A winegrowing terroir is the combination of an identifiable physical and biological environment (soil, subsoil, relief, climate). The limestone subsoil of the Champagne region favours the drainage of the soil. In some places, it is made up of seven different layers (chalk, sand, clay, limestone, etc.). The chalk of Champagne, which is very porous, constitutes a real water reservoir that ensures that the vines have sufficient water supply even during very dry summers. Although seven grape varieties can be used to make Champagne, the Chardonnay (30% of the vineyard), Pinot Meunier (32%) and Pinot Noir (38%) varieties account for more than 98% of the production.