Mud is soil, silt, loam or clay, mixed with water. It is a type of soil that is also called "clay soil". Others include the sandy soil, or sand, and garden soil. Wet mud has a soft wet texture.
Great river systems like the Amazon bring down to the delta immense amounts of mud which ends up in the sea outside the fan of the river mouth. Mudrock is what the mud may become millions of years later. Mudrocks make up fifty percent of the sedimentary rocks in the geologic record, and are easily the most widespread deposits on Earth.[1][2]