The Bernese Alps are a group of mountain ranges in the western part of the Alps, in Switzerland. Although the name suggests that they are located in the Bernese Oberland region of the canton of Bern, portions of the Bernese Alps are in the adjacent cantons of Valais, Lucerne, Obwalden, Fribourg and Vaud. The latter being informally named Fribourg Alps and Vaud Alps respectively.
The Rhône valley separates them from the Chablais Alps in the west and from the Pennine Alps in the south; the upper Rhône valley separate them from the Lepontine Alps in the south-east; the Grimsel Pass and the Aar valley separates them from the Urner Alps in the east; their northern edge is not so well defined, describing a line roughly from Lake Geneva to Lake Lucerne. The Bernese Alps are drained by the river Aar and its tributary Saane in the north, the Rhône in the south and the Reuss in the east.
One of the most considerable Alpine ranges, the Bernese Alps extend from the gorge of Saint-Maurice, through which the Rhone finds its way to Lake Geneva, to the Grimsel Pass or, depending on the definition, to the river Reuss (thus including the Urner Alps). The principal ridge, a 100 km long chain running from west (Dent de Morcles) to east (Sidelhorn), whose highest peak is the Finsteraarhorn, forms the watershed between the cantons of Berne and Valais. Except for the westernmost part, it is also the watershed between the Rhine (North Sea) and the Rhone (Mediterranean Sea).
This chain is not centered inside the range but lies close (10 to 15 km) to the Rhone river on the south. This makes a large difference between the south, where the lateral short valleys descend abruptly into the deep trench forming the valley of the Rhone and the north, where the Bernese Alps extends through a great part of the canton of Berne (Bernese Oberland), throwing out branches to the west into the adjoining cantons of Vaud and Fribourg. There the mountains progressively become lower and disappear into the hilly Swiss Plateau or into the Lake Thun and Brienz on the eastern part.
Jungfrau-Aletsch area :
The Jungfrau-Aletsch area is located in the eastern Bernese Alps in the most glaciated region of the Alps. It was inscribed as a UNESCO World Heritage Site (Swiss Alps Jungfrau-Aletsch) in 2001 and further expanded in 2007. Its name comes from the Aletsch Glacier and the two summits of the Jungfrau and Bietschhorn, which constitute some of the most impressive features of the site. The actual site (after the extension) includes other large glacier valleys such a the Fiescher Glacier and the Aar Glaciers.