapters
  USE: reports
borders
  USE: administrative and political boundaries
borehole logging
  BT:  field inventory and monitoring
  NT:  borehole temperature logging
       electrical resistivity logging
       gamma-ray logging
  RT:  geophysics
       stratigraphy
  UF:  well logging
  SN:  Method of recording the physical characteristics of the subsurface as a function of depth by observations during drilling of a well or borehole, studying the resulting core, or by lowering instruments into a drilled hole.
  TNR: 125
borehole temperature logging
  BT:  borehole logging
  RT:  geophysics
  SN:  Method of recording the measured temperature of the subsurface as a function of depth by lowering instruments into the hole.
  TNR: 126
boron
  BT:  chemical elements
  RT:  nonmetal elements
  UF:  B
  SN:  Nonmetal element with symbol B and atomic number 5 <http://periodic.lanl.gov/elements/5.html>
  TNR: 1412
botany
  BT:  life sciences
  NT:  palynology
       phycology
  RT:  drilling and coring
       ferns and fern allies
       flowering plants
       forest resources
       gymnosperms
       liverworts and hornworts
       mosses
       mycology
       nonvascular plants
       paleobotany
       plants (organisms)
       producers (organisms)
       vascular plants
       vegetation
  SN:  The science of plants.
  TNR: 127
bouguer anomaly
  BT:  gravitational field (earth)
  TNR: 1675
Br
  USE: bromine
brachiopods
  USE: bryozoans and brachiopods
bridge scour
  USE: scour
bromine
  BT:  chemical elements
  RT:  halogen elements
  UF:  Br
  SN:  Halogen element with symbol Br and atomic number 35 <http://periodic.lanl.gov/elements/35.html>
  TNR: 1414
brown tides
  USE: algal blooms
bryozoans and brachiopods
  BT:  invertebrates
  RT:  invertebrate paleontology
       invertebrate zoology
  UF:  brachiopods
       ectoprocta
  SN:  Aquatic invertebrates, usually marine, belonging to the phyla Bryozoa and Brachiopoda.  Brachiopods, or clam shells, are solitary living invertebrates characterized by two shells and a lophophore, which is a complex food gathering organ.  Bryozoans are colonial and include moss coral and moss polyps.
  TNR: 130
budget (USGS)
  USE: USGS budget
bugs
  USE: insects
building stone resources
  BT:  nonmetallic mineral resources
  RT:  economic geology
       rocks and deposits
       sedimentology
  UF:  crushed stone
       dimension stone
  SN:  Deposits of rocks used in construction, including crushed stone and dimension stone. Dimension stone includes limestone and granite, quarried in large blocks, and shaped in cubes, panels and other forms.
  TNR: 132
business and economics
  BT:  culture and demographics
  RT:  social sciences
  UF:  commerce
       economics
  SN:  The activities and processes associated with the production, distribution, and consumption of goods and services.
  TNR: 133
business partners (USGS)
  USE: USGS partnerships
butterflies and moths
  BT:  insects
  RT:  entomology
  UF:  lepidoptera
       moths
  SN:  Insects of the order Lepidoptera that have four wings with overlapping, often highly colored scales. They undergo four life cycle stages: eggs, caterpillar larvae, pupae, and the winged adults.
  TNR: 135
C
  USE: carbon
Ca
  USE: calcium
cadastral and legal land descriptions
  BT:  culture and demographics
  RT:  administrative and political boundaries
       geography
       social sciences
  UF:  land partitioning systems
       legal land descriptions
       cadastral maps
  SN:  Records in official registers showing extent, boundaries, and ownerships of land for administration and taxation.
  TNR: 136
cadastral maps
  US+: cadastral and legal land descriptions
       maps and atlases
cadmium
  BT:  chemical elements
  RT:  metal elements
  UF:  Cd
  SN:  Metal element with symbol Cd and atomic number 48 <http://periodic.lanl.gov/elements/48.html>
  TNR: 1417
caenozoic
  USE: cenozoic
calcareous nannoplankton
  BT:  algae
  RT:  micropaleontology
       phycology
       plankton
       phytoplankton
  UF:  coccoliths
  SN:  Organisms of the kingdom Protista that normally produce coccoliths, microscopic structures of calcite (calcium carbonate), during some phase of their life cycle.
  TNR: 138
calcium
  BT:  chemical elements
  RT:  alkaline earth elements
  UF:  Ca
  SN:  Alkaline earth element with symbol Ca and atomic number 20 <http://periodic.lanl.gov/elements/20.html>
  TNR: 1418
californium
  BT:  chemical elements
  RT:  actinide series elements
  UF:  Cf
  SN:  Rare earth (actinide series) element with symbol Cf and atomic number 98 <http://periodic.lanl.gov/elements/98.html>
  TNR: 1419
cambrian
  BT:  paleozoic
  TNR: 1626
camera calibration
  BT:  laboratory methods
  SN:  Optical calibration of cameras that are typically used in airborne remote sensing.
  TNR: 1670
camera tows
  USE: underwater photography
camping
  USE: recreation
canoeing
  USE: recreation
capturing (animals)
  BT:  field sampling
  RT:  specimen collecting
       zoology
  UF:  trapping (animals)
  SN:  Collecting individual animals in the field by various methods in order to obtain information about the species or population and its ecology. Capturing methods are adapted to the habits and habitats of the target species and include both live trapping and kill trapping methods.
  TNR: 140
carbon
  BT:  chemical elements
  RT:  nonmetal elements
  UF:  C
  SN:  Nonmetal element with symbol C and atomic number 6 <http://periodic.lanl.gov/elements/6.html>
  TNR: 1420
carbon-14 analysis
  BT:  radiometric dating
  RT:  carbon isotope analysis
       geochronology
  UF:  carbon dating
       radiocarbon dating
  SN:  Method to determine the age of organic geologic and archaeological specimens, aged approximately 3,000 to 50,000 years, by determining the decay of the radioactive isotope carbon-14.
  TNR: 143
carbon cycling
  BT:  biogeochemical cycling
  RT:  biochemistry
       ecology
       geochemistry
  SN:  The circulation of carbon in the biosphere, atmosphere, and hydrosphere through a series of processes that include photosynthesis, consumption, and respiration.
  TNR: 141
carbon dating
  USE: carbon-14 analysis
carbon isotope analysis
  BT:  light stable isotope analysis
  RT:  biochemistry
       carbon-14 analysis
       geochemistry
  SN:  Experimental determination of the proportion of a given stable carbon isotope (C12 or C13) in a sample.
  TNR: 142
carbon sequestration
  BT:  geochemical processes
  SN:  Long-term storage of carbon in soils and terrestrial organic material, typically of importance in understanding the balance of CO2 in the global climate system.
  TNR: 1731
careers in science
  USE: scientific careers
carnivores
  BT:  consumers (organisms)
  RT:  ecology
       zoology
  UF:  predators
  SN:  Flesh-eating animals.
  TNR: 145
cartographic data (digital)
  USE: geospatial datasets
cartography
  BT:  geography
  RT:  map coordinate systems
       maps and atlases
  UF:  digital cartography
       map making
       mapmaking
       mapping
  SN:  The science and art of making maps.
  TNR: 147
catalogs and indexes
  BT:  product types
  NT:  bibliographies
       directories
       gazetteers
  RT:  reports
       USGS clearinghouses
  UF:  indexes
       lists of publications
       metadata
  SN:  Detailed enumeration of related items listed in a given order, or alphabetical lists of topics used for information retrieval.
  TNR: 148
catastrophes
  USE: hazards
Categories
  NT:  methods
       product types
       sciences
       topics
       USGS
       time periods
  SN:  Thematic terms for categorizing information resources.  This thesaurus is intended to support finding and understanding scientific information.
  TNR: 1
caving
  USE: recreation
Cd
  USE: cadmium
Ce
  USE: cerium
cell biology
  BT:  life sciences
  RT:  flow cytometry
       molecular biology
  UF:  cellular biology
       cytology
  SN:  Branch of biology that deals with the study of the formation, structure, and physiology of cells.
  TNR: 151
cellular biology
  USE: cell biology
cenozoic
  BT:  phanerozoic
  NT:  quaternary
       tertiary
  UF:  caenozoic
  TNR: 1627
census
  USE: animal and plant census
cerium
  BT:  chemical elements
  RT:  lanthanide series elements
  UF:  Ce
  SN:  Rare earth (lanthanide series) element with symbol Ce and atomic number 58 <http://periodic.lanl.gov/elements/58.html>
  TNR: 1423
cesium
  BT:  chemical elements
  RT:  alkali metal elements
  UF:  Cs
  SN:  Alkali metal element with symbol Cs and atomic number 55 <http://periodic.lanl.gov/elements/55.html>
  TNR: 1424
Cf
  USE: californium
charts
  USE: maps and atlases
checklists
  BT:  reports
  SN:  Inventories or lists of related items for checking off or reference.
  TNR: 152
chemical analysis
  BT:  laboratory methods
  NT:  atomic absorption analysis
       chromatography
       DNA sequencing
       electrophoresis
       flow cytometry
       mass spectroscopy
       neutron activation analysis
       particle-beam spectroscopy
       polymerase chain reaction
       x-ray diffraction
       atomic emission spectroscopy
  RT:  biochemistry
       geochemistry
  UF:  detection (chemical)
       geochemical surveys
       leaching (analytical method)
       mineralogical analysis
       nuclear magnetic resonance spectroscopy
       sediment geochemistry
  SN:  Chemical techniques used to identify the composition of substances.
  TNR: 153
chemical element groups
  BT:  elements
  NT:  metal elements
       halogen elements
       alkali metal elements
       alkaline earth elements
       noble gas elements
       nonmetal elements
       rare earth elements
  SN:  Groups shown at <http://periodic.lanl.gov/>
  TNR: 1426
chemical elements
  BT:  elements
  NT:  astatine
       cerium
       dubnium
       iron
       hydrogen
       californium
       fluorine
       francium
       europium
       lawrencium
       arsenic
       antimony
       iodine
       berkelium
       fermium
       germanium
       neon
       lithium
       lutetium
       magnesium
       neodymium
       molybdenum
       chlorine
       hassium
       cesium
       copper
       carbon
       bohrium
       boron
       bromine
       indium
       helium
       gadolinium
       gallium
       meitnerium
       mercury
       cadmium
       gold
       actinium
       erbium
       bismuth
       lead
       chromium
       einsteinium
       lanthanum
       manganese
       cobalt
       barium
       aluminum
       americium
       krypton
       darmstadtium
       beryllium
       argon
       calcium
       holmium
       mendelevium
       dysprosium
       hafnium
       curium
       irridium
       neptunium
       nickel
       niobium
       nitrogen
       nobelium
       osmium
       oxygen
       palladium
       phosphorus
       platinum
       plutonium
       polonium
       potassium
       praseodymium
       prometium
       protactinium
       radium
       radon
       rhenium
       rhodium
       rubidium
       ruthenium
       rutherfordium
       samarium
       scandium
       seaborgium
       selenium
       silicon
       silver
       sodium
       strontium
       sulfur
       tantalum
       technetium
       tellurium
       terbium
       thallium
       thorium
       thulium
       tin
       titanium
       tungsten
       ununnilium
       ununnubium
       ununnunium
       uranium
       vanadium
       xenon
       ytterbium
       yttrium
       zinc
       zirconium
  SN:  Chemical substances distinguished by atomic number. http://periodic.lanl.gov/
  TNR: 1427
chemical oceanography
  USE: marine chemistry
chemistry (Earth sciences)
  USE: geochemistry
chemistry (life sciences)
  USE: biochemistry
chloride concentration
  USE: salinity
chlorine
  BT:  chemical elements
  RT:  halogen elements
  UF:  Cl
  SN:  Halogen element with symbol Cl and atomic number 17 <http://periodic.lanl.gov/elements/17.html>
  TNR: 1428
chondrites
  USE: meteorites
chromatography
  BT:  chemical analysis
  NT:  gas chromatography
       liquid chromatography
  RT:  biochemistry
       geochemistry
  SN:  Analytical techniques used to separate or partition the components of a gaseous or liquid mixture by differences in absorption rates during flow around or over surface absorbents such as columns of silica, filter papers, or gels.
  TNR: 158
chromium
  BT:  chemical elements
  RT:  metal elements
  UF:  Cr
  SN:  Metal element with symbol Cr and atomic number 24 <http://periodic.lanl.gov/elements/24.html>
  TNR: 1429
chronostratigraphy
  USE: geologic history
circulation (ocean)
  USE: ocean circulation
circulation (water)
  USE: water circulation
Cl
  USE: chlorine
clay deposits
  BT:  unconsolidated deposits
  RT:  economic geology
       nonmetallic mineral resources
       sedimentology
  SN:  Fine-grained sedimentary soil deposits, containing hydrated silicas of aluminum, that are plastic and sticky when wet and harden when heated.
  TNR: 164
clearinghouses (USGS)
  USE: USGS clearinghouses
cleavage (rock)
  USE: fracture (geologic)
climate
  USE: atmospheric and climatic processes
climate change
  BT:  atmospheric and climatic processes
  NT:  desertification
  RT:  climatology
       global change
       global warming
       greenhouse gases
  UF:  climatic change
       global climate change
       climate variability
       paleoclimate
       climate history
  SN:  Long-term alteration in the characteristic weather conditions of a region, such as changes in precipitation and temperature.
  TNR: 168
climate history
  USE: climate change
climate variability
  USE: climate change
climatic change
  USE: climate change
climatology
  BT:  atmospheric sciences
  RT:  climate change
       desertification
       meteorology
       ocean circulation
       sea-level change
  SN:  Scientific study of the characteristic weather conditions of geographic areas.
  TNR: 170
climbing
  USE: recreation
clines
  USE: ecosystems
Cm
  USE: curium
Co
  USE: cobalt
coal bed methane resources
  USE: coalbed methane resources
coalbed methane resources
  BT:  natural gas resources
  RT:  coal resources
       economic geology
  UF:  coal bed methane resources
       methane resources (coalbed)
  SN:  Resources of methane-rich gas generated and stored in coalbeds.
  TNR: 173
coal resources
  BT:  energy resources
  RT:  coalbed methane resources
       economic geology
  UF:  anthracite resources
       bituminous coal resources
       lignite resources
       subbituminous coal resources
  SN:  Fuel resources such as anthracite, lignite, bituminous coal, or coke, consisting largely of carbonaceous material and formed from fossilized plants.
  TNR: 172
coastal ecosystems
  BT:  terrestrial ecosystems
  RT:  aquatic ecosystems
       ecology
  UF:  littoral ecosystems
  SN:  Biological communities and habitats within the narrow zones of land between the margin of oceans or seas and large landmasses.
  TNR: 174
coastal fisheries
  USE: marine fishery resources
coastal fishing
  USE: marine fishery resources
cobalt
  BT:  chemical elements
  RT:  metal elements
  UF:  Co
  SN:  Metal element with symbol Co and atomic number 27 <http://periodic.lanl.gov/elements/27.html>
  TNR: 1433
coccoliths
  USE: calcareous nannoplankton
coelenterates
  BT:  invertebrates
  RT:  invertebrate zoology
       reef ecosystems
  UF:  corals
       jellyfish
       sea anemones
  SN:  Freshwater and marine invertebrates, such as corals, jellyfish, and sea anemones, belonging to the phylum Coelenterata and living as sedentary polyps or free swimming medusae.
  TNR: 177
collection of specimens
  USE: specimen collecting
college programs (USGS)
  USE: USGS college programs
colloquia (USGS)
  USE: USGS colloquia
colonization (organisms)
  USE: dispersal (organisms)
columbium
  USE: niobium
comet impact
  USE: impact cratering
commensalism
  USE: symbiosis
commerce
  USE: business and economics
commercial fishery resources
  BT:  fishery resources
  RT:  aquaculture
       aquatic biology
       ichthyology
       marine biology
       marine fishery resources
  SN:  Stocks of fish and other seafood used for marketing purposes.
  TNR: 185
commercial water use
  BT:  offstream water use
  RT:  hydraulic engineering
       hydrology
  SN:  Use of water for motels, hotels, restaurants, office buildings, and other commercial facilities and institutions.
  TNR: 186
community ecology
  BT:  population and community ecology
  RT:  ecological competition
       ecology
  SN:  Study of the relationships of species that interact in a common area.
  TNR: 187
community education (USGS)
  USE: USGS lifelong learning programs
compaction
  BT:  earth material properties
  UF:  soil compaction
  SN:  Overall density of an unconsolidated earth material.
  TNR: 1714
composite burn index
  US+: remote sensing
       fire damage
computational methods
  BT:  methods
  NT:  image analysis
       mathematical modeling
       relative abundance analysis
       spatial analysis
       statistical analysis
       topological analysis
       visualization methods
  UF:  mathematical methods
  SN:  Mathematical techniques used to analyze numerical data.
  TNR: 189
computer program
  USE: scientific software
computer science
  BT:  information sciences
  SN:  Study of computers, including their design (architecture),  uses (computations, data processing), and systems control.
  TNR: 190
conflict resolution methods
  USE: decision support methods
coniferous forests ecosystems
  USE: forest ecosystems
conodonts
  BT:  invertebrates
  RT:  invertebrate paleontology
       micropaleontology
  SN:  Microscopic teeth of primitive, boneless, eel-like animals, similar to modern hagfish, that lived in many of the world's oceans from the Cambrian through Triassic Periods of geologic time (550 to 210 million years ago).
  TNR: 192
conservation
  USE: natural resource management
conservation genetics
  US+: genetic diversity
       biological population management
consumers (organisms)
  BT:  organism groupings (non-taxonomic)
  NT:  carnivores
       herbivores
       omnivores
  RT:  ecology
       zoology
  SN:  Organisms unable to produce food from nonliving matter and dependent on ingesting other animals, plants, or particulate organic matter.
  TNR: 194
consumptive use (water)
  USE: water use
contacts (geologic)
  USE: geologic contacts
contaminant transport
  BT:  ecological processes
  RT:  ecotoxicology
  SN:  Processes involved in the movement of impurities through air, water, and soil.
  TNR: 196
contamination and pollution
  BT:  topics
  NT:  nonpoint-source pollution
       industrial pollution
       pesticide and herbicide contamination
       toxic radionuclide contamination
       toxic trace element contamination
       pharmaceutical contamination
  RT:  human impacts
       waste treatment and disposal
       ecotoxicology
       hazards
       water quality
  UF:  water pollution
       soil pollution
       natural contaminants
       pollution
       air pollution
       effluent
       outfall
  SN:  Introduction of harmful substances into the environment by human action or natural processes.
  TNR: 769
continental drift
  USE: tectonic processes
continental lithosphere
  BT:  lithosphere
  RT:  tectonophysics
  UF:  craton
  SN:  The earth's hard, outermost shell comprised of the crust and the upper part of the mantle.
  TNR: 199
continuing education (USGS)
  USE: USGS lifelong learning programs
contour lines
  USE: topography
contracts (USGS)
  USE: USGS contracts and grants
controlled burns
  USE: controlled fires
controlled fires
  BT:  fire control
  RT:  fires
       fire control
  UF:  controlled burns
       fires (controlled)
       managed fires
  SN:  Prescribed burns used to burn trees, brush, and undergrowth that would fuel a large wildfire.  Do not confuse this term with 'fire control'.  It is one of the tools used in fire control.
  TNR: 202
controlled flooding
  BT:  natural resource management
  RT:  floods
  UF:  flooding (controlled)
       managed flooding
  SN:  The deliberate inundation of land or wetland, or an increase in river flow below dams for restoration or research purposes. Do not confuse with flood control.
  TNR: 203
controlled vocabularies
  USE: terminologies and classifications
cooperative research & development agreements (CRADAs)
  USE: USGS cooperative research & development agreements (CRADAs)
cooperative research (USGS)
  USE: USGS partnerships
cooperative research and development agreements
  USE: USGS cooperative research & development agreements (CRADAs)
cooperators (USGS)
  USE: USGS partnerships
coordinate systems
  USE: map coordinate systems
copper
  BT:  chemical elements
  RT:  metal elements
  UF:  Cu
  SN:  Metal element with symbol Cu and atomic number 29 <http://periodic.lanl.gov/elements/29.html>
  TNR: 1434
coral reef ecosystems
  USE: reef ecosystems
corals
  USE: coelenterates
core (earth)
  BT:  earth structure
  NT:  inner core (earth)
       outer core (earth)
  RT:  geophysics
  SN:  The superdense center of the earth composed of two layers: a liquid outer layer and a solid inner core of metallic iron-nickel alloy.
  TNR: 211
core analysis
  BT:  laboratory methods
  RT:  drilling and coring
  SN:  Study of the composition and layers of cylindrical samples of rocks, trees, ice, and other materials extracted by drilling into a mass. Intended for broad use for the analysis of all types of core samples. The combination of this term with other terms will convey the context of the activity.
  TNR: 212
core sampling
  USE: drilling and coring
coring
  USE: drilling and coring
correlation
  USE: regression analysis
Cr
  USE: chromium
CRADAs
  USE: USGS cooperative research & development agreements (CRADAs)
craton
  USE: continental lithosphere
creep
  USE: mass wasting
crenulation (geologic)
  USE: folding (geologic)
cretaceous
  BT:  mesozoic
  TNR: 1628
crushed stone
  USE: building stone resources
crust (earth)
  BT:  earth structure
  NT:  lithosphere
  RT:  tectonophysics
  SN:  The outermost layer of the earth which is relatively thin, of lower density than the core, and rocky.
  TNR: 219
crustaceans
  BT:  arthropods
  NT:  ostracodes
  RT:  invertebrate zoology
       shellfish
  SN:  Arthropods of class Crustacea, such as crabs, lobsters, shrimp, prawns, or barnacles, with hard shells (exoskeleton) and segmented bodies with pairs of jointed appendages.
  TNR: 220
cryology
  USE: glaciology
cryosphere
  USE: snow and ice cover
cryptozoic
  USE: precambrian
crystallography
  USE: mineralogy
crystals
  USE: rocks and deposits
Cs
  USE: cesium
CTD measurement
  BT:  field inventory and monitoring
  RT:  limnology
       marine chemistry
       ocean sciences
  SN:  Instrumental determination of conductivity, temperature, and pressure as a function of depth to determine the salinity of seawater.
  TNR: 222
Cu
  USE: copper
culture and demographics
  BT:  topics
  NT:  administrative and political boundaries
       business and economics
       cadastral and legal land descriptions
       laws and regulations
       transportation
       geographic names
  RT:  geography
       social sciences
  UF:  demographics
       socioeconomics
  SN:  Information on human behavior, ways of living and thinking, and characteristics of human populations.
  TNR: 223
culturing (specimens)
  BT:  laboratory methods
  RT:  bacteriology
       microbiology
  SN:  Growing microorganisms, tissue cells, or other living matter in a specially prepared nutrient medium for diagnostic or scientific use.
  TNR: 224
Curie temperature analysis
  BT:  paleomagnetic analysis
  RT:  geophysics
  UF:  temperature analysis (Curie)
  SN:  Analysis of rock specimens using the Curie temperature point above which ferromagnetic materials lose permanent magnetism.
  TNR: 225
curium
  BT:  chemical elements
  RT:  actinide series elements
  UF:  Cm
  SN:  Rare earth (actinide series) element with symbol Cm and atomic number 96 <http://periodic.lanl.gov/elements/96.html>
  TNR: 1438
customer support (USGS)
  USE: USGS customer support and user feedback
cytology
  USE: cell biology
darmstadtium
  BT:  chemical elements
  RT:  metal elements
  UF:  Ds
  SN:  Metal element with symbol Ds and atomic number 110 <http://periodic.lanl.gov/elements/110.html>
  TNR: 1439
data
  USE: datasets
data archives (USGS)
  USE: USGS libraries and archives
databases
  USE: datasets
data downloading (USGS)
  USE: USGS data downloading
data management
  USE: information management methods
datasets
  BT:  product types
  NT:  geospatial datasets
       hydrographic datasets
       time series datasets
  RT:  USGS libraries and archives
  UF:  data
       databases
       streamflow data
       water-quality data
  SN:  Digital information in a format suitable for direct input to software that can analyze its meaning in the scientific, engineering, or business context for which the data were collected.
  TNR: 235
dating methods
  USE: age estimation methods
Db
  USE: dubnium
debris avalanches
  USE: landslides
debris flows
  USE: landslides
deciduous forest ecosystems
  USE: forest ecosystems
decision support methods
  BT:  management methods
  RT:  geographic information systems (GIS)
  UF:  conflict resolution methods
  SN:  Mathematical, analytical, and social procedures used to aid groups and individuals in the process of making decisions.  Includes protocols for discussion and mechanisms for facilitating communication among disparate groups as well as mechanical and technological aids to analysis and understanding.
  TNR: 237
decomposers
  BT:  organism groupings (non-taxonomic)
  RT:  biogeochemical cycling
       ecology
       life sciences
  SN:  Organisms, chiefly microorganisms and invertebrates, that feed on dead plant or animal matter breaking it down and recycling the resulting elements and compounds in the environment.
  TNR: 238
decomposition (organic)
  USE: biogeochemical cycling
deep sea fisheries
  USE: marine fishery resources
deep sea fishing
  USE: marine fishery resources
deforestation
  BT:  human impacts
  SN:  Reduction in the density of forest cover or tree canopy, typically by harvesting trees for human use or clearing land for other purposes such as agriculture.
  TNR: 1354
deformation (geologic)
  BT:  geologic processes
  NT:  folding (geologic)
       fracture (geologic)
  RT:  geologic structure
  UF:  rheology
       strain history
  SN:  Change in form and structure of geologic materials in response to stress, typically heat and pressure.
  TNR: 1699
degradation products (chemical)
  USE: pesticide and herbicide contamination
demographics
  USE: culture and demographics
dendroecology
  US+: ecosystem monitoring
       vegetation
density flow
  USE: sediment transport
deposition (sediment)
  USE: sedimentation
depth-to maps
  US+: structure contours
       maps and atlases
desert ecosystems
  BT:  terrestrial ecosystems
  RT:  desertification
       ecology
  SN:  Biological communities and habitats in arid areas with little precipitation, sparse, highly adapted vegetation, and extreme temperatures.
  TNR: 245
desertification
  BT:  climate change
  RT:  climatology
       desert ecosystems
       ecology
       hazards
       land use change
  SN:  The alteration of arable land to dry, barren land due to prolonged drought or the deleterious effects of human intervention including overgrazing, overpopulation, or destructive agricultural practices.
  TNR: 246
detection (chemical)
  USE: chemical analysis
developmental biology
  BT:  life sciences
  RT:  organism growth and development
  UF:  embryology
  SN:  Scientific study of the processes related to the transformation of living organisms from single cells to complex multi-celled individuals.
  TNR: 247
devonian
  BT:  paleozoic
  TNR: 1630
diadromous fish
  US+: migratory species
       fish
diagenesis
  BT:  geologic processes
  RT:  petrology
       sedimentology
  SN:  Chemical, physical, and biological changes in sediment during and after its conversion to rock (lithification).
  TNR: 248
diatoms
  BT:  algae
  RT:  micropaleontology
       phycology
  SN:  Microscopic, single-celled plants of the class Bacillariophyceae that have siliceous shells called frustules, and which grow in both marine and fresh water.
  TNR: 250
digital cartographic data
  USE: geospatial datasets
digital cartographic datasets
  USE: geospatial datasets
digital cartography
  USE: cartography
digital line graphs
  USE: geospatial datasets
dimension stone
  USE: building stone resources
dinoflagellates
  BT:  algae
  RT:  micropaleontology
       phycology
  SN:  Single-celled planktonic organisms, chiefly marine, characterized by twirling motion and whip-like flagella with affinities to both plants and animals.
  TNR: 261
dinosaurs
  BT:  reptiles
  RT:  vertebrate paleontology
  SN:  Extinct reptiles, often gigantic, chiefly terrestrial, carnivorous or herbivorous, that lived during the Mesozoic era.
  TNR: 262
directories
  BT:  catalogs and indexes
  RT:  reports
  SN:  Searchable lists of people, typically USGS staff.
  TNR: 263
disasters
  USE: hazards
disease
  USE: health and disease
disease (human)
  USE: environmental health (human)
disease vectors
  BT:  health and disease
  RT:  life sciences
  SN:  Organisms, such as insects, that transmit pathogens from one host to another.
  TNR: 267
dispersal (organisms)
  BT:  ecological processes
  RT:  ecology
       life sciences
       migration (organisms)
  UF:  colonization (organisms)
  SN:  The dissemination or geographic spread of individuals of a plant or animal population.
  TNR: 268
dissertations
  USE: reports
dissolution
  USE: erosion
dissolved constituents
  USE: water quality
dissolved contaminants
  USE: water quality
dissolved gases
  BT:  water properties
  SN:  Gases such as ammonia, oxygen, nitrogen, and carbon dioxide in solution measured in a water sample.
  TNR: 1682
dissolved oxygen
  USE: oxygen content (water)
distribution of animals
  USE: biogeography
distribution of plants
  USE: biogeography
distribution of species
  USE: biogeography
distribution services (USGS)
  USE: USGS sales and distribution services
diversity (biological)
  USE: biodiversity
DLG
  USE: geospatial datasets
DNA sequencing
  BT:  chemical analysis
  RT:  biochemistry
       genetics
  UF:  gene sequencing
       genome
  SN:  Biochemical procedure to determine the order of nucleotides in genes.
  TNR: 276
documents
  USE: reports
domestic water use
  BT:  offstream water use
  NT:  drinking water use
  RT:  hydraulic engineering
       hydrology
  UF:  public water supply
       residential water use
  SN:  Use of water for household purposes, such as drinking, food preparation, bathing, washing clothes and dishes, flushing toilets, and watering lawns and gardens.
  TNR: 278
doppler radar imaging
  BT:  radar imaging
  UF:  radar ecology
  SN:  Exploitation of the doppler effect in radar imaging to determine speed of airborne objects such as birds, butterflies, and clouds.
  TNR: 1727
dowsing
  USE: natural resource exploration
drawdown
  USE: water use
dredging
  BT:  human impacts
  RT:  hydraulic engineering
  SN:  Removal of sediments from water bodies to aid navigation.
  TNR: 1671
drilling and coring
  BT:  field sampling
  RT:  botany
       core analysis
       geology
       glaciology
       well drilling
  UF:  core sampling
       coring
       ice core sampling
  SN:  Cutting into the subsurface, for example into underground strata, ice, or a tree trunk, to remove material for examination. Intended for broad use wherever coring is done. The combination of this term with other terms will convey the context of the activity.
  TNR: 281
drinking water
  USE: drinking water use
drinking water use
  BT:  domestic water use
  RT:  water quality
  UF:  drinking water
       potable water
  TNR: 283
droughts
  BT:  atmospheric and climatic processes
  RT:  atmospheric sciences
       hazards
  SN:  Extended periods of moisture deficit over a sizeable area sufficient to have an adverse effect on vegetation, animals, or man.
  TNR: 284
Ds
  USE: darmstadtium
dubnium
  BT:  chemical elements
  RT:  metal elements
  UF:  Db
  SN:  Metal element with symbol Db and atomic number 105 <http://periodic.lanl.gov/elements/105.html>
  TNR: 1442
dust deposition
  USE: sedimentation
dust storms
  BT:  storms
  SN:  Atmospheric disturbances in which a significant amount of dust is transported.
