Two boreholes drilled in the area around Barranco León (Orce, Granada) enable to access for the first time a 80 m-long continuous sedimentary record, providing a robust geological framework for some of the oldest evidence of human presence on the European continent.
A scientific team led by members of the Centro Nacional de Investigación sobre la Evolución Humana (CENIEH) has just published in the Journal of Iberian Geology the first high-resolution study of sediment cores drilled from the archaeo-palaeontological site of Barranco León, located in Orce (Granada), which documents some of the earliest evidence of human presence in western Europe.
This study, carried out in close collaboration with members of the University of Granada, enables to establish a robust geological framework for future studies focused on the chronological and environmental context of these early occupations dated to more than one million years.
"With these two boreholes, we have access for the first time at the site to a continuous sedimentary record of about 80 metres, which almost triples the information available until now," says Mathieu Duval, senior researcher at CENIEH and co-author of the study.
The analyses have been carried out at a resolution of up to 5-10 centimetres for some parameters, generating thousands of experimental results. "Basically, we have been able to finely study the evolution of the sediment properties at Barranco León sediment over 80 m, with an unprecedented precision," says Dr Duval.
A series of petrophysical properties of the sediment were evaluated, including magnetic susceptibility, natural radioactivity, or carbonate content, resulting in a unique high-resolution record for the sedimentary sequence.
Based on these results, and with the additional the microscopic study of the sediment, a succession of up to six main lithostratigraphic units was identified. These units correspond to a series of wetland, alluvial and lacustrine depositional environments, which is characteristic of an area located on the edge of a lake, the Baza paleolake, and influenced by the variation of the water level over time.
Unique laboratories
Josep M. Parés, coordinator of the scientific programme of Geochronology and Geology, and also co-author of the study, explained: "this work is an excellent example of the research that can be carried out in the CENIEH laboratories. These laboratories offer a unique combination of world-class facilities and highly-qualified scientific-technical staff, which gives us the opportunity to study the Quaternary and our origins according to the highest standards"
The study, led by Alberto Santamaría Barragán, includes a total of 13 scientists and technicians from the Geochronology and Geology Program of CENIEH, as well as members of several departments of the University of Granada, including the Rock Drilling Unit of the Centre for Scientific Instrumentation (CIC), which carried out the mechanical drilling.
This research has been made possible thanks to the support of the Junta de Andalucía and is part of the PALEOMED project PID2021-123092NB-C22 funded by MCIN/AEI/10.13039/501100011033/FEDER, EU.
