In the secondary era, the sea covered the Chablis region, forming particularly rich limestone sediments in its depths. At the end of the Jurassic period, the upheaval of the planet caused the seas to disappear. This soil is then particular and produces the most remarkable wines: a limestone made of millions of small fossils, shells, small oysters very recognizable. The ice age that followed carved the valleys in the sedimentary layers, forming the present Chablisian relief. This geological stage bears the name of kimmeridgian given by a small village in the South of England which is in the same situation.