While traditionally the area of Port production, the Douro Valley has gradually been moving more and more to dry wine production. Currently about half the wines they produce are Port wine and half are dry wines. Terraced vineyards are very common in the Douro region. Vineyards dedicated to Port production are usually planted on schist while areas with granite-based soils are used for table wine production. The region is protected from Atlantic winds by coastal mountains and has a mediterranean climate, with hot and dry summers and cold winters. It is generally divided into three sub-regions: Baixo Corgo (“”below Corgo””), a subregion with the mildest climate and most precipitation; Cima Corgo (“”above Corgo””) where the majority of the famous Quintas are located; and Douro Superior (“”upper Douro””) the hottest and driest of the subregions.