Geological history of the morphology of the Lake Geneva basin.

Palaeogeothermal data from the Th (o) over cap nex well near Geneva indicat e that 2000 m of sediment overburden of Upper Oligocene and Miocene age hav e been eroded since Late Miocene, and mainly during the Quaternary, in the Geneva basin. The next younger marker of a palaeotopography are interglacia l sediments near Palezieux, indicating the presence of a lake at 800 m alti tude during the Middle Pleistocene, 730'000 years ago. During the Late Plei stocene, the bedrock/sediment interface, glacial and interglacial deposits show evidence that the Geneva lake basin is getting narrower and deeper dur ing major glacial advances. The sediment fill of the lake stems mainly from the last glacial cycle and melt down starting 18'000 B.P.