Le sol de la côte Brune à la côte Blonde

To the south of the appellation, the Côte blonde's parcels lie atop a substrate composed primarily of gneiss (and composite gneiss to the far south). Erosion created siliceous soils, light in colour, often with increased calcification due to the loess coating of the plateau. On the Côte blonde, and in similar locations, the clay soil or "arzel" that results from erosion to this substrate is extremely crumbly and unstable. They cannot be cultivated without being held in place by a series of dry stone walls known locally as "cheys".

To the north of the appellation, the Côte brune's parcels lie atop a substrate composed of mica-schist. When these rocks degrade, they form less siliceous soils with a higher clay content, richer in iron and dark in colour. On the hillsides of the Côte brune or similar areas, there is more clay and therefore greater stability. The hillside is carved into narrow terraces, or "chaillées", forming a type of stairway that secures the vines on its relatively flat steps.

Blonde or brune, the chemical composition of these rocks is quite similar. Their distribution can be explained by the way that they were formed some 300-350 million years ago: the pressure and temperatures were higher in the south of the appellation than to the north.

The planted parcels (a mixture of Syrah and Viognier vines) meet more frequently on the Côte blonde than on the Côte brune.