la Loire has high concentration of schist and the Muscadet-Côtes de Grandlieu sub-appellation has a mixture of granite and schist based soils. Appellations There are four main appellations of the Muscadet region. At the lowest level is the umbrella AOC Muscadet which covers the entire 32,000 acre (13,000 hectare) region. Wine expert Jancis Robinson notes that wines carrying this basic designation are normally the most simple examples of Muscadet. Since the late 1990s, this level has been excluded from using sur lie aging by AOC regulations. Next come the three sub-appellations representing different micro-climates of the region: Muscadet-Sèvre et Maine; Muscadet-Coteaux de la Loire, which includes the northernmost expanse of the area; and Muscadet-Côtes de Grandlieu, which is located in the southwestern area around the eponymous lake. As the most northern sub-appellation, the quality of wines from the Muscadet-Coteaux de la Loire can vary greatly depending on the vintage. In cooler years the grapes struggle to ripen and tend not to have the fruit to balance the acidity. In warmer years, this area tends to produce the most balanced wines. Muscadet-Côtes de Grandlieu is the most recent AOC promotion, gaining its status in 1996. Prior to gaining its own sub-appellation, this region was responsible for nearly three-quarters of the wine labeled as basic Muscadet AOC. Well made examples from Muscadet-Côtes de Grandlieu are characterized by floral bouquet and minerality. The Muscadet-Sèvre et Maine sub-appellation is the most productive and notable region of Muscadet, producing more than three-quarters of the region's entire production. (In contrast, the Muscadet-Coteaux de la Loire AOC only produces around 20% of the amount of wine of Muscadet-Sèvre et Maine) In fact, more AOC Muscadet-Sèvre et Maine is produced on a yearly basis than in any other single AOC in the entire Loire Valley. The appellation is located east and south around the city of Nantes and is named after the rivers Sèvre and Maine that flow through it. Vineyard soil composition varies throughout the region and can range from the granite and schist hillsides around the village of Saint-Fiacre-sur-Maine to the predominantly clay based soils of Vallet. The most ideally situated vineyards are located around the villages of La Chapelle-Heulin, St-Fiacre, Vallet and Vertou Around 45% of the wine made Muscadet-Sèvre et Maine is aged sur lie. The wines made in this style tend to be slightly fuller body and can have some of the texture