Mud is a mixture of water and any combination of soil, silt, and clay, and usually forms after rainfall or near water sources. Ancient mud deposits harden over geological time to form sedimentary rock such as shale or mudstone (generally called lutites). When geological deposits of mud are formed in estuaries the resultant layers are termed bay muds.
Building and construction
In the construction industry, mud is a semi-fluid material that can be used to coat, seal, or adhere materials. Depending on the composition of the mud, it can be referred by many different names, including slurry, mortar, plaster, stucco, and concrete.
Mud, cob, adobe, clay, and many other names are historically used synonymously to mean a mixture of subsoil and water possibly with the addition of stones, gravel, straw, lime, and/or bitumen. This material was used a variety of ways to build walls, roofs and floors.
Mud that is mostly clay, or a mixture of clay and sand may be used for ceramics, of which one form is the common fired brick. Fired brick are more durable but consume much more energy to produce.
Stabilized mud (earth, soil) is mud which has had a binder such as cement or bitumen added. Examples are mudcrete, landcrete, and soil cement.