Bernese Alps through which the Rhône finds its way to Lake Geneva, to the Grimsel Pass or, depending on the definition, to the river Reuss (thus including the Uri Alps). The principal ridge, a chain that runs from west (Dent de Morcles) to east (Sidelhorn), whose highest peak is the Finsteraarhorn, forms the watershed between the cantons of Bern and Valais. Except for the westernmost part, it is also the watershed between the Rhine (North Sea) and the Rhône (Mediterranean Sea). This chain is not centered inside the range but lies close (10 to 15 km) to the Rhône on the south.
Geology of the Alps and high peaks in the Pennine Alps and Hohe Tauern . The formation of the Mediterranean Sea is a more recent development and does not mark the northern extent of terranes originating within the African plate. The Alps form a northward convex arc around their southeastern foreland basin, the Po river basin (to be precise the south is in fact their hinterland). Quaternary and Neogene sediments in this basin lie discordant over the southernmost thrust units. In the northeast, southward dipping and internally thrusted Cenozoic foreland deposits (flysch and molasse) are found. This Bavarian and Swiss foreland basin is called