Cantal, France
Image courtesy Bureau de recherches géologiques et minières, France (fair use policy)
Cantal, in France's Massif Central, is the largest volcanic edifice in Europe. It dominated the countryside during the Miocene and Pliocene epochs, starting around 9 million years ago, as hot material from the mantle moved beneath south-central France. A large section of the continental crust rose a kilometer or so due to thermal expansion, and Cantal, Puy-de-Dôme, and lesser volcanoes burst from the resulting plateau. The same thing happens elsewhere over continental hotspots—Yellowstone is a prime example in the American West.
Cantal has been quiet for the last 3 million years. During the time since then, Ice Age glaciers extended down its flanks, deepening many valleys and exposing the rocky guts of the former volcano. The French geological survey has created a remarkable Web site that presents many photos of the French countryside as well as geologic notes.
