The Maas once flowed through the primeval area. But due to a fracture in the earth's crust, the ground rose more and more. This pushed the Maas to the east and the land became higher. That high piece of land is called a horst. Hence the name Maashorst. The lower-lying area is called a slenk.
On the west side of the primeval area lies one of the largest fractures: the Peelrandbreuk. Along the Peelrandbreuk many wijsgronden can be found. These are high, marshy areas where the iron-rich groundwater rises as seepage. A rare phenomenon that is nowhere in Europe as visible as here in De Maashorst near the Annabos in Uden.
Due to the wet parts of the wijsgronden, the part near the Sint Annabos had become difficult to access for hikers. The sVLU, IVN and Vogelwacht wanted to make the wijs accessible to visitors. They did this by setting up a crowdfunding campaign for the construction of a log bridge over the wettest part. This log bridge was built in 2018.