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Scientists and technicians at the Centro Nacional de Investigación sobre la Evolución Humana (CENIEH) have collaborated on a study published in the journal Geomorphology of the processes that took place in the Galería and Gran Dolina caves when they were closed, prior to the arrival of human groups and the fauna that inhabited the Sierra de Atapuerca ecosystem in Burgos. 

The results suggest that around 1 million years ago, these cavities were inundated periodically when the Arlanzón River was in flood, which gradually left layers of sands and clays, until climatic changes caused the river to excavate its valley more deeply and the waters receded.

The work was based on the application of stratigraphic and sedimentological methods which enabled detailed analysis of each layer of sediment in the lower part of the Galería Complex site, especially in the Covacha de Los Zarpazos, which were then compared with similar deposits at the base of the Gran Dolina site. 

Specifically, the techniques available at the CENIEH's Digital Mapping and 3D Analysis, Archaeometry, and Geology laboratories were used to elucidate the three-dimensional layout of the stratigraphic units, their mineralogical and chemical composition, and the size and shape of the sedimentary particles. 

“These analyses have allowed us to see what the cavity visited by the first human groups was like, as well as to identify processes of washing and geochemical transformations that might have affected age estimates for the sediments and the archaeological units”, comments the CENIEH geologist Alfonso Benito Calvo.

Led by Isidoro Campaña, of the Universidad de Málaga, and in addition to the CENIEH members, the other participating institutions were the Universidad Rovira i Virgili in Tarragona and the Instituto de Evolución en África in Madrid.