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Viveen et al. (2020) raise several issues concerning the chronostratigraphic interpretations in our recent paper on the fluvial and archaeological deposits of Lower Mino River (Mendez-Quintas et al., 2020). Here we respond to these criticisms, reinforcing the key findings of our study and questioning the validity of their arguments. We find that the concerns of Viveen et al. (2020) are based on a series of poorly founded assumptions and generalisations, invalid comparisons, and inappropriate data analyses.

The Mino River basin represents one of the main fluvial catchments draining the Atlantic side of the Iberian Peninsula. The extensive sedimentary deposits of this basin have been documented since the 19th century, but limited research has been undertaken on these features historically, and the Quaternary record of the basin has remained understudied until recently. Research carried out over the last decade on the Spanish margin of the Mino River has enabled more detailed classification and mapping of the main fluvial landforms, as well as numerical (luminescence, electron spin resonance, cosmogenic) dating of some of the deposits associated with Palaeolithic archaeological sites. Here we synthesise the existing Quaternary fluvial record for the basin, and present new geospatial and chronological analyses for the lower catchment area. Our latest examination has enabled the identification of nine fluvial terrace levels and other regionally significant sedimentary features (e.g., alluvial fans) formed in response to tectonics, eustatic changes and associated global climate changes. The chronological data and calculated incision rates indicate that the various fluvial terraces were formed during the Early to Late Pleistocene. Numerous Palaeolithic sites have been found in association with the middle terrace levels (between +40 and + 13 m above present-day river level). Primarily, these archaeological sites preserve assemblages that feature large flake Acheulean (LFA) tools, though a number of Middle Palaeolithic sites have also been documented. Direct dating of these sites, together with morphostratigraphic correlations across the terrace system, suggest that the basin has been extensively occupied by human populations during the last 300 thousand years.

Trapped charge dating of optically bleached quartz deposits that lie beyond the dose-saturation limits of conventional optically stimulated luminescence (OSL) has typically focused on two main techniques over the last decade: electron spin resonance (ESR) and thermally transferred optically stimulated luminescence (TT-OSL). In spite of a clear association between these two dating techniques through their shared dose rate terms, the exact relationships between the various ESR centre (i.e., Al and Ti) and TT-OSL dating signals remain largely unexplored. In this study we undertake ESR and luminescence signal comparisons on paired sedimentary quartz samples from two Middle Pleistocene Spanish archaeological sites (Porto Maior in northwest Spain and Cuesta de la Bajada in northeast Spain) to examine the empirical relationships between quartz dating signals across different geological provinces. For this purpose we undertake 3-dimensional (3D) thermoluminescence (TL) spectral measurements, single-grain TT-OSL dating and signal analyses, normalised multiple centre (MC) ESR signal characterisation (ESR intensities, signal composition, dose-response curve properties), MC ESR De evaluation, and ICP-OES analysis of quartz extracts to evaluate potential correlations between elemental impurity concentrations and Al, Li–Ti and Li–H centre signals. The ESR samples from Cuesta de la Bajada and Porto Maior display similar Al centre signal intensities and dose-response behaviour, but they exhibit major differences in their Ti centre properties. Geochemical analysis reveals that the Cuesta de la Bajada quartz extracts contain higher concentrations of Al and Ti impurities (15 and 21% higher, respectively) when compared with the Porto Maior quartz extracts. These compositional differences appear correlated with the relative Ti–H signal intensities for the two sample datasets but not with the relative Al and Ti–Li signal intensities. The luminescence characterisation comparisons reveal a higher proportion of TT-OSL-producing grains in the Cuesta de la Bajada samples (∼6.2% versus 1.5% for Porto Maior), and single-grain TT-OSL signal intensities that are almost an order of magnitude higher than for the Porto Maior samples. The 3D TL spectra for the Cuesta de la Bajada quartz are dominated by two major TL peaks in the red emission band (620 nm) at 265–310 °C and 365 °C (when using a heating rate of 1 °C/s), which are up to seven times more intense than the corresponding signals observed for the Porto Maior quartz. However, no major inter-sample differences were observed in the blue and UV-blue bands of the 3D TL spectra. These contrasting luminescence characteristics may be indicative of variable signal sensitisation histories related to dissimilar sedimentary recycling or geological origins between the two sites. Our results provide a useful baseline dataset for future comparative ESR and luminescence characterisation studies, and indicate a potentially close relationship between the quartz ESR Ti centre and single-grain TT-OSL signals. There is significant potential to refine understanding of these signal relationships in the future by expanding the number, and geographic coverage, of paired ESR–luminescence comparison studies, and by incorporating comparative 3D TL spectral investigations that focus exclusively on TT-OSL-producing grains (as opposed to bulk grain populations) to better elucidate luminescence trapping and recombination characteristics.