  TNR: 1696
dust transport
  USE: sediment transport
Dy
  USE: dysprosium
dynamic geology
  USE: tectonic processes
dysprosium
  BT:  chemical elements
  RT:  lanthanide series elements
  UF:  Dy
  SN:  Rare earth (lanthanide series) element with symbol Dy and atomic number 66 <http://periodic.lanl.gov/elements/66.html>
  TNR: 1444
early warning systems
  USE: hazard preparedness
earth characteristics
  BT:  topics
  NT:  atmospheric properties
       earth structure
       geologic history
       geologic structure
       gravitational field (earth)
       land surface characteristics
       magnetic field (earth)
       ocean characteristics
       rocks and deposits
       snow and ice cover
       stratigraphic sections
       topography
       earth material properties
  RT:  earth sciences
  SN:  The measurable, definable properties and features of the earth.
  TNR: 287
earth history
  BT:  geologic history
  RT:  geochemistry
       geology
       tectonophysics
  SN:  The structural and compositional changes that the earth has undergone from its formation. Use for discussions of the whole earth (or large sections of it) instead of regional studies.
  TNR: 288
earth material properties
  BT:  earth characteristics
  NT:  permeability
       porosity
       radioactivity
       resistivity
       compaction
       magnetism
  SN:  Physical characteristics of rocks and unconsolidated earth materials such as soils and sediments.
  TNR: 1367
earthquake activity maps
  US+: maps and atlases
       earthquake occurrences
earthquake epicenter maps
  US+: earthquake occurrences
       maps and atlases
earthquake forecasting
  USE: earthquake probabilities
earthquake hazards
  US+: hazards
       earthquakes
earthquake monitoring
  USE: seismic networking
earthquake occurrence maps
  US+: maps and atlases
       earthquake occurrences
earthquake occurrences
  BT:  earthquakes
  RT:  seismology
  UF:  earthquake occurrence maps
       earthquake seismology
       seismic activity
       earthquake activity maps
       earthquake epicenter maps
       ground motion maps
       seismic hazard maps
       shaking maps (seismic)
       seismicity
       strong motion
       ground motion
  SN:  Time, location, severity, and mechanism of earthquake events, including the frequency and history of events in a given area.
  TNR: 299
earthquake prediction
  USE: earthquake probabilities
earthquake preparedness
  BT:  hazard preparedness
  SN:  Awareness of the consequences of earthquake events and actions to be taken before, during, or after events.
  TNR: 301
earthquake probabilities
  BT:  risk assessment
  RT:  earthquakes
       neotectonic processes
  UF:  earthquake forecasting
       earthquake prediction
       seismicity maps
  SN:  That aspect of seismology that deals with the physical conditions or indications that precede an earthquake, in order to predict its probability, size, time, and location.
  TNR: 302
earthquakes
  BT:  geologic processes
  NT:  earthquake occurrences
  RT:  earthquake probabilities
       hazards
       seismology
       tectonic processes
       tectonophysics
       volcanic activity
  UF:  earthquake hazards
  SN:  Ground shaking caused by the sudden release of accumulated strain by an abrupt shift of rock along a fracture in the earth or by volcanic or magmatic activity, or other sudden stress changes in the earth.
  TNR: 304
earthquake seismology
  US+: seismology
       earthquake occurrences
Earth Science Information Centers (ESICs)
  USE: USGS Earth Science Information Centers (ESICs)
earth sciences
  BT:  sciences
  NT:  atmospheric sciences
       geochemistry
       geography
       geology
       geophysics
       glaciology
       hydrology
       limnology
       ocean sciences
       paleontology
       soil sciences
  RT:  earth characteristics
       natural resources
       scientific careers
  UF:  geosciences
  SN:  Broad term for all science related to the study of the earth.
  TNR: 291
earth structure
  BT:  earth characteristics
  NT:  core (earth)
       crust (earth)
       mantle (earth)
  RT:  geologic structure
       structural geology
       tectonic processes
       tectonophysics
  SN:  Major interior structural features of the planet earth.
  TNR: 292
earth tides
  BT:  geologic processes
  SN:  Periodic changes in the earth surface topography caused by the gravitational attraction of the moon and sun, measured with tiltmeters.  Used in studies of volcanic activity.
  TNR: 1683
echinoderms
  BT:  invertebrates
  RT:  invertebrate zoology
  SN:  Marine invertebrates of the phylum Echinodermata with a radial body and a calcareous exoskeleton. Includes starfishes, brittle stars, sea lilies, sea urchins, and sea cucumbers.
  TNR: 305
echo sounding
  USE: sonar methods
ecoclines
  USE: ecosystems
ecological competition
  BT:  ecological processes
  RT:  biodiversity
       community ecology
       ecology
       endangered species
  SN:  The struggle between members of two or more species for scarce environmental resources.
  TNR: 308
ecological models
  USE: ecological processes
ecological processes
  BT:  biological and physical processes
  NT:  transpiration
       algal blooms
       bioaccumulation
       biogeochemical cycling
       biological productivity
       contaminant transport
       dispersal (organisms)
       ecological competition
       ecosystem functions
       eutrophication
       extinction and extirpation
       habitat alteration
       migration (organisms)
       pollination
       succession (biological)
  RT:  ecology
       population and community ecology
       soil formation
  UF:  ecological models
       environmental processes
  SN:  Dynamic biogeochemical interactions that occur among and between biotic and abiotic components of the biosphere.
  TNR: 310
ecologic succession
  USE: succession (biological)
ecology
  BT:  life sciences
  RT:  animal behavior
       aquatic biology
       aquatic ecosystems
       benthic ecosystems
       bioaccumulation
       biodiversity
       biogeochemical cycling
       biogeography
       biological productivity
       bioremediation
       carbon cycling
       carnivores
       coastal ecosystems
       community ecology
       consumers (organisms)
       decomposers
       desert ecosystems
       desertification
       dispersal (organisms)
       ecological competition
       ecological processes
       ecosystem functions
       ecosystem monitoring
       ecosystems
       ecotoxicology
       endangered species
       endemic species
       estuarine ecosystems
       eutrophication
       extinction and extirpation
       fires
       food web
       forest ecosystems
       forest resources
       freshwater ecosystems
       global change
       global warming
       grassland ecosystems
       habitat alteration
       herbivores
       human impacts
       invasive species
       land use change
       long-term ecological monitoring
       marine ecosystems
       mercury contamination
       migration (organisms)
       migratory species
       native species
       nonindigenous species
       nutrient cycling
       omnivores
       pesticide and herbicide contamination
       plot sampling
       pollinators
       population and community ecology
       population dynamics
       producers (organisms)
       reef ecosystems
       remediation
       shrubland ecosystems
       succession (biological)
       terrestrial ecosystems
       tundra ecosystems
       vegetation
       waste treatment and disposal
       wetland ecosystems
       wetland functions
  UF:  bionomics
  SN:  Study of the relations between living plants and animals and their environment.
  TNR: 311
economic geology
  BT:  geology
  RT:  building stone resources
       clay deposits
       coal resources
       coalbed methane resources
       gas hydrate resources
       gem resources
       gold ores
       gravel deposits
       metallic ores
       mineral resources
       natural gas resources
       nonmetallic mineral resources
       energy resources
       oil resources
       oil sand resources
       oil shale resources
       sand deposits
       soil resources
  SN:  Scientific study of the formation, location, and use of marketable geologic materials including fuels, metals, minerals, and water.
  TNR: 312
economics
  USE: business and economics
ecosystem diversity
  BT:  biodiversity
  SN:  Measure of the variety of biological communities and habitats important for ecological stability.
  TNR: 314
ecosystem functions
  BT:  ecological processes
  NT:  wetland functions
  RT:  ecology
  UF:  ecosystem services
       estuarine ecosystem functions
  SN:  The total life activities of organisms in habitats and the effects of those activities on the nonliving components of the environment.
  TNR: 315
ecosystem management
  BT:  natural resource management
  RT:  ecosystem monitoring
  UF:  reintroduction (organisms)
       ecosystem preservation
  SN:  Means of controlling or directing human practices, species populations, and physical environment within an ecosystem to achieve a selected state of sustainability.
  TNR: 316
ecosystem monitoring
  BT:  field inventory and monitoring
  NT:  long-term ecological monitoring
  RT:  biogeography
       biological population management
       bioremediation
       ecology
       ecosystem management
       natural resource management
       population and community ecology
       relative abundance analysis
       remediation
  UF:  indicator species observation
       dendroecology
  SN:  Recording, evaluating, and actively intervening over time in the interaction of living and nonliving elements in a specific environment.
  TNR: 317
ecosystem preservation
  USE: ecosystem management
ecosystems
  BT:  population and community ecology
  NT:  aquatic ecosystems
       terrestrial ecosystems
       wetland ecosystems
  RT:  ecology
       habitats
  UF:  biosphere
       clines
       ecoclines
       ecotones
  SN:  The interacting populations of plants, animals, and  microorganisms occupying a certain area, and their relationship to the environment.
  TNR: 319
ecosystem services
  USE: ecosystem functions
ecotones
  USE: ecosystems
ecotoxicology
  BT:  life sciences
  RT:  bioaccumulation
       contaminant transport
       ecology
       hazards
       human impacts
       mercury contamination
       contamination and pollution
       pesticide and herbicide contamination
       plant and animal testing
       therapeutic methods
       toxic radionuclide contamination
       toxic trace element contamination
  UF:  environmental toxicology
       toxicology
  SN:  Scientific study of causes, dispersal, and effects of contaminants on the environment.
  TNR: 320
ectoprocta
  USE: bryozoans and brachiopods
Ediacaran
  BT:  Neoproterozoic
  UF:  Vendian
  SN:  The last geological period of the Neoproterozoic Era, just before the Cambrian Period of the Paleozoic Era.
  TNR: 1735
educational services (USGS)
  USE: USGS educational services
effluent
  USE: contamination and pollution
einsteinium
  BT:  chemical elements
  RT:  actinide series elements
  UF:  Es
  SN:  Rare earth (actinide series) element with symbol Es and atomic number 99 <http://periodic.lanl.gov/elements/99.html>
  TNR: 1445
electrical resistivity logging
  BT:  borehole logging
  RT:  electromagnetic surveying
       stratigraphy
  UF:  resistivity sounding
  SN:  Recordings made to identify the composition of subterranean materials at different depths in a borehole by measuring their ability to resist the flow of an electric current.
  TNR: 325
electromagnetic surveying
  BT:  field inventory and monitoring
  RT:  aeromagnetic surveying
       electrical resistivity logging
  UF:  magnetic surveying
       magnetotelluric sounding
  SN:  Method of determining the shape and constituency of near-surface earth structures by variations of responses of the materials to electrical and magnetic fields. Use for ground-based methods of imaging.
  TNR: 326
electron microscopy
  BT:  microscopy
  NT:  scanning electron microscopy
  SN:  Study of small particles of matter with a microscope that produces a magnified image by using a beam of electrons focused by magnetic lenses.
  TNR: 327
electrophoresis
  BT:  chemical analysis
  RT:  biochemistry
  SN:  Analytical technique to separate and identify components in a mixture using the differential migration of molecules based on their net charge through a paper or gel medium.
  TNR: 328
elements
  BT:  topics
  NT:  chemical elements
       chemical element groups
  SN:  Chemical elements and element groups
  TNR: 1382
elevation
  USE: topography
El Nino
  USE: ocean-atmosphere interaction
embryology
  USE: developmental biology
emergency management resources
  USE: hazards
emergency response planning
  USE: hazard preparedness
employment opportunities (USGS)
  USE: USGS employment and volunteer opportunities
endangered species
  BT:  organism groupings (non-taxonomic)
  RT:  biodiversity
       ecological competition
       ecology
       life sciences
  SN:  Plant or animal species reduced to such low numbers of individuals that they are at risk of becoming extinct.
  TNR: 332
endemic species
  BT:  native species
  RT:  biodiversity
       ecology
       life sciences
  SN:  Plant and animals species native to and confined to specific geographic areas.
  TNR: 333
endocrinology
  BT:  anatomy and physiology
  RT:  health and disease
  SN:  Study of the collection of ductless glands that secrete hormones which influence growth, gender, sexual maturity, and other attributes.
  TNR: 334
energy resources
  BT:  natural resources
  NT:  coal resources
       natural gas resources
       oil resources
       geothermal resources
  RT:  economic geology
  UF:  energy sources
       fossil fuels
  SN:  Natural resources that are used for heat and power generation, including oil, natural gas, coal, and geothermal energy.
  TNR: 799
energy sources
  USE: energy resources
engineering geology
  BT:  engineering sciences
  RT:  geology
       liquefaction
       remediation
  UF:  engineering geology maps
       geotechnical properties maps
       rock mechanics maps
  SN:  Branch of geology involved in the application of soil and rock mechanics, natural hazards, and other geological studies to the practice of engineering and construction.
  TNR: 337
engineering geology maps
  US+: maps and atlases
       engineering geology
engineering sciences
  BT:  sciences
  NT:  engineering geology
       hydraulic engineering
  RT:  instrument design and development
       mining hazards
       scientific careers
  UF:  engineering seismology
  SN:  Sciences involved in the application of scientific and mathematical principles to construction, machinery, mechanical design, mining and manufacturing processes and other practical activities.
  TNR: 339
engineering seismology
  US+: engineering sciences
       seismology
entomology
  BT:  invertebrate zoology
  RT:  arachnids
       butterflies and moths
       insects
       pollinators
  SN:  Branch of zoology involved in studying insects.
  TNR: 341
environmental analysis
  USE: environmental assessment
environmental assessment
  BT:  management methods
  NT:  TMDL
  UF:  environmental analysis
       environmental impact assessment
  SN:  The evaluation of the status of a specific ecosystem or geographic area and how a proposed change in management or a proposed project will affect that status.
  TNR: 343
environmental chemistry
  USE: biochemistry
environmental hazards
  USE: hazards
environmental health (human)
  BT:  health and disease
  NT:  human environmental safety
  RT:  human impacts
       social sciences
       toxic radionuclide contamination
       toxic trace element contamination
       virology
  UF:  disease (human)
       health (human)
       human disease
       human health
  SN:  Effects of the environment on human health.
  TNR: 345
environmental impact assessment
  USE: environmental assessment
environmental management
  USE: natural resource management
environmental planning
  USE: natural resource management
environmental processes
  USE: ecological processes
environmental toxicology
  USE: ecotoxicology
eocene
  BT:  paleogene
  TNR: 1631
eolian sediments
  USE: unconsolidated deposits
Er
  USE: erbium
erbium
  BT:  chemical elements
  RT:  lanthanide series elements
  UF:  Er
  SN:  Rare earth (lanthanide series) element with symbol Er and atomic number 68 <http://periodic.lanl.gov/elements/68.html>
  TNR: 1447
erosion
  BT:  geologic processes
  RT:  geomorphology
       glaciology
       hydrology
       sedimentology
       watershed management
       scour
  UF:  wind erosion
       dissolution
       sinkhole formation
  SN:  The process whereby materials of the earth's crust are loosened, dissolved, or worn away and simultaneously moved from one place to another.
  TNR: 353
eruption
  USE: volcanic activity
Es
  USE: einsteinium
ESICs
  USE: USGS Earth Science Information Centers (ESICs)
estuarine circulation
  US+: estuarine ecosystems
       water circulation
estuarine currents
  US+: estuarine ecosystems
       water circulation
estuarine ecosystem functions
  US+: estuarine ecosystems
       ecosystem functions
estuarine ecosystems
  BT:  aquatic ecosystems
  RT:  aquatic biology
       ecology
  UF:  estuarine circulation
       estuarine currents
       estuarine ecosystem functions
  SN:  Biological communities and habitats within sea inlets or the zones where rivers meet the seas which are subject to tidal effects and the mixture of fresh and saltwater.
  TNR: 358
Eu
  USE: europium
europium
  BT:  chemical elements
  RT:  lanthanide series elements
  UF:  Eu
  SN:  Rare earth (lanthanide series) element with symbol Eu and atomic number 63 <http://periodic.lanl.gov/elements/63.html>
  TNR: 1450
eutrophication
  BT:  ecological processes
  RT:  ecology
       limnology
       oxygen content (water)
  SN:  The process by which water becomes enriched with plant nutrients, most commonly phosphorus and nitrogen.
  TNR: 359
evaporation
  BT:  atmospheric and climatic processes
  RT:  transpiration
       water cycle
  UF:  evapotranspiration
  SN:  Transfer of water from a surface into the atmosphere.
  TNR: 1355
evapotranspiration
  US+: evaporation
       transpiration
evolution
  BT:  biological and physical processes
  UF:  gene flow
  SN:  Change in the genetic composition of populations of living organisms.
  TNR: 1702
exhibits (USGS)
  USE: USGS exhibits and facility tours
exotic species
  USE: nonindigenous species
expertise services (USGS)
  USE: USGS expertise services
exploration
  USE: natural resource exploration
exploration seismology
  US+: natural resource exploration
       seismology
extinction and extirpation
  BT:  ecological processes
  RT:  ecology
       life sciences
  UF:  extirpation
  SN:  Extinction is the complete disappearance of a species from the earth.  Extirpation is the complete disappearance (elimination) of a species from a given region, island, or area.
  TNR: 365
extirpation
  USE: extinction and extirpation
F
  USE: fluorine
facilities (USGS)
  USE: USGS facilities
facility tours (USGS)
  USE: USGS exhibits and facility tours
fall (season)
  USE: autumn
false scorpions
  USE: arachnids
farming
  USE: agriculture
faulting (geologic)
  BT:  fracture (geologic)
  SN:  Movement of earth materials along fracture surfaces.
  TNR: 1700
fauna
  USE: animals
faunal and floral census (microscopic)
  BT:  laboratory methods
  RT:  field inventory and monitoring
       microbiology
       micropaleontology
       microscopy
  UF:  pollen analysis
  SN:  Records of counts of the different microscopic species in a core, soil, sediment, rock or water sample to determine geologic age or other characteristic of the sample.  Use for microscopic examinations.
  TNR: 370
fax-on-demand (USGS)
  USE: USGS fax-on-demand services
Fe
  USE: iron
fermentation
  USE: oxidation and reduction
fermium
  BT:  chemical elements
  RT:  actinide series elements
  UF:  Fm
  SN:  Rare earth (actinide series) element with symbol Fm and atomic number 100 <http://periodic.lanl.gov/elements/100.html>
  TNR: 1453
ferns and fern allies
  BT:  vascular plants
  RT:  botany
  SN:  Spore-bearing, vascular plants having leaves known as fronds.
  TNR: 372
field centers (USGS)
  USE: USGS field centers
field experiments
  BT:  field methods
  NT:  tracer study
  SN:  Deliberate arrangement of objects and events in the field to observe the behavioral response of natural systems or organisms.
  TNR: 374
field inventory and monitoring
  BT:  field methods
  NT:  acoustic methods
       borehole logging
       CTD measurement
       ecosystem monitoring
       electromagnetic surveying
       handheld field spectroscopy
       seismic methods
       stream-gage measurement
       telemetry
       tiltmeter measurement
       video monitoring
       vocalization methods
       animal and plant census
       optical methods
       gravimeter measurement
       magnetometer measurement
       tomography
  RT:  faunal and floral census (microscopic)
       field monitoring stations
  UF:  baseline characterization
       field monitoring
       field observation
       inventory
       ocean current measurement
       ocean monitoring
       ocean wave measurement
       reconnaissance
       river discharge monitoring
       volcano monitoring
       weather monitoring
       weather observations
       precipitation measurement
       rainfall measurement
       snowfall measurement
  SN:  Repeated observation or sampling at a site, on a scheduled or event basis, for study and analysis.  In general, this category excludes sampling programs in which materials are obtained in the field and brought back to a laboratory for study and analysis.
  TNR: 375
field methods
  BT:  methods
  NT:  field experiments
       field inventory and monitoring
       field sampling
       geolocation measurement
       real-time monitoring and reporting
  SN:  Research procedures and instrumental means to measure, collect data and samples, and observe in the natural areas where the materials, phenomena, structures, or species being studied occur.
  TNR: 376
field monitoring
  USE: field inventory and monitoring
field monitoring stations
  BT:  topics
  RT:  field inventory and monitoring
  UF:  benchmarks
       field stations
       seismic monitoring stations
       stream gaging stations
  SN:  Locations where USGS scientists or their collaborators make measurements of natural phenomena.
  TNR: 1359
field observation
  USE: field inventory and monitoring
field sampling
  BT:  field methods
  NT:  animal tracking
       capturing (animals)
       drilling and coring
       plant and animal tagging
       plot sampling
       sexing (plants & animals)
       specimen collecting
       transect sampling
       trenching
       water sampling
  UF:  fish inventories
  SN:  Collecting pieces or specimens or making measurements or observations at determined intervals or areas.  Results may be used as representative of the whole research area or population.
  TNR: 379
field stations
  USE: field monitoring stations
field trip guidebooks
  USE: guidebooks
fire control
  BT:  natural resource management
  NT:  controlled fires
  RT:  controlled fires
  UF:  fire prevention
  SN:  Human intervention to restrict or prevent fires in forests and grasslands.
  TNR: 1357
fire damage
  BT:  habitat alteration
  UF:  composite burn index
       normalized burn ratio
  SN:  Destruction of surficial materials and vegetation by burning.
  TNR: 1378
fire preparedness
  US+: fires
       hazard preparedness
fire prevention
  USE: fire control
fires
  BT:  biological and physical processes
  RT:  atmospheric sciences
       controlled fires
       ecology
       hazards
       human impacts
  UF:  fire preparedness
       fires (uncontrolled)
       wildfires
  SN:  Combustion, marked by flames or intense heat, in natural settings, often ignited by lightning or human activities.  For fires set as part of natural resource management, use 'controlled fires'.
  TNR: 384
fires (controlled)
  USE: controlled fires
fires (uncontrolled)
  USE: fires
fish
  BT:  vertebrates
  RT:  ichthyology
  UF:  fish inventories
       fishes
       anadromous fish
       diadromous fish
  SN:  Cold-blooded aquatic vertebrates with fins for swimming, gills for breathing, and usually scales.
  TNR: 387
fishery management
  BT:  biological population management
  SN:  Controlling or directing numbers and life conditions of fish living in a specific locality to achieve a selected goal.
  TNR: 390
fishery resources
  BT:  natural resources
  NT:  commercial fishery resources
       inland fishery resources
       marine fishery resources
       recreational fishery resources
       subsistence fishery resources
  RT:  aquaculture
       aquatic biology
       ichthyology
       marine biology
       overfishing
  SN:  The stock of anadromous, marine, and freshwater fish in fishing areas of commercial, subsistence, and recreational value.
  TNR: 391
fishes
  USE: fish
fish farming
  USE: aquaculture
fishing (recreational)
  USE: recreation
fish inventories
  US+: fish
       field sampling
fission-track dating
  BT:  age estimation methods
  RT:  geochronology
       radiometric dating
  UF:  age dating (fission-track)
       fission-track method
  SN:  Laboratory technique for determining the age of rocks and other geological materials by counts of spontaneous and induced fission tracks left by the radioactive isotope uranium-238.
  TNR: 393
fission-track method
  USE: fission-track dating
flatworms
  BT:  worms
  RT:  invertebrate zoology
  SN:  Soft flat worms of the phylum Platyhelminthes, which are often parasitic. Includes tapeworms and flukes.
  TNR: 395
flooding (controlled)
  USE: controlled flooding
flood preparedness
  US+: hazard preparedness
       floods
floods
  BT:  hydrologic processes
  NT:  storm surge
  RT:  controlled flooding
       hazards
       hydrology
       surface water (non-marine)
       watershed management
  UF:  bankfull stage
       flood preparedness
  SN:  Relatively high water that overflows the natural or artificial banks of a stream or coastal area that submerges land not normally below water level.
  TNR: 398
flood stage
  USE: streamflow
flora
  USE: plants (organisms)
flow cytometry
  BT:  chemical analysis
  RT:  biochemistry
       cell biology
  SN:  Laboratory technique to determine the amount of DNA in cells tagged by fluorescent dye by measuring the intensity of fluorescence under a laser beam.
  TNR: 400
flowering plants
  BT:  vascular plants
  RT:  botany
  SN:  Plants known as angiosperms which periodically produce flowers which have various parts including sepals, petals, stamens, and carpels.
  TNR: 401
fluid dynamics
  USE: hydrodynamics
fluid migration
  USE: ground-water flow
fluorine
  BT:  chemical elements
  RT:  halogen elements
  UF:  F
  SN:  Halogen element with symbol F and atomic number 9 <http://periodic.lanl.gov/elements/9.html>
  TNR: 1454
fluvial processes
  USE: streamflow
flyways
  US+: biogeography
       migration (organisms)
Fm
  USE: fermium
folding (geologic)
  BT:  deformation (geologic)
  RT:  structural geology
       tectonic processes
  UF:  crenulation (geologic)
  SN:  A property of geologic structures to bend or curve from the planar layers.
  TNR: 403
foliation (geologic)
  BT:  geologic structure
  RT:  glaciation
       structural geology
       tectonic processes
  SN:  The property of rocks or glaciers splitting into thin layers or plates due to the orientation of crystals and dynamic movement.
  TNR: 404
food chain
  USE: food web
food cycle
  USE: food web
food web
  BT:  nutrient cycling
  RT:  biochemistry
       ecology
  UF:  food chain
       food cycle
       trophic level dynamics
       trophic relationships
  SN:  The complex intertwining of the interrelated food chains in an ecosystem.
  TNR: 407
foraminifera
  USE: protists
foreign species
  USE: nonindigenous species
forest ecosystems
  BT:  terrestrial ecosystems
  RT:  ecology
       forest resources
  UF:  arboreal ecosystems
       coniferous forests ecosystems
       deciduous forest ecosystems
       mixed forest ecosystems
       taiga ecosystems
  SN:  Biological communities and habitats in geographic areas with dense growths of trees and associated vegetation.
  TNR: 410
forest resources
  BT:  natural resources
  RT:  botany
       ecology
       forest ecosystems
  UF:  forestry
  SN:  Trees and associated vegetation available for human use.  Use for timber and other forest resources with economic value.
  TNR: 411
forestry
  USE: forest resources
fossil fuels
  USE: energy resources
fossils
  BT:  rocks and deposits
  NT:  ichnofossils
  RT:  biostratigraphy
       micropaleontology
       paleontology
       trilobites
  UF:  index fossils
       microfossils
  SN:  Recognizable remains such as bones, shells, leaves, burrows, impressions, or tracks of past life on the earth.
  TNR: 414
Fr
  USE: francium
fractal geometric methods
  USE: mathematical modeling
fracture (geologic)
  BT:  deformation (geologic)
  NT:  faulting (geologic)
  RT:  structural geology
       tectonic processes
  UF:  cleavage (rock)
       jointing (geologic)
  SN:  Break in a geologic structure including cracks, joints, and faults.
  TNR: 415
francium
  BT:  chemical elements
  RT:  alkali metal elements
  UF:  Fr
  SN:  Alkali metal element with symbol Fr and atomic number 87 <http://periodic.lanl.gov/elements/87.html>
  TNR: 1457
free-air anomaly
  BT:  gravitational field (earth)
  TNR: 1674
Frequently Asked Questions (FAQs)
  USE: USGS customer support and user feedback
freshwater (ground)
  USE: ground water
freshwater (surface)
  USE: surface water (non-marine)
freshwater ecosystems
  BT:  aquatic ecosystems
  RT:  aquatic biology
       ecology
       ground water
       limnology
       surface water (non-marine)
  UF:  lake ecosystems
       pond ecosystems
       river ecosystems
       spring ecosystems
       stream ecosystems
  SN:  Biological communities and habitats that exist in lakes, rivers, ponds, and other bodies of water that are not salty.
  TNR: 419
fumarolic activity
  USE: volcanic gas emission
fungi
  BT:  organisms
  RT:  mycology
  SN:  Immobile organisms of the kingdom Fungi that lack chlorophyll and that obtain nutrients from other dead or living organisms. Fungi reproduce by spores and include yeasts, molds, smuts, and mushrooms.
  TNR: 420
Ga
  USE: gallium
gadolinium
  BT:  chemical elements
  RT:  lanthanide series elements
  UF:  Gd
  SN:  Rare earth (lanthanide series) element with symbol Gd and atomic number 64 <http://periodic.lanl.gov/elements/64.html>
  TNR: 1459
gage-height monitoring
  USE: stream-gage measurement
gage height
  USE: streamflow
gallium
  BT:  chemical elements
  RT:  metal elements
  UF:  Ga
  SN:  Metalloid element with symbol Ga and atomic number 31 <http://periodic.lanl.gov/elements/31.html>
  TNR: 1460
game management
  BT:  wildlife population management
  RT:  wildlife biology
  SN:  Scientific monitoring and control of hunted wildlife.
  TNR: 422
game species
  BT:  organism groupings (non-taxonomic)
  RT:  vertebrate zoology
       wildlife biology
  SN:  Species of wild animals that are hunted for food or sport.
  TNR: 423
gamma-ray logging
  BT:  borehole logging
  RT:  stratigraphy
  SN:  Recording of the measurements of natural gamma radiation emitted from the rocks in a borehole to study the subsurface structures.
  TNR: 424
gamma-ray spectrometric surveying
  USE: aeroradiometric surveying
gas chromatography
  BT:  chromatography
  RT:  biochemistry
       geochemistry
  SN:  Chromatographic technique used to separate or partition the components of a mixture.  Solid and liquid samples are vaporized and passed through a column containing a liquid that differentially absorbs the  molecules.
  TNR: 426
gas hydrate resources
  BT:  natural gas resources
  RT:  economic geology
  UF:  methane hydrate resources
  SN:  Deposits of a crystalline solid in which water molecules trap gas molecules, usually methane, in a cagelike structure known as a clathrate occurring in sediments overlain by cold deep water.
  TNR: 427
gazetteers
  BT:  catalogs and indexes
  RT:  geographic names
  SN:  Indexed collections of geographic names.
  TNR: 1720
Gd
  USE: gadolinium
Ge
  USE: germanium
gemology
  USE: mineralogy
gem resources
  BT:  nonmetallic mineral resources
  RT:  economic geology
       mineralogy
  SN:  Deposits of rare minerals prized for their color, durability, sparkle, and clarity when cut and polished and used as ornaments or jewelry.
  TNR: 429
gene flow
  USE: evolution
gene sequencing
  USE: DNA sequencing
genetic diversity
  BT:  biodiversity
  NT:  genotype
  UF:  conservation genetics
  SN:  Measure of the variety of genes within a population pool in a given area.
  TNR: 432
genetics
  BT:  life sciences
  RT:  DNA sequencing
       molecular biology
       polymerase chain reaction
  UF:  heredity
  SN:  Branch of biology that deals with heredity or the passing of traits in living organisms from one generation to the next.
  TNR: 433
genome
  USE: DNA sequencing
genotype
  BT:  genetic diversity
  SN:  Genetic characteristics of an individual organism.
