Geomorphological map of the coastal area of the Straits of Magellan between Punta Dungeness and Bahía Inútil (Chile)

This paper presents the first results of the geomorphological survey of the coastal area Strait of Magellan between Punta Dungeness and Cabo San Isidro (Pategonia) and between Punta Catalina and Punta Yanou (Tierra del Fuego). The data on the map are mainly referred to the mapping and on land survey made during the 1991 /92 Italian Expedition within the National Antarctic Research Project. During this expedition regional-scale investigations were carried out that allowed an improvement of the features links to climatic variations of the Upper Quaternary. The studies have so far been focused on the littoral dynamics (morphological surveys of intertidal beach and beach samples). These studies allowed a preliminary reconstruction of sediment dispersion pattern from North-East to South-West , along the central axis of the Strait and in the opposite direction, in the subcoastal areas of particular physiographic units (Primera and Segunda Angostura). The research was also focused on the detailed mapping of the coastal morphological units (collection of morphostructural, stratigraphic , micropaleontological and sedimentological data, the study of active and unworke cliffs: dune bodies, paleo-shorelines, different altitude erosion surfaces etc.) which, for instance allowed to classify cliffs according to their slopes, height and position with respect to the shoreline as well s to examine the evolutionary (depositional, stable, erosive) trend of the coastal tract. On the basis of the first morphological geological and sedimentological data obtained, a zonation of the coasts of the Strait was made which, for example, allowed to distinguish between areas characterized by residual morphologies linked to the Quaternary glaciation such as drumlins, eskers, moraines. glacial flow directions, kettle holes, pro-glacial plains. erratic rock alignment (e.g. Primera and Segunda Angostura-Bahia Inutil) and areas characterized by residual morphologies linked to the sea-action , such as three different orders of terraces, paleo-cliffs, paleo-beach deposits and paleo-beach ridges (e.g. Punta Dungeness, Porvenir, Peninsula Juan Mazia). The evolutionary framework of the mapped paleo-surfaces, associated with paleo-beach deposits, linked to the Pleistocene eusta.tic changes will enable to make future correlations with similar microclimatic events in the Antarctic area thus, contributing to the reconstruction of the paleo­ geographic framework . The surveys, planned for next austral summer , will be carried out to improve the research through geomorphological and detailed sedimentological mapping at a scale of I :50.000. as well as to make an atlas of the coasts of the Strait between the Atlantic entrance and Bahia Inutil