Trapped charge dating of optically bleached quartz, which involves techniques such as electron spin resonance (ESR) and thermally transferred optically stimulated luminescence (TT-OSL), is increasingly being used to establish Middle and Early Pleistocene chronologies for archaeological, palaeontological and palaeoenvironmental sedimentary sequences. Comparative dating studies that make use of several independent or semi-independent radiometric techniques in tandem are an invaluable means of assessing the reliability of optically bleached quartz dating methods and ascertaining empirical relationships between different quartz dating signals. In this study, we undertake a comparative dating evaluation of single-grain TT-OSL and various ESR signals that exhibit different optical resetting properties (Al, Ti–Li and, where measurable, Ti–H centres) at the Middle Pleistocene archaeological site of Porto Maior, northwest Spain, which contains a distinctive, regionally significant Acheulean stone tool assemblage. We expand the existing chronological framework for Porto Maior using single-grain TT-OSL dating, derive combined numerical ages for individual depositional units using Bayesian modelling, and further examine the relationship between ESR and TT-OSL signals by reviewing a range of published comparative dating studies. The new single-grain TT-OSL ages obtained for unit PM3 at Porto Maior (225 ± 31 ka and 242 ± 32 ka) are in close agreement with previously published ESR Ti–Li ages for this unit (266 ± 23 ka and 279 ± 26 ka) and significantly younger than those reported for the Al centre (441 ± 75 ka and 452 ± 66 ka). Our broader comparison of published TT-OSL – ESR dating results also shows statistically significant agreement between single-grain TT-OSL and Ti–Li centre ages in other sedimentary settings, suggesting a potentially closer relationship between the TT-OSL-producing traps and the Ti–Li paramagnetic centres in quartz, rather than between the TT-OSL and Al centre signals. The Bayesian modelling results for Porto Maior enable us to refine the existing bracketing depositional age for the archaeological accumulation at Porto Maior and provide a stronger statistical foundation for chronostratigraphic correlations with other Acheulean archaeological deposits found in the Mino River basin. The Bayesian model indicates that the entire Porto Maior sedimentary sequence was deposited between 312.6 ± 32.6 ka and 18.8 ± 7.7 ka, and that the in situ large cutting tool assemblage from level PM4 most likely accumulated during Marine Isotope Stage 7 (mean depositional age = 210.7 ± 24.7 ka). The results of this study reinforce the usefulness of applying the multiple centre (MC) ESR dating approach in many dating contexts, and demonstrate the value of undertaking comparisons between semi-independent quartz dating signals in order to maximise the reliability of ESR and single-grain TT-OSL quartz chronologies.

