The region is Virginia's first AVA, identified in 1982. Limestone soil, which is common to the Valley, has been long associated with great wine growing regions in Europe. The Shenandoah Valley AVA's climate allows grapes to attain higher acidity, generally regarded as good in wine.The cooler, relatively dry climate, soil composition and position between two mountain chains makes the Shenandoah Valley more ideal for viticulture than any of the state's other regions. The Shenandoah Valley is relatively dry, a rain shadow between the Blue Ridge and Allegheny Mountains; the annual rainfall in the Valley is one half that of the Virginia average. The growing season in the valley is distinctly warmer and drier than in neighboring Virginia regions, which don't have the natural rain barrier from the nearby mountains and where, east of the Blue Ridge, vineyard soils are primarily clay and loam. The conditions in the Shenandoah Valley AVA are thus more hospitable than those east of the mountains for Cabernet Franc, Chambourcin, Cabernet Sauvignon, Lemberger, Petit Manseng, Petit Verdot, Pinot Noir, and Riesling.