SOIL GENESIS RELATED TO MEDIEVAL WARM PERIOD'S CLIMATIC FLUCTUATIONS IN SOUTHERN PATAGONIA AND TIERRA DEL FUEGO (ARGENTINA). CHRONOLOGICAL AND PALEOCLIMATIC CONSIDERATIONS

Geoarchaeological work carried out in five localities in Southern Patagonia and Northern Tierra del Fuego has demonstrated the presence of a pedogenesis interval represented by a mollisol, in the upper section of widespread late Holocene aeolian and colluvial deposits. This soil is buried at the archaeological sites under study but remains exposed in other areas of the same landscape. The mollisol’s origin and development may indicate an important change in environmental conditions due to the stabilization of regional aeolian and colluvial systems at that time. Furthermore, there are changes in the distribution of the archaeological record that are linked to this development. Radiocarbon dates on materials found beneath this soil (maximum ages) and those by OCR (Oxidizable Carbon Ratio) in the AC horizon (minimum ages) indicate the beginning of its development around the year 1000 BP. Chronologically, there appears to be a correspondence between the beginning of the mollisol and the presence of climatic anomalies in southern Patagonia that coincided with the so-called Medieval Warm Period. These climatic fluctuations are present in Patagonia according to dendroclimatic studies.