Fig. 1. Location of Puesto Roberts 1. Fabiani and co-authors (2014) analysed pollen and algae content to know the past vegetation communities and to infer changes in Colhué Huapi lake water level occurred during the late Holocene. At a few kilometres from PR1 and at similar elevation to that of the site a soil profile was obtained. The authors point out that from between ca. 1212 and 414 years BP a period of changes with several water level fluctua- tions of the lake developed. This trend would modify at ca. 979 years BP with a higher constancy in Cyperaceae values. Cyperaceae could expand to newer shallow regions and the decrease in algae might reflect a reduction in water level. From ca. 414 to 195 years BP lake level would PR1 site is located in an extensive depression of tectonic origin named Sarmiento Basin. The study area is located within the domain of the west winds (westerlies) caused by the collision of polar and sub- tropical air masses, producing winds of great intensity (Prohaska, 1976). The site is in an arid zone of Argentina with a mean annual precipitation Fig. 2. View of the archaeological site during the 2019 field season and ground plan. The lithic assemblage comprises 427 piece-plotted artifacts spread across the excavated surface of 15 m2. All excavated sediments has been sieved (2 mm mesh size) to recover small artifacts and fragments. The study of the artifactual assemblage and their classification in typological groups was carried out from the consideration of techno-morphological The development of horizontal spatial distributions of remains was performed using the software ArcGIS 10.5. Kernel density analysis has been applied in order to identify zones of accumulation of materials and classification of lower and higher density areas. This method calculates the density of point features around each raster cell, generating a smoothed map based on the location of points relative to one another (Silverman. 1986: Baxter et al.. 1997). Tools conservation. Lithic raw materials. Fig. 3. Weathered and recycled artifact. Left part exhibits a more recent flake removed during the recycling effort and a unifacial retouch on the edge. Right part (highlighted in green) exhibits a weathered surface. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.) Fig. 4. Nodule reconstructed by refitting in a sequence of quartzite knapped flakes. (*) Thermoalterated flake. Fig. 5. Refitted artifacts from PR1. Fig. 6. Spatial distribution of lithic assemblage. (a) Kernel density; (b) Artifact distribution; (c) Lithic assemblage according to size categories and (d) Refits lines connections.