  TNR: 1361
geochemical anomaly maps
  US+: geochemistry
       maps and atlases
geochemical processes
  BT:  biological and physical processes
  NT:  biodegradation
       ore formation
       oxidation and reduction
       reaction transport
       sorption
       carbon sequestration
  RT:  geochemistry
       soil formation
       biogeochemical cycling
  SN:  Processes affecting the amount, distribution, or structure of chemical elements in air, water, soil, rocks, and minerals.
  TNR: 435
geochemical surveys
  USE: chemical analysis
geochemistry
  BT:  earth sciences
  NT:  soil chemistry
       water chemistry
  RT:  atomic absorption analysis
       biogeochemical cycling
       carbon cycling
       carbon isotope analysis
       chemical analysis
       chromatography
       earth history
       gas chromatography
       geochemical processes
       isotopic analysis
       light stable isotope analysis
       liquid chromatography
       mass spectroscopy
       metamorphism (geological)
       neutron activation analysis
       oxygen isotope analysis
       particle-beam spectroscopy
       tritium analysis
  UF:  chemistry (Earth sciences)
       geochemical anomaly maps
  SN:  Study of the distribution of chemical elements and natural compounds on the earth and in the atmosphere and the chemical processes that affect the earth.
  TNR: 437
geochronology
  BT:  geology
  RT:  carbon-14 analysis
       fission-track dating
       radiometric dating
       rubidium-strontium analysis
       stratigraphy
       tree ring analysis
       uranium-lead analysis
       uranium-thorium analysis
  SN:  Study of the age of the earth by dating geological formations, rocks, and fossils.
  TNR: 438
geodata
  USE: geospatial datasets
geodesy
  BT:  geophysics
  RT:  geography
       land surveying
  SN:  Branch of science dealing with measuring the earth or large areas of the earth for making maps, determining the size and shape of the earth, and correlating gravitational, geological, and magnetic surveys of the earth.
  TNR: 440
geographic boundaries
  USE: administrative and political boundaries
geographic coordinate systems
  USE: map coordinate systems
geographic information sciences
  USE: geography
geographic information system (GIS) datasets
  USE: geospatial datasets
geographic information systems (GIS)
  BT:  information system design and development
  RT:  decision support methods
       geography
       geolocation measurement
       geospatial datasets
       GPS measurement
       information management methods
       information sciences
       map coordinate systems
  UF:  GIS
  SN:  Computer software that allows geospatially referenced data to be linked to geographic features. Use this term only for information that is about GIS and not for the use of GIS in applications and projects.
  TNR: 445
geographic names
  BT:  culture and demographics
  RT:  gazetteers
  SN:  Names by which cultural and geographic features are known.  Generally to be used for collections of names stored in gazetteers.
  TNR: 1719
geography
  BT:  earth sciences
  NT:  cartography
       paleogeography
  RT:  administrative and political boundaries
       aeromagnetic surveying
       aeroradiometric surveying
       altimetry measurement
       AVHRR
       bathymetry measurement
       cadastral and legal land descriptions
       culture and demographics
       geodesy
       geographic information systems (GIS)
       geolocation measurement
       GPS measurement
       hyperspectral imaging
       IFSAR
       image analysis
       infrared imaging
       land surface characteristics
       land surveying
       land use change
       LIDAR
       map coordinate systems
       microwave imaging
       multispectral imaging
       panchromatic imaging
       radar imaging
       remote sensing
       SLAR
       SMMR
       spatial analysis
       SSM/I
       thermal imaging
       topography
       topological analysis
       visible light imaging
  UF:  geographic information sciences
  SN:  Study of the earth's landforms, topography, and climate, the distribution of flora and fauna, and the distribution, culture, and activities of human populations.
  TNR: 447
geohistory
  USE: geologic history
geohydrology
  USE: hydrogeology
geolocation measurement
  BT:  field methods
  NT:  altimetry measurement
       bathymetry measurement
       GPS measurement
       land surveying
  RT:  geographic information systems (GIS)
       geography
  UF:  location measurement
       navigating
       orienteering
  SN:  Methods for establishing a geographic location on the surface of the earth.
  TNR: 450
geologic age
  USE: geologic time periods
geological oceanography
  USE: marine geology
geologic contacts
  BT:  stratigraphic sections
  NT:  unconformities
  RT:  stratigraphy
  UF:  contacts (geologic)
  SN:  Junctions of two different rock formations varying by type or age of rock, including faults, unconformities, and bedding planes.
  TNR: 452
geologic formations
  USE: bedrock geologic units
geologic hazards
  USE: hazards
geologic history
  BT:  earth characteristics
  NT:  biostratigraphy
       earth history
       lithostratigraphy
  RT:  geology
       paleontology
       paleoseismology
       stratigraphy
  UF:  chronostratigraphy
       geohistory
  SN:  Record (and inferred reconstruction) of the origin and development of the earth since its formation.
  TNR: 455
geologic maps
  US+: maps and atlases
       geology
geologic processes
  BT:  biological and physical processes
  NT:  diagenesis
       earthquakes
       erosion
       glaciation
       heat flow (earth)
       hydrothermal processes
       isostasy
       land subsidence
       liquefaction
       metamorphism (geological)
       sediment transport
       sedimentation
       tectonic processes
       volcanic activity
       earth tides
       deformation (geologic)
       soil formation
       magnetic storms
       mass wasting
  RT:  geology
       hydrology
       tsunamis
  UF:  lithification
  SN:  All types of processes involving geological structures.
  TNR: 451
geologic sections
  USE: stratigraphic sections
geologic structure
  BT:  earth characteristics
  NT:  foliation (geologic)
       lineation (geologic)
       structure contours
  RT:  earth structure
       stratigraphic sections
       structural geology
       deformation (geologic)
  SN:  General position of rocks in an area, and geometrical relationships among rocks.
  TNR: 459
geologic time
  USE: geologic time periods
geologic time periods
  BT:  time periods
  NT:  phanerozoic
       precambrian
  UF:  geologic age
       geologic time
  TNR: 1634
geologic time scales
  BT:  terminologies and classifications
  SN:  Named divisions of geologic time used to specify relationships among geologic units and structural features
  TNR: 1745
geologic units
  USE: stratigraphic sections
geology
  BT:  earth sciences
  NT:  economic geology
       geochronology
       geomorphology
       hydrogeology
       marine geology
       mineralogy
       petrology
       sedimentology
       stratigraphy
       structural geology
       volcanology
  RT:  drilling and coring
       earth history
       engineering geology
       geologic processes
       geologic history
       metamorphism (geological)
  UF:  geologic maps
       subsurface maps
  SN:  Study of the planet earth, its composition, structure, physical and chemical processes, and history since its origin.
  TNR: 464
geomagnetic field
  USE: magnetic field (earth)
geomagnetics
  USE: magnetic field (earth)
geomagnetic storms
  USE: magnetic storms
geomagnetism
  USE: magnetic field (earth)
geomorphology
  BT:  geology
  RT:  bathymetry
       erosion
       land subsidence
       land surface characteristics
       landslides
       topography
  UF:  speleology
  SN:  Branch of geology dealing with surface land features and the processes that create and change them.
  TNR: 468
geophysical maps
  US+: maps and atlases
       geophysics
geophysics
  BT:  earth sciences
  NT:  geodesy
       marine geophysics
       seismology
       tectonophysics
  RT:  borehole logging
       borehole temperature logging
       core (earth)
       Curie temperature analysis
       gravitational field (earth)
       heat flow (earth)
       inner core (earth)
       isostasy
       laboratory-induced magnetization analysis
       magnetic field (earth)
       magnetic hysteresis analysis
       magnetic susceptibility analysis
       mantle (earth)
       metamorphism (geological)
       natural remanent magnetization analysis
       outer core (earth)
       paleomagnetic analysis
  UF:  geophysical maps
  SN:  Branch of geology studying the physical characteristics and phenomena of the earth and its atmosphere.
  TNR: 470
geosciences
  USE: earth sciences
geospatial analysis
  BT:  spatial analysis
  RT:  image analysis
       topological analysis
  SN:  Detailed study of information such as measurements, counts, and computations as a function of geographical location.
  TNR: 472
geospatial data
  USE: geospatial datasets
geospatial datasets
  BT:  datasets
  RT:  geographic information systems (GIS)
       hydrographic datasets
       topography
  UF:  DLG
       GIS datasets
       cartographic data (digital)
       digital cartographic data
       digital cartographic datasets
       digital line graphs
       geodata
       geographic information system (GIS) datasets
       geospatial data
  SN:  Collections of related digital information that are geographically referenced.
  TNR: 474
geostatistics
  USE: statistical analysis
geotechnical properties maps
  US+: engineering geology
       maps and atlases
geothermal resources
  BT:  energy resources
  RT:  hydrogeology
       volcanology
  SN:  Energy resources related to the earth's internal heat, commonly applied to springs or vents discharging hot water or steam.
  TNR: 477
geothermics
  USE: heat flow (earth)
germanium
  BT:  chemical elements
  RT:  metal elements
  UF:  Ge
  SN:  Metalloid element with symbol Ge and atomic number 32 <http://periodic.lanl.gov/elements/32.html>
  TNR: 1463
GIS
  USE: geographic information systems (GIS)
GIS datasets
  USE: geospatial datasets
glacial geology
  USE: glaciology
glaciation
  BT:  geologic processes
  RT:  foliation (geologic)
       glaciology
       snow and ice cover
  SN:  The geologic processes involved in the formation, movement, changes, and effects of large ice masses (glaciers).
  TNR: 482
glaciers
  USE: snow and ice cover
glaciology
  BT:  earth sciences
  RT:  drilling and coring
       erosion
       glaciation
       isostasy
       snow and ice cover
  UF:  cryology
       glacial geology
  SN:  Science dealing with the features, origins, processes, and properties of snow, ice, glaciers, and ice sheets.
  TNR: 484
global change
  BT:  topics
  NT:  global warming
  RT:  atmospheric sciences
       climate change
       ecology
       ocean sciences
       sea-level change
  SN:  Changes in global environmental systems, including climate, land, oceans, fresh water, atmosphere and ecology throughout earth's history.
  TNR: 485
global climate change
  USE: climate change
global positioning measurement
  USE: GPS measurement
global warming
  BT:  global change
  RT:  atmospheric sciences
       climate change
       ecology
       ocean sciences
  SN:  Increase in the average temperature of the earth's surface, often used to refer to the warming predicted as a result of anthropogenic emissions of greenhouse gases.
  TNR: 488
glossaries
  USE: terminologies and classifications
gold
  BT:  chemical elements
  RT:  metal elements
  UF:  Au
  SN:  Metal element with symbol Au and atomic number 79 <http://periodic.lanl.gov/elements/79.html>
  TNR: 1464
gold ores
  BT:  metallic ores
  RT:  economic geology
       mineralogy
  SN:  Mineral deposits from which gold, a heavy, yellow, malleable metal, valuable as ornaments, jewelry, or coinage, can be extracted.
  TNR: 490
governmental units
  USE: administrative and political boundaries
GPS measurement
  BT:  geolocation measurement
  RT:  geographic information systems (GIS)
       geography
  UF:  global positioning measurement
  SN:  Determination of distance and location using instruments receiving signals from the Global Positioning System, a system of satellites for identifying earth locations.
  TNR: 492
grain-size analysis
  BT:  laboratory methods
  NT:  sieve-size analysis
  RT:  sedimentology
  UF:  grainsize analysis
       granulometry
       particle-size analysis
  SN:  Method of studying soils, sediments, sands, or rock by determining the size, distribution, and proportion of selected particles.
  TNR: 493
grainsize analysis
  USE: grain-size analysis
grants (USGS)
  USE: USGS contracts and grants
granulometry
  USE: grain-size analysis
grasses
  USE: vegetation
grassland ecosystems
  BT:  terrestrial ecosystems
  RT:  ecology
  UF:  mixed grass ecosystems
       plains ecosystems
       prairie ecosystems
       short grass ecosystems
       tall grass ecosystems
  SN:  Biological communities and habitats with ground cover of grasses and other herbaceous plants, but few trees.  Examples include prairies, meadows, and savannas.
  TNR: 499
gravel deposits
  BT:  unconsolidated deposits
  RT:  economic geology
       nonmetallic mineral resources
       sedimentology
  SN:  Alluvial accumulations of small unconsolidated rock fragments, such as pebbles and cobbles, used in construction as fill, ground cover, or aggregate for concrete.
  TNR: 500
gravimeter measurement
  BT:  field inventory and monitoring
  UF:  gravimetric methods
       gravimetry
  SN:  Use of a specialized instrument for measuring the earth's gravity at a given location.
  TNR: 1668
gravimetric methods
  USE: gravimeter measurement
gravimetry
  USE: gravimeter measurement
gravitational field (earth)
  BT:  earth characteristics
  NT:  isostatic anomaly
       free-air anomaly
       bouguer anomaly
  RT:  geophysics
  UF:  gravity anomaly maps
       gravity field
       gravity
  SN:  Region or space around earth's mass which exerts a force that mutually attracts other masses in proportion to the product of the two masses and the distance between them.
  TNR: 501
gravity
  USE: gravitational field (earth)
gravity anomaly maps
  US+: gravitational field (earth)
       maps and atlases
gravity field
  USE: gravitational field (earth)
gray water
  USE: wastewater use
greenhouse effect
  BT:  atmospheric and climatic processes
  RT:  greenhouse gases
  SN:  Local, regional, or global warming in the atmosphere due to the higher heat capacity of certain gases such as carbon dioxide, methane, and ozone.
  TNR: 1704
greenhouse gases
  BT:  atmospheric composition
  RT:  atmospheric sciences
       climate change
       ozone layer
       greenhouse effect
  SN:  Atmospheric gases, including carbon dioxide, fluorocarbons, methane, nitrous oxide, sulfur hexafluoride, ozone, and water vapor, that trap radiant (infrared) energy keeping the earth's surface warmer than it would otherwise be.
  TNR: 506
grey water
  USE: wastewater use
grid coordinate systems
  USE: map coordinate systems
grizzly bears
  USE: bears
ground-water
  USE: ground water
ground-water/surface-water interaction
  USE: ground-water and surface-water interaction
ground-water and surface-water interaction
  BT:  hydrologic processes
  UF:  aquifer-surface water interaction
       ground water/surface water interaction
       ground-water/surface-water interaction
       hyporheic zone processes
       surface water/ground water interaction
       surface-water/ground-water interaction
  SN:  Traditionally, management of water resources has focused on surface water or ground water as if they were separate entities. As development of land and water resources increases, it is apparent that development of either of these resources affects the quantity and quality of the other. Nearly all surface-water features (streams, lakes, reservoirs, wetlands, and estuaries) interact with ground water. These interactions take many forms. In many situations, surface-water bodies gain water and solutes from ground-water systems and in others the surface-water body is a source of ground-water recharge and causes changes in ground-water quality. As a result, withdrawal of water from streams can deplete ground water or conversely, pumpage of ground water can deplete water in streams, lakes, or wetlands. Pollution of surface water can cause degradation of ground-water quality and conversely pollution of ground water can degrade surface water.
  TNR: 1692
ground-water flow
  BT:  hydrologic processes
  RT:  ground water
       hydrogeology
       water cycle
       reaction transport
  UF:  fluid migration
       ground-water flow modeling
       ground-water movement
       groundwater flow
  SN:  Movement of subsurface water in the saturated zone from areas of recharge to areas of discharge.
  TNR: 514
ground-water flow modeling
  USE: ground-water flow
ground-water level
  BT:  ground water
  NT:  unsaturated zone
  RT:  surface-water level
  UF:  aquifer level
       potentiometric surface
       water table
  SN:  Depth in a well or aquifer at which ground water occurs.
  TNR: 1344
ground-water movement
  USE: ground-water flow
ground-water quality
  BT:  water quality
  RT:  ground water
       hydrology
       water chemistry
  UF:  groundwater quality
  SN:  Fitness of subsurface water for use based on its composition and properties.
  TNR: 518
ground motion
  USE: earthquake occurrences
ground motion maps
  US+: maps and atlases
       earthquake occurrences
ground transportation
  USE: transportation
groundwater
  USE: ground water
ground water
  BT:  water resources
  NT:  ground-water level
  RT:  freshwater ecosystems
       ground-water flow
       ground-water quality
       hydrogeology
  UF:  freshwater (ground)
       ground-water
       groundwater
       water subsurface
  SN:  All water that exists beneath the land surface, but more commonly applied to water in fully saturated soils and geologic formations.
  TNR: 513
ground water/surface water interaction
  USE: ground-water and surface-water interaction
groundwater flow
  USE: ground-water flow
groundwater flow modeling
  USE: mathematical modeling
groundwater geology
  USE: hydrogeology
groundwater quality
  USE: ground-water quality
guidebooks
  BT:  reports
  UF:  field trip guidebooks
  SN:  Books intended to direct and instruct travelers in a given area and often geared to special interests, such as observing local birds, understanding geological features, or locating endemic plants.
  TNR: 519
guidelines
  USE: reports
gymnosperms
  BT:  vascular plants
  RT:  botany
  SN:  Seed-bearing woody vascular plants, such as the conifers (pine, spruce, fir, etc.), whose seeds are not enclosed in an ovary or fruit, but are exposed.
  TNR: 521
H
  USE: hydrogen
H5N1
  USE: avian influenza
habitat alteration
  BT:  ecological processes
  NT:  fire damage
  RT:  ecology
  UF:  habitat destruction
       habitat fragmentation
  SN:  Natural or human-related changes in the environments where plants and animals live.
  TNR: 522
habitat destruction
  USE: habitat alteration
habitat fragmentation
  USE: habitat alteration
habitats
  BT:  population and community ecology
  RT:  ecosystems
  SN:  Parts of the physical environment where plants and animals live. Use in combination with terms from "organisms" and "organism groupings (informal)" to indicate the topic of a species or group of species' habitat.
  TNR: 525
hadean
  BT:  precambrian
  TNR: 1635
hafnium
  BT:  chemical elements
  RT:  metal elements
  UF:  Hf
  SN:  Metal element with symbol Hf and atomic number 72 <http://periodic.lanl.gov/elements/72.html>
  TNR: 1466
halogen elements
  BT:  chemical element groups
  RT:  fluorine
       chlorine
       bromine
       iodine
       astatine
  TNR: 1467
hand-held field spectroscopy
  USE: handheld field spectroscopy
handheld field spectroscopy
  BT:  field inventory and monitoring
  UF:  hand-held field spectroscopy
  SN:  Use of portable equipment to measure spectral reflectance of materials in the field.
  TNR: 527
hardness (water)
  USE: water hardness
harmful algal blooms
  US+: hazards
       algal blooms
hassium
  BT:  chemical elements
  RT:  metal elements
  UF:  Hs
  SN:  Metal element with symbol Hs and atomic number 108 <http://periodic.lanl.gov/elements/108.html>
  TNR: 1468
hazard mitigation
  USE: hazard preparedness
hazard preparedness
  BT:  management methods
  NT:  earthquake preparedness
       aviation safety
  UF:  early warning systems
       emergency response planning
       fire preparedness
       flood preparedness
       hazard mitigation
       landslide preparedness
       tsunami preparedness
  SN:  Awareness of the consequences of hazards and actions to be taken before, during, or after hazards occur or are encountered.
  TNR: 530
hazards
  BT:  topics
  RT:  scour
       algal blooms
       desertification
       droughts
       earthquakes
       ecotoxicology
       fires
       floods
       human impacts
       landslides
       liquefaction
       mining hazards
       contamination and pollution
       social sciences
       storms
       tsunamis
       volcanic activity
       impact cratering
       magnetic storms
  UF:  catastrophes
       disasters
       earthquake hazards
       emergency management resources
       environmental hazards
       geologic hazards
       harmful algal blooms
  SN:  Potential dangers from both natural processes (e.g., earthquakes, floods, and climate change) and human impacts on the environment.
  TNR: 531
He
  USE: helium
health (human)
  USE: environmental health (human)
health and disease
  BT:  topics
  NT:  disease vectors
       environmental health (human)
       avian influenza
  RT:  bacteriology
       endocrinology
       histology
       immunology
       life sciences
       parasitology
       pathology
       social sciences
  UF:  disease
       nutrition
  SN:  Normal and abnormal conditions of plant and animal bodies.  Covers both human and non-human health and disease topics. For human health and disease, use the narrower term 'environmental health (human)'.
  TNR: 533
heat flow (earth)
  BT:  geologic processes
  RT:  geophysics
  UF:  geothermics
       heatflow (earth)
  SN:  Energy transferred by a difference in temperature through the surface of the earth.
  TNR: 534
heatflow (earth)
  USE: heat flow (earth)
helium
  BT:  chemical elements
  RT:  noble gas elements
  UF:  He
  SN:  Noble gas element with symbol He and atomic number 2 <http://periodic.lanl.gov/elements/2.html>
  TNR: 1470
herbicide contamination
  USE: pesticide and herbicide contamination
herbivores
  BT:  consumers (organisms)
  RT:  ecology
       zoology
  SN:  Animals that eat chiefly plants or their products, such as seeds, nectar, and fruit.
  TNR: 537
heredity
  USE: genetics
herpetology
  BT:  vertebrate zoology
  RT:  amphibians
       reptiles
  SN:  Branch of zoology concerned with the study of reptiles and amphibians.
  TNR: 539
Hf
  USE: hafnium
Hg
  USE: mercury
high-pressure liquid chromatography
  USE: liquid chromatography
hiking
  USE: recreation
histology
  BT:  anatomy and physiology
  RT:  health and disease
  SN:  Branch of anatomy concerned with the microscopic structure of plant and animal tissue.
  TNR: 540
Ho
  USE: holmium
holmium
  BT:  chemical elements
  RT:  lanthanide series elements
  UF:  Ho
  SN:  Rare earth (lanthanide series) element with symbol Ho and atomic number 67 <http://periodic.lanl.gov/elements/67.html>
  TNR: 1474
holocene
  BT:  quaternary
  TNR: 1636
horizontal datums
  USE: map coordinate systems
horseshoe crabs
  BT:  arthropods
  RT:  invertebrate zoology
  SN:  Marine arthropods, usually classed as Merostomata, which have a broad crescent (horseshoe-shaped) cephalothorax.
  TNR: 543
horticulture
  USE: agriculture
HPAI
  USE: avian influenza
HPLC
  USE: liquid chromatography
Hs
  USE: hassium
human disease
  USE: environmental health (human)
human environmental safety
  BT:  environmental health (human)
  RT:  social sciences
  UF:  safety issues (human)
  SN:  Monitoring and managing potentially harmful factors in the environment for human safety.
  TNR: 546
human health
  USE: environmental health (human)
human impacts
  BT:  topics
  NT:  deforestation
       land use change
       mining hazards
       overfishing
       overgrazing
       abandoned mines and quarries
       waste treatment and disposal
       dredging
  RT:  acid deposition
       ecology
       ecotoxicology
       environmental health (human)
       fires
       hazards
       invasive species
       land subsidence
       social sciences
       contamination and pollution
  SN:  The effects, intentional or unintentional, beneficial or harmful, direct or indirect, which human activities have upon the environment and living things.
  TNR: 548
hunting
  USE: recreation
hurricanes
  BT:  storms
  RT:  meteorology
  UF:  typhoons
  SN:  Severe cyclones, or revolving storms, originating over the equatorial regions of the earth, accompanied by torrential rain, lightning, and winds with a speed greater than 74 miles per hour.
  TNR: 549
hydraulic engineering
  BT:  engineering sciences
  RT:  agricultural water use
       commercial water use
       domestic water use
       industrial water use
       instream water use
       irrigation
       mining water use
       offstream water use
       power generation water use
       wastewater use
       water use
       water resource management
       dredging
  UF:  hydraulic models
       hydraulics
  SN:  Branch of engineering which applies the physical properties of fluids, such as flow and pressure, to the design and use of machinery, pumps, pipelines, etc.
  TNR: 550
hydraulic models
  USE: hydraulic engineering
hydraulics
  USE: hydraulic engineering
hydroacoustics
  USE: acoustic doppler current profiling
hydrodynamics
  BT:  hydrology
  UF:  fluid dynamics
  SN:  Principles of fluid dynamics applied to water bodies.
  TNR: 1678
hydroelectric power generation water use
  USE: power generation water use
hydrogen
  BT:  chemical elements
  RT:  alkali metal elements
  UF:  H
  SN:  Alkali metal element with symbol H and atomic number 1 <http://periodic.lanl.gov/elements/1.html>
  TNR: 1476
hydrogeology
  BT:  geology
  RT:  geothermal resources
       ground water
       ground-water flow
       hydrothermal processes
       water resources
       hydrology
  UF:  geohydrology
       groundwater geology
       hydrographic sections
  SN:  Study of subsurface waters and geologic aspects of surface waters.
  TNR: 554
hydrographic datasets
  BT:  datasets
  RT:  geospatial datasets
  SN:  Datasets for graphs showing variation of water elevation, velocity, streamflow, or other property of water with respect to time.
  TNR: 555
hydrographic sections
  USE: hydrogeology
hydrologic cycle
  USE: water cycle
hydrologic maps
  US+: hydrology
       maps and atlases
hydrologic processes
  BT:  biological and physical processes
  NT:  runoff
       water cycle
       floods
       ground-water flow
       streamflow
       water circulation
       percolation
       saltwater intrusion
       scour
       ground-water and surface-water interaction
  RT:  precipitation (atmospheric)
  TNR: 1667
hydrology
  BT:  earth sciences
  NT:  hydrodynamics
  RT:  agricultural water use
       commercial water use
       domestic water use
       erosion
       floods
       geologic processes
       ground-water quality
       hydrothermal processes
       industrial water use
       instream water use
       irrigation
       limnology
       marine water quality
       meteorology
       mining water use
       nutrient content (water)
       ocean sciences
       offstream water use
       oxygen content (water)
       power generation water use
       precipitation (atmospheric)
       stream discharge
       river reaches
       river systems
       salinity
       sediment transport
       streamflow
       stream-gage measurement
       surface water (non-marine)
       surface water quality
       suspended material (water)
       wastewater use
       water circulation
       water hardness
       water pH
       water properties
       water quality
       water resources
       water sampling
       water temperature
       water use
       wetland functions
       hydrogeology
  UF:  hydrologic maps
  SN:  Branch of earth science that deals with water as it occurs in the atmosphere, on the surface of the ground, and underground.
  TNR: 560
hydrophytes
  USE: aquatic vegetation
hydrosphere
  USE: water resources
hydrothermal processes
  BT:  geologic processes
  RT:  hydrogeology
       hydrology
  SN:  Natural phenomena relating to heated water generated by igneous activity.
  TNR: 562
hyperspectral imaging
  BT:  remote sensing
  RT:  geography
  SN:  Multispectral imaging technique that records many bands of imagery at very narrow bandwidths.
  TNR: 563
hyporheic zone processes
  USE: ground-water and surface-water interaction
hypoxia
  USE: oxygen content (water)
hysteresis
  USE: magnetic hysteresis analysis
I
  USE: iodine
ice
  USE: snow and ice cover
ice age
  USE: pleistocene
ice core sampling
  US+: drilling and coring
       snow and ice cover
ice storms
  BT:  storms
  SN:  Storms in which falling snow or rain freezes on contact with surfaces on the ground.
  TNR: 568
ichnofossils
  BT:  fossils
  RT:  biostratigraphy
       paleontology
  UF:  trace fossils
  SN:  Fossilized remains of the traces of animal activity from different geologic time periods including burrows, tracks, trails, borings, and other features found in sedimentary structures.
  TNR: 569
ichthyology
  BT:  vertebrate zoology
  RT:  commercial fishery resources
       fish
       fishery resources
       inland fishery resources
       marine fishery resources
       overfishing
       recreational fishery resources
  SN:  Branch of zoology concerned with the study of fish.
  TNR: 570
ICP-AES
  USE: atomic emission spectroscopy
IFSAR
  BT:  remote sensing
  RT:  geography
  UF:  Interferometric Synthetic Aperture Radar (IFSAR)
       SAR interferometry
       InSAR
  SN:  Interferometric comparison of radar reflectance imagery of the same area at different times to determine changes in the land surface, typically from a space-borne sensor.
  TNR: 571
igneous rocks
  BT:  rocks and deposits
  NT:  volcanic rocks
       Plutonic rocks
  RT:  petrology
  SN:  Rocks formed from melted rock that has cooled and solidified.
  TNR: 572
image analysis
  BT:  computational methods
  RT:  geography
       geospatial analysis
       spatial analysis
  SN:  Pattern analysis of the shapes and textures of images to identify features and derive information about them.
  TNR: 574
image collections
  BT:  product types
  UF:  aerial photos
       air photos
       orthoimagery
       orthophotographs
       AVHRR images
       LIDAR images
       Landsat images
       aerial photographs
       photographs
       pictures
       scientists-at-work photographs
       remote-sensing data
       remote-sensing images
       satellite images
  SN:  Visible representations of objects produced by optical or spectral instruments or cameras.
  TNR: 575
immunology
  BT:  anatomy and physiology
  RT:  health and disease
  SN:  Branch of biology which studies the body's production of lymphocytes, antibodies, and macrophages in response to foreign substances or pathogenic organisms.
  TNR: 576
impact cratering
  BT:  biological and physical processes
  RT:  hazards
       planetary bodies
  UF:  bolide impact
       meteor impact
       comet impact
       asteroid impact
  SN:  Impact of extraterrestrial objects such as asteroids, comets, and meteorites on Earth.
  TNR: 1718
impoundment
  USE: water resource management
In
  USE: indium
in-stream water use
  USE: instream water use
indexes
  USE: catalogs and indexes
index fossils
  USE: fossils
indicator species observation
  USE: ecosystem monitoring
indigenous species
  USE: native species
indium
  BT:  chemical elements
  RT:  metal elements
  UF:  In
  SN:  Metalloid element with symbol In and atomic number 49 <http://periodic.lanl.gov/elements/49.html>
  TNR: 1479
inductively coupled plasma-atomic emission spectrometry
  USE: atomic emission spectroscopy
industrial minerals
  USE: mineral resources
industrial pollution
  BT:  contamination and pollution
  NT:  mine drainage
  RT:  abandoned mines and quarries
  UF:  polychlorinated biphenyls
       PCBs
  SN:  Introduction of harmful substances into the environment by manufacturing, power generation, mining, or material processing.
  TNR: 1723
industrial water use
  BT:  offstream water use
  RT:  hydraulic engineering
       hydrology
  SN:  Use of water for industrial purposes such as fabrication, processing, washing, and cooling, and including such industries as steel, chemical and allied products, paper and allied products, mining, and petroleum refining.
  TNR: 581
inert gases
  USE: noble gas elements
infiltration (water)
  USE: percolation
informal education (USGS)
  USE: USGS lifelong learning programs
information centers (USGS)
  USE: USGS information services
information management methods
  BT:  management methods
  RT:  geographic information systems (GIS)
  UF:  data management
  SN:  Activities focused on scientific information creation, description, storage, and retrieval for evaluation and analysis.
  TNR: 584
information sciences
  BT:  sciences
  NT:  biological informatics
       computer science
  RT:  geographic information systems (GIS)
       information system design and development
       metadata development
       scientific careers
  SN:  Sciences dealing with the compilation, processing, classification, display, transmission, storage, and retrieval of recorded knowledge.
