I’ve been doing a lot of exploring of the AVAs of Napa recently, and people have been wonderful about letting me poke around their vineyards. Here, I’m checking out the sandstone and shale of the Pine Ridge knoll in the Stags Leap District, which basically is a fallen mountain peak of Great Valley Sequence bedrock from when the earth moved so much that the Vaca range got too tall, and portions cascaded down to form the knobs that litter the valley’s center-south districts.