The initial silt from the top and sides of a newly dug feature (ditch, gully, pit, etc.) that falls naturally to the bottom. It occurs as a result of the immediate weathering of the sides and top due to wind or the action of precipitation. Unless the feature was cleaned of this material in antiquity, it may be recognized in many archaeological features, and any material found in it may date from around the time of the original digging. However, a more ancient artifact which was lying on the ground surface close to the lip of the ditch may tumble into the fill when the edges of the trench crumble and collapse.