<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="2.1" 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."/><bt><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="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="2.1.7" name="Coarse-grained mixed clastic rock" parent="2.1" scope="A mixture of clastic sedimentary rocks varying from siltstone to conglomerate, dominated by rocks containing coarse sand-sized or gravel-sized particles."/><term thcode="4" code="2.1.5" name="Conglomerate" parent="2.1" scope="A coarse-grained clastic sedimentary rock, composed of rounded to subangular fragments larger than 2 mm in diameter typically containing fine-grained particles in the interstices, and commonly cemented by calcium carbonate, iron oxide, silica, or hardened clay..."/><term thcode="4" code="2.1.2" name="Fine-grained mixed clastic rock" parent="2.1" scope="A mixture of clastic sedimentary rocks varying from mudstone to sandstone, dominated by rocks containing clay-sized or silt-sized particles"/><term thcode="4" code="2.1.4" name="Medium-grained mixed clastic rock" parent="2.1" scope="A mixture of clastic sedimentary rocks varying from siltstone to conglomerate, dominated by rocks containing sand-sized particles"/><term thcode="4" code="2.1.1" name="Mudstone" parent="2.1" scope="A general term that includes claystone, siltstone, shale, and argillite, and that should be used only when the amounts of clay-sized and silt-sized particles are not known or specified, or cannot be precisely identified..."/><term thcode="4" code="2.1.8" name="Olistostrome" parent="2.1" scope="A sedimentary deposit consisting of a chaotic mass of intimately mixed heterogeneous materials (such as blocks and muds) that accumulated as a semi-fluid body by submarine gravity sliding or slumping of unconsolidated sediments."/><term thcode="4" code="2.1.3" name="Sandstone" parent="2.1" scope="A medium-grained clastic sedimentary rock composed of abundant sand-sized fragments, which may have a finer-grained matrix (silt or clay), and which is more or less indurated by a cementing material..."/><term thcode="4" code="2.1.6" name="Sedimentary breccia" parent="2.1" scope="A breccia (coarse-grained clastic rock composed of angular broken rock fragments held together by a mineral cement or a fine-grained matrix) formed by sedimentary processes"/></nt></descriptor>