Journey to the Earth's core

This part of the Alps is a land of sedimentary mountains. The limestone was formed over millions of years by the accumulation of sediment and seashells at the bottom of an ocean (between 250 and 50 million years ago). These massifs are marked by the presence of numerous sinkholes and chasms carved out by the water as it dissolved the limestone. The nearby Jean-Bernard chasm, with a depth of -1602 metres below sea level, is one of the best-known in the world.