Soft, plastic, sticky or slippery matter, generally containing water and clay minerals derived from fine-grained soil/regolith/sediment materials. Mud is commonly composed of clay-size particles, but often contains mixtures of sand- and silt-size particles as well as microorganisms. Potter et al. (2005) considers mud a sedimentological field term for unconsolidated fine-grained sediments of any composition and consisting of 50% or more of particles smaller than 0.0063 mm (i.e., clay and silt size fractions).
Cf., geotherapy, matured mud, pelotherapy, poultice, Udden-Wentworth scale