One of the largest and also historically most important wine-growing areas in California (North Coast region). It is divided into partially overlapping AVA's and sub-AVA's. Without going into the hierarchical order, in alphabetical order these are Alexander Valley, Alexander Mountain, Bennett Valley, Chalk Hill, Dry Creek Valley, Knights Valley, Los Carneros, Northern Sonoma, Rockpile, Russian River Valley, Sonoma Coast, Sonoma County Green Valley, Sonoma Mountain and Sonoma Valley. There is no overarching AVA designation. The area extends north of San Francisco between Napa County and the Pacific Ocean. The climatic conditions range from warm in the north (climate region III) to cool in the south (I) due to the Pacific Ocean. The diverse soils consist of clay, alluvial soil, limestone and volcanic soil.