Aporte del análisis de colecciones a las modalidades de aprovisionamiento: El caso de los sitios cantera-taller del Valle de Yocavil (Noroeste Argentino) [Contribution to the analysis of collection procurement mechanisms

Abstract

Contribution to the analysis of collection procurement mechanisms: The case of the quarry workshop sites of Yocavil Valley (Northwest Argentina) In this paper we propose to analyze and compare four collections of artifacts, which come from surface sites located south of the Calchaquies Valleys. The quarry-workshop sites from Ampajango, El Bordo and Los Zazos have been previously studied and some of its parts are in the Museum of Natural Sciences of the National University of La Plata and in the Museum of Anthropology of the National University of Rosario, both in Argentina. These sites had been characterized as the first hunter-gatherer occupations in the valley of Yocavil (Cigliano 1964; 1968), mainly conformed by bifaces, scrapers and cores, most of them covered by a particular rock coating (rock varnish), which is desert varnish. In this paper we offer a revision and a new interpretation of such artifact assemblages. The questions that guide our work are: Will a new analysis of these collections allow us to observe complex processes such as reuse-recycling? What role did these spaces have at a regional level in sourcing decisions and exploitation of raw materials? By looking at the collections we have detected two problems. First, a greater presence of desert varnish on the parts collected during our fieldwork (Carbonelli 2013) in comparison with the ones in the above named collections. This variable is particularly relevant because a greater number of artifacts with varnish present are more likely to reveal cases of reuse-recycling; that is to say temporal difference between different sets of flaked stone. To solve this problem, we conducted a Chi 2 analysis in order to test the null hypothesis of the absence of a difference between the proportions of artifacts with varnish from our collections and museum collections. Secondly, we detected an existing imbalance between the high frequency of knapping tools in detriment of debitage and cores in museum collections. In order to quantitatively address the diversity of each set, we compared the typological classes of each of the matching sets. Diversity is a way of measuring the variation since it describes attributes of a population composed of classes (attributes) that vary in frequency (wealth), which allows us to discuss structural issues of the sample. To explore the richness we use indicators that are not too sensitive to sample size, such as the Simpson Dominance Index and Eveness. From the methodological aspect, statistical analysis allowed us to recognize the biases that built the samples. The Chi 2 tests indicate to us that there is a lower proportion of artifacts with desert varnish in the collections than what would fit reality. This manifests mainly in the absence of cases of reuse-recycling, evident in the differences of varnish between flaked artifacts. Moreover, the analysis of diversity warns us that there is an over-representation of finished tool type artifacts in collections, which makes difficult the description of the production sequence. Based on these biases, through techno-morphological analysis we characterized the lithic production of quarry-workshop sites. Generally speaking, they present an expeditious technology comprises of amorphous cores and partial bifaces, which were then used as cores. Even in the case of bifaces, there was no great effort put into their production, since many of them were still in the process of being knapped. The presence of an informal component in sets are also denoted by the presence of cortex in most knapped artifacts resulting in sequences of short reductions, without achieving a complete knapping of both sides. This low knapping of the sets is explained if we combine these observations with the results of our survey of potential and effective sources of raw materials (Carbonelli 2012, 2013b). The pieces of the collections come from places close to areas of good to fair quality raw materials, so expeditious technology with a small holding of bifaces and cores is consistent.