To understand the identity of the early Acheulean, it is necessary to discriminate between the variables that influenced the selection of technological strategies. Functionality of the archaeological sites is crucial in assessing the manufacturing strategies of lithic tools. To achieve this goal, analysis of the post-depositional processes must be evaluated. When bone remains have been preserved, anthropic animal processing can be identified through zooarchaeological and taphonomic analyses, and the spatial relationships among all the components can also be assessed, especially when bone surface is not sufficiently preserved. There are two levels present at Thiongo Korongo, ~1.3 Ma, TKLF and TKSF. These are in autochthonous position with no significant temporal diachrony but with substantial technological differences in the manufacturing of the lithic tools, which enables the analysis of the influence of human activities on technological behaviour. In order to evaluate this issue at TKSF, we present lithic, faunal, taphonomic, fabric, and spatial analyses. An assemblage of megaherbivores, among which Sivatherium is outstanding, dominate the TKSF faunal remains. Cortical preservation is poor; there is no intervention of carnivores, the rate of green fractures is low, and a few cut marks on size 5 and 3b animals were identified. Hence, apparently human intervention on the fauna was not intensive. Spatial and geostatistical analyses hints of a specific area where megaherbivores were processed by humans. Through wear use and biomarker analyses on stone tools, we are currently trying to understand the activities that were carried out in the remaining paleosurface. At paleosurface TKLF, the main anthropogenic input could be related to activities other than animal resource exploitation, in which large handaxes were necessary. Without the assessment of site functionality and chronological context, this data could have lead to the differences observed at TKLF and TKSF being attributed to different Acheulean stages.

This paper presents for the first time an experimental protocol for the assessment of use-wear produced when using Precambrian and metamorphic white Naibor Soit quartzite (NQ) flakes. NQ is the most recurrent raw material from the archaeological sites of the Olduvai Gorge during the Early Stone Age (ESA). The objective of this study is to provide a preliminary description of the experimentally produced use-wear traces that can be applied to the analysis of sites like the Acheulean site of Thiongo Korongo (TK, Olduvai Gorge, Tanzania) or other sites from Olduvai where NQ was used to tool production. This experimental protocol incorporates a broad range to tasks including plant processing (underground storage organs [USOs], wood, herbaceous plants, and canes) and carcass processing (butchery and bone processing). The most novel activity of this experimental protocol is the processing of USOs. For this we have replicated different steps of tuber processing including the cutting, peeling, and scraping of five varieties of USOs (Beta vulgaris, Daucus carota, Ipomoea batatas, Pastinaca sativa and Zingiber, officinale) with differences in hardness, fibrosity, water content, and peel regularity. After analysing micro and macro-wear traces on the experimental flakes, several criteria for distinguishing between different activities (scraping, cutting, peeling, sawing, cutting, butchery) and the different materials being processed were identified. These criteria are based on the presence, continuity, and morphology of macro-scars along with the presence, distribution, nature, and intensity of different micro traces (micro-scars, attrition, striations, pits, rounding, polish). Additionally, we have identified several processes that limit the formation of traces, including the tendency of some activities to weaken NQ edges and shorten the duration of use.

The evolution of the landscape surrounding the rivers of the Madrid basin during the Middle Pleistocene is summarised in the present paper. Patterns of adaptation of human populations who settled on the riverbanks have been established in this area through geoarchaeological data recovered from associated deposits, mainly in the Manzanares and Jarama rivers. An exceptional paleoenvironmental record has been documented for the last 379,000 years in the sequences studied in the centre of the Iberian Peninsula. Pollen and non-pollen samples were studied in eight sequences obtained from different sedimentary environments of two terraces, one located in the Manzanares river (Complex Terrace of Butarque) and the other in the Jarama river (Complex Terrace of Arganda), both in Madrid (Spain). The findings show the constant presence of Pinus, sometimes as the prevailing species, and Juniperus as an element of the regional vegetation. The local vegetation is characterised by open Mediterranean forest and riverside woodlands, which together with the aquatic taxa demonstrates the presence of water. The occasional presence of deciduous forest taxa, probably related to riverside woodlands, suggest warmer conditions. Ubiquitous taxa prevail among the herbaceous strata. These types of plants do not require specific ecological conditions, but could suggest a certain degree of humidity and explain the low values of xeric taxa and sub-continental steppe grasslands. The development of nitrophilous taxa, associated with the presence of fauna, is consistent with the faunal remains recorded from the sites. However, the pollen record shows changes in the structure of the vegetation in all sequences (progressive increase in the tree component), as well as in the composition of the plant landscape (decrease of the Mediterranean taxa and increase of xeric and steppe grasslands), due to temperature and humidity rate related changes. Climatic oscillations are observed across the stratigraphic sequence, and discussed in light of the archaeological evidence for the human occupation of inland Iberia.

