Missing the point: re-evaluating the earliest lithic technology in the Middle Orinoco

The Culebra site, located in close proximity to the Atures Rapids, is one of the very few open-air occupations in the entire Orinoco valley that is thought to date to the early Holocene. Following renewed excavations in this location, we characterize the stone technology in unprecedented detail and perform both quantitative and qualitative analyses of the assemblage deposited in the first cultural layers. Additionally, we directly date the sediment forming the depositional context of the assemblage using stratigraphically stable components of soil organic matter. Coupled with our stratigraphic and paedological data, the deposit is, contrary to established estimates, shown to date to the late Holocene, well after the appearance of ceramics in the region. The toolkit identified through the lithic analysis, therefore, does not reflect an Archaic hunter–gatherer adaptation as previously assumed. Our findings are placed in the context of previous research in the Orinoco and lowland South America more broadly. More work is needed to understand the changing role of different stone tool reduction sequences with reference to adaptational strategies and bioclimatic variability

Genesis, properties and management of salt-affected soils in the Flooding Pampas, Argentina

The Flooding Pampa is a plain, covering around 90,000 km2 composed of eolian and alluvial deposits. It is characterized by its geomorphology, with low (0.1–0.01%) slopes and elevations, including the coastal flat. A significant fraction of the region has permanent or temporary lagoons, generally connected with the underground water. Two kinds of water excesses are distinguished: (i) waterlogging of low duration and intensity and (ii) floods, intense and prolonged. Most soils have developed from loessial and loessoid sediments. They are composed mainly of a pyroclastic volcanic association, with a variable proportion of plagioclases, quartz, volcanic glass, lithoclasts and heavy minerals. However, the soils of the East sector of the region were generated by the influence of the sediments from the Rio de la Plata. They show a higher proportion of kaolinitic, smectites and interstratified expansible clays, than other soils of the region. Most salt-affected soils of the region belong to the US Soil Taxonomy Orders of Mollisols, Alfisols, Entisols and Vertisols. Their limitations are not easy to reverse technically and from the economic and ecological point of view. Conversely, it is reasonable to introduce management and reclamation technologies adapted to those limiting conditions.Fil: Imbellone, Perla Amanda. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Geomorfología y Suelos; ArgentinaFil: Taboada, Miguel Angel. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Suelos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Damiano, Francisco. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Recursos Naturales. Instituto de Clima y Agua; ArgentinaFil: Lavado, Raul Silvio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales; Argentin