A tide-dominated system, with a narrow reflective high-tide beach composed of coarse sediments, fronted by wide (100's to several 1000's of metres), low gradient (<1°) mud flats with tidal drainage channels.
Mangroves or other vegetation may grow in the upper intertidal zone. These beaches occur in sheltered environments where there is a source of mud nearby and where waves are insufficient to remove muds. They are similar to the reflective + tidal sand flats , with mud, rather than sand, occupying the intertidal zone. Usually calm conditions at the shore, but a low wind chop prevails during strong onshore winds. It's a long distance to the low tide shore where deep tidal channels and currents may prevail.
NIWA