North Coast Napa Valley: Volcanic soils (e.g., tufa and basalt) in mountain vineyards. Alluvial soils (e.g., gravel, sand, and clay) on the valley floor. Loam (a mix of sand, silt,...

North Coast Napa Valley: Valley Floor: 0–400 feet (0–120 m). Mountain Vineyards (e.g., Mount Veeder, Howell Mountain): 1,400–2,200 feet (425–670 m). Sonoma County: Coastal Areas: Near sea level to 1,000...