Karst features interpretation using ground-penetrating radar: A case study from the Sierra de Atapuerca, Spain

Revision of TD1 and TD2 stratigraphic sequence of Gran Dolina cave (Sierra de Atapuerca, Spain)

“…89 Ma; Duval et al, 2022). This stratigraphic section mainly matches with the Railway Trench borehole (BH2 in Bermejo et al, 2020), composed of fine clays and fine sands. The limitation of the mechanical drilling is that it avoids observing the sedimentary details in the borehole and prevents a direct correlation between it and the main section.…”

“…The limitation of the mechanical drilling is that it avoids observing the sedimentary details in the borehole and prevents a direct correlation between it and the main section. Nonetheless, this borehole and the GPR survey demonstrate that Gran Dolina cave continues to the west (Bermejo et al, 2020), and, therefore, the flow direction was from east to west.…”

“…Tres Simas is three vertical shafts connected in their lower part with Galería. The stratigraphic sequence of Galería Complex has 13 m of thickness in the current section, which continues with at least 17 m under the current path (Bermejo et al, 2020); thus the cave has more than 30 m thick of sediments. The Galería sediments have been separated into five litho-stratigraphic units, from the bottom to the top, GI to GV units (Pérez-González et al, 1995, 2001.…”

“…1 General location, geological map of the Sierra de Atapuerca (simplified from and map of the Atapuerca multilevel cave system (modified from Ortega et al, 2013). The underground karstic infills of the Railway Trench are pale green (Bermejo et al, 2020). Legend: 1, Jurassic; 2, Early Cre-taceous; 3, Late Cretaceous; 4, Oligocene; 5, Miocene; 6, Fluvial terraces; 7, Cones; 8, Floodplains and valley floors; 9, Semi-endorheic areas; 10, Seasonal pools; 11, Glacis; 12, Landslides; 13, Colluvium; 14, Dolina floors; 15, Drainage network; 16, Inferred overturned anticline; 17, Faults; 18, Roads; 19, Urban areas; 20, Archaeological sites 2012; Pablos et al, 2012;Parés et al, 2013;Rodríguez-Gómez et al, 2013), and the TD10 unit that includes two rich layers of stone tools and fauna interpreted as a human campsite dated to about 0.35 Ma (Falguères et al, 1999(Falguères et al, , 2013Moreno et al, 2015;Ollé et al, 2013).…”

“…It was reached at seven meters depth, showing a total of nine meters of the sedimentary sequence of sterile sediments mainly composed of sand, silt, and clay. After, a borehole was drilled in the Railway Trench next to the Gran Dolina site revealing 10-m thick sediment fill composed of silts and clays (Bermejo et al, 2020). These sediments were included in the TD1 and TD2 units of Gran Dolina, defined as autochthonous facies (Campaña et al, 2017) following the definition of White (2007) and Ford and Williams (2007), and previous works in Sierra de Atapuerca sites (Pérez-González et al, 1995.…”