Abstract The Iberian Peninsula comprises the most extensive outcrops of Ordovician rocks in Europe. They are mainly situated within the different ‘zones’ of the Variscan Iberian Massif (also referred to as the Hesperian Massif), except the South Portuguese Zone, as well as in the Palaeozoic massifs of the Iberian Cordillera (an isolated part of the Iberian Massif), the Catalonian Coastal Ranges, the Pyrenees and the Betic Cordillera (Fig. 4.1 ). Geological sketch map of the Iberian Peninsula showing the distribution of Ordovician rocks (in black) with reference to the main Precambrian and Palaeozoic exposures (stippled). Key: A–G, Hesperian (Iberian) Massif: A, Cantabrian Zone; B, West Asturian-Leonese Zone; C, Iberian Cordillera; D, Galicia–Trás-os-Montes Zone; E, Central Iberian Zone; F, Ossa Morena Zone; G, South Portuguese Zone (dotted lines indicate zone boundaries); H, Betic Cordilleras; I, Catalonian Coastal Ranges; J, Pyrenees. 1–42, Main Ordovician reference sections and fossil localities in Spain: 1, Cabo Peñas; 2, ‘folds and nappes region’; 3, Sueve area; 4, Rececende and Villaodrid synclines (Mondoñedo Nappe); 5, Los Oscos thrust-sheet; 6, Vega de Espinareda synclinorium; 7, Caurel–Peñalba syncline; 8, Castrillo syncline; 9, Eastern Iberian Chains; 10, Albarracín anticlinorium (Western Iberian Cordillera); 11, Serranía de Cuenca anticlinorium; 12, Cabo Ortegal area; 13, Sil and Truchas synclines; 14, Alcañices synclinorium; 15, Guadarrama area (eastern ‘Central System’); 16, Verín-Bragança region; 17, Tamames syncline; 18, Sierra de San Pedro and Cáceres syncline; 19, Cañaveral-Monfragüe syncline; 20, Guadarranque syncline; 21, Herrera del Duque syncline; 22, Corral de Calatrava syncline; 23, Almadén syncline; 24, Torre

Abstract Chile possesses one of the most pronounced climate gradients in the world, extending from the world’s driest desert in the northern part of the country, where precipitation is measured in millimetres per decade, down to the channel and fiords region in southern Patagonia where rainfall can average up to 7 m per year or more. In contrast, thermal buffering by the Pacific Ocean contributes to ameliorating extreme temperatures, generating a latitudinal temperature gradient that is considerably less pronounced than across similar latitudinal ranges in other parts of the world ( Miller 1976 ; Axelrod et al. 1991 ). Coupled with millions of years of geographic isolation induced by the massive barrier imposed by the Andean Cordillera, Chile today possesses a highly endemic fauna and flora whose distribution is tightly linked to these gradients ( Arroyo et al. 1996 ; Hinojosa & Villagrán 1997 ). Considering its geographic position and tectonic setting, it is hence not surprising that the geomorphology of Chile over the last two million years or so, i.e. the ‘Quaternary’ (see Gradstein et al. 2004 ), has been strongly influenced by climate along this broad latitudinal gradient. Whereas ancient landscapes preserved for millions of years exist in the hyperarid Atacama, repeatedly glaciated landscapes predominate in southern Chile. Elucidating the precise chronology of these Quaternary events affecting the western margin of southern South America is of great relevance to a number of scientific disciplines including ecology, palaeo-climatology, evolutionary biology, population genetics, phylogeography, biogeography and conservation. Consequently, records of past climate and