The so-called Middle Weser Valley begins where the actual Weser Valley (in the
Weser Uplands) ends at the Porta Westfalica gap between the
Wiehen Hills on the west and the
Weser Hills on the east. By its formal definition, the Middle Weser begins ten kilometres further north at the
Minden Aqueduct, flowing across the
North German Plain through
Petershagen and
Nienburg. Conceptually, the
Middle Weser Valley ends near Hoya, where the Middle Weser reaches the Breslau-Magdeburg-Bremen
glacial valley. As a
natural region the Middle Weser Valley, which consists of
flood plains and
river terraces, is a strip of land up to wide on both sides of the Middle Weser. It is counted as part of the
Dümmer Geest Depression and the
Middle Weser Region. Of particular note are the Weseraue and Staustufe Schlüsselburg nature reserves. == Political division ==