<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="2" name="Sedimentary rock" parent="0" scope="A rock resulting from the consolidation of loose sediment that has accumulated in layers..."/><bt><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."/></bt><nt><term thcode="4" code="2.2" name="Carbonate rock" parent="2" scope="A sedimentary rock composed of more than 50% by weight carbonate minerals."/><term thcode="4" code="2.6" name="Chemical sedimentary rock" parent="2" scope="A sedimentary rock composed primarily of material formed directly by precipitation from solution or colloidal suspension or by the deposition of insoluble precipitates."/><term thcode="4" code="2.1" name="Clastic rock" parent="2" scope="A composed principally of broken fragments that are derived from preexisting rocks or minerals and that have been transported some distance from their place of origin."/><term thcode="4" code="2.7" name="Coal" parent="2" scope="A readily combustible rock containing more than 50% by weight and more than 70% by volume carbonaceous material, formed by compaction and induration of variously altered plant remains..."/><term thcode="4" code="2.3" name="Mixed carbonate/clastic rock" parent="2" scope="An undivided mixture of carbonate and clastic sedimentary rocks."/><term thcode="4" code="2.8" name="Mixed coal/clastic rock" parent="2" scope="An undivided mixture of coal and clastic sedimentary rock."/><term thcode="4" code="2.4" name="Mixed volcanic/clastic rock" parent="2" scope="An undivided mixture of volcanic rock and clastic sedimentary rock."/><term thcode="4" code="2.5" name="Phosphorite" parent="2" scope="A sedimentary rock with a high enough content of phosphate minerals to be of economic interest."/></nt></descriptor>