![The upper part of the Iberian Peninsula, Cantabrian Margin, with the location of the studied Atxurra‐Armiña cave and locations mentioned regarding Cantabrian Margin landscape evolution: 1, Oiartzun river terraces (del Val et al., 2019); 2, Praileaitz and Urtiaga II caves (Aranburu et al., 2015); 3, Deba river terraces (Arriolabengoa, 2015; del Val et al., 2019); 4, Lezetxiki II cave (Arriolabengoa et al., 2018a); 5, Nervion river terraces (del Val et al., 2019); 6, Pindal cave (Jiménez‐Sánchez et al., 2006); 7, Cobiheru cave (Ballesteros et al., 2017); 8, Picos de Europa caves (Ballesteros et al., 2019); 9, Asturian marine terraces (Álvarez‐Marrón et al., 2008). Below, development of the studied Atxurra‐Armiña cave system within the current landscape (geological information derived from EVE, 1986). [Color figure can be viewed at wileyonlinelibrary.com]](https://www.researchgate.net/publication/342184650/figure/fig1/AS:903328875700226@1592381795465/The-upper-part-of-the-Iberian-Peninsula-Cantabrian-Margin-with-the-location-of-the_Q320.jpg)
![Topographic plan of the Atxurra‐Armiña cave, showing the three parts differentiated in this work, and their different significant features.
[Color figure can be viewed at wileyonlinelibrary.com]](https://www.researchgate.net/publication/342184650/figure/fig2/AS:903328888258570@1592381798823/Topographic-plan-of-the-Atxurra-Armina-cave-showing-the-three-parts-differentiated-in_Q320.jpg)
![Photographs of different morphological features and sedimentary bodies (modified from Arriolabengoa et al., 2018b). (a) Outer Atxurra: stratified and siliceous nodule conduit, where the roof has collapsed, with some collapsed blocks beneath the current soil. (b) Outer Atxurra: relict of the ceiling channel, superimposed by the vadose vertical development of the gallery. (c) Outer Atxurra: the only perched speleothem 2m above the current cave floor. (d) Inner Atxurra, gravitational speleothem overlapped by currently eroded fluviokarstic deposits. (e) Inner Atxurra: the roof of the conduit containing anastomotic channels at the bedding plane, allocthonous fluviokarstic deposits surrounding them, eroded
gravitational speleothems and roof pendant morphologies along the wall. (f) Inner Atxurra: superimposed horizontal notches, initial stage of wall roof pendants, perched flowstone at around 2m in height from the current cave floor, and allochthonous fluviokarstic deposits near the top of the conduit. (g) Armiña cave: the ceiling channel, initial stage of roof pendants and a 1‐m‐wide notch. (h) Armiña cave: scarp of the flowstone, being filled by the current active flowstone. Abbreviations: A.C, anastomotic channel; C.C, ceiling channel; E.G.S, eroded gravitational speleothem; 1st F, fluviokarst
before gravitational speleothem; 2nd F, fluviokarst after speleothem formation; N, notch; R.P, roof pendant; P.S, perched speleothem. [Color figure can be viewed at wileyonlinelibrary.com]](https://www.researchgate.net/publication/342184650/figure/fig3/AS:903328896667648@1592381800452/Photographs-of-different-morphological-features-and-sedimentary-bodies-modified-from_Q320.jpg)
![The overall stratigraphy of the three parts of the cave (stratigraphic scheme modified from Arriolabengoa et al., 2018b). [Color figure can be viewed at wileyonlinelibrary.com]](https://www.researchgate.net/publication/342184650/figure/fig4/AS:903328900861954@1592381801910/The-overall-stratigraphy-of-the-three-parts-of-the-cave-stratigraphic-scheme-modified_Q320.jpg)
![Location of the 19 different rock art sectors and the archaeological context (modified from Garate et al., 2020). [Color figure can be viewed at wileyonlinelibrary.com]](https://www.researchgate.net/publication/342184650/figure/fig5/AS:903328909238272@1592381803108/Location-of-the-19-different-rock-art-sectors-and-the-archaeological-context-modified_Q320.jpg)
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From cave geomorphology to Palaeolithic human behaviour: speleogenesis, palaeoenvironmental changes and archaeological insight in the Atxurra‐Armiña cave (northern Iberian Peninsula)
Abstract and Figures
A detailed geomorphological study was performed in the Atxurra‐Armiña cave system (northern Iberian Peninsula) to decode landscape evolution, palaeoenvironmental changes and human use of a cave within an Inner Archaeological Context. The results show an average incision rate of the river of <0.083 mm a–1 for at least the last 419 ka, with interruptions due to sedimentary inputs. Moreover, allostratigraphic units comprising fluviokarstic deposits at the base and flowstone formation at the top have been shown to be climatically controlled, formed either during glacial–interglacial cycles or during interstadial cycles. Finally, when the cave was used by humans in the Late Magdalenian, the lower entrance was closed, and they must therefore have entered the cave through the upper entrance. To reach the sectors selected to decorate the panels, they probably travelled from the upper cave level, as the current crawlway was wider than today, according to our U/Th dating. Once these visitors reached the panels, the floor in the main gallery would have been around 15 cm lower than at present. However, the morphology of the conduit was similar; this has significant implications for understanding and interpreting the human use of the cave during the Palaeolithic.
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... 17,700-13,500 cal yr BP). Since these caves were decorated, there have been erosive events-usual in the area in interglacial-glacial transitions (Aranburu et al., 2015;Arriolabengoa et al., 2018Arriolabengoa et al., , 2020Stoll et al., 2013)-such as those observed in the vestibule of Santimamiñe, where the episode of Almp's stratigraphic alteration might have occurred within the Alleröd oscillation (c. 14,000-13,500 cal yr BP) and/or Preboreal (c. ...
... Our 3D models have subsequently been modified, on the basis of morphological data obtained from geological studies (e.g. Arriolabengoa et al., 2020) and comparing older and more recent graphic documents, taken from the data of early explorers (e.g. Aranzadi et al., 1925;Barandiarán, 1964), using Meshlab® (to cut and work independently in areas of interest) and Blender®. ...
The endokarst landscape is the result of long erosion and sedimentation processes that have modelled an environment in which capricious forms abound. Despite being a hostile environment for human life, these caves must have attracted the attention of human groups from as early as the Palaeolithic. It is striking that many examples of rock art appear to be closely symbiotic with their natural support; nevertheless, it is difficult to confirm any relationship in the distribution of the decorated spaces, based on their morphology. Moreover, if we start from the hypothesis—widely accepted, but not demonstrated—that Palaeolithic cave art is a system of visual communication, the visibility of the art or the number of people who could be accommodated in the decorated sectors should be determining factors. In order to avoid making subjective appraisals when analysing these factors, we have designed a Python script with a workflow to work directly with 3D models of caverns using GISs, which can be easily replicated and edited by other researchers. Application of this script in the Magdalenian caves of Atxurra, Santimamiñe and Altxerri (Northern Spain) has allowed us to compare them accurately based on their visibility features. This has shown that in some cases, there may have been prior planning to enhance the visibility of some figures. In all cases, the groups of figures are located in deep and hidden parts of the caves, usually in sectors with limited capacity to accommodate people, which would be consistent with a system of restricted communication.
... The concentration of Upper Paleolithic sites in such a specific landscape feature questions choice of the site frequentation by the prehistoric people [16][17][18] . An essential first step in conducting such analyses is to ascertain whether current features were already part of the landscape when a site was being used 9,11 . The present study aims to trace the evolution of this landscape in order to determine whether the meander cutoff and Pont d' Arc had already formed 37 ka cal BP, when the Chauvet cave was frequented by Upper Palaeolithic societies. ...
... Similar approaches combining relative and absolute dating of geomorphological objects have been used successfully at numerous archaeological sites 11,14,37,38 . www.nature.com/scientificreports/ ...
