Terroir - Soil and climate
Situated on a low plateau sloping towaeds the
Garonne, the diversity of soils and sub-soils give the various
Sauternes vineyards their special personality.
However, what gives them their extraodinary
originality is the frequency of morning fog in autumn, which is quickly
dispered by the heat of sun.
The Ciron river is chiefly responsible for this.
It used to join the Garonne at Cérons, but its course was
diverted during the 16th century by the Benedictine monks. Nowadays it
flows into the Garonne between Barsac and Preignac.
This morning humidity followed by warm sun
encourages the proliferation of "noble rot" on the ripe grapes. This
fungus, called "Botrytis cinerea", penetrates the grapes via stomata
and causes the fruit to shirvel, thus concentrating the juice contained
within the pulp and increasing the sugar content.