The limit of the Allgäu Alps in the north is indistinct. One more restricted variant runs from the confluence of the Weißach and Bregenzer Ach along the Weißach to Oberstaufen. It then continues along the Konstanzer Ache and the Großer Alpsee lake to Immenstadt and onwards through the villages of Rettenberg, Wertach, Nesselwang to Pfronten-Ried. Then it continues along the Vils stream to where it discharges into the Lech near the town of Vils. However, there are more mountains north of this line which, albeit not especially high - are made of the same rock as the larger mountains of the Allgäu Alps and were uplifted by the same orogenic processes. If these ridges are counted as part of the Allgäu Alps, then the northern boundary runs from Lake Constance near Lindau to Isny and northwards around the Adelegg to Kempten. From there it goes via Nesselwang and Füssen to the Lech, the boundary running north of the Falken ridge.