<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-269" name="Gravel Mixes" parent="SC-263" scope="Substrate Group: Geologic Substrate surface layer contains 30% to &lt; 80% 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-272" name="Muddy Gravel" parent="SC-269" scope="Substrate Subgroup: Geologic Substrate is 30% to &lt; 80% Gravel, with Mud composing 50% or more of the remaining Mud-Sand mix."/><term thcode="62" code="SC-271" name="Muddy Sandy Gravel" parent="SC-269" scope="Substrate Subgroup: Geologic Substrate is 30% to &lt; 80% Gravel, with Sand composing from 50% to &lt; 90% of the remaining Sand-Mud mix."/><term thcode="62" code="SC-270" name="Sandy Gravel" parent="SC-269" scope="Substrate Subgroup: Geologic Substrate is 30% to &lt; 80% Gravel, with Sand composing 90% or more of the remaining Sand-Mud mix."/></nt></descriptor>