<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="GC-191" name="Mollusk Reef" parent="GC-184" scope="Geoform: An area of many shell reefs surrounded and intermixed with channels and unvegetated flats."/><bt><term thcode="62" code="GC-184" name="Biogenic" parent="GC-C052" scope="Geoform Origin: Biogenic geoforms are physical features and landforms that were created by the action of living organisms (bioherms). ..."/><term thcode="62" code="GC-C052" name="Geoform (levels 1 and 2 subcomponents)" parent="GC-C005"/><term thcode="62" code="GC-C005" name="Geoform" 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="GC-192" name="Fringing Mollusk Reef" parent="GC-191" scope="Geoform Type: Narrow, linear reefs, which are usually lying below the marsh platform. These reefs form along the shore of tidal creeks, and they are typically intertidal (see Figure 6.5)."/><term thcode="62" code="GC-193" name="Linear Mollusk Reef" parent="GC-191" scope="Geoform Type: Narrow straight or sinuous, ridge-like reefs formed primarily by oysters but also by other mollusks. ..."/><term thcode="62" code="GC-194" name="Patch Mollusk Reef" parent="GC-191" scope="Geoform Type: Mounded, generally round or lobate reefs that have some vertical relief above the surrounding substrate. These are usually intertidal, but they can occur in subtidal settings (see Figure 6.7)."/><term thcode="62" code="GC-195" name="Washed Shell Mound" parent="GC-191" scope="Geoform Type: Generally linear accumulations of dead shell that form high in the intertidal zone along tidal creeks and on the landward side of barrier islands. ..."/></nt></descriptor>