The valley has a length of over 20 kilometers and extends from upstream Benzenrade in the southeast to downstream Sittard in the northwest. On the north side of Sittard the valley merges into the lowlands of Central Limburg. Between Heerlen and Nuth the valley is part of the Heerlen Basin. In the northeast the valley is bordered by the Doenrade Plateau, into which the Kakkertdal and the Watersleijergrub cut. In the southwest, the valley is bounded by the Ubachsberg Plateau (including Kunderberg), the Central Plateau and the Graetheide Plateau, which corresponds to the course of the Benzenrader Fault.
On the slopes of the valley there are several forests, including the Imstenraderbos and the Stammenderbos, and nature reserves, including the Geleenbeekdal and the Kunderberg.