Lake Geneva is divided into three parts because of its different forms of formation (sedimentation, tectonic folding, glacial erosion): According to the Swiss Federal Office of Topography, swisstopo, "Lac de Genève" designates that part of the "Petit Lac", which lies within the cantonal borders of Geneva (excluding the cantonal exclave Céligny), so about from Versoix–Hermance to the Rhône outflow in Geneva. The Chablais Alps border is its southern shore, the western Bernese Alps lie over its eastern side. The high summits of Grand Combin and Mont Blanc are visible from some places. Compagnie Générale de Navigation sur le lac Léman (CGN) operates
Geology of the Alps valleys repeatedly covered all of the Swiss plain and shoved the topsoil into the low rolling hills seen today. They scooped out the lakes and rounded off the limestone hills along the northern border. The last great glacier advance in the Alps ended some 10,000 years ago, leaving the large lake now known as Lake Neuchatel. The ice in this region reached some 1,000 m (0.6 mi) in depth and flowed out of the region behind Lake Geneva some 100 km (60 mi) to the South. Today large granite boulders are found scattered in the forests in the region. These