Mud

Definition of Mud: Fine-grained sediment composed of clay and silt, often containing organic matter, in which the clay fraction (typically ≥20%) imparts cohesive properties that control the bulk behaviour. This is the common definition for Mud, other definitions can be discussed in the article

Mud deposit on an intertidal flat; the dark coloration (iron sulfides) indicates oxygen-depleted conditions a few centimeters below the surface.

Fine cohesive minerals and organic matter, collectively designated as mud, are a major component of sediments in coastal and marine environments. Their cohesive properties lead to distinct geotechnical, transport, erosion, and sedimentation behavior compared to non-cohesive sediments such as sand.

Mud influences seabed stability, bedforms, and the development of features such as tidal flats and estuaries. It also underpins key habitats, including mangroves and salt marsh. In addition, mud plays an important role in biogeochemical cycles and ecosystem dynamics, for example through its effects on water turbidity, light availability, and oxygen conditions (anoxia). Consequently, mud has significant economic and environmental implications, particularly for navigation (e.g., harbor siltation), water quality, and biodiversity.

Despite its importance for both physical and ecological processes, understanding of mud dynamics remains largely based on empirical observations rather than on fully developed quantitative theory.

Several Coastal Wiki articles deal with various aspects of mud dynamics:

Dynamics of mud transport: Comprehensive introduction to the processes and modelling of mud erosion, sedimentation and transport

Flocculation cohesive sediments: The cohesive properties of mud their influence on settling processes

Sediment deposition and erosion processes: Empirical relationships of mud deposition and erosion processes based on laboratory and field studies

Fluid mud: Formation and properties of fluid mud layers and their role in wave damping

Estuarine turbidity maximum: Processes driving mud accumulation in estuaries and their impact

Coastal mud belt: Processes contributing to mud accumulation and mud bank formation in the nearshore coastal zone

Coastal and marine sediments: Origin, characteristics, properties, deposits and spatial distribution of coastal and marine sediments

The ecology of muddy shores is discussed in the article Mangroves and in articles related to Salt marsh.