  TNR: 585
information services (USGS)
  USE: USGS information services
information system design and development
  BT:  topics
  NT:  geographic information systems (GIS)
       metadata development
  RT:  information sciences
  SN:  Use for the design and development of information systems.  Do not use for general cases in which information systems are part of the activity.
  TNR: 587
infrared imaging
  BT:  remote sensing
  NT:  AVHRR
       AVIRIS
  RT:  geography
  SN:  Method of remote sensing in which optical sensors produce visible representations of infrared rays or radiated heat from the observed objects and the temperature variations are represented by different colors in the image.
  TNR: 588
inland fishery resources
  BT:  fishery resources
  RT:  aquatic biology
       ichthyology
  SN:  Stocks of fish available to be taken in lakes, streams, ponds, rivers, and other inland bodies of water.
  TNR: 589
inner core (earth)
  BT:  core (earth)
  RT:  geophysics
  SN:  The solid interior part of the earth's core, presumed to be composed principally of iron with an alloy of about 10 percent oxygen, sulfur, or nickel, or perhaps some combination of these three elements.  The inner core is about 1221 kilometers thick.
  TNR: 590
InSAR
  USE: IFSAR
insecticide contamination
  USE: pesticide and herbicide contamination
insects
  BT:  arthropods
  NT:  butterflies and moths
       bees and wasps
  RT:  entomology
  UF:  bugs
  SN:  Small arthropod animals of the class Insecta with bodies in 3 segments (head, thorax, and abdomen). They have 3 pairs of legs, 2 antennae, and usually one or two pairs of wings. Includes flies, mosquitoes, beetles, butterflies, bees, crickets, and dragonflies.
  TNR: 591
instream water use
  BT:  water use
  NT:  power generation water use
       wastewater use
  RT:  hydraulic engineering
       hydrology
  UF:  in-stream water use
  SN:  Water that is used, but not withdrawn, from a surface-water or groundwater source for such purposes as hydroelectric power generation, navigation, water-quality improvement, fish propagation, and recreation.  Sometimes called nonwithdrawal use or in-channel use.
  TNR: 592
instrument design and development
  BT:  topics
  RT:  engineering sciences
  UF:  tool development
  SN:  Includes the design and development of software for a particular instrument.
  TNR: 594
insular ecology
  USE: island ecosystems
interactive map servers (USGS)
  USE: USGS map servers
interagency programs (USGS)
  USE: USGS interagency programs
Interferometric Synthetic Aperture Radar (IFSAR)
  USE: IFSAR
international programs (USGS)
  USE: USGS international programs
internships (USGS)
  USE: USGS internships
interstices
  USE: porosity
introduced species
  USE: nonindigenous species
intrusive rocks
  USE: Plutonic rocks
invader species
  USE: invasive species
invasive species
  BT:  nonindigenous species
  RT:  biodiversity
       ecology
       human impacts
       life sciences
  UF:  biological invasions
       invader species
  SN:  Plant, animal, or microbe species that is non-native (or alien) to the ecosystem under consideration and whose introduction causes or is likely to cause economic or environmental harm, or harm to human health.
  TNR: 602
inventory
  USE: field inventory and monitoring
invertebrate paleontology
  BT:  paleontology
  RT:  bryozoans and brachiopods
       conodonts
       invertebrate zoology
       invertebrates
       trilobites
  SN:  Branch of paleontology which deals with fossil animals without backbones.
  TNR: 604
invertebrates
  BT:  animals
  NT:  arthropods
       bryozoans and brachiopods
       coelenterates
       conodonts
       echinoderms
       mollusks
       sponges
       worms
       tunicates
  RT:  invertebrate paleontology
       invertebrate zoology
  SN:  Animals having no backbone or spinal column, such as insects, mollusks, crustaceans, worms, and similar organisms.
  TNR: 606
invertebrate zoology
  BT:  zoology
  NT:  entomology
  RT:  arachnids
       arthropods
       bryozoans and brachiopods
       coelenterates
       crustaceans
       echinoderms
       flatworms
       horseshoe crabs
       invertebrate paleontology
       invertebrates
       mollusks
       ostracodes
       roundworms
       segmented worms
       shellfish
       sponges
       worms
  SN:  Branch of biology dealing with animals having no backbones or spinal columns.
  TNR: 605
iodine
  BT:  chemical elements
  RT:  halogen elements
  UF:  I
  SN:  Halogen element with symbol I and atomic number 53 <http://periodic.lanl.gov/elements/53.html>
  TNR: 1481
Ir
  USE: irridium
iron
  BT:  chemical elements
  RT:  metal elements
  UF:  Fe
  SN:  Metal element with symbol Fe and atomic number 26 <http://periodic.lanl.gov/elements/26.html>
  TNR: 1483
irridium
  BT:  chemical elements
  RT:  metal elements
  UF:  Ir
  SN:  Metal element with symbol Ir and atomic number 77 <http://periodic.lanl.gov/elements/77.html>
  TNR: 1484
irrigation
  BT:  agricultural water use
  RT:  hydraulic engineering
       hydrology
  SN:  Artificial application of water on lands to assist in the growing of crops and pastures or to maintain vegetative growth in recreational lands such as parks and golf courses.
  TNR: 607
island ecosystems
  BT:  terrestrial ecosystems
  UF:  insular ecology
  SN:  Communities of living organisms on islands.
  TNR: 1706
isostasy
  BT:  geologic processes
  RT:  geophysics
       glaciology
  SN:  Condition of equilibrium or buoyancy of the earth's crust above the mantle.
  TNR: 608
isostatic anomaly
  BT:  gravitational field (earth)
  TNR: 1673
isotopic analysis
  BT:  laboratory methods
  NT:  light stable isotope analysis
       radiometric dating
  RT:  biochemistry
       geochemistry
  SN:  Experimental determination of the proportion of a given isotope (or isotopes) in a sample.
  TNR: 609
isotopic tracer study
  USE: tracer study
jellyfish
  USE: coelenterates
jointing (geologic)
  USE: fracture (geologic)
journal articles
  USE: reports
journals
  USE: reports
jurassic
  BT:  mesozoic
  TNR: 1638
K
  USE: potassium
K-12 programs (USGS)
  USE: USGS K-12 programs
K-Ar dating
  USE: potassium-argon analysis
kayaking
  USE: recreation
keystone species
  BT:  organism groupings (non-taxonomic)
  SN:  Species whose abundance and ecological role has a dramatic effect on the other species in an ecosystem.
  TNR: 615
Kr
  USE: krypton
kriging
  BT:  statistical analysis
  SN:  Statistical analysis technique which uses interpolation to best predict unknown data values from data observed at known locations.
  TNR: 616
krypton
  BT:  chemical elements
  RT:  noble gas elements
  UF:  Kr
  SN:  Noble gas element with symbol Kr and atomic number 36 <http://periodic.lanl.gov/elements/36.html>
  TNR: 1487
La
  USE: lanthanum
laboratories (USGS)
  USE: USGS laboratories
laboratory-induced magnetization analysis
  BT:  paleomagnetic analysis
  RT:  geophysics
  SN:  Laboratory method to study rocks using magnetometers to measure remanent magnetic fields induced in the samples.
  TNR: 620
laboratory methods
  BT:  methods
  NT:  chemical analysis
       core analysis
       culturing (specimens)
       faunal and floral census (microscopic)
       grain-size analysis
       isotopic analysis
       meristics
       microscopy
       paleomagnetic analysis
       petrography
       plant and animal testing
       therapeutic methods
       tree ring analysis
       camera calibration
       age estimation methods
  SN:  Experimental techniques to analyze and test samples in a place equipped and designed for the work.
  TNR: 619
laboratory reference materials
  USE: materials standards
lahars
  BT:  landslides
  RT:  volcanic activity
  SN:  Downslope flow of ash and rock debris resulting from volcanic activity.
  TNR: 1362
lake circulation
  USE: water circulation
lake ecosystems
  USE: freshwater ecosystems
land partitioning systems
  USE: cadastral and legal land descriptions
Landsat images
  US+: image collections
       multispectral imaging
landscape
  USE: land surface characteristics
landslide maps
  US+: landslides
       maps and atlases
landslide preparedness
  US+: hazard preparedness
       landslides
landslides
  BT:  mass wasting
  NT:  lahars
  RT:  geomorphology
       hazards
       landslide susceptibility assessment
  UF:  avalanches
       debris avalanches
       debris flows
       landslide maps
       landslide preparedness
       mudflows
       rockfalls
       slides (land)
  SN:  Downslope movement of rock, soil, or artificial fill under the influences of gravity.
  TNR: 639
landslide susceptibility assessment
  BT:  risk assessment
  RT:  landslides
  UF:  landslide susceptibility maps
       slope stability
       slope stability maps
  SN:  Estimation of the probability of occurrence and likely severity of landslides in a given area.
  TNR: 637
landslide susceptibility maps
  US+: maps and atlases
       landslide susceptibility assessment
land subsidence
  BT:  geologic processes
  RT:  geomorphology
       human impacts
  UF:  land subsidence maps
  SN:  Settling, compaction, or caving in of land caused by subsurface mining, ground-water withdrawal, or pumping of oil and gas.
  TNR: 624
land subsidence maps
  US+: maps and atlases
       land subsidence
land surface characteristics
  BT:  earth characteristics
  RT:  geography
       geomorphology
       sea-floor characteristics
  UF:  landscape
       physiography
  SN:  Features and attributes of earth's land surface.
  TNR: 626
land surveying
  BT:  geolocation measurement
  RT:  geodesy
       geography
  UF:  surveying
  SN:  Determining property boundaries, land area, elevations, and locations of features on the surface of the land by calculations based on the instrumental measurements of angles and distances or by use of global positional satellites.
  TNR: 627
land use and land cover
  BT:  topics
  SN:  The vegetation, water, natural surface, and cultural features on the land surface.
  TNR: 628
land use change
  BT:  human impacts
  RT:  desertification
       ecology
       geography
       social sciences
  UF:  urbanization
  SN:  Effect of changing land use patterns on ecological systems.
  TNR: 629
land use maps
  USE: maps and atlases
La Nina
  USE: ocean-atmosphere interaction
lanthanide series elements
  BT:  rare earth elements
  RT:  lanthanum
       cerium
       praseodymium
       neodymium
       prometium
       samarium
       europium
       gadolinium
       terbium
       dysprosium
       holmium
       erbium
       thulium
       ytterbium
       lutetium
  TNR: 1489
lanthanum
  BT:  chemical elements
  RT:  lanthanide series elements
  UF:  La
  SN:  Rare earth (lanthanide series) element with symbol La and atomic number 57 <http://periodic.lanl.gov/elements/57.html>
  TNR: 1490
lava
  USE: volcanic rocks
lava flows
  USE: volcanic activity
lawrencium
  BT:  chemical elements
  RT:  actinide series elements
  UF:  Lr
  SN:  Rare earth (actinide series) element with symbol Lr and atomic number 103 <http://periodic.lanl.gov/elements/103.html>
  TNR: 1491
laws and regulations
  BT:  culture and demographics
  UF:  legal processes
       legislation
       statutes
  SN:  Legal statements of the government regarding actions people or corporations might undertake.
  TNR: 1684
leaching (analytical method)
  USE: chemical analysis
lead
  BT:  chemical elements
  RT:  metal elements
  UF:  Pb
  SN:  Metalloid element with symbol Pb and atomic number 82 <http://periodic.lanl.gov/elements/82.html>
  TNR: 1492
lead-210 dating
  USE: radiometric dating
legal land descriptions
  USE: cadastral and legal land descriptions
legal processes
  USE: laws and regulations
legislation
  USE: laws and regulations
lepidoptera
  USE: butterflies and moths
Li
  USE: lithium
libraries (USGS)
  USE: USGS libraries and archives
lichens
  BT:  organisms
  RT:  mycology
       phycology
  SN:  Plants that are composed of a fungus and an alga growing together symbiotically and often found growing on rocks or tree trunks.
  TNR: 647
LIDAR
  BT:  remote sensing
  RT:  geography
  UF:  LIDAR images
       LIght Detection and Ranging (LIDAR)
  SN:  LIDAR (LIght Detection and Ranging) is an airborne laser-ranging technique commonly used for acquiring high-resolution topographic data.
  TNR: 648
LIDAR images
  US+: image collections
       LIDAR
life-long learning programs (USGS)
  USE: USGS lifelong learning programs
life history
  USE: population and community ecology
lifelong learning programs (USGS)
  USE: USGS lifelong learning programs
life sciences
  BT:  sciences
  NT:  anatomy and physiology
       aquatic biology
       biochemistry
       botany
       cell biology
       developmental biology
       ecology
       ecotoxicology
       genetics
       marine biology
       microbiology
       molecular biology
       morphology (biological)
       mycology
       parasitology
       pathology
       systematics and taxonomy
       zoology
  RT:  biodiversity
       biological informatics
       biological productivity
       biota
       decomposers
       disease vectors
       dispersal (organisms)
       endangered species
       endemic species
       extinction and extirpation
       health and disease
       invasive species
       migration (organisms)
       native species
       natural resources
       nonindigenous species
       organism groupings (non-taxonomic)
       organisms
       paleontology
       plant and animal tagging
       scientific careers
       sexing (plants & animals)
  UF:  biological sciences
       biology
  SN:  Branches of science that study living and fossil organisms.
  TNR: 650
LIght Detection and Ranging (LIDAR)
  USE: LIDAR
light stable-isotope analysis
  USE: light stable isotope analysis
light stable isotope analysis
  BT:  isotopic analysis
  NT:  beryllium isotope analysis
       carbon isotope analysis
       oxygen isotope analysis
       tritium analysis
  RT:  biochemistry
       geochemistry
  UF:  light stable-isotope analysis
       stable isotope analysis
  SN:  Analytical technique using mass spectrometry to measure the different isotopic forms of low mass (light) elements such as oxygen, hydrogen, carbon, nitrogen and sulfur that occur in samples.
  TNR: 654
lignite resources
  USE: coal resources
limnology
  BT:  earth sciences
  RT:  aquatic ecosystems
       bathymetry
       benthic ecosystems
       CTD measurement
       eutrophication
       freshwater ecosystems
       hydrology
       surface water (non-marine)
       surface water quality
       water resources
  SN:  Scientific study of the physical and biological characteristics of inland bodies of water such as lakes and ponds.
  TNR: 657
lineaments
  USE: lineation (geologic)
lineation (geologic)
  BT:  geologic structure
  RT:  structural geology
       tectonic processes
  UF:  lineaments
  SN:  Linear topographic feature on the earth's surface or in rocks.
  TNR: 660
liquefaction
  BT:  geologic processes
  RT:  engineering geology
       hazards
  SN:  Physical process which can occur during an earthquake.  Clay-free soil deposits (primarily sands and silts)temporarily lose strength and behave as viscuous fluids, resulting in ground failure.
  TNR: 661
liquid chromatography
  BT:  chromatography
  RT:  biochemistry
       geochemistry
  UF:  HPLC
       high-pressure liquid chromatography
  SN:  Chromatographic technique to separate or partition the components of a mixture in which samples are liquid and passed through a column.
  TNR: 662
lists of publications
  USE: catalogs and indexes
lithification
  USE: geologic processes
lithium
  BT:  chemical elements
  RT:  alkali metal elements
  UF:  Li
  SN:  Alkali metal element with symbol Li and atomic number 3 <http://periodic.lanl.gov/elements/3.html>
  TNR: 1494
lithologic maps
  US+: maps and atlases
       rocks and deposits
lithology
  USE: rocks and deposits
lithosphere
  BT:  crust (earth)
  NT:  continental lithosphere
       oceanic lithosphere
  RT:  mantle (earth)
       rocks and deposits
       tectonophysics
  SN:  The solid outer zone of the earth comprising the crust and the upper layer of the mantle.
  TNR: 667
lithostratigraphy
  BT:  geologic history
  RT:  tephrochronology
       stratigraphy
  SN:  Branch of stratigraphy dealing with the study of units of rock. Each unit is composed of a body of rock which is dominated by a certain lithology or similar color, mineralogic composition, and grain size.
  TNR: 668
littoral ecosystems
  USE: coastal ecosystems
liverworts and hornworts
  BT:  nonvascular plants
  RT:  botany
       mosses
  SN:  Simple green land plants of the phyla Bryophyta with leaves and a stem and always without roots.
  TNR: 669
livestock husbandry
  USE: agriculture
livestock water use
  USE: agricultural water use
location measurement
  USE: geolocation measurement
loess
  USE: unconsolidated deposits
long-term ecological monitoring
  BT:  ecosystem monitoring
  RT:  ecology
  SN:  Data collection over a period of years or decades to assess changes in selected biological communities and habitats.
  TNR: 672
lower carboniferous
  USE: mississippian
Lr
  USE: lawrencium
Lu
  USE: lutetium
luminescence dating
  BT:  age estimation methods
  UF:  optically-stimulated luminescence dating
       thermoluminescence dating
       TL/OSL dating
  SN:  Dating methods that involve the analysis of the optical properties of minerals exposed to environmental radiation.  Typically used to determine the age of subaerial exposure of surficial sediments.
  TNR: 1677
lutetium
  BT:  chemical elements
  RT:  lanthanide series elements
  UF:  Lu
  SN:  Rare earth (lanthanide series) element with symbol Lu and atomic number 71 <http://periodic.lanl.gov/elements/71.html>
  TNR: 1497
macroinvertebrates
  BT:  organism groupings (non-taxonomic)
  RT:  aquatic biology
  SN:  Invertebrate animals large enough to be studied without a microscope.
  TNR: 673
magma
  USE: Plutonic rocks
magnesium
  BT:  chemical elements
  RT:  alkaline earth elements
  UF:  Mg
  SN:  Alkaline earth element with symbol Mg and atomic number 12 <http://periodic.lanl.gov/elements/12.html>
  TNR: 1498
magnetic anomaly maps
  US+: magnetic field (earth)
       maps and atlases
magnetic field
  USE: magnetic field (earth)
magnetic field (earth)
  BT:  earth characteristics
  RT:  geophysics
       magnetic storms
  UF:  geomagnetic field
       geomagnetics
       geomagnetism
       magnetic anomaly maps
       magnetic field
       magnetosphere
  SN:  The magnetic region surrounding earth.  It is generated by the dipolar characteristic of earth's core whereby earth itself acts as a great spherical magnet with poles near, but not exactly at, the North and South poles.
  TNR: 677
magnetic hysteresis analysis
  BT:  paleomagnetic analysis
  RT:  geophysics
  UF:  hysteresis
  SN:  Nondestructive evaluation of ferromagnetic materials.  The evaluation is based on measurement of the variation of intensity of magnetization within an applied magnetic field due to changes in the magnetic domain structure of the materials under study.
  TNR: 678
magnetic storms
  BT:  geologic processes
  RT:  hazards
       magnetic field (earth)
  UF:  geomagnetic storms
  SN:  A period of time during which the earth\'s magnetic field varies rapidly.  During magnetic storms, satellite electronics can be damaged through the build up and subsequent discharge of static electric charges and astronauts and high-altitude pilots can be subjected to increased levels of radiation.
  TNR: 1721
magnetic surveying
  US+: aeromagnetic surveying
       electromagnetic surveying
magnetic susceptibility
  BT:  magnetism
  SN:  Degree to which a rock type or other earth material can acquire and retain the orientation and intensity of an applied magnetic field.
  TNR: 1742
magnetic susceptibility analysis
  BT:  paleomagnetic analysis
  RT:  geophysics
  SN:  Nondestructive evaluation and location of magnetic materials in rock based on measuring the intensity of attraction of the materials to an induced magnetic field. Applications include geological and soil surveys, paleomagnetic studies, sedimentology, archaeological prospecting and core logging.
  TNR: 680
magnetism
  BT:  earth material properties
  NT:  remanent magnetism
       magnetic susceptibility
  SN:  Strength and orientation of the permanent magnetic field in a given sample of an earth material
  TNR: 1741
magnetometer measurement
  BT:  field inventory and monitoring
  UF:  magnetometry
  SN:  Use of specialized instruments designed to measure the earth's magnetic field at a given location.
  TNR: 1669
magnetometry
  USE: magnetometer measurement
magnetosphere
  USE: magnetic field (earth)
magnetotelluric sounding
  USE: electromagnetic surveying
malacology
  USE: zoology
mammalogy
  BT:  vertebrate zoology
  RT:  mammals
  SN:  Branch of zoology concerned with the study of mammals.
  TNR: 685
mammals
  BT:  vertebrates
  NT:  bears
       bats
  RT:  mammalogy
  SN:  Vertebrate animals, generally large, with skin covered by hair and large brain cavities.  Females have mammary glands for feeding the young, who are usually born quite mature.
  TNR: 686
managed fires
  USE: controlled fires
managed flooding
  USE: controlled flooding
management methods
  BT:  methods
  NT:  decision support methods
       environmental assessment
       hazard preparedness
       information management methods
       natural resource management
       risk assessment
  SN:  Techniques of judiciously controlling or directing resources for a predetermined goal.
  TNR: 689
manganese
  BT:  chemical elements
  RT:  metal elements
  UF:  Mn
  SN:  Metal element with symbol Mn and atomic number 25 <http://periodic.lanl.gov/elements/25.html>
  TNR: 1499
mangroves
  USE: aquatic vegetation
mantle (earth)
  BT:  earth structure
  NT:  asthenosphere
  RT:  geophysics
       lithosphere
  SN:  Zone of earth's interior between the crust and the core.  It is 2,900 kilometers (1,740 miles) thick and consists of a dense upper layer (upper mantle) and a partially molten lower layer (lower mantle), separated by a transition zone.
  TNR: 690
manuals
  BT:  reports
  UF:  technical instructions
       user guides
  SN:  Documents giving instructions on using specified equipment or accomplishing specified tasks.
  TNR: 691
map coordinate systems
  BT:  topics
  RT:  cartography
       geographic information systems (GIS)
       geography
  UF:  coordinate systems
       geographic coordinate systems
       grid coordinate systems
       horizontal datums
       map projections
       vertical datums
  SN:  Systems using sets of numbers combined with geometric nets or grids to specific positions on a map or globe.
  TNR: 692
mapmaking
  USE: cartography
map making
  USE: cartography
mapping
  USE: cartography
mapping centers (USGS)
  USE: USGS mapping centers
map projections
  USE: map coordinate systems
maps
  USE: maps and atlases
map sales (USGS)
  USE: USGS sales and distribution services
maps and atlases
  BT:  product types
  RT:  cartography
  UF:  cadastral maps
       earthquake activity maps
       ground motion maps
       seismic hazard maps
       shaking maps (seismic)
       earthquake epicenter maps
       engineering geology maps
       geotechnical properties maps
       rock mechanics maps
       subsurface maps
       geophysical maps
       land subsidence maps
       slope stability maps
       aeromagnetic maps
       atlases
       basement maps
       depth-to maps
       earthquake occurrence maps
       geochemical anomaly maps
       geologic maps
       gravity anomaly maps
       hydrologic maps
       land use maps
       landslide maps
       landslide susceptibility maps
       lithologic maps
       magnetic anomaly maps
       maps
       paleotectonic maps
       quadrangle maps
       relief maps
       seismic reflection survey maps
       species distribution maps
       surficial geologic maps
       tectonic maps
       thickness maps
       charts
       topographic maps
       seismicity maps
  SN:  Representation, usually on a flat surface, of a part or whole of the Earth or other parts of the universe.  Collections of maps linked digitally or bound together in a book are called atlases.
  TNR: 700
map servers (USGS)
  USE: USGS map servers
maps on demand (USGS)
  USE: USGS maps on demand
marine biology
  BT:  life sciences
  RT:  aquatic biology
       aquatic ecosystems
       benthic ecosystems
       commercial fishery resources
       fishery resources
       marine ecosystems
       marine fishery resources
       migratory species
       ocean sciences
       recreational fishery resources
       reef ecosystems
       whaling
  UF:  biological oceanography
  SN:  Branch of biology concerned with the organisms and habitats of the seas and oceans.
  TNR: 702
marine chemistry
  BT:  water chemistry
  RT:  CTD measurement
       marine water quality
       ocean characteristics
       ocean salinity
       ocean sciences
  UF:  chemical oceanography
       ocean chemistry
       water properties (marine)
  SN:  Branch of chemistry that deals with the properties, composition, structure, and interaction of substances in the seas and oceans.
  TNR: 703
marine ecosystems
  BT:  aquatic ecosystems
  NT:  reef ecosystems
  RT:  aquatic biology
       ecology
       marine biology
  SN:  Biological communities composed of plants and animals living primarily in or on seawater.
  TNR: 704
marine fishery resources
  BT:  fishery resources
  NT:  whaling
  RT:  aquatic biology
       commercial fishery resources
       ichthyology
       marine biology
       reef ecosystems
  UF:  coastal fisheries
       coastal fishing
       deep sea fisheries
       deep sea fishing
       reef fisheries
       reef fishing
  SN:  The stock of fisheries located in seas and oceans.
  TNR: 705
marine geology
  BT:  geology
  RT:  marine geophysics
       ocean sciences
       sea-floor characteristics
       side-scan sonar methods
  UF:  geological oceanography
  SN:  Branch of geology concerned with the composition, geologic history, and earth processes of the ocean floor and the continental margin.
  TNR: 706
marine geophysics
  BT:  geophysics
  RT:  marine geology
       ocean characteristics
       ocean processes
       ocean sciences
       side-scan sonar methods
  SN:  Branch of earth sciences concerned with the physical processes of the oceans and continental margins.
  TNR: 707
marine water quality
  BT:  water quality
  RT:  hydrology
       marine chemistry
       ocean sciences
  UF:  ocean water quality
  SN:  Observed intrinsic characteristics of marine waters affecting their ability to support life or facilitate biological processes such as waste decomposition.
  TNR: 708
marsh ecosystems
  USE: wetland ecosystems
marshland ecosystems
  USE: wetland ecosystems
mass spectrometry
  USE: mass spectroscopy
mass spectroscopy
  BT:  chemical analysis
  RT:  biochemistry
       geochemistry
  UF:  mass spectrometry
  SN:  Instrumental technique to separate and identify molecules.  Gaseous ions are formed, with or without fragmentation.  Their mass/charge ratios and relative electrical abundance are then measured or the spectra are recorded.
  TNR: 711
mass wasting
  BT:  geologic processes
  NT:  landslides
  UF:  slumps
       creep
  SN:  The down slope movement of earth material under the influence of gravity.
  TNR: 1736
materials standards
  BT:  product types
  UF:  laboratory reference materials
       standard reference samples
  SN:  Physical materials such as chemicals, rocks, water, or biological materials that are used for reference when carrying out laboratory analysis.
  TNR: 1729
mathematical methods
  USE: computational methods
mathematical modeling
  BT:  computational methods
  NT:  mathematical simulation
  RT:  spatial analysis
  UF:  fractal geometric methods
       groundwater flow modeling
       modeling (mathematical)
       numerical methods
       streamflow modeling
  SN:  Creating mathematical expressions to represent a simplified view of real-world systems.
  TNR: 713
mathematical simulation
  BT:  mathematical modeling
  SN:  A computer algorithm or model, which was created to represent a simplified version of a real world situation.
  TNR: 715
Md
  USE: mendelevium
media relations (USGS)
  USE: USGS media relations
meetings (USGS)
  USE: USGS meetings
meitnerium
  BT:  chemical elements
  RT:  metal elements
  UF:  Mt
  SN:  Metal element with symbol Mt and atomic number 109 <http://periodic.lanl.gov/elements/109.html>
  TNR: 1501
memos
  USE: reports
mendelevium
  BT:  chemical elements
  RT:  actinide series elements
  UF:  Md
  SN:  Rare earth (actinide series) element with symbol Md and atomic number 101 <http://periodic.lanl.gov/elements/101.html>
  TNR: 1502
mercury
  BT:  chemical elements
  RT:  metal elements
  UF:  Hg
  SN:  Metal element with symbol Hg and atomic number 80 <http://periodic.lanl.gov/elements/80.html>
  TNR: 1503
mercury contamination
  BT:  toxic trace element contamination
  RT:  biochemistry
       ecology
       ecotoxicology
  SN:  Biological disturbances caused by mercury compounds that have entered the environment.
  TNR: 720
meristics
  BT:  laboratory methods
  RT:  morphology (biological)
       systematics and taxonomy
  UF:  morphometrics
  SN:  Branch of zoology concerned with classifying animals by counting and measuring body parts.
  TNR: 721
mesozoic
  BT:  phanerozoic
  NT:  cretaceous
       jurassic
       triassic
  TNR: 1640
metadata
  USE: catalogs and indexes
metadata development
  BT:  information system design and development
  RT:  information sciences
  SN:  Use for the development of metadata schemes and applications.  Do not use for general cases where metadata are part of the activities.
  TNR: 723
metal elements
  BT:  chemical element groups
  RT:  scandium
       titanium
       vanadium
       chromium
       manganese
       iron
       cobalt
       nickel
       copper
       zinc
       yttrium
       zirconium
       niobium
       molybdenum
       technetium
       ruthenium
       rhodium
       palladium
       silver
       cadmium
       hafnium
       tantalum
       tungsten
       rhenium
       osmium
       irridium
       platinum
       gold
       mercury
       rutherfordium
       dubnium
       seaborgium
       bohrium
       hassium
       meitnerium
       darmstadtium
       ununnilium
       ununnunium
       ununnubium
       aluminum
       gallium
       germanium
       indium
       tin
       antimony
       thallium
       lead
       bismuth
       polonium
  TNR: 1504
metallic ores
  BT:  mineral resources
  NT:  gold ores
  RT:  economic geology
       mineralogy
       nonmetallic mineral resources
  UF:  ore deposits (metallic)
  SN:  Resources from which ductile, malleable, opaque,and reflective metals that are also good heat and electricity conductors can be extracted.
  TNR: 724
metallogeny
  USE: ore formation
metamorphic rocks
  BT:  rocks and deposits
  RT:  metamorphism (geological)
       petrology
  SN:  Sedimentary or igneous rocks which have undergone such intense changes in temperature, pressure, structural stress, or chemical environment that they are transformed into denser rocks.
  TNR: 725
metamorphism (biological)
  USE: metamorphosis
metamorphism (geological)
  BT:  geologic processes
  RT:  geochemistry
       geology
       geophysics
       metamorphic rocks
  SN:  Process by which rocks are altered in composition and texture by extreme heat, high pressure, or the action of chemicals.
  TNR: 727
metamorphosis
  BT:  organism growth and development
  UF:  metamorphism (biological)
  SN:  Transformation in animals, such as amphibians and insects, from one developmental stage to another.
  TNR: 726
meteor impact
  USE: impact cratering
meteorites
  BT:  planetary bodies
  RT:  rocks and deposits
  UF:  chondrites
       bolides
       meteors
  SN:  Masses of rock or metal from space that reach the earth's surface without burning up.  Use for 'meteors' or 'meteoroids' as well as 'meteorites'. USGS is more likely to have information about 'meteorites' since these are objects found on the earth.
