Muddy Deposit is a term used to describe a type of sedimentary deposit that is composed of a mixture of clay, SILT, and organic matter. The crossword solutions for this term are SLUDGE (6 letters), SILT (4 letters), and SAPROPEL (8 letters). SLUDGE is a type of sedimentary deposit that is composed of clay and organic matter. SILT is a type of sedimentary deposit that is composed of fine particles of sand, clay, and other materials. Sapropel is a type of sedimentary deposit that is composed of organic matter and clay.