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    Napa Valley

    USA

    Thirty miles of valley where volcanic and marine soils meet, and half of the world's soil orders.

    30–50° N30–50° SequatorNapa
    Vineyard area
    19 108 ha1
    Country
    USA
    Rocks in the profile
    topsoil, alluvium, volcanic rock

    Volcanoes and the sea

    The valley was formed by tectonic plate movement and volcanic activity, and soils of volcanic and marine origin sit side by side.2 Half of the world's 12 soil orders occur here.1 Alluvial fans spread from the hills onto the valley floor, where soils are deeper and more fertile; hillside soils are thin and rocky.2

    topsoilalluviumvolcanic rock
    Schematic profile based on the sources, not to scale.

    Cabernet country

    Cabernet Sauvignon covers 10,284 hectares, 54% of the vineyard.1 The valley is 30 miles long and five miles across at its widest.3 It produces about 4% of California's wine grapes.4

    The climate is dry Mediterranean.5 The AVA is defined in federal regulation 27 CFR 9.23 and contains 17 nested AVAs.6,1

    Timeline

    1. 1968

      The Napa Valley Agricultural Preserve is created, the first in the United States.1

    2. 1981

      Napa Valley becomes California's first American Viticultural Area.4

    Grapes

    Soils

    Sources

    1. Napa Valley Fast Facts. Napa Valley Vintners, 2025. level 4 · checked 2026-10-13
    2. Soils and geology. Napa Valley Vintners. level 4 · checked 2026-10-13
    3. Geography. Napa Valley Vintners. level 4 · checked 2026-10-13
    4. Napa Valley. Napa Valley Vintners. level 4 · checked 2026-10-13
    5. Climate. Napa Valley Vintners. level 4 · checked 2026-10-13
    6. 27 CFR § 9.23 Napa Valley. TTB / eCFR. level 1 · checked 2026-10-13