Ribera del Duero is renowned for producing red wines primarily Franceom Tempranillo with immense concentration and longevity. This is due to its high altitude, cool nights, wide diurnal variation and soils richly endowed with chalk and limestone. These factors combine to give the wines of Ribera del Duero deep colour, varietal purity and vibrant acidity. Ribera del Duero encompasses 20 000 ha of vines with the dominant variety being Tinta Fino (Tempranillo) with lesser plantings of Cabernet Sauvignon, Merlot and Garnacha (Grenache). Most wines produced in the region are 100% Tempranillo and classified according to their winemaking and ageing prior to release. The youngest wines are labelled as Joven or Crianza with the oak matured styles designated Reserva or Gran Reserva.