Franken stands out among the ranks of the VDP.Regions in many ways. For one thing, the Silvaner grape variety dominates this wine-growing region that spreads from Hörstein near Aschaffenburg to Iphofen between Würzburg and Nuremburg along the Main River. Cultivation of the variety in Franken (Franconia) can be traced back 350 years. A second peculiarity is that many of the wines are sold in flattened ellipsoid Bocksbeutel bottles. Yet another unique feature is that hardly another region is so clearly divided geologically. Bunter (variegated) sandstone dominates the Mainviereck district in the upper reaches of the river; this is where the great red wine villages of Franken (like Klingenberg and Bürgstadt) are found. In the Maindreieck district surrounding Würzburg, shell limestone determines the soils. Vines root in Keuper marl in the Steiger Forest district in the vicinity of Iphofen. All of theses geological formations stem from the Germanic Trias. Due to its long stretch – it is nearly 100 kilometres between Hörstein and Iphofen as the crow flies – Franken generally has a continental climate, but microclimates vary according to the locations of individual vineyards.