The current surface of the regional park is a flat, low plain (the average height above sea level is 2-5 meters) which’s relief was created by the last icing Nemunas delta's glacial hand. Later the surface was reshaped by the pre glacial lakes and the accumulation of delta. All these processes has been accompanied by persistent tectonic sinking (activity of this process is now 1- 2 mm per year). Intensification of farming in the Nemunas river basin, thinned forests and surface waters washing large areas the delta has intensified transfer and accumulation of alluvium. They sat down and accumulated in the delta plain, estuaries and closed some branch openings. Out of touch and siltation of river beds turned into separate strings of little lakes. Deltoid deposits sealed off once the former bay and now the lake - Krokų Lanka. A similar fate awaits Kniaupas bay. The large quantity of silt led to a rapid growth of the delta front, the formation of new islands. Due to the silt delta coast moved 4-8 km. to the west, this process takes place in island Rusė now. Here the coast slides up to the lagoon several meters every year.