The Chauvet cave (UNESCO World Heritage site, France) is located in the Ardèche Gorge, a unique physical and cultural landscape. Its setting within the gorge—overlooking a meander cutoff containing a natural arch called the Pont d’Arc—is also remarkable. Investigating possible associations between sites’ physical and cultural settings, chronologies of human occupation, and access conditions has become a major theme in archeological research. The present study aims to reconstruct the landscape of the Pont d'Arc meander cutoff during the Upper Paleolithic, when humans were present in the Chauvet Cave. We used uranium-series and electron spin resonance analyses to date the formation of the Pont d’Arc natural arch in the Combe d’Arc meander cutoff, near the Chauvet Cave. Results show that the meander became totally cutoff between 108 and 138 ka (95%). Hence, the natural arch formed before the Upper Paleolithic and the first known human presence in the Chauvet Cave, dated to 37 ka cal BP. These results allowed us to reconstruct a key part of the landscape surrounding the Chauvet Cave when it was being used by Upper-Paleolithic societies.
... Estos trabajos pueden ser de índole local (p. ej., Quinif y Marie, 1998;Bartolomé et al., 2015bBartolomé et al., , 2021bArriolabengoa et al., 2020), o de integración regional (Stoll et al., 2013;Ballesteros et al., 2015). ...
Enlace al Vol. Completo: https://recyt.fecyt.es/index.php/CUGEO/issue/view/4351/847
El presente número especial se centra en la mayoría de los métodos de datación que nos pueden ofrecer fechas numéricas y sus correspondientes errores para los materiales Cuaternarios. Los diferentes artículos recogen las técnicas más novedosas o punteras, aunque las más comúnmente usadas en el estudio del Cuaternario, como el Paleomagnetismo, Potasio-Argón (K/Ar) o Carbono 14 (C14) no se han incluido. Esto ha sido debido a que los especialistas con los que se había contactado para la redacción de estos artículos desgraciadamente no pudieron concretar su participación por diferentes motivos. En cualquier caso, son de los métodos más antigua y comúnmente usados en el estudio del Cuaternario, y de sobra conocidos por la mayoría de cuaternaristas, existiendo diferentes obras de referencia para los mismos, aunque no sea en castellano.
La presente obra recoge casi una veintena de métodos que, de una u otra forma, nos aportan fechas y edades numéricas con un importante bagaje geocronológico y apoyo isotópico, geoquímico, biogeoquímico o arqueológico. Partimos de las dataciones epigráficas, cerámicas o numismáticas que nos ofrece la arqueología (01. Campos et al.) para adentrarnos en los métodos arqueomagnéticos (02. Carrancho et al.), dendrocronológicos (03. Génova-Fuster y Díez-Herrero), liquenométricos
(04. Pérez-López) y de estudio de sedimentos varvados (05. Corella y Martín-Puerta) que nos permiten fechar materiales, formas, procesos y eventos energéticos históricos, holocenos o de edad post-glaciar. La contribución de (06.) Cearreta et al., nos explica de qué manera el análisis de radionucleidos de vida corta como el Plomo (210Pb), Cesio (137Cs) o Plutonio (239,240Pu) ayuda en la datación de procesos geológicos muy recientes, especialmente aquellos relacionados con procesos de contaminación y/o del estudio del todavía “nonato” Antropoceno.
Los dos siguientes artículos nos ofrecen cómo se pueden combinar fechas procedentes de diferentes métodos de datación (C14; Th/U, TL, OSL, etc.) para el establecimiento de “modelos cronológicos robustos” que profundicen en las tasas de sedimentación de zonas lagunares y sus implicaciones paleoclimáticas (07. Moreno et al.), o para el establecimiento de cronologías fiables mediante la
generación de “cronofunciones” (08. Silva y Roquero) que relacionen fechas y alturas relativas de terrazas fluviales u otros elementos geomorfológicos, ofreciéndonos marcos geocronológicos regionales “low-cost”.
Bardají y Lario (09. y 10.) ahondan en los principios de la “estratigrafía isotópica marina” (Marine Isotopic Stages), mostrándonos las bases y actualizaciones más recientes de tales escalas isotópicas, con especial referencia al último ciclo glaciar (MIS 4 - MIS 1): estadiales e interestadiales de Groenlandia; Eventos Dansgaard-Oeschger y Eventos Heinrich.
Los siguientes artículos se basan en el uso de los estudios micropaleontológicos como herramienta de datación, tanto en estudios de sondeos marinos (11. Alonso-García et al.), como en registros continentales lacustres o de rellenos kársticos fundamentalmente (12. Cuenca-Bescós). Tanto el estudio de microforaminíferos como de micromamíferos no nos aportan una cronología “sensu stricto” por sí mismos, pero su combinación con dataciones o curvas isotópicas relacionadas permiten el establecimiento de marcos cronológicos robustos para sondeos marinos, continentales y secuencias kársticas. Los primeros son muy importantes para el último ciclo interglaciar-glaciarinterglaciar, y las segundas, relevantes en el establecimiento de cronologías alrededor del tránsito Pleistoceno inferior-medio y más antiguas. . El siguiente artículo aborda la datación isotópica Th/U (13. Múñoz-García y Martín-Chivelet) todo un “tótem” de la geocronología del Cuaternario que se ha aplicado a sistemas kársticos (espeleotemas), terrazas marinas (gasterópodos), corales, calcretas y demás materiales geológicos con un
contenido importante y de precipitación primaria de CO3Ca. A continuación, se aborda la técnica de datación por “racemización de aminoácidos” (14. Torres et al.), que analiza la degradación de aminoácidos en elementos de origen biológico muy diversos, como foraminíferos, moluscos, crustáceos, y diferentes tipos de fósiles de mamíferos (huesos y dientes), lo que permite establecer cronologías en secuencias difícilmente datables por otros métodos. Es una técnica no muy utilizada, pero ampliamente aplicada en España debido al trabajo del Laboratorio de Estratigrafía Biomolecular de la Universidad Politécnica de Madrid (UPM).
La siguiente dupla de artículos se ocupa del análisis de dos de las técnicas de datación más modernamente introducidas en España, y de amplio uso en la actualidad, como son la “Termoluminiscencia y la Termoluminiscencia Ópticamente Estimulada”, TL y OSL en sus siglas convencionales (15. Medialdea- Utande y García-Silva) y la “Resonancia Paramagnética Electrónica”, ESR (16. Duval). La versatilidad de estas técnicas de datación al no requerir materiales específicos, sino más bien ampliamente distribuidos sobre la corteza terrestre, como son granos de cuarzo y feldespato, es la que ha hecho que estas sean las herramientas geocronológicas que han multiplicado exponencialmente el número de dataciones disponibles en España. A ello se le une la disponibilidad de análisis en los laboratorios de datación del Centro Nacional para el Estudio de la Evolución Humana (CENIEH) al que pertenecen los primeros firmantes de ambos artículos. Un último artículo (17. Alcalá Reygosa et al.) nos ilustra en las más modernas aplicaciones de la “datación por cosmogénicos terrestres de materiales y formas volcánicas recientes”, comentándonos algunos ejemplos en volcanes monogenéticos holocenos de México.
Todos los trabajos han sido revisados por pares, incluyendo un importante elenco de investigadores que han actuado como revisores.
... Estos trabajos pueden ser de índole local (p. ej., Quinif y Marie, 1998;Bartolomé et al., 2015bBartolomé et al., , 2021bRodríguez et al., 2018;Pérez-Mejías et al., 2019;Arriolabengoa et al., 2020), o de integración regional Ballesteros et al., 2015). ...
El método de U/Th permite datar materiales diversos de hasta 600.000 años de antigüedad. En este trabajo se revisan sus fundamentos y las técnicas analíticas disponibles, centrándose en su aplicación más habitual, que es la datación de carbonatos. En concreto, se discuten su potencial y limitaciones en la datación de espeleotemas, travertinos, calcretas, cementos, corales y moluscos aprovechando los ejemplos publicados en España. El cálculo de edades mediante U/Th se basa en la serie de desintegración del 238U e involucra medidas de 238U, 234U y 230Th. Su fundamento radica en el fraccionamiento entre los radionucleidos del uranio y del torio en los sistemas naturales. En el caso de la precipitación de carbonato puro, éste incorpora uranio en el momento de su formación, pero está libre de torio inicial de tal forma que, pasado un tiempo, todo el 230Th medido en la muestra deriva de la desintegración del 234U y esta relación permite calcular la edad de formación del mineral. Teóricamente, por tanto, el carbonato a datar: (1) debe incorporar cierta cantidad de uranio en el momento de su formación, (2) no debe incorporar cantidad significativa de torio y (3) debe comportarse como un sistema cerrado. De estas premisas, la segunda y la tercera no siempre se cumplen por lo que el método se ha adaptado a estos casos añadiendo cálculos y correcciones adicionales. Dada la variedad de carbonatos susceptibles de ser datados, este método es de amplia aplicación en paleoclimatología, paleontología, arqueología, estratigrafía, geomorfología, tectónica y oceanografía, entre otras disciplinas.
