<descriptor thcode="62"><thesaurus thcode="62" name="Coastal and Marine Ecological Classification Standard" scope="Categories of ecosystems for coastal, estuarine, and marine environments." creator="FGDC" rights="public domain" date="2017-05-10" codetype="alpha" prefix="cmecs" uri="https://www2.usgs.gov/science/CMECS" tblname="cmecs" root_code="root" contact="pschweitzer"><category><term thcode="25" code="16" name="hierarchical" parent="11" scope="Substantive broader-narrower relationships exist among the terms."/><term thcode="25" code="16" name="hierarchical" parent="11" scope="Substantive broader-narrower relationships exist among the terms."/></category><altlabel><altlabel>CMECS</altlabel><altlabel>CMECS</altlabel><altlabel>Coastal and Marine Ecological Classification Standard (CMECS)</altlabel><altlabel>Coastal and Marine Ecological Classification Standard (CMECS)</altlabel></altlabel></thesaurus><term thcode="62" code="SC-273" name="Gravelly" parent="SC-263" scope="Substrate Group: Geologic Substrate surface layer contains 5% to &lt; 30% Gravel (particles 2 millimeters to &lt; 4,096 millimeters in diameter). ..."/><bt><term thcode="62" code="SC-263" name="Coarse Unconsolidated Substrate" parent="SC-029" scope="Substrate Subclass: Geologic Substrate surface layer contains &gt; 5% Gravel (particles 2 millimeters to &lt; 4,096 millimeters). These sediments are classified using the upper three rows of the Folk (1954) Gravel-Sand-Mud diagram."/><term thcode="62" code="SC-029" name="Unconsolidated Mineral Substrate" parent="SC-025" scope="Substrate Class: Geologic Substrates with less than 50% cover of Rock Substrate. ..."/><term thcode="62" code="SC-025" name="Geologic Substrate" parent="SC-C003" scope="Substrate Origin: Benthic substrates where percent cover of Rock and Unconsolidated Mineral Substrate exceeds percent cover of both Biogenic and Anthropogenic Substrates, considered separately. ..."/><term thcode="62" code="SC-C003" name="Substrate" parent="root"/><term thcode="62" code="root" name="CMECS" scope="Coastal and Marine Ecological Classification Standard: Category terms encompassing waters from the head of tide or inland incursion of ocean salinity to the splash zone of the coasts to the deepest portions of the oceans and the deep waters of the Great Lakes."/></bt><nt><term thcode="62" code="SC-276" name="Gravelly Mud" parent="SC-273" scope="Substrate Subgroup: Geologic Substrate is 5% to &lt; 30% Gravel, and the remaining Sand-Mud mix is 50% or more Mud."/><term thcode="62" code="SC-275" name="Gravelly Muddy Sand" parent="SC-273" scope="Substrate Subgroup: Geologic Substrate is 5% to &lt; 30% Gravel, and the remaining Sand-Mud mix is 50% to &lt; 90% Sand."/><term thcode="62" code="SC-274" name="Gravelly Sand" parent="SC-273" scope="Substrate Subgroup: Geologic Substrate is 5% to &lt; 30% Gravel, and the remaining Sand-Mud mix is 90% or more Sand."/></nt></descriptor>