Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Oude Maasje is a former distributary of the river Maas (or Meuse), which runs parallel to the current canalised Bergse Maas. The hydrological distribution of the Maas changed during the later Middle Ages, when a major flood forced it to shift its main course towards the Merwede river. However, during another series of severe floods the Maas found an additional path towards the sea near Geertruidenberg, resulting in the creation of the Biesbosch wetlands and Hollands Diep estuaries. Thereafter, the Maas split near Heusden into two main distributaries, one flowing north to join the Merwede, and one flowing directly to the sea.