Cluse de Chambéry, Water gap in Chambéry, France

The Cluse de Chambéry is a broad, flat glacial valley about 10 km long and 1.5 to 2.6 km wide, bounded by the Chaîne de l'Épine, the Bauges and the Chartreuse. Its floor is a patchwork of fields, industrial zones and the urban centre of Chambéry, with the Leysse, Albanne and Hyères rivers converging at the city.

The valley is glacial in origin: ice flowing from the Isère valley (Combe de Savoie and Grésivaudan) shaped it during the Quaternary. When the glaciers melted, the floor filled with marshy fluvio-lacustrine alluvium extending the deposits at the southern end of Lac du Bourget. Chambéry later grew on this flat, drained floor, hemmed in by the Chartreuse, Bauges and Épine ranges.

The name "cluse" refers to the valley's role as a passage between the Bauges, Chartreuse and Épine ranges. Where flat land runs short, housing estates were built on the slopes: Bellevue and Biollay on the first Chartreuse foothills, the Hauts-de-Chambéry ZUP on the Lémenc hill, and Cognin's dozen towers at the mouth of the Hyères valley. Parking is often buried under buildings erected from the 1970s, and some estates stand on concrete slabs, as at Le Covet, Cognin, Barberaz and Barby.

The cluse is crossed by the A43 and A41 motorways, the RN 201 urban bypass, the RN 6 (D 1006) and RN 504 (D 1504), plus the Culoz–Modane and Saint-André-le-Gaz–Chambéry railway lines. A greenway, the avenue verte nord de Chambéry, also runs through it. The floor is narrow, from 1.5 km at Servolex to 2.6 km near the lake, so roads and rail share limited space.

The cluse is a glacial valley, carved when ice from the Isère valley (Combe de Savoie and Grésivaudan) flowed through during the Quaternary. When the glaciers melted, the floor filled with marshy fluvio-lacustrine alluvium that extended the deposits at the southern end of Lac du Bourget.