... In the Pyrenees, clastic deposits in caves are common but there have been few sedimentological studies. Previous studies on cave sediments in the Pyrenees include the pioneer work of Robert, (1981) highlighting the variety and singularity of the clastic sediments in the Granito cave, Oliva-Urcia et al., (2014) in Seso cave, Quinif and Maire, (1998) in the Northwestern Pyrenees, and, more recently, by Aranburu et al., (2015) and Arriolabengoa et al., (2018Arriolabengoa et al., ( , 2020 in the southwestern Pyrenees. ...
In Alpine regions, speleothem development on karst systems largely occurs during warm interglacial or interstadial phases due to their limited growth during cold stages. Still, recent attention has been given to the role of clastic sediments in caves, less dependent on temperature conditions. Yet, only a small number of caves worldwide preserve both speleothems and detrital deposits. Here we present an outstanding record of fine-grain laminated sediments and carbonate speleothems from the Granito cave (South Central Pyrenees, Spain) associated with seasonal to annual hydroclimatic pulses through the Last Glacial Cycle (LGC). Analysis of cave clastic facies together with new absolute dates on glacial deposits along the valley has provided new insights into the karst-glacial interactions in relation with long-term landscape evolution, with support of geomorphological, sedimentological, mineralogical, palynological, geochemical and geochronological data (U/Th series, OSL and IRSL).
The Granito cave was formed before 153.6±1.2 ky (Marine Isotopic Stage, MIS 6), as indicated by the oldest stalagmites dated in the cave, although speleothem formation occurred preferentially during MIS 5 and the Holocene interglacial stages. A 60 m thick clastic deposit was IRSL dated from 71.8±5.6 ky to after 26.5±2.5 ky corresponding with the maximum ice extent (MIE) during the LGC and subsequent glacial stabilization at 30.3±1.7 – 36.2±2.2 ky. The sediment infill was produced by water ponded in the cave coeval with the presence of glacial ice blocking the cave entrance. The cave clastic sequence includes channel, slackwater and backswamp facies, interpreted to result from pulses of sediment-laden water flow under vadose and phreatic flow regimes. The cave sediment’s mineralogical composition points to an exogenous source associated with glacial till sediments overlying the hillslope above the cave and along the Ara River valley. The palynological results obtained from the cave sediments show the dominance of an open landscape composed of steppe vegetation indicating cold glacial climatic conditions. The opening of the cave occurred before 14.9±1.5 ky, the stabilization age of the innermost Ara glacier moraine, giving rise to scouring and cut-and-fill sequences within the detrital infill. Speleothem growth during the Holocene indicates the return to warm climatic conditions with the development of a soil and vegetation cover above the cave. This study shows how a combined interpretation of clastic and speleothem lithofacies is critical for elucidating landscape evolution and surface-groundwater palaeohydrological changes in northern Iberia during the LGC.
U‐series dating is a group of dating methods based on a disequilibrium within the 238 U or 235 U decay chains and the return over time to the secular equilibrium between a parent nuclide and its long‐life daughter. This chapter aims to take stock since the 2000s and to highlight recent analytical developments and applications to archaeological studies. It highlights recent discussions on the need to correct the ages for the detrital fraction and the discussions on possible post‐depositional alteration, which could, in some cases, bias the radiometric ages. The chapter presents some applications of archaeological case studies. These include the dating of: flowstones interbedded with archaeological layers; thin secondary carbonate crusts over/under rock art; soot or microcharcoal layers trapped in speleothems; and speleothem growths, breaks, and shifts as markers of human cave occupation or constructions.
The systematic evaluation of accessibility to different sectors in caves with Palaeolithic rock art is crucial to interpret the contexts of prehistoric human activity that took place inside them, especially if focused on the areas that are harder to reach. 3D models have been employed in a GIS to process spatial information, calculate numerical cost values and estimate optimal transit routes or needed times to reach several sectors inside a cave, based on morphological features and movement types. These have been obtained through empirical observations and experimental archaeology. Previous geomorphological studies are necessary to determine any geological or anthropic changes that may have occurred in the endokarst since its use in the Upper Palaeolithic. The method has been applied in Atxurra Cave, with satisfactory results, and the accessibility to different archaeological sectors has been compared objectively. This will enable the objective and quantitative assessment of accessibility to the deep sectors of other prehistoric caves in the future, and thus establish recurring or specific patterns among the human groups that created the Ice Age art.
RESUMEN El yacimiento de la cueva de Atxurra fue excavado entre 1934 y 1935 por J.M. Barandiarán Ayerbe. Las condiciones de la excavación, la tardía publicación de los resultados y los avatares sufridos por los materiales arqueológicos recuperados han condicionado el análisis y la interpretación del yacimiento y de su secuencia estratigráfica. Recientemente el yacimiento ha sido objeto de una revisión arqueológica que ha propiciado una nueva lectura de la secuencia. A la luz de estas nuevas informaciones proponemos una revisión integral de la excavación de la década de 1930. Se discute, a partir del estudio de la industria lítica, ósea, cerámica y de los restos de macrofauna la pertinencia de la división estratigráfica propuesta por I. Barandiarán Maestu en los años 1960. Como resultado se propone la existencia de una ocupación Gravetiense en la base de la secuencia, la ausencia de Solutrense, la presencia de Magdaleniense Inferior, de Magdaleniense Superior, la ausencia de Aziliense y la presencia de Neolítico-Calcolítico. LABURPENA Atxurrako leizeko aztarnategia 1934-1934ean induskatu zuen J.M. Barandiaran Aierbek. Aztarnategiaren analisia eta interpretazioa eta sekuentzia estratigrafikoa baldintzatu egin dituzte aipatu dugun indusketa haren baldintzek, emaitzak berandu argitaratu izanak eta berresku-ratutako material arkeologikoek jasandako gorabeherek. Duela gutxi, berrazterketa arkeologiko bat egin zaio aztarnategiari eta hortik sekuent-ziaren irakurketa berria atera da. Informazio berri horien harira, 1930eko hamarkadako indusketaren berrazterketa osoa egitea proposatzen dugu. Industria litikoaren, hezur-eta zeramika-industriaren eta makrofauna-hondakinen azterketatik abiatuta eztabaidatu dugu I Barandiaran Maestuk 1960ko hamarkadan proposatutako zatiketa estratigrafikoaren egokitasuna. Horren emaitza gisa, proposatu dugu okupazio Gravet-tiarra dagoela sekuentziaren oinarrian, Solutre aldirik ez, Behe Madeleine aldiaren presentzia, Goi Madeleine aldiarena ere bai, Azil aldirik ez eta Neolito-Kalkolitoaren presentzia ere bai. ABSTRACT The cave of Atxurra was excavated by J.M. Barandiarán Ayerbe between 1934 and 1935. The circumstances of the excavation, and the vicissitudes suffered with the archaeological remains biased the analysis and interpretation of the site and its stratigraphic sequence. Recently, the site has been revisited, and a new interpretation of the archaeological sequence is proposed here with an integral review of the 1930´s excavation. Considering the new data obtained from the lithic, bone tool, ceramic and macromammal assemblages, the validity on the cultural sequence defended by I. Barandiarán Maestu in the 1960´s is discussed. As a result, the existence of a Gravettian occupation in the base of the sequence, the absence of Solutrean, the presence of Lower Magdalenian and Upper Magdalenian, the absence of Azilian and the presence of Neolithic-Calcolithic occupations at the cave are proposed. (1)
The intraplate deformation of Iberia during the Cenozoic produced a series of ranges and deformation belts with a wide variety of structural trends. The Spanish-Portuguese Central System is the most prominent feature crossing over the whole of central Iberia. It is a large thick-skinned crustal pop-up with NE-SW to E-W thrusts. However, the 500-km-long left-lateral strike-slip Messejana-Plasencia fault, also NE-SW oriented, bends these thrusts to produce NE-SW local paleostresses close to the fault, which seems to be consistent with a common deformational arrangement. This is also supported by the similar sedimentary infilling characteristics found in the surrounding Cenozoic basins. The moment of the maximum intraplate deformation is registered at the same time in all these basins during the upper Priabonian-lower Chattian. As there are two possible sources for the intraplate compressive stresses, the Pyrenean (N-S shortening) orogen to the north and the Betic (NW-SE shortening) orogen to the south, neither can simply explain both simultaneous movements (NE-SW strike-slip and NE-SW thrusting). The deduced age of the main deformation indicates a Pyrenean origin. In contrast, the concept of strain partitioning between the two types of faults gives as a result an overall north trending compression. Existing data do not support crustal detachment from the Betics neither from the Pyrenees but are consistent with a crustal uplift related to lithospheric folding. The subsequent Betic-related stress field only slightly reworked previously Pyrenean-related structures, except for the Portuguese sector, where tectonic activity occurred mainly in the Upper Miocene.
