<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="WC-674" name="Water Mass" parent="WC-C012" scope="Hydroform Class: The Water Mass Hydroform Class refers to a parcel of water with homogeneous properties (e.g., chemical, physical). ..."/><bt><term thcode="62" code="WC-C012" name="Hydroform" parent="WC-C001"/><term thcode="62" code="WC-C001" name="Water Column" 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="WC-675" name="Background Mesoscale Field" parent="WC-674" scope="Hydroform: A water mass characterized by organized ocean-surface currents formed by coupled eddies (at the mesoscale length scale); responsible for much of water movement on the ocean surface."/><term thcode="62" code="WC-676" name="Fumarole Plume" parent="WC-674" scope="Hydroform: A plume of hot gases venting from the sea bottom associated with volcanic or tectonic activity from cracks in the Earth's crust; often a site of significant chemoautotrophic activity."/><term thcode="62" code="WC-677" name="Hydrothermal Plume" parent="WC-674" scope="Hydroform: A discharge of hot fluids from sea-bottom vents associated with volcanic or tectonic activity. ..."/><term thcode="62" code="WC-678" name="Ice" parent="WC-674" scope="Hydroform: Frozen form of water, which is less dense than liquid water; ice floats on the surface of liquid water, sometimes extending into deep water zones. ..."/><term thcode="62" code="WC-679" name="Mesoscale Lens" parent="WC-674" scope="Hydroform: A trapped, homogeneous parcel of water lying within (or atop) larger ocean fields due to density differences. These hydroforms are 30 - 300 kilometers in size."/><term thcode="62" code="WC-680" name="Microscale Lens" parent="WC-674" scope="Hydroform: A homogeneous parcel of water on the order of meters to a few kilometers positioned within (or atop) a larger ocean fields of different density."/><term thcode="62" code="WC-682" name="Winter Water Mass" parent="WC-674" scope="Hydroform: The mass of water produced?and introduced to oceans?as a result of melting winter ice formations. These water masses tend to be fresher than surrounding waters, and they often flow over the denser salt water."/></nt></descriptor>