The successive fossil amphibian and reptile assemblages from the Middle to Late Pleistocene sites from the Manzanares and Jarama River Valleys (Madrid, central Spain) permitted the reconstruction of part of the climate instability with high-amplitude and rapid shifts of the last 450 ka and their associated landscapes: Aridos-1 (MIS11b), Valdocarros II (MIS8a/7e), Estanque de Tormentas de Butarque ETB-H02 (MIS7d or MIS6), PRERESA (MIS7/6 or MIS5a) and HAT (MIS5a). This work aims to present a regional synthesis of the palaeoclimatic and palaeoenvironmental data obtained from the herpetofaunal assemblages for these two valleys and their influence on the biodiversity during the Pleistocene. As a whole, these archaeo-paleontological localities document a total of 20 taxa (8 anurans and 12 reptiles) thus representing 76.9% of the modern authochtonous herpetofauna of the southeast of the Region of Madrid. Taking as a reference the modern situation in the area, the successive herpetofaunal assemblages permits a hypothetical landscape reconstruction where three different periods are represented with a glacial landscape (ETB-H02), a landscape of transition from cool to temperate climatic conditions (Valdocarros II), and an interglacial landscape (Aridos-1, HAT, PRERESA, and today). Environment is particularly open during dry periods, independently of if it is cold or warm. The main difference between an interglacial and a glacial period is the opposite representation of woodlands vs. moist environments: the last ones being more represented during cold periods than during warm periods. Finally, as documented by the succession from Valdocarros II, periods of transition between cold and warm climate are more forested but at the expense of humid meadows progressively. According to the relation between richness, biodiversity and climatic and environmental factors, a clear correlation appears between reptile richness and woodlands. In a similar way, mean annual precipitation (MAP) is revealed to be the most influent factor on reptile local diversity certainly because of its implications on vegetal cover extension and ecosystem productivity and resources. For amphibians the MAP does not influence dominancy but species richness: anuran richness being higher for lower MAP. Such an unusual pattern is certainly due to the fact that there are no strict forest-dweller anurans within the archaeological assemblages and that most of the anurans present in the sites are well adapted to arid conditions.

Ambrona is located in a karst landscape, and occupies a key geographic position, a transit area with natural routes connecting the three main drainage basins in the interior of the Iberian Peninsula. The site dates from the middle of MIS 11 and consists of fluvial-lacustrine deposits. Investigation of Ambrona, traditionally linked to that of Torralba (both sites are in the province of Soria, in Spain), has played a significant role in increasing our knowledge of the Acheulean in Europe, especially in the debate on hunting versus scavenging. Over the course of a century, more than 3400 m 2 have been excavated at Ambrona by four teams, led respectively by the Marquis of Cerralbo (1914–1916), C. Howell (1961–1963), C. Howell and L.G. Freeman (1980–1983), and M. Santonja and A. Perez-Gonzalez (1993–2000). In this paper we present, in their stratigraphic context, the results of our technological analysis of complete lithic series found during the excavations of the Lower Stratigraphic Member at Ambrona carried out from 1993 to 2000. During this period we excavated 685 m 2 . Only in Level AS3 was a large part of the lithic industry found in primary position, whereas the assemblages in the other levels had been greatly influenced by sedimentary processes. The whole lithic assemblage comprises 728 items. We shall analyze the chaines operatoires evidenced in each of the five identified levels, according to the raw materials used. Tools made on flake include very specialized types, but retouching is usually not intense; tool-maintenance processes are barely documented. The knapping methods used were mainly discoidal, bifacial and multipolar. Except for a few local limestone items, the knapped stones found at Ambrona (quartz, quartzite and limestone) were brought to the site, sometimes from dozens of kilometers away. The study of this collection confirms its attribution to the Acheulean techno-complex, with its characteristic handaxes and cleavers.

