Whilst the AVA covers a much larger region, the area planted to vine is just shy of seven-hundred hectares, with most vineyards located around the western slopes of the Mayacamas Mountains. Elevation varies between individual sites but some plots reach heights of five-hundred metres above sea level and thus escape the cooling influence of the fog that so often sweeps through the valley at lower levels. Characterised by volcanic soils and a warmer microclimate than the wider [Russian River Valley AVA](/ava/russian-river-valley-ava), Chalk Hill is a visually appealing appellation that is home to a small number of boutique wineries. A range of grapes have found success in this unique terroir. Amongst them, the red varieties [Cabernet Sauvignon](/cabernet-sauvignon), [Merlot](/merlot) and [Syrah](/syrah), which occupy elevated sites on the hillside and benefit from an ideal aspect and abundant sunshine during the growing season. White grapes such as [Chardonnay](/chardonnay), [Sauvignon Blanc](/sauvignon-blanc) and [Sémillon](/semillon), are principally planted at lower altitudes close to the river from which the larger AVA takes its name. Around one and a half hour’s drive from San Francisco passing over the iconic Golden Gate Bridge, wine tourism is a key feature of the economy here. The majority of Chalk Hill’s wineries offer tours and tastings, led by the somewhat emblematic [Chalk Hill Estate](/producer/chalk-hill-estate) - whose packages perfectly reflect [Sonoma County’s](/county/sonoma-county) style of informal indulgence. The wines here, like those of other cellars in the appellation are wide ranging, luxurious and very often exceptional in quality. Deep, intense [Bordeaux](/region/bordeaux) blends and exquisite, mineral-rich [Sauvignon Blancs](/sauvignon-blanc) are amongst the wines for which this AVA is renowned.