Come learn about the geology of northern Napa County. We will be hiking up to an overlook facing south toward Calistoga and the Bay. Learn about the volcanism of the region, the source of the hot springs, and the quicksilver mining of northern Napa County. Along the way we will stop by the site where Robert Louis Stevenson and his wife Fanny honeymooned. We will meet at the Mt. St. Helena Trailhead parking lot in Robert Louis Stevenson State Park, approximately 7.5 miles north of the intersection of Silverado Trail and Highway 29.