Vineyard plantings began on the mountainsides west of the town of Sonoma in the 1880s, as early viticultural pioneers found much to like in the well-drained volcanic soils of the Mayacamas range that separates Sonoma Valley from Napa Valley. More than a century later, those same hillsides would become both one of California’s most important centres of organic viticulture and one of its most distinctive mountain growing regions.

In fact, in 2013, these folded lava hillsides were separated from the larger Sonoma Valley AVA and defined as the Moon Mountain District, named after a peak of the same name enclosed within its boundaries. (See the Southern Sonoma map from The World Atlas of Wine.)

The AVA encompasses 17,663 acres (7,148 acres) of land and more than 1,500 acres (over 600 ha) of vineyards, with its boundaries defined through a combination of volcanic soils and elevation. About 16 wineries make their homes within the AVA, with more than 70 vineyards supplying fruit not only to those resident wineries but also to dozens of outside producers.

Several California appellations claim volcanic soils. Others offer high-elevation growing conditions. A handful are home to historic vineyards. The Moon Mountain District is unusual in combining all three, while also serving as one of the cradles of California’s modern organic viticulture movement.

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Photo at top: Lasseter Winery’s Trinity Ridge vineyard. Photo by Michael Housewright Photography, courtesy of Moon Mountain Winegrowers Association.