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The Galería complex is located in the intermediate level of the Atapuerca multilevel karst in Burgos (Spain). The Galería complex is formed by three subsections filled with sediments and connected to each other: Covacha de los Zarpazos, Galería site, and Tres simas. These cavities are filled with extensively dated entrance facies, rich in fossil and archaeological materials, and on the other hand, with interior facies, barely dated and without fossil and archaeological remains. Studying in greater depth the interior facies deposits is of interest as they record the entrenchment of the regional fluvial system and a transition period between the formation of the intermediate and lower levels of the Atapuerca endokarst. Previous geological works suggest that these interior facies in the Galería-Tres Simas Complex should have been deposited during the Lower Pleistocene-Middle Pleistocene; however, geochronological studies have provided disparate ages by ESR and OSL on the top of the interior facies. Therefore, the objective of this study is to date the lowermost part of the interior facies to complete the chronological framework of the Galería complex and, to provide minimum dates for the formation of this keyhole cross section. With this objective, 5 and 22 samples were taken to be dated by ESR and Paleomagnetism, respectively. Our first results suggest Middle Pleistocene ESR ages that are in agreement with previous results obtained by OSL. In contrast, paleomagnetic data reveal reversal polarity. These results may suggest postsedimentary processes or geological events that underestimate the ages obtained by trapped charge dating techniques. Our results are important to better understand this interval of the fluvio-karstic system of the Sierra de Atapuerca, which preceded the opening of the Gran Dolina and Gallery cavities and their infill by entrance deposits. [ABSTRACT FROM AUTHOR]

Pleistocene fluvial incision acceleration resulting in narrow and deeply entrenched valleys has been widely described and is generally attributed to uplift rate increase or greater climatic severity. In this paper, the long-term downcutting pattern of the Upper Ebro River and driving mechanisms are assessed, and we reconstruct the valley incision recorded by an outstanding sequence of 22 river terraces. Dating of 8 fluvial levels by means of the ESR, TCN, and OSL techniques, spanning the last 1.2 Ma, reveals a long-term incision deceleration pattern. The estimated age-incision model indicates a decrease in the incision rates, showing a long-term deceleration during the final Early Pleistocene (from 0.42 to 0.18 m/ka), and a tendency towards a steady state or base level stabilization from the Middle Pleistocene (0.15–0.03 m/ka) to the Late Pleistocene (0.03 m/ka). This incision pattern does not support climate change as a long-term incision-acceleration driver by itself, demonstrating the need for base level lowering effects to have operated. Upper Ebro deceleration incision is explained by the headward attenuation of the incision wave induced by the opening of the Ebro Cenozoic Basin in a geodynamic context characterized by an absence of significant uplift over the last million years. This trend could have changed the aggressor-victim roles of the rivers involved in fluvial captures at the drainage divide. The documented incision deceleration pattern differs from that reported for other valleys in the Iberian Peninsula, suggesting that the degree of maturity of the fluvial systems depends on their relative position with respect to the capture point, in addition to tectonic and lithostructural factors. In the Late Pleistocene-Holocene, a short-lived incision rate increase is recorded, corresponding to the last terrace dissection phase, during the transition from the last glacial MIS 2 to the interglacial MIS 1. • Incision acceleration is widely reported during Pleistocene valley entrenchment. • However, the Upper Ebro valley contains a complex sequence of fluvial terraces • which were dated within the last 1.2 Ma using ESR, TCN and OSL techniques • and indicate an incision deceleration pattern. • This suggests that the river incision is tending to a steady state. [ABSTRACT FROM AUTHOR]