North Coast

1. 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, and clay) is also widespread.
2. Sonoma County:
   • Goldridge soils (sandy loam) in Russian River Valley.
   • Volcanic soils in Dry Creek Valley and Alexander Valley.
   • Clay and marine sediments in coastal areas.
3. Los Carneros:
   • Clay-dominated soils, ideal for cool-climate varieties like Pinot Noir and Chardonnay.
4. Mendocino County:
   • Varied soils, including alluvial soils near the river valleys and volcanic soils in upland areas.
5. Lake County:
   • Volcanic soils rich in minerals, especially around Clear Lake.
6. West Sonoma Coast:
   • Sandy and loamy soils with marine influences.

Central Coast

1. Santa Barbara:
   • Sandy and clay loam soils, with marine sediment in coastal areas.
2. Monterey County:
   • Gravelly and sandy soils in the Salinas Valley.
   • Alluvial deposits in low-lying areas.
3. Paso Robles:
   • Limestone-rich soils, which retain moisture.
   • Sandy and clay soils, with some alluvial deposits.
4. San Luis Obispo County:
   • Volcanic soils and marine sedimentary soils.
5. Santa Cruz Mountains:
   • Decomposed shale and sandstone.
   • Loamy and rocky soils at higher elevations.
6. Livermore Valley:
   • Gravelly soils with good drainage.
7. San Benito County:
   • Limestone soils mixed with loam and clay.

Inland Valleys

1. Lodi and the Delta:
   • Sandy loam soils, with good drainage.
   • Rich alluvial soils from nearby rivers.
2. Sacramento Valley:
   • Fertile alluvial soils, ideal for high-yield vineyards.
3. San Joaquin Valley:
   • Sandy and clay soils, often requiring irrigation.

Sierra Foothills

1. Amador County:
   • Decomposed granite and volcanic soils.
   • Rocky soils with good drainage.
2. El Dorado County:
   • Granite-based soils with sandy loam.
   • Volcanic influences in higher elevations.
3. Other Counties (Placer, Nevada, Yuba, Calaveras):
   • Rocky, granitic soils with moderate fertility.

Southern California

1. Temecula Valley:
   • Granitic soils with sandy loam.
   • Good drainage, suitable for Rhône and Mediterranean varietals.
2. Los Angeles County:
   • Alluvial soils with sandy and clay compositions.
3. San Diego County:
   • Decomposed granite with sandy loam.
4. Cucamonga Valley:
   • Sandy soils, particularly suited for Zinfandel.

Far North California

Sandy loam and clay soils in river valleys.