Micromorphological analysis is an invaluable research tool for reconstructing detailed depositional and post-depositional processes of cave infill sequences and for providing paleoenvironmental insight. In this work, we present the results of a micromorphological and mineralogical study of the sedimentary sequence at the Lezetxiki II cave (northern Iberian Peninsula). The cave forms part of the Lezetxiki archaeological complex which has yielded early Middle Palaeolithic tools and archaic human remains. We have identified three main clastic sedimentary processes as being significant at Lezetxiki II: 1) fluviokarst or runoff processes, which are characterised by yellow sandy illite-rich microfacies; 2) infiltration processes, which produce a massive red silty-clay vermiculite-rich microfacies; and 3) inwash processes, which generate a reworked illite and vermiculite rich silty sand microfacies. The most common post-depositional processes observed are calcite precipitation infilling pore spaces, and compression structures derived from specific vertical loading events. In order to improve the chronological framework of the sedimentary sequence at Lezetxiki II, we have revised previous radiometric and relative dating results from faunal and archaeological remains and have dated the lowermost stratigraphic level using single-grain thermally-transferred optically-stimulated luminescence dating. Sedimentation at the Lezetxiki II cave started during Marine Isotope Stage (MIS) 7 through fluviokarst processes. We interpreted that runoff prevailed during MIS 6, while soil infiltration processes became more significant towards the MIS 5 optimum. Gradually, inwash processes prevailed over infiltration until the end of the interglacial phase. During the following glacial phases, runoff and erosion dominated but were subsequently replaced by inwash processes during MIS 1.
Numerous studies have shown that the relative frequency of retouched pieces can help to distinguish forager mobility strategies amongst individual layers at a single site and, potentially, at multiple sites across regions (Riel-Salvatore and Barton, 2004; Riel-Salvatore et al., 2008; Barton & Riel-Salvatore, 2014). We use this proxy measure and other lines of evidence to evaluate Late Pleistocene human land-use practices from 47 Upper Paleolithic and Mesolithic sites in northern coastal Spain.
To monitor mobility strategies we examine the proportion of retouched pieces to total lithics, focusing on backed pieces which probably served mostly as replaceable inserts in organic armatures for hunting weapons. Kuhn (1995) argued that foragers at some distance from a residential base would have had to rely on replaceable elements for the tools and weapons they carried with them. Assemblages with low total lithic densities but a high proportion of backed pieces would most likely represent the remains of short-term camps where hunting weapons were repaired in the field, whereas those with high lithic densities and relatively few backed pieces would likely represent residential bases where hunting weapons were manufactured.
The analysis also links variation in lithic assemblages to paleoclimate and topography and uses 951 radiocarbon dates to identify demographic ‘pulses’ under the assumption that – ceteris paribus – the density of dates and the density of population are at least roughly linearly correlated with one another (French and Collins, 2015). Increases and decreases in regional population density can be detected and compared to episodes of climate change measured by the GISP2 and NGRIP2 ice cores over the Pleniglacial, Tardiglacial (MIS 2) and the early Holocene. Data insufficiencies, incomparable typologies, and adequacy of reporting are also discussed.
Traditionally, studies of Palaeolithic cave art have largely ignored or directly overlooked the red spots of anthropogenic origin that do not belong to figurative categories, in spite of their importance in quantitative terms in this type of art. This paper highlights their importance for a better understanding of the multiple causes of the cave remains commonly classi- fied as “rock or cave art.”
To this end, we analysed these spots directly in a number of caves (Etxeberri, Lumentxa, Nerja and Morrón). This al- lowed us to differentiate between intentional and other incidental or involuntary red spots. Furthermore, depending on the intrinsic and extrinsic characteristics of these spots, as well as information provided by archaeological and ethnographic findings, we related them to the body painting of their authors.
Therefore, an identifiable part of the red spots so common in Palaeolithic cave art (and which could therefore not be considered as art sensu stricto) to have been produced involuntarily. This was also related with the customs of the Palae- olithic groups that frequented the innermost areas of the caves and who used to decorate their bodies with ochre-based paint.
Appréhender la part des processus naturels et de l'Homme dans la facture et la construction des sites d'art rupestre est depuis longtemps au cœur des travaux menés en archéologie. L'accent est mis ici sur la géomorphologie qui, par l'analyse de l'évolution physique des sites archéologiques, interroge le rôle respectif des processus morphogéniques et des agents anthropiques. Une nouvelle dimension de l'approche géomorphologique est ici proposée en l'interrogeant sur la part de l'homme dans morphologie des sites étudies ainsi que sur le statut des objets qui y sont présents.. Les recherches menées sur différents sites ornés, dont la grotte Chauvet-Pont-d'Arc (France) et le site de Nawarla Gabarnmang (Terre d'Arnhem, Australie), nous amène à poser le concept de "géomorpho-archéologie". Ces deux sites se caractérisent par des aménagements anthropiques qui ont pu être identifiés via une approche géomorphologique ouverte sur les problématiques archéologiques et ethnoarchéologiques, notammenet sur la part respective de l'Homme et de la Nature dans leur facture paysagère. L'approche géomorpo-archéologique a permis pour la grotte de Chauvet-Pont-d'Arc d'identifier une diversité d'aménagement anthropiques ; seuls l'exemple de la structure du Cactus est ici traité. Pour le site de Nawarla Gabarnmang, c'est la dimension construite e ce site orné majeur qui a pu être mise en évidence à partir du relevé géomorphlogique
Advances in areas of archaeological science with a strong geological, sedimentological or pedological component have significantly furthered the understanding of formation processes, improved interpretations and helped develop site preservation over the last twenty years. Here, we examine some of those subject areas and their progress, with a view to charting future directions for this growing body of knowledge.
A complete and optimized scheme of lettered marine isotope substages spanning the last 1.0 million years is proposed. Lettered substages for Marine Isotope Stage (MIS) 5 were explicitly defined by Shackleton (1969), but analogous substages before or after MIS 5 have not been coherently defined. Short-term discrete events in the isotopic record were defined in the 1980s and given decimal-style numbers, rather than letters, but unlike substages they were neither intended nor suited to identify contiguous intervals of time. Substages for time outside MIS 5 have been lettered, or in some cases numbered, piecemeal and with conflicting designations. We therefore propose a system of lettered substages that is complete, without missing substages, and optimized to match previous published usage to the maximum extent possible. Our goal is to provide order and unity to a taxonomy and nomenclature that has developed ad hoc and somewhat chaotically over the decades. Our system is defined relative to the LR04 stack of marine benthic oxygen isotope records, and thus it is grounded in a continuous record responsive largely to changes in ice volume that are inherently global.
