Soil and terroir

Terroir is the sum of a site's natural factors: soil, subsoil, slope, altitude and microclimate. Soil plays a central role in several ways. Free-draining soils such as gravel and sand force roots to search deeper for water, stressing the vine just enough — a stressed vine concentrates aromas into fewer berries. Calcareous soils, as in Champagne and Chablis, preserve acidity in the grape and often impart a chalky mineral character. Clay soils retain moisture and warmth and produce fuller, softer wines, as in Pomerol. Slate, common in the Mosel, absorbs solar heat during the day and radiates it at night — helping the grape ripen despite the cool climate.