  TNR: 730
meteorology
  BT:  atmospheric sciences
  RT:  atmospheric and climatic processes
       climatology
       hurricanes
       hydrology
       ocean currents
       ocean sciences
       planetary sciences
       storms
       tornadoes
  SN:  Branch of science dealing with the short-term variations of atmospheric conditions including wind, precipitation, temperature, humidity, cloud cover, and air pressure.
  TNR: 731
meteors
  USE: meteorites
methane hydrate resources
  USE: gas hydrate resources
methane resources (coalbed)
  USE: coalbed methane resources
methods
  BT:  Categories
  NT:  computational methods
       field methods
       laboratory methods
       management methods
       photography
       remote sensing
       videography
  SN:  Techniques, methods, procedures, or strategies for research, management, collection, or analysis of scientific information in USGS.
  TNR: 734
Mg
  USE: magnesium
microbes
  BT:  organism groupings (non-taxonomic)
  UF:  microorganisms
  SN:  Microscopic, typically one-celled organisms.
  TNR: 1707
microbiology
  BT:  life sciences
  NT:  bacteriology
       virology
  RT:  archaea
       bacteria
       culturing (specimens)
       faunal and floral census (microscopic)
       plankton
       producers (organisms)
       protists
  SN:  Branch of biology dealing with organisms too small to be seen without the use of a microscope.
  TNR: 735
microclimate
  USE: atmospheric and climatic processes
microfossils
  USE: fossils
microorganisms
  USE: microbes
micropaleontology
  BT:  paleontology
  RT:  calcareous nannoplankton
       conodonts
       diatoms
       dinoflagellates
       faunal and floral census (microscopic)
       fossils
       protists
  SN:  Branch of paleontology dealing with fossils too small to be seen without a microscope.
  TNR: 738
microscope methods
  USE: microscopy
microscopy
  BT:  laboratory methods
  NT:  electron microscopy
       optical microscopy
  RT:  faunal and floral census (microscopic)
  UF:  microscope methods
  SN:  Laboratory methods using instruments that employ optical lenses or radiation to study objects too small to be seen by the naked eye.
  TNR: 740
microtomy
  BT:  optical microscopy
  SN:  Laboratory methods using special instruments, or microtomes, to cut very thin slices of specimens for microscopic studies.
  TNR: 741
microwave imaging
  BT:  remote sensing
  NT:  SMMR
       SSM/I
  RT:  geography
       radar imaging
  SN:  Remote sensing method using short high frequency electromagnetic waves reflected or radiated from the ground.
  TNR: 742
migration (organisms)
  BT:  ecological processes
  RT:  animal behavior
       biogeography
       dispersal (organisms)
       ecology
       life sciences
       migratory species
  UF:  biological invasions
       flyways
       seasonal migration
  SN:  The movement of animals, often periodical, from one area to another due to seasonal changes, availability of food, or climatic conditions.
  TNR: 743
migratory species
  BT:  organism groupings (non-taxonomic)
  RT:  animal behavior
       aquatic biology
       biogeography
       ecology
       marine biology
       migration (organisms)
       zoology
  UF:  anadromous fish
       diadromous fish
  SN:  Species that have a pattern of moving from one geographical area to another, primarily according to the seasons, and usually traveling long distances along established routes.
  TNR: 744
mine drainage
  BT:  industrial pollution
  RT:  mining hazards
  SN:  Introduction of harmful substances into the environment from mines and tailings.
  TNR: 1724
mineralogical analysis
  USE: chemical analysis
mineralogy
  BT:  geology
  RT:  gem resources
       gold ores
       metallic ores
       mineral resources
       x-ray diffraction
  UF:  crystallography
       gemology
  SN:  Branch of earth sciences concerned with the study of naturally occurring inorganic elements or compounds.
  TNR: 747
mineral resources
  BT:  natural resources
  NT:  metallic ores
       nonmetallic mineral resources
  RT:  economic geology
       mineralogy
  UF:  industrial minerals
       minerals
  SN:  Natural occurrences of useful inorganic elements or compounds.
  TNR: 745
minerals
  USE: mineral resources
mining and quarrying
  BT:  natural resource extraction
  UF:  quarrying
  SN:  Extracting mineral deposits from a pit, tunnel, or excavation.
  TNR: 749
mining hazards
  BT:  human impacts
  RT:  engineering sciences
       hazards
       social sciences
       waste treatment and disposal
       mine drainage
  SN:  Dangerous conditions which result from the extraction of naturally occurring mineral deposits.  Includes tunnel collapses, fires, and explosions.
  TNR: 750
mining water use
  BT:  offstream water use
  RT:  hydraulic engineering
       hydrology
  SN:  Water use for the extraction of naturally occurring mineral deposits by mining or quarrying.
  TNR: 751
miocene
  BT:  neogene
  TNR: 1641
mississippian
  BT:  paleozoic
  UF:  lower carboniferous
  TNR: 1642
mites
  USE: arachnids
mitigation
  USE: remediation
mixed forest ecosystems
  USE: forest ecosystems
mixed grass ecosystems
  USE: grassland ecosystems
Mn
  USE: manganese
Mo
  USE: molybdenum
modeling (mathematical)
  USE: mathematical modeling
molecular biology
  BT:  life sciences
  RT:  cell biology
       genetics
       organism growth and development
  SN:  Branch of biology concerned with the study of physiology at the molecular level.
  TNR: 756
molluscs
  USE: mollusks
mollusks
  BT:  invertebrates
  RT:  invertebrate zoology
       shellfish
  UF:  molluscs
  SN:  Invertebrates belonging to the phylum Mollusca with soft, nonsegmented bodies, often covered by a hard shell.  Includes snails, clams, oysters, whelks, mussels, slugs, octopuses, and squids.
  TNR: 757
molybdenum
  BT:  chemical elements
  RT:  metal elements
  UF:  Mo
  SN:  Metal element with symbol Mo and atomic number 42 <http://periodic.lanl.gov/elements/42.html>
  TNR: 1509
morphology (biological)
  BT:  life sciences
  RT:  meristics
  SN:  The scientific study of the form, shape, and structure of plants and animals and their fossil remains.
  TNR: 758
morphometrics
  USE: meristics
mosses
  BT:  nonvascular plants
  RT:  botany
       liverworts and hornworts
  SN:  Simple green land plants, member of the phyla Bryophyta, along with liverworts and hornworts.  They have leaves and a stem, but always lack roots.
  TNR: 760
moths
  USE: butterflies and moths
Mt
  USE: meitnerium
mudflows
  USE: landslides
multispectral imaging
  BT:  remote sensing
  RT:  geography
  UF:  Landsat images
       thematic mapper
  SN:  A method of remote sensing that obtains optical representations in two or more ranges of frequencies or wave lengths.
  TNR: 765
multivariate statistical analysis
  BT:  statistical analysis
  SN:  Statistical study using a number of independent variables or measurements of the same attribute.
  TNR: 766
mutualism
  USE: symbiosis
mycology
  BT:  life sciences
  RT:  botany
       fungi
       lichens
  SN:  Branch of biology concerned with the study of fungi.
  TNR: 767
N
  USE: nitrogen
Na
  USE: sodium
native species
  BT:  organism groupings (non-taxonomic)
  NT:  endemic species
  RT:  biodiversity
       ecology
       life sciences
       nonindigenous species
  UF:  indigenous species
  SN:  Organisms originating in the area where they live.
  TNR: 768
natural attenuation (harmful chemicals)
  USE: biodegradation
natural contaminants
  USE: contamination and pollution
natural gas resources
  BT:  energy resources
  NT:  coalbed methane resources
       gas hydrate resources
  RT:  economic geology
  UF:  petroleum resources (gas)
  SN:  Stocks of naturally formed hydrocarbon gases which are usually associated with petroleum fields.  Useful for heating, they are principally methane, but can be ethane, butane, or propane.
  TNR: 770
natural remanent magnetism
  USE: remanent magnetism
natural remanent magnetization analysis
  BT:  paleomagnetic analysis
  RT:  geophysics
  UF:  natural remnant magnetization analysis
  SN:  Method which measures the intensity and direction of residual magnetism in rocks to determine their age and history.
  TNR: 771
natural remnant magnetization analysis
  USE: natural remanent magnetization analysis
natural resource assessment
  BT:  natural resource management
  UF:  resource assessment
  SN:  Estimation of the actual or potential value of natural materials and processes.
  TNR: 773
natural resource exploration
  BT:  topics
  UF:  dowsing
       exploration seismology
       exploration
       prospecting
       seismic exploration
  SN:  Techniques for locating deposits or stocks of useful minerals, water, and other resources using reconnaissance or instrumental methods.
  TNR: 774
natural resource extraction
  BT:  topics
  NT:  mining and quarrying
       well drilling
       placer deposit mining
  UF:  resource extraction
  SN:  Removal of natural materials or properties (such as heat) for use.
  TNR: 775
natural resource management
  BT:  management methods
  NT:  biological population management
       controlled flooding
       ecosystem management
       natural resource assessment
       remediation
       water resource management
       watershed management
       fire control
  RT:  ecosystem monitoring
       natural resources
       population and community ecology
  UF:  conservation
       environmental management
       environmental planning
       resource conservation
       resource restoration
  SN:  Using a combination of techniques to control or direct the use of resources and limit population size to reach a predetermined goal, such as sustainability.
  TNR: 776
natural resources
  BT:  topics
  NT:  mineral resources
       energy resources
       soil resources
       fishery resources
       forest resources
       water resources
  RT:  earth sciences
       life sciences
       natural resource management
  SN:  Stocks of anything naturally occurring that have a beneficial use for man including economic, nutritional, recreational, aesthetic, and other benefits.
  TNR: 777
navigating
  USE: geolocation measurement
Nb
  USE: niobium
Nd
  USE: neodymium
Ne
  USE: neon
nekton
  BT:  organism groupings (non-taxonomic)
  SN:  Free-swimming aquatic organisms able to move without depending on waves, currents, and tides.
  TNR: 779
nematodes
  USE: roundworms
neodymium
  BT:  chemical elements
  RT:  lanthanide series elements
  UF:  Nd
  SN:  Rare earth (lanthanide series) element with symbol Nd and atomic number 60 <http://periodic.lanl.gov/elements/60.html>
  TNR: 1516
neogene
  BT:  tertiary
  NT:  miocene
       pliocene
  TNR: 1643
neon
  BT:  chemical elements
  RT:  noble gas elements
  UF:  Ne
  SN:  Noble gas element with symbol Ne and atomic number 10 <http://periodic.lanl.gov/elements/10.html>
  TNR: 1517
Neoproterozoic
  BT:  proterozoic
  NT:  Ediacaran
  SN:  The latest geologic era of the Proterozoic Eon.
  TNR: 1734
neotectonic processes
  BT:  tectonic processes
  RT:  earthquake probabilities
       structural geology
       tectonophysics
  UF:  neotectonics
  SN:  Changes which took place during geological time after the Miocene era and are associated with the structural forces that affect the deformation, uplift, and movement occurring in the earth's crust.
  TNR: 781
neotectonics
  USE: neotectonic processes
neptunium
  BT:  chemical elements
  RT:  actinide series elements
  UF:  Np
  SN:  Rare earth (actinide series) element with symbol Np and atomic number 93 <http://periodic.lanl.gov/elements/93.html>
  TNR: 1518
neutron activation analysis
  BT:  chemical analysis
  RT:  biochemistry
       geochemistry
  SN:  Sensitive laboratory technique for both qualitative and quantitative analysis of elements in samples.  Target nuclei are bombarded with neutron beams to start nuclear reactions which emit characteristic gamma ray radiations.
  TNR: 783
new mapping projects (USGS)
  USE: USGS news
new projects (USGS)
  USE: USGS news
news (USGS)
  USE: USGS news
newsletters
  USE: reports
news releases
  BT:  official communications
  UF:  press releases
  SN:  Short information memoranda issued by organizations to highlight new activities, appointments, or discoveries for the news media.
  TNR: 787
Ni
  USE: nickel
nickel
  BT:  chemical elements
  RT:  metal elements
  UF:  Ni
  SN:  Metal element with symbol Ni and atomic number 28 <http://periodic.lanl.gov/elements/28.html>
  TNR: 1520
niobium
  BT:  chemical elements
  RT:  metal elements
  UF:  Nb
       columbium
  SN:  Metal element with symbol Nb and atomic number 41 <http://periodic.lanl.gov/elements/41.html>
  TNR: 1521
nitrogen
  BT:  chemical elements
  RT:  nonmetal elements
  UF:  N
  SN:  Nonmetal element with symbol N and atomic number 7 <http://periodic.lanl.gov/elements/7.html>
  TNR: 1522
nitrogen content
  USE: nutrient content (water)
No
  USE: nobelium
nobelium
  BT:  chemical elements
  RT:  actinide series elements
  UF:  No
  SN:  Rare earth (actinide series) element with symbol No and atomic number 102 <http://periodic.lanl.gov/elements/102.html>
  TNR: 1524
noble gas elements
  BT:  chemical element groups
  RT:  helium
       neon
       argon
       krypton
       xenon
       radon
  UF:  inert gases
  TNR: 1525
non-formal education (USGS)
  USE: USGS lifelong learning programs
non-indigenous species
  USE: nonindigenous species
non-native species
  USE: nonindigenous species
non-vascular plants
  USE: nonvascular plants
nonindigenous species
  BT:  organism groupings (non-taxonomic)
  NT:  invasive species
  RT:  biodiversity
       ecology
       life sciences
       native species
  UF:  alien species
       exotic species
       foreign species
       introduced species
       non-indigenous species
       non-native species
  SN:  Organisms accidentally or intentionally introduced into areas where they did not previously originate or live.
  TNR: 797
nonmetal elements
  BT:  chemical element groups
  RT:  boron
       carbon
       nitrogen
       oxygen
       silicon
       phosphorus
       sulfur
       arsenic
       selenium
       tellurium
  TNR: 1526
nonmetallic mineral resources
  BT:  mineral resources
  NT:  building stone resources
       gem resources
  RT:  clay deposits
       economic geology
       gravel deposits
       metallic ores
       sand deposits
  UF:  ore deposits (non-metallic)
  SN:  Useful mineral deposits that are not metals.  Includes materials used for construction, decoration, fuel, and other purposes.
  TNR: 798
nonpoint-source pollution
  BT:  contamination and pollution
  SN:  Contamination of the environment from sources spread widely across an area, not from a small number of identifiable locations.
  TNR: 1363
nonvascular plants
  BT:  plants (organisms)
  NT:  liverworts and hornworts
       mosses
  RT:  botany
  UF:  non-vascular plants
  SN:  Simple plants which lack conducting tissues known as vascular bundles, a group of specialized cells made up of xylem and phloem.
  TNR: 801
normalized burn ratio
  US+: fire damage
       remote sensing
Np
  USE: neptunium
nuclear magnetic resonance spectroscopy
  USE: chemical analysis
nuclear reactors (USGS)
  USE: USGS nuclear reactors
nuclear waste repositories
  USE: waste treatment and disposal
nuisance species
  BT:  organism groupings (non-taxonomic)
  SN:  Organisms whose presence or behavior has undesirable effects on human activities.
  TNR: 1728
numerical methods
  USE: mathematical modeling
nutrient balance
  USE: nutrient cycling
nutrient content (water)
  BT:  water properties
  RT:  hydrology
       nutrient cycling
       water chemistry
  UF:  nitrogen content
       phosphorus content
  SN:  Contaminants in water that nourish organisms, especially plants. Includes nitrogen and phosphorus, either of which can lead to the harmful growth of algae and other plants when present to excess in a body of water.
  TNR: 806
nutrient cycling
  BT:  biogeochemical cycling
  NT:  food web
  RT:  biochemistry
       ecology
       nutrient content (water)
  UF:  nutrient balance
  SN:  The exchange of elements or compounds essential for the nourishment of organisms in an ecosystem.
  TNR: 807
nutrition
  USE: health and disease
O
  USE: oxygen
observatories (USGS)
  USE: USGS observatories
ocean-atmosphere interaction
  BT:  atmospheric and climatic processes
  RT:  atmospheric sciences
       ocean processes
       ocean sciences
  UF:  El Nino
       La Nina
  SN:  Processes, including momentum, heat, gas and other exchanges, which result in profound effects on climate and interactions between the air in the lowest part of the atmosphere and the oceans.
  TNR: 823
ocean bottom characteristics
  USE: sea-floor characteristics
ocean characteristics
  BT:  earth characteristics
  NT:  ocean salinity
       ocean temperature
       sea-floor characteristics
       sea-level change
  RT:  marine chemistry
       marine geophysics
       ocean processes
       ocean sciences
       oceanic lithosphere
       surface water (non-marine)
       water resources
       sea ice concentration
  UF:  ocean monitoring
       oceans
  SN:  The attributes and process of seas and oceans.
  TNR: 810
ocean chemistry
  USE: marine chemistry
ocean circulation
  BT:  ocean processes
  RT:  climatology
       ocean currents
       ocean sciences
       tides (oceanic)
       water circulation
  UF:  circulation (ocean)
  SN:  Movement of large masses of water within an ocean.
  TNR: 812
ocean current measurement
  US+: field inventory and monitoring
       ocean currents
ocean currents
  BT:  ocean processes
  RT:  meteorology
       ocean circulation
       ocean sciences
       tides (oceanic)
  UF:  ocean current measurement
  SN:  Recurrent strong flows of seawater generated by wind or variations in water density along a given path.
  TNR: 814
oceanic lithosphere
  BT:  lithosphere
  RT:  ocean characteristics
       sea-floor characteristics
       tectonophysics
  SN:  The solid outer zone of the earth, covered by seawater, and comprised of the crust and the upper layer of the mantle.
  TNR: 824
ocean monitoring
  US+: field inventory and monitoring
       ocean characteristics
oceanography
  USE: ocean sciences
ocean processes
  BT:  biological and physical processes
  NT:  ocean circulation
       ocean currents
       ocean waves
       tides (oceanic)
  RT:  marine geophysics
       ocean characteristics
       ocean sciences
       ocean-atmosphere interaction
       surface water (non-marine)
  UF:  oceans
  SN:  Recurrent natural changes that are physical, biological, or chemical, actively affecting the seas and oceans.
  TNR: 816
oceans
  US+: ocean processes
       ocean characteristics
ocean salinity
  BT:  ocean characteristics
  RT:  marine chemistry
       ocean sciences
       salinity
  SN:  Measure of the percentage of dissolved salts in seawater.
  TNR: 817
ocean sciences
  BT:  earth sciences
  NT:  paleoceanography
  RT:  bathymetry
       CTD measurement
       global change
       global warming
       hydrology
       marine biology
       marine chemistry
       marine geology
       marine geophysics
       marine water quality
       meteorology
       ocean characteristics
       ocean circulation
       ocean currents
       ocean processes
       ocean salinity
       ocean temperature
       ocean waves
       ocean-atmosphere interaction
       sea-floor characteristics
       sea-level change
       tides (oceanic)
       tsunamis
       underwater photography
  UF:  oceanography
       physical oceanography
  SN:  Sciences involved in the study of geological, biological, chemical, and physical characteristics and processes of the oceans.
  TNR: 818
ocean temperature
  BT:  ocean characteristics
  NT:  sea surface temperature
  RT:  atmospheric sciences
       ocean sciences
  UF:  temperature (ocean)
  SN:  Distribution of heat in the oceans, including surface water, thermocline and mode waters, and deep waters.  Includes discussion and measures of both in-situ and potential temperature.
  TNR: 819
ocean tides
  USE: tides (oceanic)
ocean water quality
  USE: marine water quality
ocean wave measurement
  US+: ocean waves
       field inventory and monitoring
ocean waves
  BT:  ocean processes
  NT:  tsunamis
  RT:  ocean sciences
  UF:  ocean wave measurement
       water waves
  SN:  A periodic movement of seawater caused by wind, tide, and currents.
  TNR: 822
off-stream water use
  USE: offstream water use
official communications
  BT:  product types
  NT:  news releases
       policies and regulations
       speeches and testimony
  SN:  Corporate releases of information by USGS not generally intended to document the details of scientific data or techniques for a scientific audience.
  TNR: 1349
offstream water use
  BT:  water use
  NT:  agricultural water use
       commercial water use
       domestic water use
       industrial water use
       mining water use
  RT:  hydraulic engineering
       hydrology
  UF:  off-stream water use
  SN:  Water withdrawn or diverted from a ground- or surface-water source for public-water supply, industry, irrigation, livestock, thermoelectric power generation and other uses.  Sometimes called off-channel use or withdrawal.
  TNR: 828
oil resources
  BT:  energy resources
  NT:  oil sand resources
       oil shale resources
  RT:  economic geology
  UF:  petroleum resources (oil)
  SN:  Deposits (pools) of highly valuable liquid hydrocarbons or fossil fuels.
  TNR: 829
oil sand resources
  BT:  oil resources
  RT:  economic geology
  UF:  tar sand resources
  SN:  Deposits of sandstone or unconsolidated sand containing bitumen that can be extracted as an oil resource.
  TNR: 830
oil shale resources
  BT:  oil resources
  RT:  economic geology
  SN:  Deposits of finely grained sedimentary rock containing kerogen that can be distilled to produce liquid or gaseous hydrocarbons.
  TNR: 831
oligocene
  BT:  paleogene
  TNR: 1644
omnivores
  BT:  consumers (organisms)
  RT:  ecology
       zoology
  SN:  Animals that eat both plant and animal materials.
  TNR: 832
ontogeny
  USE: organism growth and development
open houses (USGS)
  USE: USGS open houses
optical backscatterance sensing
  USE: optical methods
optically-stimulated luminescence dating
  USE: luminescence dating
optical methods
  BT:  field inventory and monitoring
  UF:  optical backscatterance sensing
       optical reflectance measurement
  SN:  Measurement of light transmission or reflectance in the field to estimate, for example, the density of suspended sediment in water bodies.
  TNR: 1672
optical microscopy
  BT:  microscopy
  NT:  microtomy
  RT:  petrography
  SN:  Scientific techniques using a microscope with one or more lenses illuminated with visible light to view small objects.
  TNR: 835
optical reflectance measurement
  USE: optical methods
oral presentations
  USE: speeches and testimony
ordering services (USGS)
  USE: USGS sales and distribution services
ordovician
  BT:  paleozoic
  TNR: 1645
ore deposits (metallic)
  USE: metallic ores
ore deposits (non-metallic)
  USE: nonmetallic mineral resources
ore formation
  BT:  geochemical processes
  UF:  metallogeny
  SN:  Geochemical processes resulting in concentration of useful chemical elements and compounds, in earth materials.  Typically refers to metal ores.
  TNR: 1703
organic decomposition
  USE: biogeochemical cycling
organism groupings (non-taxonomic)
  BT:  topics
  NT:  biota
       consumers (organisms)
       decomposers
       endangered species
       game species
       keystone species
       macroinvertebrates
       migratory species
       native species
       nekton
       nonindigenous species
       plankton
       pollinators
       producers (organisms)
       shellfish
       vegetation
       wildlife
       benthos
       microbes
       parasites
       nuisance species
  RT:  life sciences
       organisms
  SN:  Used for categories of living organisms that are not taxonomic and that include species from more than one taxonomic group.
  TNR: 841
organism growth and development
  BT:  physiological processes
  NT:  metamorphosis
  RT:  developmental biology
       molecular biology
  UF:  ontogeny
  SN:  Changes that living things undergo as they progress from inception as a single cell to adult forms.
  TNR: 842
organisms
  BT:  topics
  NT:  algae
       animals
       archaea
       bacteria
       fungi
       lichens
       plants (organisms)
       protists
       viruses
  RT:  life sciences
       organism groupings (non-taxonomic)
  UF:  biological organisms
  SN:  Living individuals that grow, reproduce, and die.
  TNR: 843
orienteering
  USE: geolocation measurement
ornithology
  BT:  vertebrate zoology
  RT:  birds
       pollinators
  SN:  Branch of biology concerned with the study of birds.
  TNR: 845
orthoimagery
  US+: image collections
       aerial photography
orthophotographs
  US+: image collections
       aerial photography
Os
  USE: osmium
osmium
  BT:  chemical elements
  RT:  metal elements
  UF:  Os
  SN:  Metal element with symbol Os and atomic number 76 <http://periodic.lanl.gov/elements/76.html>
  TNR: 1530
osmosis
  BT:  physiological processes
  SN:  Transfer of substances through biological membranes.
  TNR: 1364
ostracodes
  BT:  crustaceans
  RT:  invertebrate zoology
  SN:  Small aquatic crustaceans belonging to the subclass Ostracoda, characterized by a bivalve shell.
  TNR: 848
outer core (earth)
  BT:  core (earth)
  RT:  geophysics
  SN:  Outer zone of the earth's core between the mantle and the inner core.
  TNR: 849
outfall
  USE: contamination and pollution
over-fishing
  USE: overfishing
over-grazing
  USE: overgrazing
overfishing
  BT:  human impacts
  RT:  fishery resources
       ichthyology
       social sciences
       wildlife biology
  UF:  over-fishing
  SN:  Taking too many fish from an area beyond the capacity for the population to replenish its numbers. The balance of the ecosystem is upset, leading to long-term depletion of fish stock.
  TNR: 852
overgrazing
  BT:  human impacts
  UF:  over-grazing
  SN:  The practice of allowing animals to eat vegetation, especially ground cover, beyond the capacity of the plant population to replenish itself. Leads to erosion and other harm to the ecosystem.
  TNR: 853
oxidation and reduction
  BT:  geochemical processes
  UF:  fermentation
  SN:  Addition or reduction of oxygen in a compound accompanied by exchange of electrons among atoms.
  TNR: 1708
oxygen
  BT:  chemical elements
  RT:  nonmetal elements
  UF:  O
  SN:  Nonmetal element with symbol O and atomic number 8 <http://periodic.lanl.gov/elements/8.html>
  TNR: 1531
oxygen content (water)
  BT:  water properties
  RT:  eutrophication
       hydrology
       water chemistry
  UF:  anoxia
       dissolved oxygen
       hypoxia
  SN:  Measurement of the concentration of oxygen dissolved in water, which is an important indicator of the condition of a water body.
  TNR: 854
oxygen isotope analysis
  BT:  light stable isotope analysis
  RT:  biochemistry
       geochemistry
  SN:  Experimental determination of the proportion of a given stable oxygen isotope in a sample.
  TNR: 855
ozone layer
  BT:  atmospheric composition
  RT:  atmospheric sciences
       greenhouse gases
  UF:  ozonesphere
  SN:  Upper atmosphere layer composed of ozone, a gas made up of molecules comprised of three oxygen atoms, which helps to shield the earth from ultraviolet rays.
  TNR: 856
ozonesphere
  USE: ozone layer
P
  USE: phosphorus
Pa
  USE: protactinium
palaeozoic
  USE: paleozoic
paleobotany
  BT:  paleontology
  RT:  botany
       palynology
  SN:  Branch of paleontology concerned with the study of fossil plants and plant life in the geologic past.
  TNR: 858
paleoceanography
  BT:  ocean sciences
  RT:  paleontology
  SN:  Study of the oceans in the geologic past, including their physical, chemical, biologic, and geologic history.
  TNR: 859
paleocene
  BT:  paleogene
  TNR: 1647
paleoclimate
  USE: climate change
paleogene
  BT:  tertiary
  NT:  eocene
       oligocene
       paleocene
  TNR: 1648
paleogeography
  BT:  geography
  SN:  Study of the history of earth surface characteristics; geomorphology in the past.
  TNR: 1679
paleomagnetic analysis
  BT:  laboratory methods
  NT:  Curie temperature analysis
       laboratory-induced magnetization analysis
       magnetic hysteresis analysis
       magnetic susceptibility analysis
       natural remanent magnetization analysis
  RT:  geophysics
  SN:  Determination of the intensity and direction of residual magnetism in rocks to study changes in the earth's magnetic field during past geologic time.
  TNR: 860
paleontology
  BT:  earth sciences
  NT:  invertebrate paleontology
       micropaleontology
       paleobotany
       vertebrate paleontology
  RT:  biostratigraphy
       fossils
       geologic history
       ichnofossils
       life sciences
       paleoceanography
  UF:  paleozoology
       phylogeny
       taphonomy
  SN:  Study of life in past geologic time based on fossil plants and animals.
  TNR: 861
paleoseismology
  BT:  seismology
  RT:  geologic history
  SN:  Branch of seismology concerned with ancient earthquakes.  Clues which indicate seismic activities in the geologic past are used  to date and determine the effects of those earthquakes.
  TNR: 862
paleotectonic maps
  US+: maps and atlases
       tectonic processes
paleozoic
  BT:  phanerozoic
  NT:  cambrian
       devonian
       mississippian
       ordovician
       pennsylvanian
       permian
       silurian
  UF:  palaeozoic
  TNR: 1649
paleozoology
  USE: paleontology
palladium
  BT:  chemical elements
  RT:  metal elements
  UF:  Pd
  SN:  Metal element with symbol Pd and atomic number 46 <http://periodic.lanl.gov/elements/46.html>
  TNR: 1534
palynology
  BT:  botany
  RT:  paleobotany
       plants (organisms)
  SN:  Branch of botany concerned with the study of pollen and spores, especially fossil remains. These are used to study plant life and dispersal in geologic history and to date deposits.
  TNR: 865
pamphlets, brochures, and booklets
  USE: reports
panchromatic imaging
  BT:  remote sensing
  RT:  geography
  SN:  Photographic technique which uses emulsions, films, or plates sensitive to all colors in light to produce black-and-white photographs. Often used in aerial and satellite photography.
  TNR: 867
papers (publications)
  USE: reports
parasites
  BT:  organism groupings (non-taxonomic)
  SN:  Symbiotic organisms that are detrimental to the host.
  TNR: 1709
parasitism
  USE: symbiosis
parasitology
  BT:  life sciences
  RT:  health and disease
       wildlife biology
  SN:  Branch of biology concerned with the study of organisms that, living on or in another organism, take nutrition from the host and often harm it.
  TNR: 871
particle-beam spectroscopy
  BT:  chemical analysis
  RT:  biochemistry
       geochemistry
  SN:  Analytical technique using a concentrated beam of charged subatomic particles.
  TNR: 872
particle-size analysis
  USE: grain-size analysis
partnerships (USGS)
  USE: USGS partnerships
pathobiology
  USE: pathology
pathology
  BT:  life sciences
  RT:  health and disease
       plant and animal testing
       therapeutic methods
  UF:  pathobiology
  SN:  Branch of biology concerned with the study of the causes, progress, symptoms, diagnosis, and effects of diseases.
  TNR: 876
Pb
  USE: lead
PCBs
  USE: industrial pollution
Pd
  USE: palladium
pedogenesis
  USE: soil formation
pedology (soils)
  USE: soil sciences
pennsylvanian
  BT:  paleozoic
  UF:  upper carboniferous
  TNR: 1650
percolation
  BT:  hydrologic processes
  RT:  permeability
  UF:  infiltration (water)
  SN:  The movement of water through fractures or interstices of a rock or soil.
  TNR: 1365
periphyton
  BT:  vegetation
  RT:  algae
  SN:  A plant assemblage including microbial communities of algae and cyanobacteria living attached to submerged aquatic vegetation.
