Quaternary volcanic rocks are found mainly in the Nicaraguan Depression and form two major groups: the Marrabios and the Sierras formations. The Marrabios Cordillera starts in the northwest with Cosiguina volcano and continues to the southeast with San Cristobal, Casitas, La Pelona, Telica and Rota. The Hoyo, Monte Galan, Momotombo and Momotombito volcanoes are built upon ignimbrite deposits from the nearby Malpaisillo caldera. South-east of Lake Managua lie Chiltepe, the Nejapa alignment, Masaya, Apoyo and Mombacho which overlie the Sierras ignimbrites, erupted from the Sierras Caldera surrounding Masaya volcano. Further south in Lake Cocibolca (or Lake Nicaragua), Zapatera, Concepcion and Maderas volcanoes mark the end of Nicaraguan section of the CAVF.