<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="1036" name="sedimentation" parent="451" scope="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."/><uf><usefor name="alluvial sedimentation"/><usefor name="deposition (sediment)"/><usefor name="dust deposition"/></uf><bt><term thcode="2" code="451" name="geologic processes" parent="101" scope="All types of processes involving geological structures."/><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."/><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><rt><term thcode="2" code="66" name="atmospheric deposition (chemical &amp; particulate)" parent="63" scope="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)."/><term thcode="2" code="1035" name="sedimentary rocks" parent="1005" scope="Rocks formed by the consolidation of loose, uncemented pieces of sediments."/><term thcode="2" code="1037" name="sedimentology" parent="464" scope="Branch of earth sciences concerned with the study of the origin, composition, transport, and changes of materials deposited by water, wind, or ice."/></rt></descriptor>