The cover mud is a mixture of clay, silt, and sandy soil, and has the grading with a uniformity coefficient (=D_60/D_10) at which secure burrows of sand crabs, etc., can be formed, and the cover mud thus prepared is added to an inter tidal zone. 粘土・シルト・砂質土を混合してスナガニ類の安定な巣穴が形成できる均等係数(=D_60/D_10)の粒度とした被覆土を潮間帯域に客土する。 - 特許庁