The Soil & Terrain of Alexander Valley
The Diversity in Alexander Valley Soil & Terrain
Relatively young geologically, the walls of the valley were formed by volcanic activity uplifting the earth’s crust. These mountain soils are nutrient poor and unfertile. They receive abundant sun exposure and induce scarce, concentrated and flavorful grapes.
These are prime conditions for the Zinfandel and the red Bordeaux varietals which are Cabernet Sauvignon, Merlot, Cabernet Franc, Malbec, and Petit Verdot. These varietals are also grown in the warmer sections of the valley floor.
The geology throughout the valley floor is mainly sedimentary. This is due to the fact that the Russian River travels the length of the narrow AVA. Soils are alluvial, sandy and well-drained leading to large root systems and healthy vines. Sedimentary stones are common in many vineyards and can act as heat retainers.
The hills surrounding Alexander Valley are made of the ancient Franciscan Complex. Most of these rocks are 50-150 million years old. It was once part of the ocean floor and has marine fossils and debris as evidence. The Mayacamas Mountains are part of the Franciscan Complex as well as some of the hills surrounding the Russian River.
The Alexander Valley is one of the few California AVAs that can compete with the Napa Valley in Cabernet Sauvignon production. Producers include Chateau Souverain, Geyser Peak Winery, and Seghesio Family Winery.
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