Sonoma, northern california town, valley, and one of the state’s most important wine counties. Sonoma county is one of the larger of northern California’s coastal counties, and one of its most historic. Sonoma Valley is a very small portion of Sonoma county but it rivals and occasionally beats nearby napa Valley for réclame. Vineyards are everywhere in the county, and have been since the last third of the 19th century. Sprawling, geologically and climatically diverse, it is the most resolutely amoebic of all the fine wine regions, having divided and redivided itself into avas and sub-AVAs until they run three layers deep in several places, four in a few, and eight in one. Growing conditions are a little more homogeneous than the welter of names suggests, but Sonoma still gives would-be gurus some of their most engaging opportunities to define subtle boundaries by taste and taste alone. The full roster follows.