<descriptor thcode="2"><thesaurus thcode="2" name="USGS Thesaurus" scope="Topics and methods of scientific study carried out by USGS, with product types, scientific disciplines, geologic time, and types of institutional structure and activities.  Broad and shallow, used to help people find scientific information." creator="U.S. Geological Survey" rights="Public domain" edition="2.0" date="2020-01-09" codetype="number" prefix="topic" uri="https://www2.usgs.gov/science/USGSThesaurus" tblname="term" nonpref="nonpref" relterm="relterm" root_code="1" contact="pschweitzer"><category><term thcode="25" code="29" name="distinct labels" parent="26" scope="Preferred labels (descriptor texts) are distinct within the thesaurus. A concept can be specified either by its unique identifier (code) or by the text of its descriptor."/><term thcode="25" code="16" name="hierarchical" parent="11" scope="Substantive broader-narrower relationships exist among the terms."/><term thcode="25" code="13" name="transitive" parent="12" scope="Narrower terms have an &quot;is a&quot; relationship with their broader terms, and generally can be described as part-of, type-of, or instance-of the broader term."/><term thcode="25" code="21" name="disciplines" parent="2" scope="Broad categories of human inquiry or activity, such as scientific disciplines."/><term thcode="25" code="20" name="methods" parent="2" scope="Actions taken to obtain or analyze information"/><term thcode="25" code="19" name="organizational functions" parent="2" scope="Things that organizations do, typically including various types of programs, projects, and services."/><term thcode="25" code="7" name="temporal" parent="2" scope="Terms indicate periods of time, such as chronostratigraphic units, named historical periods or intervals surrounding known historical events, or seasons."/><term thcode="25" code="5" name="theme" parent="2" scope="Terms indicate domains of human concern, such as scientific discipline, societal problems, or characteristics of earth, space, oceans, and living things."/><term thcode="25" code="29" name="distinct labels" parent="26" scope="Preferred labels (descriptor texts) are distinct within the thesaurus. A concept can be specified either by its unique identifier (code) or by the text of its descriptor."/><term thcode="25" code="16" name="hierarchical" parent="11" scope="Substantive broader-narrower relationships exist among the terms."/><term thcode="25" code="13" name="transitive" parent="12" scope="Narrower terms have an &quot;is a&quot; relationship with their broader terms, and generally can be described as part-of, type-of, or instance-of the broader term."/><term thcode="25" code="21" name="disciplines" parent="2" scope="Broad categories of human inquiry or activity, such as scientific disciplines."/><term thcode="25" code="20" name="methods" parent="2" scope="Actions taken to obtain or analyze information"/><term thcode="25" code="19" name="organizational functions" parent="2" scope="Things that organizations do, typically including various types of programs, projects, and services."/><term thcode="25" code="7" name="temporal" parent="2" scope="Terms indicate periods of time, such as chronostratigraphic units, named historical periods or intervals surrounding known historical events, or seasons."/><term thcode="25" code="5" name="theme" parent="2" scope="Terms indicate domains of human concern, such as scientific discipline, societal problems, or characteristics of earth, space, oceans, and living things."/></category><altlabel><altlabel>USGSThesaurus</altlabel><altlabel>USGSThesaurus</altlabel></altlabel></thesaurus><term thcode="2" code="101" name="biological and physical processes" parent="1174" scope="All continuing activities, functions, and phenomena associated with organisms and non-living matter."/><uf><usefor name="bioenergetic processes"/></uf><bt><term thcode="2" code="1174" name="topics" parent="1" scope="Themes, subjects, and concerns for which USGS information resources are relevant."/><term thcode="2" code="1" name="Categories" scope="Thematic terms for categorizing information resources.  This thesaurus is intended to support finding and understanding scientific information."/></bt><nt><term thcode="2" code="63" name="atmospheric and climatic processes" parent="101" scope="Phenomena affecting or occurring within the mass of gases that surrounds the earth, including its physics, chemistry, dynamics, and weather conditions."/><term thcode="2" code="1799" name="coastal processes" parent="101" scope="Processes unique to coastal areas including longshore transport, beach erosion, storm surge, shoreline change, delta formation, barrier island migration, beach stabilization by vegetation"/><term thcode="2" code="310" name="ecological processes" parent="101" scope="Dynamic biogeochemical interactions that occur among and between biotic and abiotic components of the biosphere."/><term thcode="2" code="1800" name="estuarine processes" parent="101" scope="Processes affecting estuaries including tides, waves, mixing of fluvial and marine waters"/><term thcode="2" code="1702" name="evolution" parent="101" scope="Change in the genetic composition of populations of living organisms."/><term thcode="2" code="384" name="fires" parent="101" scope="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'."/><term thcode="2" code="435" name="geochemical processes" parent="101" scope="Processes affecting the amount, distribution, or structure of chemical elements in air, water, soil, rocks, and minerals."/><term thcode="2" code="451" name="geologic processes" parent="101" scope="All types of processes involving geological structures."/><term thcode="2" code="2295" name="hydrocarbon reservoir processes" parent="101" scope="Interactions among groundwater, hydrocarbons, and rock properties of subsurface geological formations, affecting the potential of those formations to form, trap, and permit the passage and extraction of hydrocarbons."/><term thcode="2" code="1667" name="hydrologic processes" parent="101"/><term thcode="2" code="1718" name="impact cratering" parent="101" scope="Impact of extraterrestrial objects such as asteroids, comets, and meteorites on Earth."/><term thcode="2" code="816" name="ocean processes" parent="101" scope="Recurrent natural changes that are physical, biological, or chemical, actively affecting the seas and oceans."/><term thcode="2" code="1347" name="physiological processes" parent="101" scope="Characteristics and processes of individual organisms that are not the direct result of their interaction with other organisms or with the environment."/></nt></descriptor>