You can’t talk about the deep heart of France without mentioning its volcanoes. They’ve made frequent appearances in this blog, in stories about Blaise Pascal’s groundbreaking experiments on barometric pressure done at the top of the Puy de Dome, the grinding challenge of the mountain stages of the Tour de France, or the medieval lava quarries at Volvic that gave so many landmark buildings in this region their characteristic gray-black color. The volcanoes dominate the skyline behind the Auvergne’s largest cities, and even though they are all dormant (for now) their superheated internal plumbing feeds the hot springs that have brought tourists here since the first humans inhabited the area.