<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="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."/><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="1.1" name="Alluvium" parent="1" scope="A general term for clay, silt, sand, gravel or similar unconsolidated detrital material, deposited during comparatively recent geologic time by a stream or other body of running water, as a sorted or semi-sorted sediment..."/><term thcode="4" code="1.7" name="Biogenic material" parent="1" scope="An organic material produced directly by the physiologic activities of organisms, either plant or animal"/><term thcode="4" code="1.9" name="Clay or mud" parent="1" scope="A loose, earthy, extremely fine-grained, natural sediment composed primarily of clay-size or colloidal particles and characterized by high plasticity and by a considerable content of clay minerals..."/><term thcode="4" code="1.3" name="Eolian material" parent="1" scope="Sediments such as loess or sand deposited by the action of the wind"/><term thcode="4" code="1.6" name="Glacial drift" parent="1" scope="A general term applied to all rock material (clay, silt, sand, gravel, boulders) transported by a glacier and deposited directly by or from the ice, or by running water emanating from a glacier."/><term thcode="4" code="1.12" name="Gravel" parent="1" scope="A loose accumulation of rock fragments composed predominantly of more or less rounded pebbles and small stones"/><term thcode="4" code="1.2" name="Lake or marine sediment" parent="1" scope="A sedimentary deposit laid down conformably on the floor of, or along the shore of, a lake, sea, or ocean, usually consisting of coarse material near the shore and sometimes passing into clay and limestone in deeper water..."/><term thcode="4" code="1.5" name="Mass wasting material" parent="1" scope="Deposits formed by the dislodgement and downslope transport of soil and rock material under the direct application of gravitational body stresses."/><term thcode="4" code="1.8" name="Residuum" parent="1" scope="An accumulation or rock debris formed by weathering and remaining essentially in place after all but the least soluble constituents have been removed..."/><term thcode="4" code="1.11" name="Sand" parent="1" scope="A loose aggregate of unlithified mineral or rock particles of sand size (1/16 to 2 mm); an unconsolidated deposit consisting essentially of medium-grained clastic particles."/><term thcode="4" code="1.10" name="Silt" parent="1" scope="A loose aggregate of unlithified mineral or rock particles of silt size (1/256 to 1/16 mm); an unconsolidated deposit consisting essentially of fine-grained clastic particles."/><term thcode="4" code="1.4" name="Volcanic ash" parent="1" scope="A fine pyroclastic material (under 2.0 mm in diameter).  The term usually refers to the unconsolidated material..."/></nt></descriptor>