  TNR: 1366
permafrost
  BT:  rocks and deposits
  SN:  Rocks and deposits in which the interstitial waters remain perennially frozen.
  TNR: 1370
permeability
  BT:  earth material properties
  RT:  percolation
  UF:  soil permeability
  SN:  The ability of fluids to pass through an earth material, typically depending on the connectedness of pore space in the material.
  TNR: 1368
permian
  BT:  paleozoic
  TNR: 1651
personnel (USGS)
  USE: USGS personnel
pest control
  BT:  biological population management
  SN:  Intentional reduction in the abundance of specific harmful organisms in a given area.
  TNR: 1685
pesticide and herbicide contamination
  BT:  contamination and pollution
  RT:  biochemistry
       ecology
       ecotoxicology
  UF:  biocide contamination
       degradation products (chemical)
       herbicide contamination
       insecticide contamination
  SN:  Pollution resulting from chemical agents applied to crops, rights of way, lawns, or residences to control weeds, insects, fungi, nematodes, rodents or other pests (pesticides) or kill undesirable plants (herbicides).
  TNR: 879
petrography
  BT:  laboratory methods
  RT:  optical microscopy
       petrology
       rocks and deposits
  UF:  thin section analysis
  SN:  Use of optical microscopy for the description and classification of rocks.
  TNR: 880
petroleum resources (gas)
  USE: natural gas resources
petroleum resources (oil)
  USE: oil resources
petrology
  BT:  geology
  RT:  diagenesis
       igneous rocks
       metamorphic rocks
       petrography
       rocks and deposits
       sedimentary rocks
  SN:  Branch of earth sciences concerned with the origin, structure, alteration, and composition of rocks.
  TNR: 883
pH (water)
  USE: water pH
phanerozoic
  BT:  geologic time periods
  NT:  cenozoic
       mesozoic
       paleozoic
  TNR: 1652
pharmaceutical contamination
  BT:  contamination and pollution
  SN:  Unintentional release of pharmaceutical compounds into the environment; work focuses on the effects of these compounds on organisms and water resources.
  TNR: 1693
phosphorus
  BT:  chemical elements
  RT:  nonmetal elements
  UF:  P
  SN:  Nonmetal element with symbol P and atomic number 15 <http://periodic.lanl.gov/elements/15.html>
  TNR: 1537
phosphorus content
  USE: nutrient content (water)
photo galleries (USGS)
  USE: USGS exhibits and facility tours
photogrammetry
  USE: remote sensing
photographs
  US+: photography
       image collections
photography
  BT:  methods
  NT:  aerial photography
       underwater photography
  RT:  videography
  UF:  photographs
  SN:  Process of using chemical reactions on sensitized emulsions, films or plates exposed to light (or other forms of radiant energy) to produce images or representations of objects.
  TNR: 889
photosynthesis
  BT:  physiological processes
  SN:  Conversion of sunlight, water, and nutrients into energy by plants.
  TNR: 1371
phycology
  BT:  botany
  RT:  algae
       algal blooms
       calcareous nannoplankton
       diatoms
       dinoflagellates
       lichens
       plankton
  UF:  algology
  SN:  Branch of biology concerned with the study of algae.
  TNR: 890
phylogeny
  USE: paleontology
physical oceanography
  USE: ocean sciences
physiography
  USE: land surface characteristics
physiological processes
  BT:  biological and physical processes
  NT:  osmosis
       photosynthesis
       organism growth and development
       bioluminescence
  SN:  Characteristics and processes of individual organisms that are not the direct result of their interaction with other organisms or with the environment.
  TNR: 1347
physiology
  USE: anatomy and physiology
phytoplankton
  BT:  plankton
  RT:  calcareous nannoplankton
  SN:  Small, mostly microscopic aquatic plants such as algae and bacteria suspended in water.
  TNR: 1372
pictures
  USE: image collections
placer deposit mining
  BT:  natural resource extraction
  SN:  Extraction of minerals, typically metal ores, from unconsolidated surficial materials such as stream sediments.
  TNR: 1373
plains ecosystems
  USE: grassland ecosystems
planetary bodies
  BT:  topics
  NT:  meteorites
  RT:  planetary sciences
       impact cratering
  SN:  Large celestial masses of rock, metal, or gas orbiting around a star.  Use for extraterrestrial bodies.
  TNR: 900
planetary sciences
  BT:  sciences
  RT:  meteorology
       planetary bodies
       scientific careers
  UF:  astronomy
       planetology
  SN:  Scientific study of the solid bodies of the solar system, including planets, moons, asteroids, meteorites, and interplanetary materials.
  TNR: 901
planetology
  USE: planetary sciences
plankton
  BT:  organism groupings (non-taxonomic)
  NT:  phytoplankton
  RT:  aquatic biology
       calcareous nannoplankton
       microbiology
       phycology
  UF:  planktonic ecosystems
       zooplankton
  SN:  Floating aquatic plants (phytoplankton) and animals (zooplankton) which are often microscopic and drift with the current in lakes, rivers, and oceans.
  TNR: 903
planktonic ecosystems
  US+: plankton
       aquatic ecosystems
planning reports
  USE: reports
plant and animal tagging
  BT:  field sampling
  RT:  life sciences
  UF:  animal tagging
       banding
       bird banding
       radioisotope tagging
       tagging
  SN:  Methods of attaching a tag or marker to an organism as long-term identification for study purposes.
  TNR: 906
plant and animal testing
  BT:  laboratory methods
  RT:  anatomy and physiology
       ecotoxicology
       pathology
  UF:  animal testing
  SN:  Use of live or dead organisms for scientific study.
  TNR: 907
plant distribution
  USE: biogeography
plants (organisms)
  BT:  organisms
  NT:  nonvascular plants
       vascular plants
  RT:  botany
       palynology
       vegetation
  UF:  flora
  SN:  Organisms which belong to the plant kingdom. Commonly multicellular, they produce food through photosynthesis.
  TNR: 909
plate tectonics
  USE: tectonic processes
platinum
  BT:  chemical elements
  RT:  metal elements
  UF:  Pt
  SN:  Metal element with symbol Pt and atomic number 78 <http://periodic.lanl.gov/elements/78.html>
  TNR: 1538
pleistocene
  BT:  quaternary
  UF:  ice age
  TNR: 1653
pliocene
  BT:  neogene
  TNR: 1654
plot sampling
  BT:  field sampling
  RT:  ecology
       transect sampling
       trenching
  SN:  Outlining small areas of land within a larger area to use as samples to study biological populations or ecosystems.
  TNR: 911
Plutonic rocks
  BT:  igneous rocks
  UF:  intrusive rocks
       magma
  SN:  Rocks formed at considerable depth by crystallization of magma and/or by chemical alteration. They are characteristically medium- to coarse-grained, of granitoid texture.
  TNR: 1341
plutonium
  BT:  chemical elements
  RT:  actinide series elements
  UF:  Pu
  SN:  Rare earth (actinide series) element with symbol Pu and atomic number 94 <http://periodic.lanl.gov/elements/94.html>
  TNR: 1539
Pm
  USE: prometium
Po
  USE: polonium
podcasts
  USE: sound recordings
polar bears
  USE: bears
policies (USGS)
  USE: USGS policies and regulations
policies and regulations
  BT:  official communications
  RT:  reports
       USGS policies and regulations
  UF:  regulations
  SN:  Rules, orders, and procedures issued by organizations or governments for administrative, controlling, and managing purposes.
  TNR: 913
political boundaries
  USE: administrative and political boundaries
pollen analysis
  USE: faunal and floral census (microscopic)
pollination
  BT:  ecological processes
  RT:  pollinators
  SN:  Wind, bees, or other agents transfer plant pollen from flower anthers or cones to stigmas, thereby fertilizing plants for reproduction.
  TNR: 915
pollinators
  BT:  organism groupings (non-taxonomic)
  RT:  ecology
       entomology
       ornithology
       pollination
       zoology
  SN:  Organisms that aid in the growth and distribution of plants by transferring pollen as a byproduct of their feeding activities.
  TNR: 916
pollution
  USE: contamination and pollution
polonium
  BT:  chemical elements
  RT:  metal elements
  UF:  Po
  SN:  Metalloid element with symbol Po and atomic number 84 <http://periodic.lanl.gov/elements/84.html>
  TNR: 1542
polychlorinated biphenyls
  USE: industrial pollution
polymerase chain reaction
  BT:  chemical analysis
  RT:  biochemistry
       genetics
  SN:  Biochemical technique that uses enzymes to replicate new nucleotides of DNA from DNA triphosphates using DNA as a template.
  TNR: 919
pond ecosystems
  USE: freshwater ecosystems
population and community ecology
  BT:  topics
  NT:  animal behavior
       biodiversity
       biogeography
       community ecology
       ecosystems
       habitats
       population dynamics
       symbiosis
  RT:  biological population management
       ecological processes
       ecology
       ecosystem monitoring
       natural resource management
       relative abundance analysis
  UF:  life history
       population energetics
       radar ecology
  SN:  Interactions of a single species (population) or an association of different species (community) occupying a particular region, including their biotic and abiotic environments.
  TNR: 921
population dynamics
  BT:  population and community ecology
  RT:  algal blooms
       biogeography
       ecology
  SN:  Changes in the size, composition, or structure of aggregates of single or multiple species in a specific area over time.
  TNR: 922
population energetics
  USE: population and community ecology
porosity
  BT:  earth material properties
  UF:  interstices
       soil porosity
  SN:  The proportion of open space in a rock or unconsolidated material.
  TNR: 1369
posters
  BT:  product types
  SN:  Large single sheets of paper or board imprinted with informative text and graphics. Intended for hanging or flat display.
  TNR: 924
potable water
  USE: drinking water use
potassium
  BT:  chemical elements
  RT:  alkali metal elements
  UF:  K
  SN:  Alkali metal element with symbol K and atomic number 19 <http://periodic.lanl.gov/elements/19.html>
  TNR: 1543
potassium-argon analysis
  BT:  radiometric dating
  UF:  K-Ar dating
  SN:  Radiometric age determination by comparison of the concentrations of radioactive potassium and argon daughter products.
  TNR: 1374
potentiometric surface
  USE: ground-water level
power generation water use
  BT:  instream water use
  RT:  hydraulic engineering
       hydrology
  UF:  hydroelectric power generation water use
       thermoelectric power generation water use
  SN:  Use of water in the process of producing electric energy by transforming other forms of energy.
  TNR: 925
powerpoint
  USE: presentation materials
Pr
  USE: praseodymium
prairie ecosystems
  USE: grassland ecosystems
praseodymium
  BT:  chemical elements
  RT:  lanthanide series elements
  UF:  Pr
  SN:  Rare earth (lanthanide series) element with symbol Pr and atomic number 59 <http://periodic.lanl.gov/elements/59.html>
  TNR: 1545
precambrian
  BT:  geologic time periods
  NT:  archaean
       hadean
       proterozoic
  UF:  cryptozoic
  TNR: 1655
precipitation (atmospheric)
  BT:  atmospheric and climatic processes
  RT:  hydrologic processes
       atmospheric deposition (chemical & particulate)
       atmospheric sciences
       hydrology
       storms
       water cycle
  UF:  rainfall measurement
       snowfall measurement
       precipitation measurement
       rain
       rainfall
       snow
       snowfall
  SN:  Any or all forms of water particles that fall from the atmosphere, such as rain, snow, hail and sleet.
  TNR: 927
precipitation measurement
  US+: field inventory and monitoring
       precipitation (atmospheric)
predators
  USE: carnivores
presentation materials
  BT:  product types
  UF:  powerpoint
  SN:  Diagrams, photos, and text gathered together as part of a presentation given in a meeting or class.
  TNR: 1738
press relations (USGS)
  USE: USGS media relations
press releases
  USE: news releases
price lists (USGS)
  USE: USGS sales and distribution services
pricing and ordering (USGS)
  USE: USGS sales and distribution services
proceedings
  USE: reports
producers (organisms)
  BT:  organism groupings (non-taxonomic)
  RT:  botany
       ecology
       microbiology
  SN:  Organisms, chiefly green plants, which use inorganic elements, compounds, and light to produce their food (photosynthesis). They are a source of food for animals.
  TNR: 935
product support (USGS)
  USE: USGS product support
product types
  BT:  Categories
  NT:  official communications
       catalogs and indexes
       datasets
       reports
       image collections
       maps and atlases
       posters
       scientific software
       videos
       materials standards
       presentation materials
       sound recordings
       animations
       terminologies and classifications
  SN:  General representation of the information in a resource, such as a map or data set.
  TNR: 808
programs (USGS)
  USE: USGS programs
prometium
  BT:  chemical elements
  RT:  lanthanide series elements
  UF:  Pm
  SN:  Rare earth (lanthanide series) element with symbol Pm and atomic number 61 <http://periodic.lanl.gov/elements/61.html>
  TNR: 1546
prospecting
  USE: natural resource exploration
protactinium
  BT:  chemical elements
  RT:  actinide series elements
  UF:  Pa
  SN:  Rare earth (actinide series) element with symbol Pa and atomic number 91 <http://periodic.lanl.gov/elements/91.html>
  TNR: 1547
proterozoic
  BT:  precambrian
  NT:  Neoproterozoic
  TNR: 1656
protists
  BT:  organisms
  RT:  algae
       microbiology
       micropaleontology
  UF:  foraminifera
       protozoans
       radiolaria
  SN:  Unicellular eukaryotes (organisms possessing nucleated cells) with affinities to both plants and animals. Classed in the Protista or Potoctista kingdom, they include protozoans, foraminifera, radiolarians, fungi and some algae.
  TNR: 940
protozoans
  USE: protists
Pt
  USE: platinum
Pu
  USE: plutonium
publication servers (USGS)
  USE: USGS publication servers
public water supply
  USE: domestic water use
published series
  USE: reports
pyroclastic
  USE: volcanic rocks
pyroclastic flows
  USE: volcanic activity
quadrangle maps
  US+: topography
       maps and atlases
quarrying
  USE: mining and quarrying
quaternary
  BT:  cenozoic
  NT:  holocene
       pleistocene
  TNR: 1657
Ra
  USE: radium
radar ecology
  US+: population and community ecology
       doppler radar imaging
radar imaging
  BT:  remote sensing
  NT:  SLAR
       doppler radar imaging
  RT:  geography
       microwave imaging
  SN:  A remote sensing technique which uses the reflection of pulsed high frequency radio waves to determine the speed, direction, and distance of faraway objects.
  TNR: 948
radar tomography
  USE: tomography
radioactive waste repositories
  USE: waste treatment and disposal
radioactivity
  BT:  earth material properties
  SN:  Release of subatomic particles from earth materials.  Generally the energy of these particles is used to determine the chemical elements present.
  TNR: 1701
radiocarbon dating
  USE: carbon-14 analysis
radioisotope tagging
  USE: plant and animal tagging
radioisotope tracer study
  USE: tracer study
radiolaria
  USE: protists
radiometric age determination
  USE: radiometric dating
radiometric dating
  BT:  isotopic analysis
  NT:  carbon-14 analysis
       rubidium-strontium analysis
       uranium-lead analysis
       uranium-thorium analysis
       potassium-argon analysis
  RT:  fission-track dating
       geochronology
       age estimation methods
  UF:  age dating (radiometric)
       argon-argon dating
       lead-210 dating
       radiometric age determination
  SN:  Methods for age determination of rocks and fossils by measuring the proportions of naturally occurring radioactive isotopes to their decay products.
  TNR: 954
radio telemetry
  USE: telemetry
radium
  BT:  chemical elements
  RT:  alkaline earth elements
  UF:  Ra
  SN:  Alkaline earth element with symbol Ra and atomic number 88 <http://periodic.lanl.gov/elements/88.html>
  TNR: 1551
radon
  BT:  chemical elements
  RT:  toxic radionuclide contamination
       noble gas elements
  UF:  Rn
  SN:  Noble gas element with symbol Rn and atomic number 86 <http://periodic.lanl.gov/elements/86.html>
  TNR: 1552
rain
  USE: precipitation (atmospheric)
rainfall
  USE: precipitation (atmospheric)
rainfall measurement
  US+: precipitation (atmospheric)
       field inventory and monitoring
rangeland ecosystems
  USE: terrestrial ecosystems
rare earth elements
  BT:  chemical element groups
  NT:  actinide series elements
       lanthanide series elements
  TNR: 1553
Rb
  USE: rubidium
Rb-Sr age analysis
  USE: rubidium-strontium analysis
Re
  USE: rhenium
re-establishment (organisms)
  USE: reintroduction (organisms)
reaches (hydraulic)
  USE: river reaches
reaches (streams)
  USE: river reaches
reaction transport
  BT:  geochemical processes
  RT:  ground-water flow
  SN:  Chemical reactions occurring during ground-water flow.
  TNR: 1711
real-time data
  USE: real-time monitoring and reporting
real-time monitoring and reporting
  BT:  field methods
  UF:  real-time data
  SN:  Gathering information through periodic or continuous measurement in the field to provide a view of current conditions. In some instances, observations may not be subject to rigorous review before release; this will be noted in the documentation accompanying the data.
  TNR: 1351
recharge
  USE: water cycle
reclaimed water
  USE: water resource management
reclamation
  USE: remediation
recolonization (organisms)
  USE: reintroduction (organisms)
reconnaissance
  USE: field inventory and monitoring
recreation
  BT:  topics
  UF:  biking
       bird watching
       boating
       camping
       canoeing
       caving
       climbing
       fishing (recreational)
       hiking
       hunting
       kayaking
  SN:  Pursuit of leisure-time activities, typically out of doors.
  TNR: 1352
recreational fishery resources
  BT:  fishery resources
  RT:  aquatic biology
       ichthyology
       marine biology
  UF:  recreational fishing
       sport fishing
  SN:  The stock of fish and other seafood resources in areas used for recreational fishing.
  TNR: 968
recreational fishing
  USE: recreational fishery resources
red tides
  USE: algal blooms
reef ecosystems
  BT:  marine ecosystems
  RT:  coelenterates
       ecology
       marine biology
       marine fishery resources
  UF:  coral reef ecosystems
  SN:  Biological communities formed by the skeletons of calcareous seawater organisms, usually corals.
  TNR: 971
reef fisheries
  USE: marine fishery resources
reef fishing
  USE: marine fishery resources
regression analysis
  BT:  statistical analysis
  UF:  correlation
  SN:  Statistical analysis based on the functional relationships of two or more related variables. Predicts the value of one variable when the other two are given.
  TNR: 974
regulations
  USE: policies and regulations
regulations (USGS)
  USE: USGS policies and regulations
reintroduction (organisms)
  BT:  biological population management
  UF:  re-establishment (organisms)
       recolonization (organisms)
  SN:  Return of a species to an area through the intervention of man.
  TNR: 977
relative abundance analysis
  BT:  computational methods
  RT:  ecosystem monitoring
       population and community ecology
  SN:  Determination of the percentage of individuals of one group in comparison to the total of all individuals in a given area.
  TNR: 978
relief maps
  US+: maps and atlases
       topography
remanent magnetism
  BT:  magnetism
  UF:  natural remanent magnetism
  SN:  Magnetic characteristic of rocks and deposits reflective of the earth's magnetic field at the time of the deposit's formation.
  TNR: 1676
remediation
  BT:  natural resource management
  NT:  bioremediation
  RT:  ecology
       ecosystem monitoring
       engineering geology
  UF:  mitigation
       reclamation
       restoration
  SN:  Methods for decontaminating, reclaiming, and restoring natural resources or reducing the effects of hazards.
  TNR: 980
remote-sensing data
  US+: image collections
       remote sensing
remote-sensing images
  US+: image collections
       remote sensing
remote sensing
  BT:  methods
  NT:  aeromagnetic surveying
       aeroradiometric surveying
       hyperspectral imaging
       IFSAR
       infrared imaging
       LIDAR
       microwave imaging
       multispectral imaging
       panchromatic imaging
       radar imaging
       thermal imaging
       visible light imaging
  RT:  aerial photography
       geography
       seismic methods
       telemetry
       videography
  UF:  remote-sensing data
       remote-sensing images
       airborne imaging
       composite burn index
       normalized burn ratio
       photogrammetry
       satellite altimetry
       satellite imaging
       space-borne sensing
       satellite images
  SN:  The process of detecting and monitoring the physical characteristics of an area by measuring its reflected and emitted radiation at a distance from the targeted area.  Remote sensing is used in this thesaurus to refer to methods that are solely or primarily deployed through air or space. Included in this concept are studies of biological populations using remote imaging techniques. Related methods which are used most frequently on the ground (e.g. photography), whether underwater, from airplanes or satellites, are not included in the term "remote sensing."
  TNR: 981
remote video monitoring
  USE: video monitoring
reports
  BT:  product types
  NT:  checklists
       guidebooks
       manuals
       standards
  RT:  bibliographies
       catalogs and indexes
       directories
       policies and regulations
  UF:  abstracts
       articles (publications)
       biographies
       books and book chapters
       dissertations
       documents
       guidelines
       journal articles
       journals
       memos
       newsletters
       pamphlets, brochures, and booklets
       papers (publications)
       planning reports
       proceedings
       published series
       scientific reports
       serial publications
       technical reports
       text documents
       theses
       transcripts
       workshop reports
       yearbooks
  SN:  Written items, especially those that are official, factual, or informative, often including graphics as well as text.
  TNR: 277
reptiles
  BT:  vertebrates
  NT:  dinosaurs
  RT:  herpetology
  SN:  Cold-blooded vertebrates of the class Reptilia.  Characterized by skin covered with scales or horny plates and reproduced by eggs. Includes snakes, lizards, crocodiles, alligators, turtles, and extinct species such as dinosaurs.
  TNR: 988
residential water use
  USE: domestic water use
resistivity
  BT:  earth material properties
  SN:  Electrical resistance of materials, often measured in boreholes.
  TNR: 1712
resistivity sounding
  USE: electrical resistivity logging
resource assessment
  USE: natural resource assessment
resource conservation
  USE: natural resource management
resource extraction
  USE: natural resource extraction
resource restoration
  USE: natural resource management
restoration
  USE: remediation
revegetation
  USE: bioremediation
Rf
  USE: rutherfordium
Rh
  USE: rhodium
rhenium
  BT:  chemical elements
  RT:  metal elements
  UF:  Re
  SN:  Metal element with symbol Re and atomic number 75 <http://periodic.lanl.gov/elements/75.html>
  TNR: 1558
rheology
  USE: deformation (geologic)
rhodium
  BT:  chemical elements
  RT:  metal elements
  UF:  Rh
  SN:  Metal element with symbol Rh and atomic number 45 <http://periodic.lanl.gov/elements/45.html>
  TNR: 1559
riparian ecosystems
  USE: wetland ecosystems
risk assessment
  BT:  management methods
  NT:  earthquake probabilities
       landslide susceptibility assessment
       volcanic eruption prediction
  SN:  The evaluation of the likelihood of adverse effects due to a given factor such as energy development or recurring hazardous events such as earthquakes.
  TNR: 997
river discharge
  USE: stream discharge
river discharge monitoring
  USE: field inventory and monitoring
river ecosystems
  US+: river systems
       freshwater ecosystems
river reaches
  BT:  river systems
  RT:  hydrology
  UF:  reaches (hydraulic)
       reaches (streams)
  SN:  Continuous parts of streams between two specified points.
  TNR: 1001
river systems
  BT:  surface water (non-marine)
  NT:  river reaches
  RT:  hydrology
       stream discharge
  UF:  river ecosystems
  SN:  Long water courses including main streams and tributaries.
  TNR: 1002
Rn
  USE: radon
rock composition
  USE: rocks and deposits
rockfalls
  USE: landslides
rock mechanics maps
  US+: maps and atlases
       engineering geology
rocks and deposits
  BT:  earth characteristics
  NT:  permafrost
       fossils
       igneous rocks
       metamorphic rocks
       sedimentary rocks
       unconsolidated deposits
  RT:  building stone resources
       lithosphere
       petrography
       petrology
       meteorites
  UF:  crystals
       lithologic maps
       lithology
       rock composition
  SN:  Solid masses that make up the earth's crust as well as accumulations of materials. Use for major rock types and unconsolidated deposits. For deposits of economic value, see related terms.
  TNR: 1005
roundworms
  BT:  worms
  RT:  invertebrate zoology
  UF:  nematodes
  SN:  Worms of the phylum Nematoda, often parasitic, such as hookworms and pinworms, having soft cylindrical bodies without segments.
  TNR: 1006
Ru
  USE: ruthenium
rubidium
  BT:  chemical elements
  RT:  alkali metal elements
  UF:  Rb
  SN:  Alkali metal element with symbol Rb and atomic number 37 <http://periodic.lanl.gov/elements/37.html>
  TNR: 1562
rubidium-strontium analysis
  BT:  radiometric dating
  RT:  geochronology
  UF:  Rb-Sr age analysis
  SN:  Technique for dating ancient rocks based on measuring the ratio of the isotopes strontium-87 to ribidium-87 in samples. Uses the known half-life of radioactive isotopes of rubidium-87 that decay to isotopes of strontium-87 to determine rock ages.
  TNR: 1007
runoff
  BT:  hydrologic processes
  UF:  stormwater runoff
       urban runoff
  SN:  Flow of water over land surfaces (including paved surfaces), typically from precipitation.
  TNR: 1375
rural water use
  USE: agricultural water use
ruthenium
  BT:  chemical elements
  RT:  metal elements
  UF:  Ru
  SN:  Metal element with symbol Ru and atomic number 44 <http://periodic.lanl.gov/elements/44.html>
  TNR: 1563
rutherfordium
  BT:  chemical elements
  RT:  metal elements
  UF:  Rf
  SN:  Metal element with symbol Rf and atomic number 104 <http://periodic.lanl.gov/elements/104.html>
  TNR: 1564
S
  USE: sulfur
safety issues (human)
  USE: human environmental safety
sales services (USGS)
  USE: USGS sales and distribution services
salinity
  BT:  water properties
  RT:  hydrology
       ocean salinity
       water chemistry
  UF:  chloride concentration
  SN:  Measure of the concentration of salts dissolved in a solution.
  TNR: 1010
salt-water intrusion
  USE: saltwater intrusion
saltwater intrusion
  BT:  hydrologic processes
  UF:  salt-water intrusion
  SN:  Infusion of saline waters in an aquifer or body of surface water.
  TNR: 1686
samarium
  BT:  chemical elements
  RT:  lanthanide series elements
  UF:  Sm
  SN:  Rare earth (lanthanide series) element with symbol Sm and atomic number 62 <http://periodic.lanl.gov/elements/62.html>
  TNR: 1566
sand deposits
  BT:  unconsolidated deposits
  RT:  economic geology
       nonmetallic mineral resources
       sedimentology
  SN:  Deposits of loose particles of rock or mineral (sediment) that range in size from 0.0625-2.0 millimeters in diameter.
  TNR: 1011
SAR interferometry
  USE: IFSAR
satellite altimetry
  US+: remote sensing
       altimetry measurement
satellite images
  US+: image collections
       remote sensing
satellite imaging
  USE: remote sensing
satellite photography
  USE: visible light imaging
Sb
  USE: antimony
Sc
  USE: scandium
scandium
  BT:  chemical elements
  RT:  metal elements
  UF:  Sc
  SN:  Metal element with symbol Sc and atomic number 21 <http://periodic.lanl.gov/elements/21.html>
  TNR: 1569
scanning electron microscopy
  BT:  electron microscopy
  SN:  Microscope in which a finely focused beam of electrons is scanned across a specimen. The electronic intensity variations observed are used to construct an image of the specimen.
  TNR: 1014
Scanning Multichannel Microwave Radiometer (SMMR)
  USE: SMMR
school programs (USGS)
  USE: USGS K-12 programs
science centers (USGS)
  USE: USGS science centers
science programs (USGS)
  USE: USGS science programs
sciences
  BT:  Categories
  NT:  earth sciences
       engineering sciences
       information sciences
       life sciences
       planetary sciences
       social sciences
  SN:  Major educational fields, fields of study, and professional groupings within USGS.
  TNR: 1019
scientific careers
  BT:  topics
  RT:  earth sciences
       engineering sciences
       information sciences
       life sciences
       planetary sciences
       social sciences
  UF:  careers in science
       scientists-at-work photographs
  SN:  Professions in which people carry out or support scientific research or monitoring.
  TNR: 1020
scientific reports
  USE: reports
scientific software
  BT:  product types
  UF:  computer program
  SN:  Routines, programs, and procedures devised in order to direct computers to perform specific tasks.
  TNR: 1077
scientists-at-work photographs
  US+: image collections
       scientific careers
sclerochronology
  BT:  age estimation methods
  SN:  Description of the history of individual organisms by studying the variations in thickness of accretionary layers in their skeletons.
  TNR: 1713
scour
  BT:  hydrologic processes
  RT:  hazards
       erosion
  UF:  bridge scour
  SN:  Erosion of sediment in a stream bed, often occurring at manmade structures such as bridge supports.
  TNR: 1687
scrubland ecosystems
  USE: shrubland ecosystems
Se
  USE: selenium
sea-floor characteristics
  BT:  ocean characteristics
  RT:  bathymetry
       land surface characteristics
       marine geology
       ocean sciences
       oceanic lithosphere
  UF:  ocean bottom characteristics
       sea floor characteristics
       seafloor characteristics
  SN:  Geomorphic features and geographic, compositional, and textural variation in the materials composing the ocean floor. Includes both large-scale structures (such as seamounts and rises) and fine-scale variations in rocks and deposits on the sea floor.
  TNR: 1025
sea-ice concentration
  USE: sea ice concentration
sea-level change
  BT:  ocean characteristics
  RT:  climatology
       global change
       ocean sciences
  UF:  sea-level rise
  SN:  Variation in the relative vertical position of land and ocean waters. Caused globally by changes in the distribution of ice masses and the shape of the oceans, and locally by the rate of uplift or subsidence of the land surface.  Includes both global (eustatic) and local (relative) sea-level variations.
  TNR: 1028
sea-level rise
  USE: sea-level change
sea-surface temperature
  USE: sea surface temperature
sea anemones
  USE: coelenterates
seaborgium
  BT:  chemical elements
  RT:  metal elements
  UF:  Sg
  SN:  Metal element with symbol Sg and atomic number 106 <http://periodic.lanl.gov/elements/106.html>
  TNR: 1571
seafloor characteristics
  USE: sea-floor characteristics
sea floor characteristics
  USE: sea-floor characteristics
sea floor topography
  USE: bathymetry
seagrass
  USE: aquatic vegetation
sea ice concentration
  BT:  snow and ice cover
  RT:  ocean characteristics
  UF:  sea-ice concentration
       sea ice cover
  SN:  Proportion of ocean area in a given region that contains or is covered by floating ice.
  TNR: 1722
sea ice cover
  USE: sea ice concentration
search services (USGS)
  USE: USGS search services
seasonal migration
  USE: migration (organisms)
seasons
  BT:  time periods
  NT:  autumn
       spring (season)
       summer
       winter
  TNR: 1658
sea squirts
  USE: tunicates
sea surface temperature
  BT:  ocean temperature
  RT:  AVHRR
  UF:  sst
       temperature (sea surface)
       sea-surface temperature
  SN:  Observed temperature of surface ocean waters, typically encompassing the entire mixed layer. Some observational methods, however, may measure a much smaller depth range.  Includes temperature data obtained in-situ or by remote sensing methods.
