Vineyards in the Redwood Valley AVA sit about 200 feet higher in elevation than those along the Russian River, further downstream in Ukiah and Hopland. Accordingly, the climate of this upland valley is slightly cooler, furthered by a gap in the coastal ridge which allows cool Pacific air currents to penetrate. These conditions lead to a gradual ripening of fruit that makes Redwood Valley Cabernet Sauvignon, Zinfandel, Barbera and Petite Sirah refined and complex. The notable red soil of the area also provides depth of color and flavor to the wines. The earliest vineyards in Mendocino County were planted here among the ancient redwoods by Italian immigrants, although this area did not gain official appellation status until 1997.