Middle lowlands, the so-called. The land of the Great Valleys, it is like a concave furrow stretching between the lake district and the old mountains and highlands. The lowlands cover almost half of the Polish territory (ok. 48%). The relief of this land was shaped as a result of the activity of the Scandinavian ice sheet and in the later periods of rivers: Odra River, Obry Warty, Notes, Vistula, Lunge, Bug and Narew. Steep or flat edges, indented valleys, long river terraces lined with a series of dunes, these are the characteristic types of landscape. The lowland belt is divided into: The Masovian Lowland, Greater Poland and Silesia.