Pascal et Nicolas Reverdy
My apologies for opening this profile with a lengthy geological prelude, but it seems necessary if we are to really understand the relevance of this domaine. The geology of the Loire Valley, and of Sancerre as much as anywhere else, can naturally be very complicated, and perhaps understandably it is therefore prone to simplifications. I have been told, for example, that the best limestones of Sancerre originated in the Kimmeridgian, a period in the Late Jurassic, between 155 and 150 million years ago. The Kimmeridgian is divided into three layers; simplified, the upper layers are Saint Doulchard marl (a marl is stone derived from both calcium carbonate and clay or silt, sort of part-limestone-part-mudstone), rich in the fossil Exogyra virgula, and it is this particular Kimmeridgian limestone that is said to weather into the terres blanches of the slopes above Chavignol. Deeper (older) layers of Kimmeridgian include Calcaire à Astartes, rich in the astartes fossils, and Calcaire de Tonnerre, named for Tonnerre, near Chablis. These two layers of the Kimmeridgian are generally regarded as being the source of caillottes, the ‘other’ main Sancerre limestone terroir.
Of course the truth is the geology of this fascinating wine region is just a little bit more complicated than these opening words might suggest; there is more to Sancerre than just the Kimmeridgian limestones, and there is more to Kimmeridgian than these three simple layers. Other layers have been identified, thanks in part to a long project mapping the entire geology of France carried out by the Bureau de Recherches Géologiques et Minières. These new Kimmeridgian layers include Calcaire de Buzançais and Lumachelle de Exogyra virgula, both found on the slopes around Chavignol. Even so, there is one thing we should agree on; when it comes to limestone, Kimmeridgian is king. It is true in Chablis, where the grand cru slopes all lie on Kimmeridgian bedrock, and it is true in Sancerre.
The Kimmeridgian is most readily associated with Chavignol, and the slopes of terres blenches dotted around this most famous of Sancerre villages yield some of the region’s finest wines. Indeed, this has led some to conclude that it is only Chavignol that possesses Kimmeridgian soils. Again, however, this is a simplification, because the geological survey cited above clearly indicates that the slopes beyond Chavignol are simply bursting with desirable Kimmeridgian limestones. They extend, in one form or another, west from Sancerre across to Bué, and to the slopes and plateau beyond. They also extends northwards, in a finger, with the sands and iron-rich clays of the plateau to the west, and the flinty fault line – on which lie Sancerre and Saint-Satur – to the east. There is desirable Kimmeridgian limestone, Calcaire à Astartes to be precise, upon the slope to the east of Sury-en-Vaux, one of fourteen communes eligible for the Sancerre appellation. And naturally the growers of Sury-en-Vaux make good use of these benevolent soils.