Close to the rivers of Bordeaux, there is a band of alluvial soil, which is much too rich in nutrients to produce great wine. Only the lowest appellations are grown here. The best wine from bordeaux is grown on gravel, overlying a subsoil of marl, which allows water to drain through, giving the vines that struggle for survival essential for making good wine. Most of this soil is found in the villages of the Haut-Médoc in the north, and in nothern Graves. In Saint-Emilion, the gravel instead covers a base of limestone. In Bordeaux, there are very few hillside vineyards but when they do occur, the soil is usually limestone and clay.