Nature vs. Culture: present-day spatial distribution and preservation of open-air rock art in the Côa and Douro River Valleys (Portugal)

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Analyse morphométrique et caractérisation des sols des dolines dans le district de Gorazbon de la Forêt expérimentale de Kheyrud-Kenar (nord de l’Iran)

A doline is a natural superficial enclosed depression of karst landscapes, usually circular or subcircular in plan and with a few to a hundred meters in diameter. This very distinctive and common karst landform can appear in a variety of shapes and sizes. The spatial distribution, description and evolution of dolines were investigated in the Gorazbon district of Kheyrud-Kenar Experimental Forest (northern Iran). Morphometric measurements and systematic collection of soil cover samples were performed for each observed doline during field survey. Morphometric parameters such as doline’s length, width, side slopes and perimeter were measured. Afterward, the area, depth, circularity index, length/width ratio and length/depth ratio were also calculated and used for the quantification of the individual dolines. Two other parameters were instead used to infer the degree of karstification of the study area: i.e., the spatial density of dolines and the pitting index. The laboratory determination of physical (color, texture) and chemical (pH, CaCO3, organic matter) soil properties were conducted on the collected samples. The obtained results indicate the presence of mainly solution dolines in the study area with an irregular spatial distribution, as well as a general high degree of karstification. The studied dolines show the axes of length and width with a certain asymmetry, resulting in a shape from sub-circular to elliptical. Soil characterization point out to the hypothesis of a possible incipient develop of subcutaneous shallow holes (pipes - not yet visible on surface) at the dolines bottoms, probably linked to the underground karst system (enlarged fissures and/or even caves). Doline’s longer axes seem aligned with to the major regional structural geological elements. All these data could indicate the presence of an early stage in the origin of collapse dolines, with obvious implications in terms of natural hazards. In this context, we believe that a proper decision-making in forest management, and in specific environmental planning policies, should always consider this karst quantitative information (and approach) on the mutual relationship between the forest stand development and the natural landforms that characterize the study area.Une doline est une dépression superficielle fermée dans des paysages karstiques, généralement circulaire ou subcirculaire et avec une dimension jusqu'à des centaines de mètres de diamètre. Cette forme du relief karstique, très distinctif et commun, peut apparaître dans une variété de formes et de tailles. La distribution spatiale, la description morphologique et l'évolution des dolines ont été étudiées dans le district de Gorazbon de la Forêt expérimentale de Kheyrud-Kenar (nord de l'Iran). Des mesures morphométriques et une collecte systématique d'échantillons de couverture du sol ont été effectuées pour chaque doline observée au cours du travail sur le terrain. Les paramètres morphométriques tels que la longueur, la largeur, les pentes latérales et le périmètre de la doline ont été mesurés. Ensuite, l'aire, la profondeur, l'indice de circularité, le rapport longueur/largeur et le rapport longueur/profondeur ont été calculés et utilisés pour la caractérisation morphométrique de chacune des dolines. Par la suite, deux autres paramètres ont été utilisés pour déduire le degré de karstification de la zone de la zone étudiée: la densité spatiale des dolines en nombre et la densité spatiale des dolines en aire occupée). La détermination en laboratoire des propriétés physiques (couleur, texture) et chimiques (pH, CaCO3, matière organique) du sol a été effectuée sur les échantillons prélevés. Les résultats obtenus indiquent la présence de dolines principalement dans la zone d'étude avec une distribution spatiale irrégulière, ainsi qu'un degré général élevé de karstification. Les dolines étudiées montrent les axes de longueur et de largeur avec une certaine asymétrie, résultant en une forme de sub-circulaire à elliptique. La caractérisation des sols rappelle l'hypothèse d'un éventuel début de développement de cavités peu profondes, pas encore visibles en surface, au fond des dolines, probablement liées au système karstique souterrain (des fissures élargies et/ou même des grottes). Les axes plus longs des dolines semblent alignés sur les principaux éléments géologiques structurels au niveau régional. Toutes ces données pourraient indiquer la présence d'un stade précoce dans l'origine des dolines d'effondrement, avec des implications évidentes en termes de risques naturels. Dans ce contexte, nous pensons qu'une prise de décision appropriée en matière de gestion forestière et dans des politiques spécifiques de planification environnementale devrait toujours tenir compte de ces informations quantitatives karstiques (et de cette approche) sur la relation mutuelle entre le développement des peuplements forestiers et les reliefs naturels qui caractérisent cette zone d'étude.info:eu-repo/semantics/publishedVersio

Porque é que a arte do Coa se concentra na margem esquerda? Condicionantes geológicas e ambientais para a formação e conservação dos suportes artísticos do Vale do Coa

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Geopatrimónio cársico e desenvolvimento local no Maciço de Sicó.

Este trabalho sintetiza o conhecimento geomorfológico adquirido sobre o Maciço de Sicó, um dos principais maciços calcários carsificados da Orla Meso-Cenozóica ocidental Portuguesa. São passadas em revista as principais formas e formações relacionadas com os processos cársicos (geomorfológicos, hidrológicos e espeleológicos) bem como as fases da sua evolução tendo em consideração as vicissitudes paleoambientais (principalmente tectónicas e climáticas) que as determinaram. O valor patrimonial da paisagem e, particularmente, dos seus elementos geomorfológicos, levou a um estudo com vista à inventariação, avaliação, geoconservação e divulgação deste património, tendo em vista a sua inserção e valorização em políticas de valorização local do território. Nestas, estão em curso várias iniciativas, com destaque, por exemplo, para a construção e desenvolvimento de um Centro de Interpretação a ser preparado no âmbito do desenvolvimento geoturístico do Maciço de Sicó, projecto no qual os autores deste texto estão envolvidos.info:eu-repo/semantics/publishedVersio