The systematic documentation of calcite fabrics in stalagmites and flowstones provides
robustness to palaeoclimate interpretation based on geochemical proxies, but it has been
neglected because it is difficult to transform crystal morphologies into numerical values,
and construct fabric time series. Here, general criteria that allow for coding fabrics of calcite
composing stalagmites and flowstones is provided. Being based on known models of fabric
development, the coding ascribes sequential numbers to each fabric, which reflect climaterelated
parameters, such as changes in drip rate variability, bio-mediation or diagenetic
modifications. Acronyms are proposed for Columnar types, Dendritic, Micrite, Microsparite
and Mosaic fabrics, whose use could then render possible comparison of calcite fabrics in
stalagmites and flowstones from diverse latitudinal and altitudinal settings. The climatic and
environmental significance of similarities in the geochemical signals and trends analysed
in coeval stalagmites and flowstones (or differences in the signals and trends) will be more
robust when compared with fabric time series. This is particularly true where, such as in the
Holocene, changes in geochemical values may be subtle, yet fabrics may show changes
related to variations in supersaturation, drip rate or input of detrital particles or organic
compounds. The proposed microstratigraphic logging allows recognition of changes in stable
isotope ratio or trace element values that can be ascribed to hydrology and diagenesis, with
considerable improvement of reconstructions based on the chemical proxies of stalagmites
and flowstones composed of calcite.
Investigations of prehistoric cave art have long neglected the surrounding context: space, archaeological objects, and imprints.
As a result, an integrative structural approach that analyzes cave art as part of an anthropomorphized landscape has not been
available. This article draws on urban planning and the physiology of the human eye to provide an innovative archaeospatial
analysis of cave sites. A set of relevant features from the caves of Bédeilhac, Fontanet, and Le Portel was selected and defined
(light zone, chamber type, path network, mode of movement, and available space). An analysis of the prehistoric remains in
the caves allows the reconstruction of different concentrations of human activities (cave art, archaeological objects, and
imprints). The projection of these concentrations onto the structured map of the caves results in four types of locations:
drawing location, supply location, drawing location with substantial activities, and drawing location with consumption activities.
This approach opens new avenues for the archaeological perception of caves and their inhabitants: Upper Paleolithic humans
were very familiar with caves and probably followed a master plan during their stay in the dark.
Five fabrics were identified in Alpine and Irish caves on the basis of morphological and microstructural characteristics, and related to growth mechanisms and growth environment. Columnar and fibrous fabrics grow when speleothems are continuously wet, and from fluids at near equilibrium conditions (low supersaturation; SIcc < 0.35), through the screw dislocation mechanism. The highly defective microcrystalline fabrics form at the same supersaturation range as columnar fabric but under variable discharge and the presence of growth inhibitors. Dendritic fabrics, which have the highest density of crystal defects, develop in disequilibrium conditions (high supersaturation) under periodic very low-flow-regime periods that result in prolonged outgassing. Cave calcareous tufa forms in disequilibrium conditions. Only the calcite crystals of fabrics formed at low supersaturation seem to precipitate near-isotopic-equilibrium conditions.
Geomorphologic mapping and structural data provide the preliminary results of the geomorphologic features of the Pindal Cave and surrounding area, described in this work. The landscape results from fluvial, mass wasting, karstic and marine processes, with the outstanding presence of two erosion marine surfaces called "Rasas": Pimiango (125-170 m) and Pindal (50-64 m). The origin of the cave, developed in the karstic massif reaching its highest level in Pindar Rasa, is mainly controlled by two fractures trending E-W. The geomorphologic evolution of the Cave is due to 1/block collapse from the roof related to three joint systems; 2/ the episodic infilling by detrital sediment coming from denudation of Pimiango Rasa Range and 3/ the chemical precipitation of speleotheme overlying both alluvial and collapse deposits. The present dynamics of the cave is controlled by vadose conditions and collapse processes and sporadic flooding of channel inside the cave. A lower active level is inferred from scarps developement in deposits over the floor cave.
Some of the oldest speleothems in the North Cantabrian Coast (Spain) are reported for the first time in this work. Pindal Cave is developed at 24 m above sea level, in a karstic massif reaching its highest surface in a marine terrace (rasa) located at 50-64 m above the present sea level. Several phases of evolution were previously recognized into the cave, including block collapse of the roof, episodic flooding and detrital sedimentation, and chemical precipitation of at least four speleothem generations over both alluvial and collapse deposits. Three of these speleothem generations have been dated by U/Th. The first generation yielded ages from 124,2 ± 1, 5 ka BP to 73,1 ± 0,9 ka BP, giving a minimum age for the main detritic sediments in the cave. The second one is not dated. The third generation gives an age of 3,71 ± 0,4 ka BP (mathematically corrected to 2.7 ± 0.5 ka BP), while for the youngest generation, with actively growing stalagmites in the cave, basal ages of 200 years BP are estimated by counting annual laminae. The data suggest a tentative maximum elevation rate close to 0, 2 mm/yr for the Cantabrian Margin in this area, although further chronological studies will be needed to check this hypothesis.
The evolution of the Torcas cave system (Sierra de Atapuerca) is analysed in order to shed light on the formation of the Atapuerca archaeological sites and human occupation in the area, critical for identifying the paths of the first human dispersal into Europe. The geomorphological analysis of the endokarst system and the regional base levels has revealed a multilevel cave system, with drainage directions from south to north, where old karst springs fed the Pico River. Using morphological and topographic evidence we have correlated the fluvial terraces situated at relative heights of +84–80 m and +78–70 m above the Arlanzón River (main course), with the first and second cave levels, respectively, both of Early Pleistocene age. The fluvial levels T4 (+60–67 m) and T5 (+50–54 m) are linked with the third level (Early–Middle Pleistocene), which contains fluvial deposits probably related to terrace T6 (+44–46 m). Progressive fluvial incision allowed humans to gain access to the cave system through several entrances from ~1.22 Myr until the end of the Middle Pleistocene, when these cave entrances became filled, forming the most interesting hominid-bearing deposits in Europe.
The discovery of Palaeolithic parietal art in the cave of Atxurra took place within an archaeological surveying project that has been carried out over the last decade in the eastern Cantabrian region. As a consequence of this project, the number of caves with parietal art known in this region has tripled. The case of Atxurra Cave is a remarkable contribution because of the number of parietal representations and the presence of a related external and internal archaeological context. Through this contribution, we present the main data derived from the cave study project that is currently underway, as well as its implications for the reformulation of symbolic interaction during the late Upper Palaeolithic.
Cussac Cave, discovered in 2000 in the Dordogne department of France, is one of the major decorated and sepulchral sites of the Gravettian period of the Upper Palaeolithic. It contains spectacular engravings, human remains-some of which were deposited in bear hibernation nests-and other well-preserved artefacts and traces of human and animal activity, such as human and cave bear footprints. The exceptional preservation of this cave is due to its recent discovery (followed by an extensive preservation program) and the apparent absence of human frequentation since the Gravettian period. As part of the multidisciplinary research program developed since 2008 (PCR Cussac, dir. J. Jaubert), this study aims to contribute to a better understanding of the factors natural and/or cultural-that influenced the Gravettian people in their selection and general distribution of rock art panels in the cave. We investigate the nature of the rock support, location, surroundings, accessibility, and visibility of 31 panels. For this purpose, we developed an innovative methodology combining the data recorded in a dedicated database and on topographic documents with data processing using complex statistics (Factor Analysis for Mixed Data-FAMD). Through this work, we identified three groups of panels that reveal three ways of using the cave, two of which appear homogenous. Group 1 is characterized by small panels located in narrow passageways of the Palaeolithic path in the Downstream Branch of the cave. These panels share a strong potential for visual relationships whereas it is impossible for more than four people to see a given panel at the same time. In contrast, Group 3, also mainly located in the Downstream Branch, is composed of large panels with numerous graphic entities. These panels are always located in wide corridors and distant from the natural path, and their field of visibility is thus large enough to accommodate a small group of individuals. They also share visual relationships with other panels. Finally, Group 2 contains fewer intrinsic criteria, though all the panels are situated between the beginning of the Downstream Branch and the Upstream Branch, and they are visually isolated from each other. This study yields evidence of a strong interaction between geological and cultural factors in the selection of the rock art panels in Cussac Cave. The Gravettian people that frequented Cussac Cave linked their cultural goals to what the cave had to offer in terms of geology, geomorphology and available space. They adapted to-and even optimized-both the opportunities and constraints of the cave, thus demonstrating a strong interaction between geological and cultural parameters.
