Documenting the diversity of human responses and adaptations to climate, landscapes, ecosystems, natural disasters and the changing natural resources availability in different regions of our planet, cross-disciplinary studies in Geoarchaeology provide valuable opportunities to learn from the past. Furthermore, human activity became a major player of global climatic and environmental change in the course of the late Quaternary, during the Anthropocene. Consequently, we must better understand the archaeological records and landscapes in context of human culture and the hydroclimate-environment nexus at different spatial and temporal scales. This session seeks related interdisciplinary papers and specific geoarchaeological case-studies that deploy various approaches and tools to address the reconstruction of former human-environmental interactions from the Palaeolithic period through the modern. Topics related to records of the Anthropocene from Earth and archaeological science perspectives are welcome. Furthermore, contributions may include (but are not limited to) insights about how people have coped with environmental disasters or abrupt changes in the past; defining sustainability thresholds for farming or resource exploitation; distinguishing the baseline natural and human contributions to environmental changes. Ultimately, we would like to understand how strategies of human resilience and innovation can inform our modern strategies for addressing the challenges of the emerging Anthropocene, a time frame dominated by human modulation of surface geomorphological processes and hydroclimate.
vPICO presentations: Wed, 28 Apr
In the Southern Maya Lowlands (SML), several scientific and technical obstacles hinder the knowledge of environmental and socio-environmental dynamics, that have occurred at the scale of the territories of the cities. This includes the research topic itself (nature-culture interface), the tropical forest (morphological studies and access to the field) and the morphological and sedimentary archives (taphonomy and discontinuity). The study of the socio-ecosystem of Naachtun (150-950 CE), a Maya city of the Classic period, is not exempt from these constraints. Recently, large-scale work in SML was conducted based on LiDAR analyses and fieldwork. They have profoundly renewed our knowledge of the complexity of landscape transformation and natural environments through the action of the ancient Maya (Canuto et al. 2018). They have provided new research perspectives which allow us to examine the following questions.
How did natural resource availability (water, soil and biological resources) change in the territory of the city, with respect to climate change and social demand? How did the ancient Maya adapt their resource management strategies to these changes? How important were socio-environmental risks to the resilience and sustainability of the socio-ecosystem? In order to answer these questions, a new systemic, interdisciplinary and multiscalar research program has been implemented. It includes geoarchaeology (alluvial and agrarian), archaeogeography (LiDAR analysis, spatial analysis), palaeoecology and bioarchaeology [archaeobotany (study of phytoliths, anthrocology, pedoanthracology) zooarchaeology (vertebrate and conchyological fauna remains)], spatial archaeology (agglomeration processes, power relays), palaeodemography and geochronology (14C, OSL). Current and pre-anthropic reference frames (hydrological, pedological and ecological) have also been established.
Our results reaveal the complexity of the Maya palimpsest territories produced during the ~ 1500 BCE - 1000 CE period (Preclassic and Classic periods). Hydrosedimentary flows have fluctuated in response to climate change and anthropogenic impacts, controlling the spatiotemporal dynamics of resources (water and soils). Lake levels and erosion have fluctuated according to pluricentennial-scale periods. All compartments of the hydrosystem and the sediment system were subject to transformations, to manage water and soils. A mosaic of agricultural and agroforestry strategies was developed throughout the micro-region (morphologies, practices, cropping systems, fuel economy). Intensive wetland systems and irrigated farming systems were established in poljes, sinkholes and valleys (raised fields and drained fields). In addition, in the hilly areas, agrarian systems based on terraced agriculture, rain-fed farming systems, slash-and-burn, arboriculture and horticulture systems were established. The Maya socio-ecosystem which emerged in this micro-region lasted for more than 2500 years. It experienced shits and continuities and its dynamics are framed around six main multi-secular periods. Its decline was part of the profound changes that took place in the territories of the SML cities between 750 and 1050 CE. The sustainability of this socio-ecosystem during the demographic peak of the Late and Terminal Classic (750-950 CE), before the abandonment of the epicenter of the city of Naachtun (~950 CE), is estimated and discussed in relation to the environmental carrying capacity, social demand, climate and its own resilience.
How to cite: Castanet, C., Nondédéo, P., Dussol, L., Testé, M., Purdue, L., Hiquet, J., Lemonnier, E., Garnier, A., Dorison, A., Tomadini, N., Grouard, S., Goudiaby, H., Morales-Aguilar, C., Limondin-Lozouet, N., Cavero, J., Develle-Vincent, A.-L., Hatté, C., Lanos, P., Mokadem, F., and Sipos, G.: Dynamics and sustainability of the Maya socio-ecosystem of the hinterland of Naachtun, between 1500 BCE and 1000 CE (Southern Maya Lowlands, Petén, Guatemala)., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9655, https://doi.org/10.5194/egusphere-egu21-9655, 2021.