GEOCHEMICAL EXPRESSION OF SPELEOTHEME GROWTH FROM XRFAND LA-ICP-MS: PALEOCLIMATIC IMPLICATIONS

Carbonate cave deposits have a widespread use in deciphering climatic signals from the past using several proxies (e.g. stable isotope compositions). In the western central part of Portugal, the Mesozoic sediments of the Lusitanian basin are particularly susceptible to dissolve by interaction with meteoric waters and to develop karstic caves, especially in the Lower and Middle Jurassic limestone and dolomitic limestone formations. A set of the existing caves from Sicó and Estremadura Carbonate Massifs (e.g. Soprador do Carvalho, Buraca Grande and Ourão Caves, as well as Vale do Pena and Algar do Pena Caves) were detailed study and several speleothem samples (stalagmites and flowstones) were collected aiming to contribute to the deciphering of the climatic evolution of this region. The selected cave stalagmite was collected in the main epiphreatic conduct of the Soprador do Carvalho Cave (an underground system located on the eastern border of the Sicó Massif) and was studied by handheld X-ray fluorescence to determine the major elements trends and by LA-ICP-MS for the analysis of the minor and trace-elements. The cave floor is covered by siliciclastic fine (clayey/sandy) and clast-supported conglomerate sediments carried into the cave from the adjacent areas by floodwater. As expected, the chemical composition of the speleothem is dominated by the presence of calcium with all samples presenting counts of the same magnitude for this element, although the older portion of the stalagmite has slightly lower counts than the rest of it. Iron is another remarkable element that present a subtle tendency to be more concentrated in the outer (younger) layers. With LA-ICP-MS several transects were made on the thin sections covering layers of distinct optical characteristics. The older layers, which exhibit a more hyaline aspect, have higher counts of elements such as sodium, uranium and lead and lower counts on rare-earth elements and yttrium. More, the analysed elements oscillate between high counts and low counts from layer to layer along the entire sample. The oscillatory character of the trace-element distribution in the stalagmite can be interpreted as the result of the seasonal variations of meteoric water input, and time of residence on the hanging-wall formations, with periods of more efficient dissolution of the percolating water alternating with periods of less efficiency. The more general evolution observed in the composition of older and younger sectors of the speleothem can be interpreted as being the evidence for a probable change in the paleoclimate conditions of the area and perhaps can be used to detect underground flood events during the Quaternary

Palaeolithic engravings and sedimentary environments in the Côa River Valley (Portugal): implications for the detection, interpretation and dating of open-air rock art

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Portela II (Leiria, Portugal): a specialized lithic workshop for the production of Vale Comprido points in Proto-Solutrean times?

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Timing of the Middle-to-Upper Palaeolithic transition in the Iberian inland (Cardina-Salto do Boi, Côa Valley, Portugal)

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X Conferência Internacional de Geomorfologia da IAG (Coimbra, 12 a 16 de setembro de 2022)

Por decisão das estruturas diretivas da IAG (Associação Internacional de Geomorfólogos) tomada na Índia, em 2017, aquando da realização da IX Conferência Internacional de Geomor fologia, a Conferência Internacional seguinte seria realizada em Portugal, mais exatamente na cidade de Coimbra, no ano de 2021. Fomos contactados para o efeito e aceitámos este desafio que se antevia complexo e difícil, mas que sabíamos que ir ia prestigiar a Geomorfologia portuguesa e, no seu seio, os geomorfólogos da nossa Universidade

Archaeology of the Pleistocene-Holocene transition in Portugal: synthesis and prospects

The Tardiglacial of Portugal has been associated with the Magdalenian culture and lithic industries characterized by tool miniaturization, a diversity of microlith types, and the absence of a intentional blade production. The technological characterization, the chronology and the phasing of the Portuguese Magdalenian have been defined based on data recovered from open-air sites of the Estremadura region (Central Portugal). This paper presents an overview of the research undertaken over the last twenty-five years, including results from research and preventive archaeology fieldwork outside this region, namely in the Côa, Sabor and Vouga Valleys (northern Portugal), as well as in the Guadiana Valley and Algarve regions (southern Portugal). Our chronological boundaries are the Greenland Stadial 2-1b and the 8.2 ka event, from Early Magdalenian to Early Mesolithic. Regarding vegetation, deciduous Quercus underwent expansion during the warm phases of the Tardiglacial and retracted during cold ones, when pines increased. After the Solutrean, the faunal assemblages show a decrease in the variability of the represented species and an increase in fish, birds, small mammals and rabbits (Oryctolagus cuniculus). Concerning the cultural sequence, the Middle Magdalenian remains uncharacterised. After the Upper Magdalenian, and thenceforward, the use of local raw materials and of cores-on-flakes (burin or carinated endscraper type) for bladelet production gradually increased. In terms of lithic armatures typology, a four-stage sequence can be discerned: 1) Upper Magdalenian with axial points rather than backed bladelets, quite common in previous phases; 2) Final Magdalenian with an increase in the diversity of armature types; 3) Azilian with geometric microliths, curved backed points (Azilian points) and Malaurie points, and 4) Early Mesolithic without retouched bladelet tools or at best a persistence of Azilian armature types. There were some changes in the Palaeolithic rock art of the Douro basin between phase 3 (Final Magdalenian) and phase 4 (Late Azilian): figurative animal representations give place to animal depictions characterized by their geometrical bodies, often filled-in, and red deer becomes the best-represented animal.FCT: PTDC/EPH-ARQ/0326/2014info:eu-repo/semantics/publishedVersio