Alpine caves have attracted considerable geomorphological, paleoenvironmental and hydrogeological interest since climate, glaciations, relief uplift, fluvial incision and karst aquifer control their evolution. In the Atlantic Margin of the Iberian Peninsula, Picos de Europa mountains is among of the most important karst areas of the World containing some of the deepest caves explored today. In addition, these mountains represent a reference site for the study of the Last Glacial Cycle in the SW of Europe. This work aims to reconstruct the Pliocene-Quaternary evolution of this region based on geomorphological and geochronological research (U/Th and Al/Be) carried out in four alpine caves. Cave geomorphological mapping evidences that 12 km of studied caves are made up of 47% vadose canyons and shafts, 45% phreatic/epiphreatic conduits organised in six cave levels, and 7% breakdown-modified passages. Their deposits are characterized by speleothems, including flowstones, that represent ancient cave pavements, fluvial terrace deposits with allochthonous clasts, slackwater deposits related to cave floods, and debris deposits produced by breakdown. One ²⁶ Al/ ¹⁰ Be burial age indicates a minimum age of 2.1 ± 0.5 Ma for the caves origin, allowing estimation of the mountain uplift at 0.15–0.25 mm·a ⁻¹ since the Late Pliocene. Twenty-eight new ²³⁴ U/ ²³⁰ Th ages and another six previous speleothem ages give ages ranging from MIS 8 to 1. The speleogenetic model comprises six phases of regional evolution. Phase 1: main development of cave levels with SE-directed phreatic flow in the NW of Picos de Europa, in a karst partially or totally covered by the detrital Permian-Mesozoic cover, presently eroded. Phase 2: erosion of the Permian-Mesozoic cover and onset of vadose conditions before 260 ka, in a karst-affected by fluvial captures. Phase 3: cave infill during 220–145 ka, probably caused by the erosion of Stephanian detrital outcrops. Phase 4: erosion of cave infill during 125–45 ka. Phase 5: apparent pause in the speleothem formation during 45–25 ka related to dry and cold regional conditions. Phase 6: reactivation of the speleothem precipitation since 25 ka. Regional climate, fluvial incision and the ancient presence of detrital outcrops at the surface appear to have been the main factors that controlled the cave evolution and regional geomorphological evolution throughout Pliocene and Quaternary times.
Located in north-west Botswana, Drotsky's Cave is a vast cavity hosted within dolomite known for the discoveryof archaeological strata dating back to the Late Stone Age. It is home to a colony of bats comprising several tenthousands of individuals who are responsible for the accumulation of a thick deposit of guano, on which we have conducted research in some of the deeper parts of the cavity. A detailed study of the morphologies of the dolomite walls and roofs demonstrates that part of the cave'sspeleogenesis is probably due to biogenic corrosion. This type of weathering and corrosion process is still poorlydescribedin underground environments. However, it is now accepted that the role played by bats and their drop-pings on the condition of walls, their weathering, and the enlargement of galleries and chambers bycondensation-corrosion processes, should be taken into account when considering the way deep networksevolve. In this article, we discuss the mechanisms of this biogenic corrosion in Drotsky's Cave, as well as theirmorphogenic impacts (the dissolution and recession of walls, the formation of lateral notches, arches, bellholes, and ceiling spherical cupolas), and the consequences for the wall retreat of conduits. Finally, we proposea new typological classification.The consequences of this biogenic corrosion are important for archaeological questions related to the taphonomy of archaeological remains in the buried deposits and the conservation of cave art. Because of the important im-pacts of guano on buried biological archaeological remains, such a population would have encouraged acceler-ated weathering, corrosion and dissolution of the walls, potentially contributing to the total, or partial,disappearance of any trace of human activity on the surrounding rocks.
Reported here is the first chronostratigraphic study of the Quaternary fluvial terrace deposits of three different valleys (Deba, Nerbioi, Oiartzun) located in the eastern Cantabrian margin (northern Spain), designed to understand long-term fluvial dynamics of this region. Fourteen samples were collected for numerical dating purpose, in the lowest terrace levels from 5 m to 63 m above current river channel. Optically Stimulated Luminescence dating was performed using the SAR protocol. For samples from terraces >20 m above the current river channel, over 20% of measured aliquots were above saturation of the OSL signal. Consequently, only minimum ages could be estimated. Five samples also underwent Electron Spin Resonance (ESR) dating following the Multiple Centre approach. The ESR signals of the Aluminium and Titanium (Ti-Li and Ti-H) centres were systematically measured in each sample. In particular, the ESR signal of the Ti-H centre was strong enough to derive reliable and meaningful dose estimates. Obtained age results range between ∼140 and ∼400 ka for the terrace levels from +10 to +25 m. They suggest phases of aggradation during MIS 6, MIS 8 and MIS 10, for terrace levels T+10m, T+20m and T+25m, respectively.
The geomorphological evolution of the Cobiheru Cave shows the influence of the non-carbonate coastal mountain ranges on coastal karst evolution, as well as the temporal distribution of the cold-adapted fauna sites in the Cantabrian Coast. Geomorphological observation and U/Th dating lead to the construction of an evolution model. The model comprises two episodes of cave deposition occurred at ca. 60–70 and 130–150 ka, linked to cold climate conditions, global sea-level lowstands and the erosion of alluvial fans that covered the karst. Moreover, the comparison between the Cobiheru record and some raised beaches identified in previous studies sets the beginning of the sea-level lowering in the Cantabrian Sea during the MIS 5-4 transition. Two palaeoenvironments are inferred based on finding Equus ferus and Elona quimperiana. A wet deciduous forest would have been developed on the emerged marine terrace of the Cobiheru Cave since at least the Middle Pleistocene, and an open landscape with scarce vegetation would have been present at ca. 65 ka. The erosional event identified in the Cobiheru Cave helps to understand the temporal distribution of cold-adapted mammals located in the Asturias region. The probable sites of cold-adapted fauna developed in caves and alluvial fans would have disappeared after 65 ka. Therefore, palaeontological and palaeoclimate research based on cold-adapted mammals suggests the occurrence of an hiatus in the palaeontological record prior to 50 ka. This article is protected by copyright. All rights reserved.
Terrestrial laser scanning (TLS) is increasingly used in geomorphology for the study of medium- to small scale landforms. A light weight, compact and portable TLS device has been used in the Grotta A Cave (Mt. Lessini, N Italy) to make a detailed 3D model of the underground environment. A total of 16 scans were used to survey the about 150 m long cave in less than 6 hours. The 3D model of the cave walls makes it possible to carry out morphometric measurements on the different cave environments. The TLS data allowed us to calculate cave volumes and distinguish cupola, phreatic conduit and basalt dike volumes. Wall roughness analysis also allowed recognising smaller-scale morphologies such as megascallops, differential corrosion forms and mineral crusts. These observations have enabled us to discern between different karstification processes and speleogenetic phases, highlighting the importance of condensation-corrosion on the cave passages enlargement in a quantitative way.
Very little is known about Neanderthal cultures(1), particularly early ones. Other than lithic implements and exceptional bone tools(2), very few artefacts have been preserved. While those that do remain include red and black pigments(3) and burial sites(4), these indications of modernity are extremely sparse and few have been precisely dated, thus greatly limiting our knowledge of these predecessors of modern humans(5). Here we report the dating of annular constructions made of broken stalagmites found deep in Bruniquel Cave in southwest France. The regular geometry of the stalagmite circles, the arrangement of broken stalagmites and several traces of fire demonstrate the anthropogenic origin of these constructions. Uranium-series dating of stalagmite regrowths on the structures and on burnt bone, combined with the dating of stalagmite tips in the structures, give a reliable and replicated age of 176.5 thousand years (+/-2.1 thousand years), making these edifices among the oldest known well-dated constructions made by humans. Their presence at 336 metres from the entrance of the cave indicates that humans from this period had already mastered the underground environment, which can be considered a major step in human modernity.
