Cristian M. Favier Dubois, Dalila Herrera Villegas, Ana P. Alcaraz, Marcelo Cardillo and Paula Vitale

Along the semi-arid coast of northern Patagonia (Golfo San Matías, Río Negro) mountain ranges composed of rhyolites illustrate different stages in the evolution of rock cavities. A comparative study carried out in the Punta Pórfido area allows us to evaluate rockshelter formation processes and their sedimentary fillings. Cavity morphology in this sector results from the romboidal pattern of joints in the volcanic rock and weathering processes, mainly the development of tafoni. The fillings are made up of gravel and blocks derived from the weathering of the rhyolite, with the contribution of fine sediments originating from wind and marine salts that have collaborated in the preservation of unusual organic remains. At the main cavity surveyed, Alero 2, two excavations were carried out and four radiocarbon dating samples determined the ages on charcoal to be between ca. 2200 and 7500 years cal. AP. In this contribution, we present the initial results of the geoarchaeological study of these cavities in the coastal area of Punta Pórfido to understand their development and some properties of the archaeological and taphonomic record contained in their fillings.