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

Abstract Since the comprehensive synthesis on the Argentine–Chilean Andes by Mpodozis & Ramos (1989) , important progress has been made on the stratigraphy, palaeogeographic evolution and tectonic development of the Andean Orogen in Chile. We present here an overview of this evolution considering the new information and interpretations, including some unpublished ideas of the authors. To enable the reader to delve further into the subjects treated here, we accompany the text with abundant references. In the interpretation of the stratigraphic and radioisotopic data we used the timescale of Harland et al. (1989) . During most of its history the continental margin of South America was an active plate margin. The Late Proterozoic to Late Palaeozoic evolution was punctuated by terrane accretion and westward arc migration, and can be described as a ‘collisional history’. Although accretion of some terranes has been documented for the post-Triassic history, the evolution during post-Triassic times is characterized more by the eastward retreat of the continental margin and eastward arc migration, attributed to subduction erosion, and therefore can be described as an ‘erosional history’. The intermediate period, comprising the Late Permian and the Triassic, corresponds to an episode of no, or very slow, subduction activity along the continental margin, during which a totally different palaeogeographic organization was developed and a widely distributed magmatism with essentially different affinities occurred. It is therefore possible to differentiate major stages in the tectonostratigraphic evolution of the Chilean Andes, which can be related to the following episodes of supercontinent evolution: (1) post-Pangaea