Photograph of the month

摘要

Over one km high and about five km long, the north-western wall of the Cerro Aquehuina ridge towers above the Valley of Volcanoes and presents a cross section of strongly deformed Mesozoic sedimentary formations of the Western Cordillera in the Central Andes, southern Peru. Quartzite, sandstone and shale of the Middle Jurassic-Lower Cretaceous Yura Group (Caldas 1973, Mapa Geolo-gico del Cuadrangulo de Huambo; Palacios 1995, Geologia del Peru, 55, 9) underwent five compressive phases since the Late Cretaceous and strong uplift since the Late Miocene (Megard 1984, Journal of the Geological Society of London, 1, 893).