The Reims Mountain is a large forested plateau that stretches from Reims to Epernay. Its flanks form chalky hillsides – some of them north-facing – which are suitable for vineyards. To the north-west of Reims, the soils of the Saint-Thierry massif and, to the north, the Mont de Berru have a higher percentage of sand and silica. The forest acts as a thermal barrier, bringing warm air down on the vines in the evening. These soils are the realm of pinot noir (60% of the area), a grape variety that thrives on limestone soils. The Montagne de Reims is the terroir of the Champagne appellation with the most villages classified as Grand Cru (10 out of 17).