  TNR: 1027
seaweeds
  USE: aquatic vegetation
sections (geologic)
  USE: stratigraphic sections
sections (stratigraphic)
  USE: stratigraphic sections
sedimentary rocks
  BT:  rocks and deposits
  NT:  bedforms
  RT:  petrology
       sedimentation
       sedimentology
  SN:  Rocks formed by the consolidation of loose, uncemented pieces of sediments.
  TNR: 1035
sedimentation
  BT:  geologic processes
  RT:  sedimentary rocks
       sedimentology
       atmospheric deposition (chemical & particulate)
  UF:  alluvial sedimentation
       deposition (sediment)
       dust deposition
  SN:  Process of deposition of sediments (loose, uncemented pieces of rock, mineral fragments, or biological materials).  The sediments settle out of water or air into layers on a surface.
  TNR: 1036
sediment geochemistry
  US+: unconsolidated deposits
       chemical analysis
sedimentology
  BT:  geology
  RT:  bedforms
       building stone resources
       clay deposits
       diagenesis
       erosion
       grain-size analysis
       gravel deposits
       sand deposits
       sediment transport
       sedimentary rocks
       sedimentation
       sieve-size analysis
       trenching
  SN:  Branch of earth sciences concerned with the study of the origin, composition, transport, and changes of materials deposited by water, wind, or ice.
  TNR: 1037
sediments
  USE: unconsolidated deposits
sediment transport
  BT:  geologic processes
  RT:  hydrology
       sedimentology
  UF:  alluvial transport
       bed load
       bedload
       density flow
       dust transport
       suspended load
       turbidity flow
  SN:  Transport of solid particles of unconsolidated rock and mineral fragments, chemical precipitates, or biological materials.
  TNR: 1034
segmented worms
  BT:  worms
  RT:  invertebrate zoology
  UF:  annelids
  SN:  Worms belonging to the phylum Annelida, with soft bodies divided into segments and distinct heads. Includes leeches, earthworms, and marine worms.
  TNR: 1038
seismic activity
  USE: earthquake occurrences
seismic exploration
  US+: seismic methods
       natural resource exploration
seismic hazard maps
  US+: earthquake occurrences
       maps and atlases
seismic imaging
  USE: seismic methods
seismicity
  USE: earthquake occurrences
seismicity maps
  US+: maps and atlases
       earthquake probabilities
seismic methods
  BT:  field inventory and monitoring
  NT:  seismic networking
       seismic reflection method
       seismic refraction method
  RT:  remote sensing
       seismology
  UF:  seismic exploration
       seismic imaging
       seismic profiles
       seismograms
       seismometry
  SN:  Procedures used to record and study earthquakes or earth vibrations including those that are artificially induced.
  TNR: 1042
seismic monitoring stations
  USE: field monitoring stations
seismic networking
  BT:  seismic methods
  RT:  seismology
  UF:  earthquake monitoring
  SN:  Deploying, operating, and maintaining groups and arrays of instruments for detecting and describing local movements of the earth.
  TNR: 1043
seismic profiles
  USE: seismic methods
seismic reflection method
  BT:  seismic methods
  RT:  seismology
  UF:  seismic reflection survey maps
  SN:  Geophysical technique to study the subsurface of the earth using sound waves induced by explosives, vibrating devices, or percussive equipment.  The reflections of the sound waves from the boundaries of different rocks are measured.
  TNR: 1045
seismic reflection survey maps
  US+: maps and atlases
       seismic reflection method
seismic refraction method
  BT:  seismic methods
  RT:  seismology
  SN:  Geophysical technique to study the subsurface of the earth by generating compressional waves by means of hammering or explosive methods. The variations in velocity of the waves traveling through rocks or geological layers are measured.
  TNR: 1047
seismic tomography
  USE: tomography
seismograms
  USE: seismic methods
seismology
  BT:  geophysics
  NT:  paleoseismology
  RT:  earthquake occurrences
       earthquakes
       seismic methods
       seismic networking
       seismic reflection method
       seismic refraction method
       tectonic processes
       tiltmeter measurement
       tsunamis
       volcanology
  UF:  earthquake seismology
       engineering seismology
       exploration seismology
  SN:  Branch of earth sciences concerned with the study of earthquakes and man-induced seismic waves.
  TNR: 1050
seismometry
  USE: seismic methods
selenium
  BT:  chemical elements
  RT:  nonmetal elements
  UF:  Se
  SN:  Nonmetal element with symbol Se and atomic number 34 <http://periodic.lanl.gov/elements/34.html>
  TNR: 1572
serial publications
  USE: reports
sewage disposal
  USE: waste treatment and disposal
sexing (plants & animals)
  BT:  field sampling
  RT:  life sciences
  UF:  sexing (plants and animals)
  SN:  Determination of the sex of an individual organism for study purposes, such as wildlife surveys.
  TNR: 1054
sexing (plants and animals)
  USE: sexing (plants & animals)
Sg
  USE: seaborgium
shaking maps (seismic)
  US+: maps and atlases
       earthquake occurrences
shellfish
  BT:  organism groupings (non-taxonomic)
  RT:  aquatic biology
       crustaceans
       invertebrate zoology
       mollusks
  SN:  Aquatic invertebrates with shells, usually mollusks and crustaceans. Includes clams, lobsters, and oysters.
  TNR: 1056
shorebirds
  USE: birds
short grass ecosystems
  USE: grassland ecosystems
shrubland ecosystems
  BT:  terrestrial ecosystems
  RT:  ecology
  UF:  scrubland ecosystems
  SN:  Biological land communities and habitats with sparse, low-growing vegetation.
  TNR: 1059
Side-Looking Airborne Radar (SLAR)
  USE: SLAR
side-scan sonar methods
  BT:  sonar methods
  RT:  marine geology
       marine geophysics
  UF:  Sidescan sonar methods
  SN:  Techniques of collecting data from the sea floor by towing a vehicle with SOund NAvigation and Ranging systems projecting beams of sound waves into the underwater environment. Data are collected from the returning echoes (backscatter) as the sound waves are relected back from the sea floor or sediments.
  TNR: 1061
Sidescan sonar methods
  USE: side-scan sonar methods
sieve-size analysis
  BT:  grain-size analysis
  RT:  sedimentology
  SN:  Analytic technique determining the distribution of the different sizes of particles in soil, sediment, or rock samples by measuring the percentage that will pass through mesh holes of known size.
  TNR: 1062
silicon
  BT:  chemical elements
  RT:  nonmetal elements
  SN:  Nonmetal element with symbol si and atomic number 14 <http://periodic.lanl.gov/elements/14.html>
  TNR: 1575
silurian
  BT:  paleozoic
  TNR: 1659
silver
  BT:  chemical elements
  RT:  metal elements
  UF:  Ag
  SN:  Metal element with symbol Ag and atomic number 47 <http://periodic.lanl.gov/elements/47.html>
  TNR: 1576
sinkhole formation
  USE: erosion
SLAR
  BT:  radar imaging
  RT:  geography
  UF:  Side-Looking Airborne Radar (SLAR)
  SN:  Side-looking Airborne Radar, an airborne radar imaging technique, uses an antenna mounted on an airplane or satellite to project radiation at right angles to the flight path and collect high resolution images.
  TNR: 1064
slides (land)
  USE: landslides
slope stability
  USE: landslide susceptibility assessment
slope stability maps
  US+: landslide susceptibility assessment
       maps and atlases
slumps
  USE: mass wasting
Sm
  USE: samarium
SMMR
  BT:  microwave imaging
  RT:  geography
  UF:  SMMR images
       Scanning Multichannel Microwave Radiometer (SMMR)
  SN:  Scanning Multichannel Microwave Radiometer (SMMR), a technique which uses a multichannel microwave radiometer mounted on an airplane or satellite to measure polarized microwave radiances from the atmosphere, seas or land. Temperatures, wind speeds, sea ice coverage, and terrain parameters can be obtained.
  TNR: 1069
SMMR images
  USE: SMMR
Sn
  USE: tin
snow
  USE: precipitation (atmospheric)
snow and ice cover
  BT:  earth characteristics
  NT:  sea ice concentration
  RT:  atmospheric and climatic processes
       glaciation
       glaciology
       SSM/I
       surface water (non-marine)
  UF:  cryosphere
       glaciers
       ice core sampling
       ice
       snowpack
  SN:  Accumulation of snow or ice blanketing land surfaces.
  TNR: 1072
snowfall
  USE: precipitation (atmospheric)
snowfall measurement
  US+: field inventory and monitoring
       precipitation (atmospheric)
snowpack
  USE: snow and ice cover
social sciences
  BT:  sciences
  NT:  archeology
  RT:  business and economics
       cadastral and legal land descriptions
       culture and demographics
       environmental health (human)
       hazards
       health and disease
       human environmental safety
       human impacts
       land use change
       mining hazards
       overfishing
       scientific careers
       waste treatment and disposal
  SN:  Sciences concerned with the structure and interrelationships of human societies, human institutions and organizations, and human culture over time.
  TNR: 1075
socioeconomics
  USE: culture and demographics
sodium
  BT:  chemical elements
  RT:  alkali metal elements
  UF:  Na
  SN:  Alkali metal element with symbol Na and atomic number 11 <http://periodic.lanl.gov/elements/11.html>
  TNR: 1579
soil chemistry
  BT:  geochemistry
  RT:  agriculture
       soil resources
       soil sciences
  SN:  Branch of chemistry concerned with the elements and compounds that make up soils. Includes chemical processes involving soils.
  TNR: 1078
soil compaction
  USE: compaction
soil formation
  BT:  geologic processes
  RT:  ecological processes
       geochemical processes
  UF:  pedogenesis
  SN:  Geological, geochemical, and ecological processes that work together to produce soils.
  TNR: 1710
soil permeability
  USE: permeability
soil pollution
  US+: contamination and pollution
       soil resources
soil porosity
  USE: porosity
soil resources
  BT:  natural resources
  RT:  economic geology
       soil chemistry
       soil sciences
  UF:  soil pollution
  SN:  Natural resources of unconsolidated fragmented rock, humus, and mineral matter that cover the surface of the earth.
  TNR: 1080
soil sciences
  BT:  earth sciences
  RT:  soil chemistry
       soil resources
       trenching
  UF:  pedology (soils)
  SN:  Earth sciences dealing with the origin, classification, physical, chemical, and biological properties of soils.
  TNR: 1081
sonar depth-sounding
  USE: sonar methods
sonar methods
  BT:  acoustic methods
  NT:  side-scan sonar methods
  RT:  bathymetry measurement
  UF:  echo sounding
       sonar depth-sounding
  SN:  SOund Navigation And Ranging techniques to detect submerged objects and to determine depths to the sea floor using reflections of sound waves.
  TNR: 1083
sorption
  BT:  geochemical processes
  UF:  adsorption
       absorption
  SN:  Attachment of chemical substances to materials, either externally (by adsorption) or internally (by absorption).
  TNR: 1715
sound recordings
  BT:  product types
  UF:  audio recordings
       podcasts
  SN:  Information presented in a format for listening by the user.
  TNR: 1739
space-borne sensing
  USE: remote sensing
spatial analysis
  BT:  computational methods
  NT:  geospatial analysis
  RT:  geography
       image analysis
       mathematical modeling
       topological analysis
  SN:  Use of quantitative tools to study social, economic, and geographic data in relation to distributions and patterns in geographic space.
  TNR: 1085
Special Sensor Microwave/Imager (SSM/I)
  USE: SSM/I
species distribution
  USE: biogeography
species distribution maps
  US+: biogeography
       maps and atlases
species diversity
  BT:  biodiversity
  SN:  An ecological concept incorporating both the number of species in a particular sampling area and the evenness with which individuals are distributed among the various species.
  TNR: 1089
species geographic range
  USE: biogeography
specimen collecting
  BT:  field sampling
  RT:  capturing (animals)
  UF:  collection of specimens
  SN:  Taking of samples from the environment for study.
  TNR: 1091
speeches and testimony
  BT:  official communications
  RT:  USGS meetings
  UF:  oral presentations
       talks
       testimony
  TNR: 1092
speleology
  USE: geomorphology
spiders
  USE: arachnids
sponges
  BT:  invertebrates
  RT:  invertebrate zoology
  SN:  Aquatic invertebrates belonging to the phylum Porifera having internal skeletons of silica or collagen, porous body around a cavity or cavities, and usually living in stationary communities.
  TNR: 1094
sport fishing
  USE: recreational fishery resources
spring (season)
  BT:  seasons
  TNR: 1660
spring ecosystems
  USE: freshwater ecosystems
Sr
  USE: strontium
SSM/I
  BT:  microwave imaging
  RT:  geography
       snow and ice cover
  UF:  SSM/I images
       Special Sensor Microwave/Imager (SSM/I)
  SN:  Special Sensor Microwave/Imager (SSM/I), technique using passive microwave radiometers aboard satellites to measure the microwave reflectivity of the earth, oceans, and the atmosphere.
  TNR: 1097
SSM/I images
  USE: SSM/I
sst
  USE: sea surface temperature
stable isotope analysis
  USE: light stable isotope analysis
standard reference samples
  USE: materials standards
standards
  BT:  reports
  RT:  USGS standards development
  SN:  An object or instrument of known properties used as a model, for comparison, or a set of rules used to assure quality.
  TNR: 1099
standards development (USGS)
  USE: USGS standards development
statistical analysis
  BT:  computational methods
  NT:  kriging
       multivariate statistical analysis
       regression analysis
       time series analysis
  UF:  geostatistics
  SN:  Branch of mathematics concerned with techniques to collect and interpret data.
  TNR: 1101
statutes
  USE: laws and regulations
storms
  BT:  atmospheric and climatic processes
  NT:  blizzards
       hurricanes
       ice storms
       tornadoes
       dust storms
  RT:  hazards
       meteorology
       precipitation (atmospheric)
  SN:  Atmospheric disturbances with winds of unusual force or direction. Accompanied by rain, snow, hail, or sleet, and often by thunder and lightning.
  TNR: 1102
storm surge
  BT:  floods
  SN:  Coastal high water level caused by wind from storms.
  TNR: 1730
stormwater runoff
  USE: runoff
strain history
  USE: deformation (geologic)
stratigraphic sections
  BT:  earth characteristics
  NT:  bedrock geologic units
       geologic contacts
       surficial geologic units
  RT:  geologic structure
       stratigraphy
  UF:  geologic sections
       geologic units
       sections (geologic)
       sections (stratigraphic)
  SN:  Vertical arrangement in layers of rock units whose sequence is used to study the geological history of the strata.
  TNR: 1103
stratigraphy
  BT:  geology
  RT:  bedrock geologic units
       biostratigraphy
       borehole logging
       electrical resistivity logging
       gamma-ray logging
       geochronology
       geologic contacts
       geologic history
       lithostratigraphy
       stratigraphic sections
       surficial geologic units
       unconformities
  SN:  Branch of geology concerned with the study of the formation, composition, ordering in time, and arrangement in space of stratified rocks.
  TNR: 1104
stream-flow monitoring
  USE: stream-gage measurement
stream-gage measurement
  BT:  field inventory and monitoring
  RT:  hydrology
       streamflow
       acoustic doppler current profiling
  UF:  gage-height monitoring
       stream current monitoring
       stream flow monitoring
       stream gage monitoring
       stream-flow monitoring
       stream-gage monitoring
       streamflow monitoring
  SN:  Use of specialized instruments designed for observing, checking, and recording the water discharge that occurs in a natural channel.
  TNR: 1116
stream-gage monitoring
  USE: stream-gage measurement
stream current
  USE: streamflow
stream current monitoring
  USE: stream-gage measurement
stream discharge
  BT:  streamflow
  RT:  hydrology
       river systems
       surface water (non-marine)
  UF:  river discharge
       stream discharge monitoring
  SN:  Volume of water in a stream passing a given point at a given moment in time, expressed as a measure of volume per unit of time, i.e. cubic feet per second, million gallons per day, or gallons per minute.
  TNR: 998
stream discharge monitoring
  USE: stream discharge
stream ecosystems
  USE: freshwater ecosystems
streamflow
  BT:  hydrologic processes
  NT:  stream discharge
       turbidity
  RT:  hydrology
       stream-gage measurement
       surface water (non-marine)
       water circulation
       watershed management
       surface-water level
  UF:  flood stage
       fluvial processes
       gage height
       stream current
       stream flow
       stream stage
       streamflow data
       streamflow modeling
  SN:  A type of channel flow, applied to a specific part of surface runoff in a stream, whether or not it is affected by diversion or regulation.
  TNR: 1113
stream flow
  USE: streamflow
streamflow data
  US+: datasets
       streamflow
streamflow modeling
  US+: mathematical modeling
       streamflow
stream flow monitoring
  USE: stream-gage measurement
streamflow monitoring
  USE: stream-gage measurement
stream gage monitoring
  USE: stream-gage measurement
stream gaging stations
  USE: field monitoring stations
stream stage
  USE: streamflow
strong motion
  USE: earthquake occurrences
strontium
  BT:  chemical elements
  RT:  alkaline earth elements
  UF:  Sr
  SN:  Alkaline earth element with symbol Sr and atomic number 38 <http://periodic.lanl.gov/elements/38.html>
  TNR: 1581
structural geology
  BT:  geology
  RT:  earth structure
       folding (geologic)
       foliation (geologic)
       fracture (geologic)
       geologic structure
       lineation (geologic)
       neotectonic processes
       structure contours
       tectonic processes
       tectonophysics
  SN:  Branch of geology concerned with the distribution, position, shape, and internal structure of rocks.
  TNR: 1117
structure contours
  BT:  geologic structure
  RT:  structural geology
  UF:  depth-to maps
       thickness maps
  SN:  Gridding and contouring lines drawn on geologic maps to depict boundaries of structural features.
  TNR: 1118
subbituminous coal resources
  USE: coal resources
subduction
  USE: tectonic processes
subsistence fishery resources
  BT:  fishery resources
  SN:  The stock of fish taken and eaten by local populations rather than marketed.
  TNR: 1121
subsurface maps
  US+: geology
       maps and atlases
succession (biological)
  BT:  ecological processes
  RT:  ecology
  UF:  ecologic succession
  SN:  Gradual replacement of one species in an area by another.
  TNR: 1123
sulfur
  BT:  chemical elements
  RT:  nonmetal elements
  UF:  S
  SN:  Nonmetal element with symbol S and atomic number 16 <http://periodic.lanl.gov/elements/16.html>
  TNR: 1582
summer
  BT:  seasons
  TNR: 1661
surface-water/ground-water interaction
  USE: ground-water and surface-water interaction
surface-water level
  BT:  surface water (non-marine)
  RT:  ground-water level
       streamflow
  SN:  Height of the water surface in a lake or reservoir. For water levels in flowing streams, refer to streamflow.
  TNR: 1743
surface water (non-marine)
  BT:  water resources
  NT:  river systems
       surface-water level
  RT:  floods
       freshwater ecosystems
       hydrology
       limnology
       ocean characteristics
       ocean processes
       stream discharge
       snow and ice cover
       streamflow
       surface water quality
  UF:  freshwater (surface)
  SN:  Open bodies of water, such as lakes, rivers, or streams.  All non-marine waters on the  surface of the earth, including fresh, brackish, and salt water.
  TNR: 1124
surface water/ground water interaction
  USE: ground-water and surface-water interaction
surface water quality
  BT:  water quality
  RT:  hydrology
       limnology
       surface water (non-marine)
       water chemistry
  SN:  Chemical, physical, and biological characteristics of water in lakes, rivers, or streams related to its fitness for use.
  TNR: 1125
surficial deposits
  USE: unconsolidated deposits
surficial geologic maps
  US+: surficial geologic units
       maps and atlases
surficial geologic units
  BT:  stratigraphic sections
  RT:  stratigraphy
  UF:  surficial geologic maps
  SN:  Rock units on the earth's surface.
  TNR: 1127
surveying
  USE: land surveying
suspended load
  USE: sediment transport
suspended material (water)
  BT:  water properties
  RT:  hydrology
       water chemistry
  SN:  Sediment or particles of rock, sand, soil, and organic detritus carried in suspension in the water column, in contrast to sediment that moves on or near the streambed.
  TNR: 1129
symbiosis
  BT:  population and community ecology
  UF:  commensalism
       mutualism
       parasitism
  SN:  An intimate, prolonged association between two or more organisms of different species that may or may not benefit each member.
  TNR: 1688
symposia (USGS)
  USE: USGS symposia
systematics and taxonomy
  BT:  life sciences
  RT:  meristics
  UF:  taxonomy
  SN:  Study of the identification, naming, and classification of organisms.
  TNR: 1131
Ta
  USE: tantalum
tagging
  USE: plant and animal tagging
taiga ecosystems
  USE: forest ecosystems
talks
  USE: speeches and testimony
tall grass ecosystems
  USE: grassland ecosystems
tantalum
  BT:  chemical elements
  RT:  metal elements
  UF:  Ta
  SN:  Metal element with symbol Ta and atomic number 73 <http://periodic.lanl.gov/elements/73.html>
  TNR: 1584
taphonomy
  USE: paleontology
tar sand resources
  USE: oil sand resources
taxonomy
  USE: systematics and taxonomy
Tb
  USE: terbium
Tc
  USE: technetium
Te
  USE: tellurium
technetium
  BT:  chemical elements
  RT:  metal elements
  UF:  Tc
  SN:  Metal element with symbol Tc and atomic number 43 <http://periodic.lanl.gov/elements/43.html>
  TNR: 1588
technical instructions
  USE: manuals
technical reports
  USE: reports
technical support (USGS)
  USE: USGS technical support
technology transfer (USGS)
  USE: USGS technology transfer
tectonic maps
  US+: tectonic processes
       maps and atlases
tectonic processes
  BT:  geologic processes
  NT:  neotectonic processes
  RT:  earth structure
       earthquakes
       folding (geologic)
       foliation (geologic)
       fracture (geologic)
       lineation (geologic)
       seismology
       structural geology
       tectonophysics
       volcanic activity
  UF:  continental drift
       dynamic geology
       paleotectonic maps
       plate tectonics
       subduction
       tectonic maps
       tectonics
       wilson cycle
  SN:  The structural forces affecting the deformation, uplift, and movement of the earth's crust.
  TNR: 1145
tectonics
  USE: tectonic processes
tectonophysics
  BT:  geophysics
  RT:  asthenosphere
       continental lithosphere
       crust (earth)
       earth history
       earth structure
       earthquakes
       lithosphere
       neotectonic processes
       oceanic lithosphere
       structural geology
       tectonic processes
       volcanology
  SN:  Branch of geophysics concerned with the structural forces affecting the deformation, uplift, and movement of the earth's crust.
  TNR: 1147
telemetry
  BT:  field inventory and monitoring
  RT:  animal tracking
       remote sensing
  UF:  biotelemetry
       radio telemetry
  SN:  Field technique using instruments which measure heat, radiation, speed, or other property and transmit the data to a distant receiver.
  TNR: 1148
tellurium
  BT:  chemical elements
  RT:  nonmetal elements
  UF:  Te
  SN:  Nonmetal element with symbol Te and atomic number 52 <http://periodic.lanl.gov/elements/52.html>
  TNR: 1589
temperature (air)
  USE: air temperature
temperature (ocean)
  USE: ocean temperature
temperature (sea surface)
  USE: sea surface temperature
temperature (water)
  USE: water temperature
temperature analysis (Curie)
  USE: Curie temperature analysis
tephrochronology
  BT:  age estimation methods
  RT:  lithostratigraphy
  SN:  Age determination of rocks and deposits by correlation of volcanic ash layers (tephra) that bound the deposits below and above.
  TNR: 1681
terbium
  BT:  chemical elements
  RT:  lanthanide series elements
  UF:  Tb
  SN:  Rare earth (lanthanide series) element with symbol Tb and atomic number 65 <http://periodic.lanl.gov/elements/65.html>
  TNR: 1590
terminologies and classifications
  BT:  product types
  NT:  geologic time scales
  UF:  glossaries
       controlled vocabularies
  SN:  Collections of terms often including definitions or scope notes, with some stated relationships among terms
  TNR: 1744
terrestrial ecosystems
  BT:  ecosystems
  NT:  coastal ecosystems
       desert ecosystems
       forest ecosystems
       grassland ecosystems
       shrubland ecosystems
       tundra ecosystems
       island ecosystems
  RT:  ecology
       wetland ecosystems
  UF:  rangeland ecosystems
  SN:  Communities of living organisms in a specific geographical location which exist primarily on land and not in water.
  TNR: 1156
tertiary
  BT:  cenozoic
  NT:  neogene
       paleogene
  TNR: 1662
testimony
  USE: speeches and testimony
text documents
  USE: reports
Th
  USE: thorium
thallium
  BT:  chemical elements
  RT:  metal elements
  UF:  Tl
  SN:  Metalloid element with symbol Tl and atomic number 81 <http://periodic.lanl.gov/elements/81.html>
  TNR: 1592
thematic mapper
  USE: multispectral imaging
therapeutic methods
  BT:  laboratory methods
  RT:  anatomy and physiology
       ecotoxicology
       pathology
  SN:  Methods of  restoring health with remedial agents or treatments.
  TNR: 1160
thermal imaging
  BT:  remote sensing
  RT:  geography
  SN:  Remote sensing techniques using instruments to measure emitted thermal radiation to form images of the earth's surface.
  TNR: 1161
thermoelectric power generation water use
  USE: power generation water use
thermoluminescence dating
  USE: luminescence dating
theses
  USE: reports
thickness maps
  US+: structure contours
       maps and atlases
thin section analysis
  USE: petrography
thorium
  BT:  chemical elements
  RT:  actinide series elements
  UF:  Th
  SN:  Rare earth (actinide series) element with symbol Th and atomic number 90 <http://periodic.lanl.gov/elements/90.html>
  TNR: 1593
thulium
  BT:  chemical elements
  RT:  lanthanide series elements
  UF:  Tm
  SN:  Rare earth (lanthanide series) element with symbol Tm and atomic number 69 <http://periodic.lanl.gov/elements/69.html>
  TNR: 1594
Ti
  USE: titanium
ticks
  USE: arachnids
tidal waves
  USE: tsunamis
tides (oceanic)
  BT:  ocean processes
  RT:  ocean circulation
       ocean currents
       ocean sciences
  UF:  ocean tides
  SN:  The periodic rise and fall of the level of the sea due to the gravitational attraction of the moon and sun. Occurs twice each day.
  TNR: 1168
tiltmeter
  USE: tiltmeter measurement
tiltmeter measurement
  BT:  field inventory and monitoring
  RT:  seismology
       volcanology
  UF:  tiltmeter
  SN:  Determination of tiny changes in the slope angle or tilt of the ground in order to monitor deformation caused by moving magma. Instruments detect variations in a liquid level or in the position of a pendulum.
  TNR: 1169
time periods
  BT:  Categories
  NT:  geologic time periods
       seasons
  SN:  Geologic time periods and seasons of the year
  TNR: 1663
time series analysis
  BT:  statistical analysis
  RT:  time series datasets
  SN:  Statistical analysis using frequency distribution in which time is an independent variable. A sequence of observations collected at regular time intervals is studied.
  TNR: 1171
time series datasets
  BT:  datasets
  RT:  time series analysis
  SN:  Digital information describing observations taken at regular time intervals.  The time interval may vary; the type of observed phenomena and the location typically do not.
  TNR: 1172
tin
  BT:  chemical elements
  RT:  metal elements
  UF:  Sn
  SN:  Metalloid element with symbol Sn and atomic number 50 <http://periodic.lanl.gov/elements/50.html>
  TNR: 1596
titanium
  BT:  chemical elements
  RT:  metal elements
  UF:  Ti
  SN:  Metal element with symbol Ti and atomic number 22 <http://periodic.lanl.gov/elements/22.html>
  TNR: 1597
Tl
  USE: thallium
TL/OSL dating
  USE: luminescence dating
Tm
  USE: thulium
TMDL
  BT:  environmental assessment
  UF:  total maximum daily load
  SN:  A calculation of the maximum amount of a pollutant that a waterbody can receive and still meet water-quality standards.
  TNR: 1380
tomography
  BT:  field inventory and monitoring
  UF:  seismic tomography
       radar tomography
  SN:  Observation of the internal structure of an object or, as is more typical in USGS research, a cross section of the earth's crust by changing the relative orientation of a signal generator, a sensor, or both.
  TNR: 1716
tool development
  USE: instrument design and development
topics
  BT:  Categories
  NT:  elements
       field monitoring stations
       recreation
       agriculture
       biological and physical processes
       culture and demographics
       earth characteristics
       global change
       hazards
       health and disease
       human impacts
       information system design and development
       instrument design and development
       land use and land cover
       map coordinate systems
       contamination and pollution
       natural resource exploration
       natural resource extraction
       natural resources
       organism groupings (non-taxonomic)
       organisms
       planetary bodies
       population and community ecology
       scientific careers
       water properties
       water quality
       water supply and demand
  SN:  Themes, subjects, and concerns for which USGS information resources are relevant.
  TNR: 1174
topographic maps
  US+: topography
       maps and atlases
topography
  BT:  earth characteristics
  NT:  bathymetry
  RT:  geography
       geomorphology
       geospatial datasets
  UF:  contour lines
       quadrangle maps
       relief maps
       elevation
       topographic maps
  SN:  The shape of the land surface.
  TNR: 1176
topological analysis
  BT:  computational methods
  RT:  geography
       geospatial analysis
       spatial analysis
  SN:  Branch of geometry concerned with the properties of objects that do not change even when deformed, twisted, stretched or otherwise changed in shape.
  TNR: 1177
tornadoes
  BT:  storms
  RT:  meteorology
  SN:  Violent storms characterized by whirling funnels of wind moving at great speeds.
  TNR: 1178
total maximum daily load
  USE: TMDL
tours (USGS)
  USE: USGS exhibits and facility tours
toxicology
  USE: ecotoxicology
toxic radionuclide contamination
  BT:  contamination and pollution
  RT:  ecotoxicology
       environmental health (human)
       radon
  SN:  Introduction into the environment of unstable isotopes of elements that undergo radioactive decay, emitting radiation that is harmful to organisms.
  TNR: 1180
toxic trace element contamination
  BT:  contamination and pollution
  NT:  mercury contamination
  RT:  ecotoxicology
       environmental health (human)
  SN:  Introduction into the environment of elements (such as arsenic, cadmium, lead, and mercury) which have a deleterious effect on living organisms when found naturally in only minor amounts (concentrations less than 1.0 milligram per liter) in water or sediment.
  TNR: 1181
trace fossils
  USE: ichnofossils
tracer study
  BT:  field experiments
  UF:  isotopic tracer study
       radioisotope tracer study
  SN:  Experiments in which stable, easily detected substances or radioisotopes are added to a material to follow the movement of the substance in the environment or to detect any physical or chemical changes with time.
  TNR: 1376
tracking
  USE: animal tracking
transcripts
  USE: reports
transect sampling
  BT:  field sampling
  RT:  plot sampling
       trenching
  SN:  Systematic method of collecting field data by recording observations or collecting specimens along a vector or measured course across the environment.