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.

Gran Dolina is a cavity infill of the Sierra de Atapuerca, containing three important Early and Middle Pleistocene archaeo-paleontological layers, including hominid bones, fauna and lithic remains. Due to the relevance of this site to understand human evolution in Europe, it is essential to define in detail the sedimentary processes and environments associated with the archaeological remains. Gran Dolina has a 19 m thick sedimentary infill divided into 11 lithostratigraphic units. In this work, we describe the sedimentary facies of the Early and Middle Pleistocene units and we update its stratigraphy. For that purpose, we have studied the stratigraphic excavation profiles available, where we have combined field observations with laboratory sedimentary analysis (sieving, laser diffraction, and image analysis) to characterize the texture and structure of the sediments. Through these studies, 19 sedimentary facies have been distinguished, grouped as sediment gravity flow facies, fluvial facies and autochthonous facies. The facies associations indicate two main trends in the allochthonous sequence. During the Early Pleistocene (TD4–TD7), the cavity acted as a stream sink, where channel and floodplain facies migrated along the sequence, and were interbedded with lateral gravity sediment flows. On the other hand, the Middle Pleistocene sequence between TD7 and TD10 is dominated almost exclusively by gravity flows. At least three main entrances have been inferred from input directions of the sediments, which changed over time. Sediment characteristics have allowed us to preliminarily infer environmental conditions around the cavity.

This work focusses on the Sierra de Atapuerca Thinchera karst system, in which Gran Dolina and Galeria Complex sites are located. A total of eight ERT profiles were performed over an area that covers both sites, with the aim of identifying the dimensions and continuity of these passages. The interpretation of the 2D and 3D profiles has allowed determining the extension of the conduits as well as the presence of a filled entrance that might be common to both sites. With the aid of 2D modelling experiments it was also possible to resolve some of the hypothesis raised from the interpretation of the 2D pseudosections. All these data have ultimately lead to a better understanding of the karst and sites' formation process.

The recent excavations (2008–2009) conducted at the open-air site of Las Delicias, located in the Manzanares River valley (Madrid), have revealed new important data for the understanding of the human settlement of Central Iberia during Solutrean times. In this paper, we present a geomorphological and taphonomic study of the Pleistocene deposits of Las Delicias, a technological analysis focused on the bifacial lithic reduction processes documented at the site, new Optically Stimulated Luminescence dates, and new palynological data. Together with the existence of numerous Solutrean lithic assemblages from the early 20th century excavations of the Manzanares terraces, these new data highlight the importance of the Manzanares valley as a focus of Solutrean settlement, not only related to flint procurement but also to foraging activities. Moreover, they require reconsideration of Central Iberia as a virtually unpopulated region during the Late Pleniglacial (MIS 2), and of the associated idea of its cultural dependence on the coastal areas of the Iberian Peninsula. We propose new avenues of research aimed at approaching the central region of Iberia in its own cultural and ecological terms.

Ever since Mary Leakey's initial excavations in the 1960s, TK (Thiongo Korongo) has been recognized as one of Olduvai Gorge's most important Acheulean sites. The significant concentrations of lithics and fauna reported by Mary Leakey have been augmented in recent years by Santonja et al., who argue that human activities appear to be largely related to the manufacture of lithic implements. In contrast, the faunal remains have been interpreted to be of uncertain origin, and their anthropogenic nature remains in question. This paper presents new data on the formation of the TK bone accumulation. Our results reveal a diverse list of taxa, many of which reflect open habitats. Only limited evidence of anthropogenic activity is documented.

