Volcanic Lagoon of La Alberquilla Nature · Mestanza, Sierra Morena, Ciudad Real The volcanic lagoon of La Alberquilla occupies the interior of a maar, the only volcanic outcrop in the area, formed by a hydromagmatic explosion that left small pyroclastic deposits on its western and southern edges, among ridges of Ordovician quartzite and slate. It is the only lagoon of volcanic origin in the region that sits perched atop a quartzite sierra, on privately owned land within the municipal area of Mestanza. It gained the status of Natural Monument in October 1999, when the decree was published in the Official Gazette of Castilla-La Mancha, and the protected area covers 111 hectares. It is one of the manifestations of the volcanism of Campo de Calatrava within the natural park. Photo: PNOA (Attribution) What to see and do in Mestanza