The Chamonix Valley is an exceptional site dominated by Mont Blanc, the highest point in Europe. It has attracted lovers of grandiose landscapes for over two centuries. It is in this valley that mountain tourism was born with hiking, mountaineering and winter sports. This site also attracted, very early, the crystallizers in search of the famous "rock crystals", then geologists who tried to understand the formation of the mountains. The conference proposes a journey during which the observation of landscapes and rocks makes it possible to retrace the climatic and geological history of the region from the Varisque orogeny over 400 million years ago to the Quaternary glaciations and earthquake. This conference will notably introduce the Lac Blanc excursion.