New investigations carried out over the last few years in the Madrid Tertiary basin have revealed a large number of Acheulean sites used for the exploitation of flint. The find is significantly important because it adds context to the understanding of the intense human activity in the central parts of the Iberian Peninsula during the middle Pleistocene. The sites are spread across an extensive zone of 500 ha; Set on a vast platform on the watershed between the Manzanares and Jarama rivers. The Tertiary sedimentary succession that forms the surface of the platform is comprised of about 20 m of thick green clay interbedded with several layers of flint from the Miocene Intermediate unit of the Madrid basin. During the second half of the Middle Pleistocene, seasonal flows of streams eroded the clay, leaving large numbers of flint nodules visible to the hominids. Investigations show a sustained period of active quarrying, with much of the liberated material converted into hand crafted flint axes (Through the direct manipulation of the flint nodules). The find is valuable especially due to STI exceptional state of preservation; fossilized by sandy fluvial deposits, whose sedimentation is controlled by complex localised subsidences caused by karstic processes. The current study provides geoarchaeological background and explores different models for the formation of the sites and provides a preliminary analysis of the main Acheulean assemblages and techniques for working flint nodules. The research also adds a new, rich perspective to our understanding of the region and the organized human exploitation of raw materials in the Acheulean period. The study complements the well-known river terrace sites in the wider area showing the intensity and prevalence of flint extraction and use during the period, and the handaxe tradition typology of the Madrid region (Perez de Barradas, 1924, 1929; Santonja et al., 1980; Rus y Querol, 1981; Rus y Vega, 1984; VVAA, 2002; Baena et al., 2010 ).

The emergence of alternative luminescence dating techniques, such as thermally transferred optically stimulated luminescence (TT-OSL), post-infrared infrared stimulated luminescence (pIR-IRSL) and OSL dating of individual quartz ‘supergrains’, has opened up new possibilities for establishing numerical age control on sedimentary deposits that exceed the traditional upper age limits of quartz OSL dating. In this study, we evaluate the reliability of these ‘extended-range’ luminescence dating techniques over Middle and Early Pleistocene timescales using two approaches: (i) a broad-scale synthesis of extended-range luminescence chronologies published so far as part of known-age comparison studies; (ii) a series of new TT-OSL and pIR-IRSL case studies at the palaeoanthropological sites of Galeria, Sima del Elefante and Gran Dolina (Atapuerca, Spain). The published known-age TT-OSL datasets (n = 82) and supergrain OSL datasets (n = 3) display good correspondence (i.e., suitably linear and proportion relationships) with associated age control. The known-age pIR-IRSL datasets (n = 228) display more inter-sample scatter, though there is general support for the reliability of more stringent pIR-IRSL protocols and multiple-elevated temperature pIR-IRSL approaches over Late and Middle Pleistocene timescales. While these reliability assessments are encouraging, there remains a clear need for more widespread, known-age empirical assessments of extended-range luminescence techniques beyond ∼300–400 ka. The ages obtained at Atapuerca using single-grain TT-OSL and pIR-IRSL measurement temperatures of 225 °C (pIR-IR225) are in agreement with independent age control over an age range spanning ∼240–930 ka. In contrast, the pIR-IRSL chronologies obtained using a more stringent measurement temperature of 290 °C (pIR-IR290) consistently overestimate the expected ages of the Atapuerca sequences. The single-grain TT-OSL ages obtained at Gran Dolina permit calculation of a new weighted mean age of 846 ± 57 ka for the Homo antecessor palaeoanthropological horizon (unit TD6). The known-age Atapuerca case studies highlight the feasibility, and advantages, of applying TT-OSL dating at the single-grain scale of analysis and demonstrate that the suitability of pIR-IRSL dating protocols can vary significantly at a site or regional scale. Together, our analyses show that no single extended-range luminescence dating technique is likely to be universally applicable to all samples. Collectively, however, these approaches offer good potential for obtaining reliable chronologies, and they are likely to offer the greatest benefits when applied in tandem to individual samples.