Lithics and Early Human Occupations at the Southern End of the Deseado Massif (Patagonia, Argentina)

Abstract

The purpose of this paper is to summarize available information concerning early human utilization of rock shelters and open air spaces in the southern end of the Deseado Massif, focusing on the Pleistocene-Holocene transition.The earliest occupations of the southern end of the Deseado Massif have been identified in La Gruta 1, a small rockshelter in a cliff by a lagoon, and date to the Pleistocene-Holocene transition. Archaeological remains are scarce and the archaeological sequence is discontinuous. The site has been characterized as a logistic one, taking into account its location and the characteristics of the artifacts recovered. The area where the site is located is an ancient volcanic landscape, with abundant natural depressions frequently occupied by shallow lagoons, mostly seasonal. Water levels depend on rainfall, with almost all of the lagoons showing evidence of higher water levels in the past.Rockshelters and caves are rare in this area. This is the kind of sites where, with scarce exceptions, earliest human occupations have been identified in Patagonia. The relevance of this resource for hunter-gatherers has been discussed by some researchers, who pointed out that there is a strong bias in archaeological field work toward this kind of sites and that they represent only a part of hunter-gatherers activities, a position with which we agree.In the case of La Gruta area, human occupation of rock shelters is highly discontinuous, a fact that has been related to the existence of erosive episodes during arid periods, when humans may have abandoned the area or exploited it from residential sites located in nearby spaces.Sedimentary sequences are short (between 30 and 60 cm depth), both in rockshelters made in ignimbrites (Bahía Laura group) and in fossiliferous sandstones (Monte León formation). On the contrary, between 20 and 30 km to the north and northeast of La Gruta area at Viuda Quenzana, La Martita and El Verano areas- rock shelters and caves are more abundant. They are made of the same ignimbrites, but with lesser compaction and silicification, which makes them prone to erosion. This may be the reason why sedimentary sequences are thicker in these areas, in some cases more than 2 meters depth. We should mention, in addition, that in La Martita, Viuda Quenzana and El Verano, there is more evidence of human occupation, as it is indicated by the quantity of lithic and faunal remains, as well as rock art motives. In Viuda Quenzana area, more than 45 sites with rock art have been identified within 2.5 km2, which shows a sharp contrast with La Gruta area, where only 6 sites with rock art were identified along outcrops extending 1.5 km long. Differences in archaeological remains can also, of course, be attributed to different site functions and continuity in their occupation. Another important difference between La Gruta area and these spaces located to the north is that at Viuda Quenzana and La Martita there are seasonal streams and bogs or springs, locally known as mallines. If this was also the case in the past, this would make the northern area more predictable in terms of water availability than La Gruta.To the south and southeast of La Gruta, open air spaces extend to the Chico River. To the southwest, olivinic basaltic spaces can be found. This change in the environment probably implied the utilization of different strategies for hunter-gatherers.