A revised, Last Interglacial chronology for the Middle Palaeolithic sequence of Gruta da Oliveira (Almonda karst system, Torres Novas, Portugal)

Based on previous radiocarbon and U-series (Diffusion/Adsorption) dating of bone samples, the Middle Palaeolithic has been thought to persist at Gruta da Oliveira until-37 thousand years (ka) ago. New U series ages for stratigraphically constraining speleothems, coupled with new luminescence ages for sediment infill, show that the site's-6 m-thick archaeological stratigraphy dates entirely within a < 30 ka interval spanning substages 5a-5b of Marine Isotope Stage (MIS) 5. Significant technological change is observed across the sequence, akin to that seen in the Upper Palaeolithic over similar timescales. Flake cleavers and bifaces, normatively definitional of the Vasconian facies, are restricted to a short interval correlated with Greenland Stadial (GS) 22, 85.1-87.6 ka ago. In cave and rock-shelter sites of southern and western Iberia, intact archaeological deposits securely dated to the-37-42 ka interval remain elusive. Geological dynamics (e.g., erosion, sedimentation hiatuses, palimpsest formation) and human adaptive responses to climate-driven environmental change (e.g., abandonment of now forest-covered low-and mid-altitude karst areas, concentration of settlement in alluvial plains and coastal settings) are possible explanations for this pattern. (c) 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Automated summary

Based on radiocarbon and U-series dating, it was previously believed that the Middle Palaeolithic persisted at the Gruta da Oliveira until about 37 thousand years ago. However, new dating techniques have shown significant technological changes at the site, similar to those seen in the Upper Palaeolithic. Intact archaeological deposits from the 37-42 ka interval remain elusive in southern and western Iberia, possibly due to geological dynamics and human adaptive responses to climate change.