Chamonix glacier valley

This U-shaped valley was carved out over 10,000 years ago by glaciers that extended as far as Lyon! All glaciers move forward by deforming and sliding under their own weight: the front of the glacier melts with the warmer temperatures of the valley, while the back is rejuvenated by the compacting of the snow at higher altitudes.
These gigantic currents of ice, which are invisible to the naked eye, have carved out and eroded the valley where the town of Chamonix now stands.