Inactive swallow hole Buco dei Vinchi developed along a plane dividing selenitic gypsum stratum and an underlying shale interlayer, mostly by antigravitative erosion and by post-antigravitative erosion. It formed through six speleogenetic phases starting from a phreatic phase followed by several antigravitative erosion (= paragenetic) and post-antigravitative erosion phases and vadose phase. During first antigravitative erosion phase, the phreatic protoconduits evolved into small antigravitative conduits with typical cross-section in shape of an inversed U or a bulb. At the end of this phase the small antigravitative conduits converged and merged together in successive stages to form ever-bigger conduits, until - at a certain point - most of them flowed into a single, much wider antigravitative conduit, which later evolved into a composite conduit. We demonstrate that the subhorizontal flat ceilings are not a characteristic feature of the antigravitative passages tout court - as claimed by most authors -, but instead they evolved in caves during periods when the piezometric surface was tangent to the vault of the cave (post-antigravitative erosion phenomenon). Thus these flat ceilings are traces of 'paleo-piezometric surfaces'; moreover these flat ceilings, being sub-horizontal originally, can provide important information on possible tectonic movements or breakdowns occurred after their formation. The possible ages of the karstic phenomena in the selenitic gypsum near Bologna are discussed. This paper points out that the Buco dei Vinchi and the Cava a Filo swallow holes, presently located in "topographic highs", were very probably in "topographic lows" at the time of their hydrologic activity, and that this is evidence of a relief inversion started at least 127,000 years ago. Therefore the beginning of the first karstic phenomena in the Bologna karst area is much older than this date. It is explained why the absolute altimetrical lowering of the Monte Croara karst sub-area (with respect to the present sea level) should be of about - 0.39 mm/year.
The western Pyrenean area contains extensive karst areas, however, their genesis and development are still mostly unknown. In this work, we make a general description of the karst landscape in different karst areas: 1) Rasa type; 2) Cone-type karst; and 3) Alpine-type karst. The first two types are present in the littoral area, where geomorphological evolution mostly depends on sea level and climatic changes. We focused our study in two karst areas of the littoral cone-type karst. We correlate different caves created from different stable water table levels. Three representative caves are studied in detail, studying their stratigraphic record based on allostratigraphy. Finally we dated the different phases of speleothem formation in the three caves. Using all this information, we defined four stable paleowater table levels, at 50, 150, 220 and 350 m asl, controlled by sea level changes and isostatic uplift events. The lowest level is the youngest, with an age of c. 1 Ma. We discovered that the interior of the three caves display very similar endokarst allostratigraphic sequences, characterized firstly by an erosion phase, a fluvio-karst input, flowstone speleothem formation and finally dripping speleothem formation. The chronological data shows a correlation between these phases and Pleistocene climatic phases; the erosion phase is related to the falling sea level, fluviokarst detrital input is related to cold (glacial) stages and the for-mation of speleothems is related to the warmest (interglacial) moments and high sea level periods.
Speleothem growth requires humid climates sufficiently warm to stimulate soil CO2 production by plants. We compile 283 U/Th dates on 21 stalagmites from six cave systems in the NW coast of Spain to evaluate if there are patterns in stalagmite growth that are evidence of climatic forcing. In the oldest stalagmites, from marine oxygen isotope stage (MIS) 7–5, growth persists through the glacial period. Hiatuses and major reductions in growth rate occur during extreme minima in summer insolation. Stalagmites active during the last interglaciation cease growth at the MIS 5–4 boundary (74 ka), when regional sea-surface temperature cooled significantly. During MIS 3, only two stalagmites grew; rates were highest between 50 and 60 ka during the maximum in summer insolation. One stalagmite grew briefly at 41 ka, 36.5 and 28.6 ka, all during warm phases of the Dansgaard–Oeschger cycles. A pronounced Holocene optimum in stalagmite growth occurs from 9 to 6 ka. The cessation of most growth by 4.1 ka, coincident with broad increases in aridity over the Mediterranean and areas influenced by the North African Monsoon, suggest that regions such as NW Spain, with dominant Atlantic moisture sources, also experienced increased aridity at this time.
The main corridor that has acted as an entrance to the Iberian Peninsula through the Western Pyrenees was as an important communication route in Western Europe during the Paleolithic. This is an area where, despite having documented intense human occupation during different periods of the Upper Paleolithic, the symbolic activity seems incomprehensibly limited compared to other regions, such as the Cantabrian, the Northern Pyrenees, or Dordogne.
The reactivation of research during this last decade, when referring to cave art, leads to a very different model than the one that had been previously posed for this region, mainly due to a series of new discoveries, some of which are worth mentioning, such as Askondo and Lumentxa, or others of lower interest such as Astigarraga, Praile Aitz, and Aitzbitarte IV. The re-examination and revision of previously known representations has also contributed to the development of this new model, especially thanks to the research carried out in sites such as Santimamiñe, Altxerri, Isturitz, Oxocelhaya, Sasiziloaga, Sinhikole, or Sainte Colome, as has the revision of the great amount of portable art, mainly from Isturitz, as well as the discovery of new objects from Antoliña, Ekain, Praile Aitz, Aitzbitarte III, Santa Catalina, Arlanpe, and Bourrouilla. Due to these advances, the image that we have of the artistic activity around the epicentre that was the Gulf of Biscay has substantially varied in a way that allows us to carry out a more detailed approximation to a series of relevant questions such as the chronology of the artistic representations, the variability of their contexts, the technical and formal relations among different neighbouring regions, and their relation to the non-symbolic archaeological record.
Petrophysical techniques commonly used for material characterization are applied for the first time to speleothem samples to investigate the porosity and hydric behavior of calcite stalagmites used in paleoclimatology. These techniques allow the determination of the stalagmites' potential to undergo diagenetic transformations when substantial changes in drip waters occur in the cave environment. The petrophysical techniques include water absorption under vacuum and by capillarity, nuclear magnetic resonance, environmental scanning electron microscopy, and mercury intrusion porosimetry. The studied samples comprise five common calcite microfabrics, which have markedly different porosities and hydric behaviors and, as a consequence, different sensibilities to diagenetic processes related to the influx of water. The experiments show that stalagmites can behave as complex, small-scale hydrological systems and that the circulation of water through them by complex nets of interconnected pores might be common. As the circulation of water favors diagenetic transformations that involve geochemical and isotopic changes, the characterization of flow patterns is key for outlining areas that are susceptible to such modifications, which is critical to paleoclimatic studies that are based on speleothems because geochemical and stable isotopic data are used as paleoenvironmental proxies and absolute ages are obtained by using radioactive isotope ratios. These potential modifications also have obvious implications for studies based on fluid inclusions in speleothems.The integrated methodology, which uses primarily non-destructive techniques, shows a high potential for characterization of any type of speleothem and other continental carbonates such as tufas or sinters.
We have developed techniques for measuring 234U and 230Th on Faraday cups with precisions of 1–3 epsilon units (1 ε-unit=1 part in 104) using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). Using a Thermo-Scientific Neptune with desolvation nebulization, we obtained ionization/transmission efficiencies of 1–2% for both U and Th. We set up protocols to correct for tailing, prepared U and Th gravimetric standards, tested a Th mass fractionation correction procedure based on U isotopes, and identified natural calcite samples likely to be in U–Th isotopic secular equilibrium. The measured atomic ratios, 234U/238U=54.970 (±0.019)×10−6 and 230Th/238U=16.916 (±0.018)×10−6, for these calcite samples were identical within errors (quoted 2σ uncertainties calculated combining all sources of error). Half-life values calculated from these ratios are consistent with previous values, but have much smaller errors: 245,620±260 a for 234U and 75,584±110 a for 230Th (quoted 2σ uncertainties calculated using all sources of error). In calculating a 230Th age, some of the systematic errors included in estimating the full error in the half-lives effectively cancel. Removing these uncertainties (uncertainty in the 238U half-life value, uncertainty in our gravimetric uranium and thorium standards, and uncertainty in the absolute isotopic composition of the uranium standard), yields effective uncertainties for the purposes of 230Th dating of ±70 a for the 234U half-life value and ±30 a for the 230Th half-life value. Under ideal circumstances, with our methods, the 2σ uncertainty in age, including uncertainty in half-life values is ±10 a at 10 ka, ±100 a at 130 ka, ±300 a at 200 ka, ±1 ka at 300 ka, ±2 ka at 400 ka, ±6 ka at 500 ka, and ±12 ka at 600 ka. The isotopic composition of a sample with an age <800 ka can clearly be resolved from the isotopic composition of a sample in secular equilibrium, assuming closed system behavior. Using these techniques, we analyzed a Sanbao Cave (Hubei, China) stalagmite that formed between 510 and 640 ka ago. As the half-life values were determined independent of the Sanbao Cave ages, the observed co-variation between stalagmite δ18O and Northern Hemisphere summer insolation is consistent with accurate ages and half-life values.
