The Puy-de Dôme-department is home to a large number of maars, mainly basaltic volcanic craters. Some form vast lakes, such as Lake Servières south of Orcival in the Monts-Dore chain, while others only persist in the form of wetlands. Some maars have even completely disappeared on the surface, such as the Fond de Jaude maar in the center of Clermont-Ferrand. The department also comprises trachytic maars, of which Lake Pavin (108.7 acres / 44 ha) is the most famous local representative.