Cienega Valley AVA
One of the most unique AVA's in all of California wine, Cienga Valley is actually two AVA's cobbled together, at least it would be by French standards. Within the United States, AVA's are built around areas which offer the best possible marketing devices, whereas the French split their wine regions into much smaller AVA's which are each unique to sunlight, soil type etc.
Cienga Valley is split down the middle by the San Andreas fault which means that on either side of the fault itself, soil types are completely unrelated, with portions of vineyards having one soil type literally on top of another.
At about 1,100 feet above sea level, Cienga Valley is part of the wider Central Coast AVA.