An oasis in the middle of the Patagonian desert: the Valley of Genoa at the Holocene

SCHEINSOHN, V.; F.RIZZO; LEONARDT, SABRINA

Paris

Congreso; XVIII Congres Mondiale de la Union International de Sciences Prehistoriques et Protohistoriques; 2018

Union International de Sciences Prehistoriques et Protohistoriques

Arid and semiarid environments, which constitute a big part of Earth environments, share similar characteristics around the world. Since there is a limited scope of biological answers to deal with their abiotic selective pressures, mainly determined by moisture scarcity (Brown et al., 1979) it is reasonable to expect biotic convergence on them. Although humans had avaster array of answers, given by cultural behaviors, past climatic fluctuations, even of minor magnitude, should have a stronger impact in these environments. In Patagonia (southern South America), two principal climate drivers are highly signicant: latitude (related to solar insulation and mean annual temperature), and the presence of theAndes Mountains, with its influence on the precipitation regime and winds. The frequent winds coming from the Pacic Ocean ascend when reaching the Andes, while cooling adiabatically and generating high precipitation on the western slopes. They contribute to a rainshadow in the eastern side of the Andes, which generates true desert conditions (Montes et al.2017). Hence, in few kilometers human populations has the chance to have a quick access to Andean forest resources to theWest or to the lava mesa and plateaus (highlands) to the East.In this paper we will characterize the late Holocene of the Central-West Chubut area and specically we will refer to the Genoa Valley which conforms one of the biggest wetlands or malln in Patagonia (Horne, 2010). Being located between the Cordillera de los Andes and the Precordillera hills it is surrounded by highlands. The presence of minor wetlands and peatlands at the alluvial plain and adjacent tributary streams, springs and water bodies warrant the presence of guanaco herds looking for high quality pastures. This area was archaeologically unknown until our team began a research project in 2012.We will explore as a rst approach to this subject if archaeological distributions in the steppe and the forest could be correlated with the known Holocene climatic fluctuations, as recent work allow to consider, and how the occupation of this area was developed.