  TNR: 1186
transpiration
  BT:  ecological processes
  RT:  evaporation
  UF:  evapotranspiration
  SN:  Evaporation of water from plants.
  TNR: 1356
transportation
  BT:  culture and demographics
  UF:  air transportation
       aviation
       ground transportation
  SN:  Movement of people or materials from one place to another for economic, political, or recreational purposes.
  TNR: 1689
trapping (animals)
  USE: capturing (animals)
tree ring analysis
  BT:  laboratory methods
  RT:  geochronology
       age estimation methods
  UF:  age dating (tree ring)
  SN:  Study of the variations in width and number of tree rings to date historical events and to study periods of climatic and hydrologic changes.
  TNR: 1188
trees
  USE: vegetation
trenching
  BT:  field sampling
  RT:  plot sampling
       sedimentology
       soil sciences
       transect sampling
  SN:  Field method used by earth scientists to study the underground structure of an area. A long narrow ditch is dug to locate geologic features, such as a fault.
  TNR: 1189
triassic
  BT:  mesozoic
  TNR: 1664
trilobites
  BT:  arthropods
  RT:  fossils
       invertebrate paleontology
  SN:  Extinct marine arthropods of the class Trilobita with segmented bodies and jointed appendages found as Paleozoic fossils in many parts of the world.
  TNR: 1190
tritium-helium dating
  USE: tritium analysis
tritium analysis
  BT:  light stable isotope analysis
  RT:  biochemistry
       geochemistry
  UF:  tritium-helium dating
  SN:  Mass spectrometric measurement of the decay of the radioactive isotope of hydrogen in water samples as a means of dating and investigating changes in water.
  TNR: 1191
trophic level dynamics
  USE: food web
trophic relationships
  USE: food web
tsunami preparedness
  US+: hazard preparedness
       tsunamis
tsunamis
  BT:  ocean waves
  RT:  geologic processes
       hazards
       ocean sciences
       seismology
  UF:  tidal waves
       tsunami preparedness
  SN:  Large destructive sea waves generated by earthquakes, volcanic eruptions, or large landslides.
  TNR: 1195
tuff
  USE: volcanic rocks
tundra ecosystems
  BT:  terrestrial ecosystems
  RT:  ecology
  SN:  Biological communities and habitats located in the treeless plains of Arctic regions where the subsoil is permanently frozen.
  TNR: 1196
tungsten
  BT:  chemical elements
  RT:  metal elements
  UF:  W
  SN:  Metal element with symbol W and atomic number 74 <http://periodic.lanl.gov/elements/74.html>
  TNR: 1600
tunicates
  BT:  invertebrates
  UF:  sea squirts
       urochordates
  SN:  Marine organisms of the subphylum tunicata of the phylum chordata.
  TNR: 1733
turbidity
  BT:  streamflow
  UF:  turbulence
  SN:  Internal roughness of the water column within a body of water.
  TNR: 1377
turbidity flow
  USE: sediment transport
turbulence
  USE: turbidity
typhoons
  USE: hurricanes
U
  USE: uranium
unconformities
  BT:  geologic contacts
  RT:  stratigraphy
  SN:  The contact between older rocks and younger sedimentary rocks where erosion had removed some of the older rocks before the younger rocks were deposited.
  TNR: 1198
unconsolidated deposits
  BT:  rocks and deposits
  NT:  clay deposits
       gravel deposits
       sand deposits
  UF:  alluvium
       eolian sediments
       loess
       sediments
       surficial deposits
       sediment geochemistry
  SN:  Loosely bound sediments such as sand, gravel, and silt which tend to accumulate in low areas or valleys.
  TNR: 1199
underwater contours
  USE: bathymetry
underwater photography
  BT:  photography
  RT:  ocean sciences
  UF:  camera tows
  SN:  Photographs taken below the water surface, usually in marine, lacustrine, and estuarine environments.  Subjects are typically benthic organisms and sedimentary structures on the sea floor.
  TNR: 1201
unsaturated zone
  BT:  ground-water level
  UF:  vadose zone
  SN:  The portion of the subsurface above the ground water table.
  TNR: 1717
ununnilium
  BT:  chemical elements
  RT:  metal elements
  UF:  Uuu
  SN:  Metal element with symbol Uuu and atomic number 111 <http://periodic.lanl.gov/elements/111.html>
  TNR: 1602
ununnubium
  BT:  chemical elements
  RT:  metal elements
  UF:  Uub
  SN:  Metal element with symbol Uub and atomic number 113 <http://periodic.lanl.gov/elements/113.html>
  TNR: 1603
ununnunium
  BT:  chemical elements
  RT:  metal elements
  UF:  Uun
  SN:  Metal element with symbol Uun and atomic number 112 <http://periodic.lanl.gov/elements/112.html>
  TNR: 1604
upper carboniferous
  USE: pennsylvanian
uranium
  BT:  chemical elements
  RT:  actinide series elements
  UF:  U
  SN:  Rare earth (actinide series) element with symbol U and atomic number 92 <http://periodic.lanl.gov/elements/92.html>
  TNR: 1605
uranium-lead analysis
  BT:  radiometric dating
  RT:  geochronology
  SN:  Radiometric dating technique to determine the age of earth materials from the ratio of the radioactive isotopes of uranium-235 or uranium-238 to the lead isotope decay products in the sample. The ratio is compared to the known half-life of the uranium isotopes.
  TNR: 1202
uranium-thorium analysis
  BT:  radiometric dating
  RT:  geochronology
  SN:  Radiometric dating technique used to determine the age of earth materials based on determining the ratio of uranium-238 to the decay product thorium-230. The ratio is compared to the known half-life of the uranium isotope.
  TNR: 1203
urbanization
  USE: land use change
urban runoff
  USE: runoff
urochordates
  USE: tunicates
user feedback (USGS)
  USE: USGS customer support and user feedback
user guides
  USE: manuals
user services (USGS)
  USE: USGS user services
USGS
  BT:  Categories
  NT:  USGS budget
       USGS contracts and grants
       USGS facilities
       USGS news
       USGS organization
       USGS personnel
       USGS policies and regulations
       USGS programs
       USGS user services
       USGS community relations
  SN:  Activities, processes, and organizational concepts relevant to USGS itself.
  TNR: 1208
USGS budget
  BT:  USGS
  UF:  budget (USGS)
  TNR: 1209
USGS clearinghouses
  BT:  USGS information services
  RT:  catalogs and indexes
       USGS search services
  UF:  clearinghouses (USGS)
  TNR: 1210
USGS college programs
  BT:  USGS educational services
  UF:  college programs (USGS)
  TNR: 1211
USGS colloquia
  BT:  USGS meetings
  UF:  colloquia (USGS)
  TNR: 1212
USGS community involvement
  USE: USGS community relations
USGS community relations
  BT:  USGS
  UF:  USGS community involvement
  SN:  Interaction and communication with people and public organizations outside USGS to assist with decision-making, not specifically directed to general scientific education.
  TNR: 1695
USGS contracts and grants
  BT:  USGS
  NT:  USGS cooperative research & development agreements (CRADAs)
       USGS technology transfer
  UF:  contracts (USGS)
       grants (USGS)
  TNR: 1213
USGS cooperative research & development agreements (CRADAs)
  BT:  USGS contracts and grants
  RT:  USGS partnerships
  UF:  CRADAs
       cooperative research & development agreements (CRADAs)
       cooperative research and development agreements
  TNR: 1214
USGS customer support and user feedback
  BT:  USGS user services
  NT:  USGS product support
       USGS technical support
  UF:  Frequently Asked Questions (FAQs)
       customer support (USGS)
       user feedback (USGS)
  TNR: 1215
USGS data downloading
  BT:  USGS information services
  UF:  data downloading (USGS)
  TNR: 1216
USGS disciplines
  BT:  USGS organization
  UF:  USGS divisions
  TNR: 1217
USGS divisions
  USE: USGS disciplines
USGS Earth Science Information Centers (ESICs)
  BT:  USGS information services
  RT:  USGS sales and distribution services
  UF:  ESICs
       Earth Science Information Centers (ESICs)
  TNR: 1218
USGS educational services
  BT:  USGS user services
  NT:  USGS college programs
       USGS internships
       USGS K-12 programs
       USGS lifelong learning programs
       USGS meetings
  UF:  educational services (USGS)
  TNR: 1219
USGS employment and volunteer opportunities
  BT:  USGS personnel
  UF:  employment opportunities (USGS)
       volunteer opportunities (USGS)
  TNR: 1220
USGS exhibits and facility tours
  BT:  USGS user services
  NT:  USGS open houses
  UF:  exhibits (USGS)
       facility tours (USGS)
       photo galleries (USGS)
       tours (USGS)
  TNR: 1221
USGS expertise services
  BT:  USGS information services
  UF:  Ask-A services (USGS)
       expertise services (USGS)
  TNR: 1222
USGS facilities
  BT:  USGS
  NT:  USGS field centers
       USGS laboratories
       USGS mapping centers
       USGS nuclear reactors
       USGS observatories
       USGS science centers
       USGS visitor centers
  UF:  facilities (USGS)
  TNR: 1223
USGS fax-on-demand services
  BT:  USGS information services
  UF:  fax-on-demand (USGS)
  TNR: 1224
USGS field centers
  BT:  USGS facilities
  UF:  field centers (USGS)
  TNR: 1225
USGS information services
  BT:  USGS user services
  NT:  USGS clearinghouses
       USGS data downloading
       USGS Earth Science Information Centers (ESICs)
       USGS expertise services
       USGS fax-on-demand services
       USGS libraries and archives
       USGS map servers
       USGS media relations
       USGS publication servers
       USGS sales and distribution services
       USGS search services
  UF:  accessing USGS data and products
       information centers (USGS)
       information services (USGS)
  TNR: 1226
USGS interagency programs
  BT:  USGS programs
  UF:  interagency programs (USGS)
  SN:  Activities in which USGS works with other Federal agencies or non-governmental organizations.
  TNR: 1227
USGS international programs
  BT:  USGS programs
  UF:  international programs (USGS)
  TNR: 1228
USGS internships
  BT:  USGS educational services
  UF:  internships (USGS)
  TNR: 1229
USGS K-12 programs
  BT:  USGS educational services
  UF:  K-12 programs (USGS)
       school programs (USGS)
  TNR: 1230
USGS laboratories
  BT:  USGS facilities
  UF:  laboratories (USGS)
  TNR: 1231
USGS libraries and archives
  BT:  USGS information services
  RT:  datasets
       USGS search services
  UF:  archives (USGS)
       data archives (USGS)
       libraries (USGS)
  TNR: 1232
USGS lifelong learning programs
  BT:  USGS educational services
  UF:  community education (USGS)
       continuing education (USGS)
       informal education (USGS)
       life-long learning programs (USGS)
       lifelong learning programs (USGS)
       non-formal education (USGS)
  TNR: 1233
USGS mapping centers
  BT:  USGS facilities
  RT:  USGS map servers
       USGS maps on demand
  UF:  mapping centers (USGS)
  TNR: 1235
USGS map servers
  BT:  USGS information services
  RT:  USGS mapping centers
       USGS maps on demand
  UF:  interactive map servers (USGS)
       map servers (USGS)
  TNR: 1234
USGS maps on demand
  BT:  USGS sales and distribution services
  RT:  USGS map servers
       USGS mapping centers
  UF:  maps on demand (USGS)
  TNR: 1236
USGS media relations
  BT:  USGS information services
  UF:  USGS press relations
       media relations (USGS)
       press relations (USGS)
  TNR: 1237
USGS meetings
  BT:  USGS educational services
  NT:  USGS colloquia
       USGS symposia
       USGS workshops
  RT:  speeches and testimony
  UF:  meetings (USGS)
  TNR: 1238
USGS news
  BT:  USGS
  UF:  new mapping projects (USGS)
       new projects (USGS)
       news (USGS)
       what's new (USGS)
  TNR: 1239
USGS nuclear reactors
  BT:  USGS facilities
  UF:  nuclear reactors (USGS)
  TNR: 1240
USGS observatories
  BT:  USGS facilities
  UF:  observatories (USGS)
  TNR: 1241
USGS offices
  BT:  USGS organization
  TNR: 1242
USGS open houses
  BT:  USGS exhibits and facility tours
  UF:  open houses (USGS)
  TNR: 1243
USGS organization
  BT:  USGS
  NT:  USGS disciplines
       USGS offices
       USGS partnerships
       USGS regional organization
       USGS teams
  TNR: 1244
USGS partnerships
  BT:  USGS organization
  RT:  USGS cooperative research & development agreements (CRADAs)
  UF:  business partners (USGS)
       cooperative research (USGS)
       cooperators (USGS)
       partnerships (USGS)
  TNR: 1245
USGS personnel
  BT:  USGS
  NT:  USGS employment and volunteer opportunities
  UF:  personnel (USGS)
  TNR: 1246
USGS policies and regulations
  BT:  USGS
  RT:  policies and regulations
  UF:  policies (USGS)
       regulations (USGS)
  TNR: 1247
USGS press relations
  USE: USGS media relations
USGS product support
  BT:  USGS customer support and user feedback
  UF:  product support (USGS)
  TNR: 1249
USGS programs
  BT:  USGS
  NT:  USGS interagency programs
       USGS international programs
       USGS science programs
       USGS standards development
  UF:  programs (USGS)
  TNR: 1250
USGS publication servers
  BT:  USGS information services
  UF:  publication servers (USGS)
  TNR: 1251
USGS regional organization
  BT:  USGS organization
  TNR: 1252
USGS sales and distribution services
  BT:  USGS information services
  NT:  USGS maps on demand
  RT:  USGS Earth Science Information Centers (ESICs)
  UF:  distribution services (USGS)
       map sales (USGS)
       ordering services (USGS)
       price lists (USGS)
       pricing and ordering (USGS)
       sales services (USGS)
  TNR: 1253
USGS science centers
  BT:  USGS facilities
  UF:  science centers (USGS)
  TNR: 1254
USGS science programs
  BT:  USGS programs
  UF:  science programs (USGS)
  TNR: 1255
USGS search services
  BT:  USGS information services
  RT:  USGS clearinghouses
       USGS libraries and archives
  UF:  search services (USGS)
  TNR: 1256
USGS standards development
  BT:  USGS programs
  RT:  standards
  UF:  standards development (USGS)
  TNR: 1257
USGS symposia
  BT:  USGS meetings
  UF:  symposia (USGS)
  TNR: 1258
USGS teams
  BT:  USGS organization
  TNR: 1259
USGS technical support
  BT:  USGS customer support and user feedback
  UF:  technical support (USGS)
  TNR: 1260
USGS technology transfer
  BT:  USGS contracts and grants
  UF:  technology transfer (USGS)
  TNR: 1261
USGS user services
  BT:  USGS
  NT:  USGS customer support and user feedback
       USGS educational services
       USGS exhibits and facility tours
       USGS information services
  RT:  USGS visitor centers
  UF:  user services (USGS)
  SN:  The user services facet contains terms to describe types of services provided by the USGS. For the most part, these are generic terms and not the names of specific services.
  TNR: 1262
USGS visitor centers
  BT:  USGS facilities
  RT:  USGS user services
  UF:  visitor centers (USGS)
  TNR: 1263
USGS workshops
  BT:  USGS meetings
  UF:  workshops (USGS)
  TNR: 1264
Uub
  USE: ununnubium
Uun
  USE: ununnunium
Uuu
  USE: ununnilium
V
  USE: vanadium
vadose zone
  USE: unsaturated zone
vanadium
  BT:  chemical elements
  RT:  metal elements
  UF:  V
  SN:  Metal element with symbol V and atomic number 23 <http://periodic.lanl.gov/elements/23.html>
  TNR: 1610
vascular plants
  BT:  plants (organisms)
  NT:  ferns and fern allies
       flowering plants
       gymnosperms
  RT:  botany
  SN:  Plants which have a specialized conductive system. Includes xylem and phloem: club mosses, ferns, cycads, gymnosperms, and angiosperms.
  TNR: 1265
vegetation
  BT:  organism groupings (non-taxonomic)
  NT:  periphyton
       weeds
       aquatic vegetation
  RT:  botany
       ecology
       plants (organisms)
  UF:  grasses
       trees
       dendroecology
  SN:  Plant life or general plant cover in an area.
  TNR: 1266
Vendian
  USE: Ediacaran
vertebrate paleontology
  BT:  paleontology
  RT:  dinosaurs
       vertebrates
  SN:  Branch of paleontology dealing with fossil animals that have spinal columns.
  TNR: 1267
vertebrates
  BT:  animals
  NT:  amphibians
       birds
       fish
       mammals
       reptiles
  RT:  vertebrate paleontology
       vertebrate zoology
  SN:  Animals possessing a vertebral column or backbone including birds, fishes, amphibians, reptiles, and mammals.
  TNR: 1269
vertebrate zoology
  BT:  zoology
  NT:  herpetology
       ichthyology
       mammalogy
       ornithology
  RT:  game species
       vertebrates
  SN:  Branch of zoology that deals with animals that have spinal columns.
  TNR: 1268
vertical datums
  USE: map coordinate systems
videography
  BT:  methods
  RT:  photography
       remote sensing
       video monitoring
  SN:  The process of recording and editing analog or digital video.
  TNR: 1276
video monitoring
  BT:  field inventory and monitoring
  RT:  videography
  UF:  remote video monitoring
  SN:  Field study employing the use of filming or repeated photography with stationary optical or digital cameras to observe changes in a feature or organism.
  TNR: 1273
videos
  BT:  product types
  SN:  Animation or other motion pictures, including videotape and DVD products.
  TNR: 1350
virology
  BT:  microbiology
  RT:  environmental health (human)
       viruses
  SN:  Branch of biology dealing with viruses and viral diseases.
  TNR: 1279
viruses
  BT:  organisms
  RT:  virology
  SN:  Very small particles visible only with an electronic microscope. Considered to be complex molecules and not living organisms, these are often causes of disease in plants, animals, and bacteria.
  TNR: 1280
visible light imaging
  BT:  remote sensing
  RT:  geography
  UF:  satellite photography
  SN:  Remote sensing methods using electromagnetic radiation which is visible to the human eye to react with the coating on a photographic plate or film.
  TNR: 1281
visitor centers (USGS)
  USE: USGS visitor centers
visualization
  USE: visualization methods
visualization methods
  BT:  computational methods
  UF:  visualization
  SN:  The application of two-dimensional or three-dimensional graphical techniques for the analysis and interpretation of complex numerical data.
  TNR: 1284
vocalization methods
  BT:  field inventory and monitoring
  RT:  wildlife biology
  SN:  Series of methods used to (a) record sonograms (sound spectrogram) of animal sounds which are analyzed to identify the presence of species in an area and to determine distinct sound patterns within a species, e.g., mating calls, danger alerts; (b) attract species to an area for inventory or monitoring by playing recorded animal sounds or mimicking them.
  TNR: 1285
volcanic activity
  BT:  geologic processes
  NT:  volcanic gas emission
  RT:  hazards
       tectonic processes
       volcanology
       lahars
       aviation safety
       volcanic eruption prediction
       earthquakes
  UF:  eruption
       lava flows
       pyroclastic flows
       volcanism
       volcano monitoring
       volcanic tremors
  SN:  Episodes during which gases, ash, and lava (molten rock) escape from vents in the earth's crust, accompanied by minor tremors.
  TNR: 1286
volcanic ash
  USE: volcanic rocks
volcanic eruption prediction
  BT:  risk assessment
  RT:  volcanic activity
  SN:  Estimation of future volcanic activity using geological and geophysical observations.
  TNR: 1698
volcanic gas emission
  BT:  volcanic activity
  UF:  fumarolic activity
  SN:  Emission of gases from fumaroles and volcanoes.
  TNR: 1358
volcanic rocks
  BT:  igneous rocks
  UF:  lava
       pyroclastic
       tuff
       volcanic ash
  SN:  A generally finely crystalline or glassy igneous rock resulting from volcanic action at or near the earth's surface, either ejected explosively or extruded as lava. The term includes near-surface intrusions that form a part of the volcanic structure.
  TNR: 1340
volcanic tremors
  USE: volcanic activity
volcanism
  USE: volcanic activity
volcanology
  BT:  geology
  RT:  geothermal resources
       seismology
       tectonophysics
       tiltmeter measurement
       volcanic activity
  UF:  vulcanology
  SN:  The branch of geology that deals with volcanism and the processes involved in magma flow and eruption through a vent in the earth's surface.
  TNR: 1289
volcano monitoring
  US+: field inventory and monitoring
       volcanic activity
volunteer opportunities (USGS)
  USE: USGS employment and volunteer opportunities
vulcanology
  USE: volcanology
W
  USE: tungsten
wasps
  USE: bees and wasps
waste repositories
  USE: waste treatment and disposal
waste treatment
  USE: waste treatment and disposal
waste treatment and disposal
  BT:  human impacts
  RT:  ecology
       mining hazards
       contamination and pollution
       social sciences
       wastewater use
  UF:  nuclear waste repositories
       radioactive waste repositories
       sewage disposal
       waste repositories
       waste treatment
       wastewater treatment
  SN:  The chemical and physical methods to recycle or dispose of materials which, without treatment, are deemed to have no further value or are too contaminated to be used.
  TNR: 1293
wastewater
  USE: wastewater use
wastewater treatment
  USE: waste treatment and disposal
wastewater use
  BT:  instream water use
  RT:  hydraulic engineering
       hydrology
       waste treatment and disposal
  UF:  gray water
       grey water
       wastewater
  SN:  Water that is reused after release from a wastewater treatment plant.
  TNR: 1295
water-quality
  USE: water quality
water-quality data
  US+: water quality
       datasets
water balance
  USE: water budget
water birds
  USE: birds
water budget
  BT:  water supply and demand
  UF:  water balance
  SN:  An accounting of the inflow, outflow, and storage changes of water in a hydrologic unit.
  TNR: 1297
water chemistry
  BT:  geochemistry
  NT:  marine chemistry
  RT:  ground-water quality
       nutrient content (water)
       oxygen content (water)
       salinity
       surface water quality
       suspended material (water)
       water hardness
       water pH
       water properties
       water quality
       water sampling
       water temperature
  SN:  Branch of chemistry that deals with the elements and compounds in water.
  TNR: 1298
water circulation
  BT:  hydrologic processes
  RT:  atmospheric circulation
       hydrology
       ocean circulation
       streamflow
  UF:  circulation (water)
       estuarine circulation
       estuarine currents
       lake circulation
  SN:  The flow of water in a body of water due to wind or other forces or variations in density or temperature. Use 'water circulation' for situations that are not specifically covered by narrower terms. Use 'ocean circulation' for water circulation in the oceans.
  TNR: 1299
water cycle
  BT:  hydrologic processes
  RT:  evaporation
       precipitation (atmospheric)
       ground-water flow
  UF:  hydrologic cycle
       recharge
  SN:  Interchange of water among land, oceans, and atmosphere.
  TNR: 1360
water demand
  USE: water supply and demand
waterfowl
  USE: birds
water hardness
  BT:  water properties
  RT:  hydrology
       water chemistry
  UF:  hardness (water)
  SN:  Indicator of the concentration of alkaline salts in water, mainly calcium and magnesium, as a measure of water quality.
  TNR: 1301
water pH
  BT:  water properties
  RT:  hydrology
       water chemistry
  UF:  pH (water)
  SN:  The negative logarithm of the hydrogen ion concentration or activity of a water solution. Used for expressing both acidity (pH less than 7) and alkalinity (pH greater than 7), with 7 considered neutral.
  TNR: 1302
water pollution
  US+: water resources
       contamination and pollution
water properties
  BT:  topics
  NT:  nutrient content (water)
       oxygen content (water)
       salinity
       suspended material (water)
       water hardness
       water pH
       water temperature
       dissolved gases
  RT:  hydrology
       water chemistry
       water quality
  SN:  Measurable physical and chemical characteristics of water from different sources.
  TNR: 1304
water properties (marine)
  USE: marine chemistry
water quality
  BT:  topics
  NT:  ground-water quality
       marine water quality
       surface water quality
  RT:  aquatic biology
       drinking water use
       hydrology
       water chemistry
       water properties
       contamination and pollution
  UF:  dissolved constituents
       dissolved contaminants
       water-quality data
       water-quality
  SN:  The chemical, physical, and biological characteristics of water, usually in respect to its suitability for a particular purpose.
  TNR: 1306
water resource management
  BT:  natural resource management
  RT:  hydraulic engineering
  UF:  artificial recharge
       impoundment
       reclaimed water
  SN:  Methods of controlling or directing resources and activities related to water for a predetermined goal.
  TNR: 1307
water resources
  BT:  natural resources
  NT:  ground water
       surface water (non-marine)
  RT:  hydrogeology
       hydrology
       limnology
       ocean characteristics
  UF:  hydrosphere
       water pollution
  SN:  Stocks of water, the liquid derived from precipitation. A constituent of living matter and necessity for all life, it covers a large proportion of the earth's surface.
  TNR: 1308
water sampling
  BT:  field sampling
  RT:  hydrology
       water chemistry
  SN:  Methods of collecting a representative part of a body of water for testing in controlled conditions.
  TNR: 1309
watershed management
  BT:  natural resource management
  RT:  erosion
       floods
       streamflow
  SN:  Controlling and directing the resources and activities associated with the land and streams of a drainage basin to maintain the supply and quality of water and prevent floods, erosions, and other destructive conditions.
  TNR: 1318
water subsurface
  USE: ground water
water supply and demand
  BT:  topics
  NT:  water budget
       water use
  UF:  water demand
  SN:  The quantities of water resources in an area that are easily available and the amount of water that is needed for all uses.
  TNR: 1311
water table
  USE: ground-water level
water temperature
  BT:  water properties
  RT:  hydrology
       water chemistry
  UF:  temperature (water)
  SN:  The degrees of heat of water from a given source at a specific time.
  TNR: 1312
water use
  BT:  water supply and demand
  NT:  instream water use
       offstream water use
  RT:  hydraulic engineering
       hydrology
  UF:  consumptive use (water)
       drawdown
       water utilities
  SN:  Water withdrawal for a specific purpose, such as domestic use, irrigation, or industrial processing.
  TNR: 1313
water utilities
  USE: water use
water waves
  USE: ocean waves
weather
  USE: atmospheric and climatic processes
weather monitoring
  US+: atmospheric and climatic processes
       field inventory and monitoring
weather observations
  US+: atmospheric and climatic processes
       field inventory and monitoring
weeds
  BT:  vegetation
  SN:  Plants whose presence in an area is undesirable.
  TNR: 1697
well drilling
  BT:  natural resource extraction
  RT:  drilling and coring
  SN:  The process of artificial excavation for the purpose of withdrawing water, oil, or gas from underground.
  TNR: 1325
well logging
  USE: borehole logging
wetland ecosystems
  BT:  ecosystems
  RT:  wetland functions
       aquatic biology
       ecology
       terrestrial ecosystems
  UF:  marsh ecosystems
       marshland ecosystems
       riparian ecosystems
  SN:  Ecosystems whose soil is saturated for long periods seasonally or continuously, including marshes, swamps, and ephemeral ponds.  More detailed terms for wetlands can be selected from the FGDC Wetland Classification <http://fgdc.gov/standards/status/sub3_4.html>.
  TNR: 1326
wetland functions
  BT:  ecosystem functions
  RT:  wetland ecosystems
       ecology
       hydrology
  SN:  Processes related to wetlands such as support of ecosystems, evaporation effects on weather, nutrient cycles, etc.
  TNR: 1327
whaling
  BT:  marine fishery resources
  RT:  marine biology
  SN:  Taking whales from the ocean for marketing or subsistence purposes.
  TNR: 1328
what's new (USGS)
  USE: USGS news
wildfires
  USE: fires
wildlife
  BT:  organism groupings (non-taxonomic)
  RT:  animals
       wildlife biology
  SN:  Undomesticated organisms living in natural settings without dependence on man.
  TNR: 1331
wildlife biology
  BT:  zoology
  RT:  animal tracking
       game management
       game species
       overfishing
       parasitology
       vocalization methods
       wildlife
       wildlife population management
  SN:  Branch of biology dealing with living organisms, usually mammals, birds, or fishes, that are not domesticated or dependent on man.
  TNR: 1332
wildlife population management
  BT:  biological population management
  NT:  game management
  RT:  biogeography
       wildlife biology
  SN:  Monitoring and control of wildlife as a sustainable natural asset.
  TNR: 1333
wilson cycle
  USE: tectonic processes
wind
  BT:  atmospheric and climatic processes
  UF:  wind erosion
  SN:  Local air movements.
  TNR: 1690
wind erosion
  US+: erosion
       wind
winter
  BT:  seasons
  TNR: 1666
workshop reports
  USE: reports
workshops (USGS)
  USE: USGS workshops
worms
  BT:  invertebrates
  NT:  flatworms
       roundworms
       segmented worms
  RT:  invertebrate zoology
  SN:  Invertebrate animals of the phyla Annelida, Nematoda, Memertea, or Plathyhelminthes, that have long thin rounded or flat bodies without obvious appendages.
  TNR: 1336
x-ray diffraction
  BT:  chemical analysis
  RT:  mineralogy
  SN:  Study of crystals which uses short wave electromagnetic radiations (x-rays). The xrays, scattered by the crystal atoms, show a characteristic interference pattern that is dependent upon the structure of the crystal.
  TNR: 1337
Xe
  USE: xenon
xenon
  BT:  chemical elements
  RT:  noble gas elements
  UF:  Xe
  SN:  Noble gas element with symbol Xe and atomic number 54 <http://periodic.lanl.gov/elements/54.html>
  TNR: 1613
Y
  USE: yttrium
Yb
  USE: ytterbium
yearbooks
  USE: reports
ytterbium
  BT:  chemical elements
  RT:  lanthanide series elements
  UF:  Yb
  SN:  Rare earth (lanthanide series) element with symbol Yb and atomic number 70 <http://periodic.lanl.gov/elements/70.html>
  TNR: 1616
yttrium
  BT:  chemical elements
  RT:  metal elements
  UF:  Y
  SN:  Metal element with symbol Y and atomic number 39 <http://periodic.lanl.gov/elements/39.html>
  TNR: 1617
zinc
  BT:  chemical elements
  RT:  metal elements
  UF:  Zn
  SN:  Metal element with symbol Zn and atomic number 30 <http://periodic.lanl.gov/elements/30.html>
  TNR: 1618
zirconium
  BT:  chemical elements
  RT:  metal elements
  UF:  Zr
  SN:  Metal element with symbol Zr and atomic number 40 <http://periodic.lanl.gov/elements/40.html>
  TNR: 1619
Zn
  USE: zinc
zoology
  BT:  life sciences
  NT:  invertebrate zoology
       vertebrate zoology
       wildlife biology
  RT:  animals
       capturing (animals)
       carnivores
       consumers (organisms)
       herbivores
       migratory species
       omnivores
       pollinators
  UF:  malacology
  SN:  Branch of biology that deals with the reproduction, development and growth, anatomy, physiology, and behavior of animals.
  TNR: 1339
zooplankton
  USE: plankton
Zr
  USE: zirconium