Grésivaudan

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The Grésivaudan (Vallée du Grésivaudan, old spelling: Graisivaudan ) is mainly in the Isère department ; it is a valley of the French Alps and includes part of the lower reaches of the Isère river .

Panorama of the Grésivaudan as seen from Sept-Laux. To the left Grenoble , in the middle of Le Touvet , right Chambery in the Savoie department .

The alluvial plain of the Isère between Grenoble and the mouth of the Arc is usually referred to as Grésivaudan . Some geologists and geographers see the Grésivaudan as the alluvial plain between Tullins (below Grenoble) and Albertville . That is why one speaks of Bas-Grésivaudan (between Tullins and Grenoble) and Haut-Grésivaudan (between Grenoble and Albertville).

View of the Grésivaudan valley from Sept-Laux

The Grésivaudan marks the border between the French pre-Alps , which consist mainly of limestone massifs ( Bauges , Chartreuse and Vercors ), and the actual Alps, which consist mainly of granite and metamorphic rocks ( Vanoise massif , Belledonne ). It is part of the alpine furrow ("Sillon alpin"), a group of valleys and depressions in the south-south-west - north-north-east orientation, and includes the lower reaches of the Drac , the upper Grésivaudan, the valley of the Arly and the upper reaches of the Arve and partly the valley from Chamonix . Geologically, one can also add the upper reaches of the Rhone in Switzerland ( canton Valais ). The Sillon alpin thus extends over the departments Isère, Savoie and Haute-Savoie .

The most important places of the Grésivaudan are (from north to south): Albertville , Montmélian , Pontcharra , the agglomeration of Grenoble and Moirans .

View into the Grésivaudan valley from the summit of the Croix de Belledonne , in the background the Massif de la Chartreuse

Emergence

The Grésivaudan is a trough valley . Its trough profile was formed by influences from the Ice Age and the Post-Ice Age. The excavation of the valley since the Würm Ice Age took place in the following stages:

  • The Isère glacier formed in the valley as a result of the climatic cooling.
  • It stretched down to Tullins, was formed by the Rhone Glacier , which spread out in the north of the Isère department on one of the Lyon plains.
  • Over thousands of years, the subsoil and the side walls of the valley eroded, giving it a U-profile.
  • At the same time, the ice built up, the drainage of which was blocked by the Voreppe Gorge and the Rhone Glacier. At Grenoble the ice was about 1,600 meters thick.
  • Since the beginning of the current warm period around 10,000 years ago, the Isère glacier has gradually retreated, leaving behind an extensive lake similar to the great lakes in Italy ( Lake Maggiore , Lake Como and Lake Lugano ), which completely filled the Isèretal between Tullins and Albertville.
  • The rivers eroded the surrounding mountains, the rocks of which were deposited in this lake. After the lake was filled with stones, today's situation arose: a plain lined with steep walls, the level of which corresponds to the water level at that time.

Hydropower

The Grésivaudan was the cradle of hydropower , which was to become the main driving force behind the industrial development of the valley: near Lancey in the municipality of Villard-Bonnot Reste, you can find the first buildings by Aristide Bergès from 1869.

Coordinates: 45 ° 19 '  N , 5 ° 57'  E