California's beautiful and remarkably fertile Sonoma Valley has grown over the decades to become one of the United States' most respected and profitable wine regions, with wineries within the region benefiting from the superb Californian sunshine, low rainfall and wonderfully rich soils. Because of this vital combination of excellent conditions, the region is able to grow a wide range of grape varietals for use in the production of an impressive array of wines, with many different red and white wine grapes flourishing each year and producing excellent and characterful results. The soils have been enriched by volcanic activity, and the presence of geothermal springs, which make this region a unique one, and very much the beating heart of California's ever growing wine industry. Although primarily associated with the Rhone region of France, the precise origins of the Viognier grape variety are unknown, and the subject of much debate. However, these fine and delicate green skinned grapes are an important varietal for many of France's most elegant white wines, and they are quickly beginning to spread around the New World, too, where wineries are discovering their unique qualities and unusual character. Viognier grapes are notoriously difficult to grow, due to the fact they are highly susceptible to mildew, but wineries persevere with them nonetheless, producing wines which are highly aromatic and have a great, fruit-forward character. Their delicate aroma suggests sweetness due to its flowery, sappy nature, but the wine itself generally very dry and crisp, and full of summery, light and refined qualities.