Champagne chalk is composed of calcite granules derived from the skeletons of marine micro-organisms (coccolites) and is characterized by the presence of belemnite fossils (mollusks from the secondary era). Its high porosity makes it a veritable water reservoir (300 to 400 liters per m3), ensuring an adequate water supply for the plant, even in the driest summers.
Chalk retains water by capillary action, forcing the vine to absorb it. This results in moderate water stress during the growing season, favoring the balance between the fruit's various acids, sugar and aroma precursors that will be revealed in the wine to come.