Although the effects of sedimentation in caves have been recognised for many years, its role in speleogenesis is frequently overlooked. Influxes of sediment into a cave system fundamentally alter the way cave passages develop, either by alluviation in a vadose environment, forcing lateral corrosion and the development of notches, or by upwards dissolution in a phreatic environment through a process known as paragenesis. Sediment influxes affect the hydrological functioning of a karst aquifer by changing the way conduits behave and subsequently develop both in plan and long section.Here we give an overview of the mechanisms of cave sedimentation and describe how the process of alluviation and paragenesis affect speleogenesis. A characteristic suite of meso- and micro-scale dissolutional features can be used to recognise paragenetic development, which is reviewed here. In a vadose environment these include alluvial notches, whilst in a phreatic environment, half tubes, anastomoses and pendants, bedrock fins and paragenetic dissolution ramps result. Using these to identify phases of sedimentation and paragenesis is crucial for reconstructing denudation chronologies from cave deposits. We suggest that sedimentation and paragenesis are most likely to occur in certain geomorphological situations, such as ice marginal and periglacial environments, beneath thick residual soils and where rivers can transport fluvial sediment into a cave, either via stream sinks or back-flooding.
Along the Asturian coast of northern Spain an uplifted wave-cut platform extends for ∼ 100 km east–west. The steep cliff which bounds the gently seaward-dipping platform to the north increases in height from 30 m in the west to 100 m in the east and reflects the overall eastward increase in platform elevation. The southern edge of the 2–4 km-wide platform runs along the foothills of the Cantabrian Mountains, as constrained by a high-resolution digital elevation model. The marine platform, which was carved into deformed Paleozoic bedrock with abundant quartzite beds, is largely covered by weathered marine and continental sediments. Quartzite samples from flat bedrock outcrops which are currently not covered by sediment or soil yield cosmogenic nuclide concentrations (21 Ne, 10 Be and 26 Al) that demonstrate a long and complex exposure history, including periods of burial with partial or complete shielding from cosmic rays. The combination of multiple cosmogenic nuclides yields a minimum age of 1–2 Ma for the platform. Taking into account (i) the horizontal and vertical extent of the platform, (ii) the high resistance to erosion of the quartzitic bedrock, and (iii) published data on the magnitude of past sea level fluctuations, we suggest that the wave-cut platform formed in the Pliocene. Subvertical faults cutting the platform at high angles to the coastline offset the southern edge of the platform by 20 to 40 m and reactivate the pre-existing anisotropy in the Paleozoic bedrock. Uplift and crustal deformation of the coastal region have occurred after platform formation in the Pliocene and may still be active. The slow deformation of the northern edge of the Iberian plate including the Cantabrian Mountains may result from the ongoing slow convergence at an incipient subduction zone extending along the coast of northern Spain.
New determinations of the half-lives of 235U and 238U have been made. Improved techniques have allowed the half-life values to be measured with greater accuracy than has been heretofore achieved. Samples were prepared by molecular plating and counted in a intermediate-geometry α-proportional counter with an extremely flat pulse-height plateau. The small amount of residual nonplated uranium was counted in a 2π counter. Energy analysis with a silicon-junction detector was used to measure the presence of "foreign" activities. For 235U, the measured specific activity was (4798.1±3.3) (dis/min)/(mg 235U), corresponding to a half-life of (7.0381±0.0048) × 108 yr. For 238U, the specific activity was measured as (746.19±0.41) (dis/min)/(mg 238U), corresponding to a half-life of (4.4683±0.0024) × 109 yr. Errors quoted are statistical (standard error of the mean), based upon the observed scatter of the data. This scatter exceeds that expected from counting statistics alone. We believe that systematic errors, if present, will no more than double the quoted errors.
The purpose of this paper is to illustrate how calcareous sediments from Pleistocene and Holocene rockshelters and open caves of the Western Mediterranean can provide a stratigraphic record of abrupt climate change. The method proposed here is based on microstratigraphic examination of sedimentary sequences using microscopic techniques. The most important processes for characterizing the sensitivity of each cave to climate variables are: (1) the modes and rate of carbonate sediment production, (2) the nature and intensity of the pedogenic processes responsible for the synchronous alteration of carbonate materials (either those derived from the cave walls or those deposited on the ground surface), and (3) the supply of allogenic sediments, particularly by eolian activity. The cave sediment sequences presented record the marked coolings known as Dansgaard-Oeschger stadials and Heinrich events that occurred during the Pleistocene and the Holocene, as demonstrated by the high resolution records from ice and deep sea cores. At Abric Romanì in northeastern Spain, a series of sharp climatic deteriorations of increasing severity is shown to have occurred synchronously with the transition from the Middle to the Upper Paleolithic, with a period of seasonal frost and strong winds at ca. 37,000 yr B.P., tentatively correlated with Heinrich event 4. At Pigeon Cave, Taforalt (northern Morocco), the transition from the Aterian to Ibero-Maurusian/Epipalaeolithic cultures is dated to around 24,000–20,000 yr B.P. and is punctuated by a series of short cold pulses with evidence for seasonal freezing, soil erosion, and minimal evapotranspiration. In El Miron cave in north-central Spain, the exceptional nature of the Younger Dryas cooling produced a marked destabilization of the cave walls and roof. At El Miron, the stratigraphic evidence for sediment removal due to the rapid percolation of snow melt under a degraded soil cover allows us to reconstruct the nature of the negative excursion at ca. 8200 yr B.P. This example also illustrates how climate-controlled pedogenic processes can create a stratigraphic signature which has often been confused with a sedimentary hiatus. We conclude that cave sediments provide a valuable record of Pleistocene and Holocene climate changes. In appropriate contexts, these sequences allow us to examine the ecological stress generated by these unique global events at a local and regional level and improve our understanding of the complex anthropological processes that occurred at the same time. © 2001 John Wiley & Sons, Inc.
The subdivision and ordering of Quaternary sediments and landforms is very often based on geomorphology. Quaternary landforms such as moraines, river terraces, palaeoshorelines, and indeed any other landform, can be arranged and ordered in time based on their relative position in the landscape. Morphostratigraphy is the subdivision of sedimentary units primarily on the basis of surface form. Whilst surface form is often used as a criterion for separating sedimentary units, morphostratigraphy also usually incorporates lithological criteria to aid stratigraphical subdivision, and morpho- and lithostratigraphy are often interlinked in Quaternary science. However, another approach–allostratigraphy–has increasingly been applied to subdivide and order Quaternary sediment landforms. Allostratigraphy uses discontinuities to subdivide sedimentary successions. Allostratigraphy enables lateral variations in lithology to be included within the same stratigraphical unit. Furthermore, it enables lithologically similar sediments stacked on top of each other to be divided into separate units based on discontinuities. This paper examines the applications of morpho-, litho- and allostratigraphy to subdivide sediment-landform assemblages and critically reviews their role in Quaternary stratigraphy.
The great November 5, 1985 Potomac Valley flood was responsible for the release of 1800 m3 of alluvial and colluvial sediment from the walls of the entrance doline of Mystic Cave. Flood waters were sufficiently powerful to flush the entire mass of sediment not only into the cave but through the cave. Remnants of the sediment mass in the form of sand bars and a few cobbles wedged in speleothems were the only evidence in the cave that the huge mass of sediment had moved through. The sediment moved as a suspended mass in water moving at peak velocities of many meters per second. Present day cave sediments must be interpreted with the understanding that entire sediment fillings can be transported or rearranged by single extreme events.
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