Selective sedimentation refers to sedimentation and is the effect that heavier clasts end up in a moving water medium (such as a river) than the lighter parts. For example, gravel of the sediments is deposited first and clay is transported to further from the source area. In the case of the Meuse river, gravel has only ended until about central Limburg because it is heavier than clay and so earlier in the river course.
In mining and water treatment, selective sedimentation is used to separate the fraction with the small particles from a suspension.
wiki
