Palaeogeographical reconstruction of the Sierra de Atapuerca Pleistocene sites (Burgos, Spain)

The Sierra de Atapuerca is an anticlinal ridge of Mesozoic carbonate rocks on the NW edge of the Iberian Chain (Northern Spain, Burgos), surrounded by subhorizontal continental sediments of the NE Duero Cenozoic Basin under endorheic conditions. The shift to exorheic conditions in the Duero Basin lead to the onset of an episodic downcutting phase and the development of the Atapuerca multilevel cave system, containing several sites from the Early and Middle Pleistocene. In this work, we have reconstructed the Pleistocene palaeogeographical evolution of the SW flank of the Sierra de Atapuerca, where these archaeological sites are located. The study is based on a detailed geomorphological and geological analysis, combined with Global Navigation Satellite System (GNSS) and 3D LiDAR data, and GIS modeling. These techniques have been applied to analyse the small valleys and the interfluve on the SW flank of the SW Sierra de Atapuerca. The results were combined with the regional base levels recorded by fluvial terraces and the chronostratigraphic sequences of the Sierra de Atapuerca sites. These reconstructions have allowed us to model the palaeogeographical evolution in the nearby area of the cave sites during the Early-Middle Pleistocene, coupling the main formation phases of the sites with the local physical landscape changes that occurred outside the caves. Surface processes are defined by incision phases entailing mitigate knickpoint recession and slope retreatment, and local aggradational phases associated with caves opened and captured by fluvial incision. This reconstruction provides the local physical palaeogeographical habitats developed during the Pleistocene hominid occupation of the Sierra de Atapuerca.