A vast inland sea (is there any other kind?) once covered Napa and Sonoma Counties. The salt water nourished the soil over thousands of years. The Mayacamas Mountains, along with other coastal ranges, are a portrait of the land’s geology, from earthquakes to volcanoes.
Mount St. Helena, at 4,344 feet, is Napa’s tallest reminder of long-gone volcanoes the roiled 2.4 million years ago. Magma still bubble below her hills. It produces the area’s powerful geysers and Calistoga’s soothing mineral waters.
When the ancient sea receded, it left bays and lagoons that became fertile valleys. The Napa and Russian rivers formed, and they rolled through the valleys. As the rivers ran from mountains to plains, the ash and soil mixed. It is this ideal combination that produces world-class wines from exquisite vineyards.
Today, the soil is rich with minerals, and the land is just rocky enough to create excellent drainage. The weather is perfect for grapes. Cool, moist ocean air meets the dry eastern desert air. In the morning, fog chills the vineyards. It burns off during the day and the sun warms the vines. At sunset, the breezy cool air returns.
Perhaps the most important ingredient this Mr. St. Helena recipe is rain. Napa and Sonoma Counties are wet from December through April. Then the skies clear until November. This helps prevent rot on the grapes when they are at their most vulnerable—just before harvest.
People are the nourishing factor in fine wine, but Mother Nature is the key.