<descriptor thcode="4"><thesaurus thcode="4" name="Lithologic classification of geologic map units" scope="Rock types commonly found on geologic maps. Terms may combine compositional, textural, and genetic characteristics. Also includes unconsolidated materials that may be mapped as units. Not specific enough for categorizing hand samples or outcrops." creator="U.S. Geological Survey" rights="Public domain" edition="6.2" date="2004-08-16" codetype="alpha" prefix="lithclass" uri="http://www.usgs.gov/science/Lithclass6.2" tblname="lith" nonpref="lithnp" relterm="lithrt" root_code="0" contact="pschweitzer"><category><term thcode="25" code="10" name="persons" parent="2" scope="Terms specify individual people, typically by name."/><term thcode="25" code="30" name="ambiguous labels" parent="26" scope="A given preferred label may be used for more than one concept in the thesaurus. A concept must be specified using its unique identifier (code). This may occur in the names of places or people."/><term thcode="25" code="17" name="pseudohierarchical" parent="11" scope="Broader-narrower relationships exist in the vocabulary but have no semantic relation to the terms themselves, for example, a list of peoples' names arranged hierarchically by the first letter of the surname."/><term thcode="25" code="14" name="not transitive" parent="12" scope="Narrower terms cannot reliably be understood as parts of, types of, or instances of the terms that are broader than them."/><term thcode="25" code="9" name="organizations" parent="2" scope="Terms specify human organizations, their subdivisions and relationships, as well as characteristics of such organizations."/><term thcode="25" code="10" name="persons" parent="2" scope="Terms specify individual people, typically by name."/><term thcode="25" code="30" name="ambiguous labels" parent="26" scope="A given preferred label may be used for more than one concept in the thesaurus. A concept must be specified using its unique identifier (code). This may occur in the names of places or people."/><term thcode="25" code="17" name="pseudohierarchical" parent="11" scope="Broader-narrower relationships exist in the vocabulary but have no semantic relation to the terms themselves, for example, a list of peoples' names arranged hierarchically by the first letter of the surname."/><term thcode="25" code="14" name="not transitive" parent="12" scope="Narrower terms cannot reliably be understood as parts of, types of, or instances of the terms that are broader than them."/><term thcode="25" code="9" name="organizations" parent="2" scope="Terms specify human organizations, their subdivisions and relationships, as well as characteristics of such organizations."/></category><altlabel><altlabel>Lithclass6.2</altlabel><altlabel>Lithclass6.2</altlabel></altlabel></thesaurus><term thcode="4" code="0" name="Earth material" scope="Geologic map unit classification (Bruce R. Johnson) version 6.2: A hierarchical classification of earth materials for digital geologic maps."/><nt><term thcode="4" code="5" name="Metamorphic rock" parent="0" scope="A rock derived from pre-existing rocks by mineralogical, chemical, and/or structural changes, essentially in the solid state, in response to marked changes in temperature, pressure, shearing stress, and chemical environment, generally at depth in the earth's crust."/><term thcode="4" code="4" name="Plutonic rock" parent="0" scope="A rock formed at considerable depth by crystallization of magma and/or by chemical alteration.  It is characteristically medium- to coarse-grained, of granitoid texture."/><term thcode="4" code="2" name="Sedimentary rock" parent="0" scope="A rock resulting from the consolidation of loose sediment that has accumulated in layers..."/><term thcode="4" code="6" name="Tectonite" parent="0" scope="A rock whose fabric reflects the history of its deformation."/><term thcode="4" code="1" name="Unconsolidated material" parent="0" scope="A sediment that is loosely arranged or unstratified, or whose particles are not cemented together, found either at the surface or at depth."/><term thcode="4" code="3" name="Volcanic rock" parent="0" scope="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 a lava.  The term includes near-surface intrusions that form a part of the volcanic structure."/></nt></descriptor>