A wine terroir combines an identifiable physical and biological environment(soil, subsoil, topography and climate) with applied winemaking practices, conferring distinctive characteristics on the produce of these vineyards.
The limestone subsoil (comprising chalk, limestone, sandstones and marls) provides good drainage and also explains why certain Champagne wines have a distinctly mineral taste.
The Champagne chalk is made up of the skeletons of marine micro-organisms and mollusc fossils from the Secondary Era. It is highly porous.
This means it acts as a reservoir, storing 300-400 litres of water per m3 which provides the vines with a steady supply of water even in the driest summers.