ABSTRACT
The commonly twice-a-day flooding and drainage largely defines the character and composition of sediments of the intertidal zone. Sediments are supplied through nearby delta distributaries, by the erosion of headlands, from the adjacent sea floor, and, from greater distances, in suspension. In situ production of sediment by biological activity may be an additional to dominant source of sediment. Intertidal sediments occur along all coasts, but thickness of the deposits and the areal extent vary. Grain size is a reflection of the distance to source areas and of the transport capacity of the hydrodynamic system. Thus, eroding cliff coasts along uplifted bedrock may be characterized by winnowed pebble beaches, while in subsiding areas rivers and marine processes supply large amounts of sandy, silty, and clayey sediments. Microbial activity defines the character of the intertidal zone in carbonate systems to a much greater extent than in siliciclastic systems.