Key words: Palaeoenvironments, Holocene, Palynofacies, Microcharcoal, Fire signal, Anthropisation
The Bao Bolon valley, located in a Sudano-Sahelian context and overlapping both the Gambia and Saloum river basins, in western Senegal, is subject to strong seasonal rainfall contrasts. These particular conditions are usually badly appropriate to the good conservation of sedimentary archives. Moreover, this region is well known for his important archaeological heritage which includes the megalithic necropolis of Wanar classified on the UNESCO World Heritage list.
In addition to archaeological research, paleoenvironmental studies have been carried out at the Wanar site. Fluvial archives have been investigated and provide rich sedimentary records covering the entire Holocene period. Thus, the cultural and abiotic contexts of the middle Bao Bolon valley are now well documented (Laporte et al. 2017, Stern et al. 2019). Nevertheless, the biotic aspect, i.e. the landscapes and their evolution, still remains poorly documented in this region. Ongoing studies aim to better understand the Holocene palaeoenvironments and protohistoric agro-sylvo-pastoral systems by reconstituting biotic environments.
Due to the lack of pollen material, we focus on other, more abundant, organic elements recorded in the sedimentary archives. The study of organic matter has been first conducted through the palynofacies analysis. Among the different types of organic particles, we pay special attention to microcharcoals. Microcharcoals are often the longest lasting organic matter because carbonization protects the particles from degradation (except mechanical degradation). Their analysis focuses on the relative and absolute abundance, the morphology and the size of the particles. Microcharcoals are a relevant indicator of fire signals. Fires, whatever their origin, whether they are natural or anthropogenic, contribute to the changing and shaping of environmental landscapes. Therefore, high resolution palynofacies analyses contribute to a better understanding of the physical and anthropogenic transformations of the Holocene landscapes in the Bao Bolon middle valley.
The first results show a relative permanence of the signal of vegetation fires during the Holocene. The fluctuations of this burning activity are still under study. An important change seems to take place in the second half of the twentieth century. Further studies, in particular on phytoliths are under process. They will complete the interpretation of the landscapes dynamics during the Holocene.
How to cite: Weisskopf, E., Stern, M., El Madouri, L., Landry, D., Garnier, A., and Ballouche, A.: High resolution palynofacies analysis to understand Holocene Sudanian landscapes. First data from the Bao Bolon middle valley (Senegal)., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12988, https://doi.org/10.5194/egusphere-egu21-12988, 2021.
Monumental funerary landscapes are paramount representations of the relationship between environment and superstructural human behavior. Their formation sometimes requires millennia and they cover wide territories, often adding up to complex palimpsests of monuments belonging to different time periods. In this regard, the funerary landscape of the semi-arid foothill region of Kassala (Eastern Sudan) represents a solid example. Therein, a comprehensive geoarchaeological investigation conducted by means of field survey and remote sensing allowed the creation of a regional geomorphological base-map and a dataset of funerary monuments. The latter comprises several thousand raised stone-built tombs spanning from the early first millennium AD clusters of tumuli (belonging to the pan-African traditions) to regionally exclusive variants of medieval Islamic funerary architecture (qubbas). Funerary monuments are found as eye-catching scatters of hundreds of elements along the foothills of the many rocky outcrops dotting the pediplain of the western periphery of the Eritrean Highlands. In this study, the two categories of monuments were not considered as separate burialscapes, but rather examined as a unique, diachronic funerary landscape in its relationship with the geological and geomorphological settings and constraints. Point Pattern Analysis (PPA) was employed to determine the main environmental drivers of their locations on a regional scale, as well as to assess the existence of superstructural factors acting on their aggregation at the local scale. Our results strongly suggest the presence of a geological/environmental/societal synthesis underlying the choice of monuments’ location: at the regional scale, the pattern follows a precise set of rules residing in the concomitant presence of stable, gently rolling slopes and available metamorphic rock slabs; at the local scale, the clustering is heavily conditioned by superstructural dynamics that most likely reside in kinship and collective social memory of local Beja people. We suggest that the creation of the funerary landscape of Eastern Sudan is the result of a repeated and well coded social behavior of the Beja people, semi-nomadic cattle breeders known to have inhabited the region since “time immemorial”. Despite their mobile lifestyle and cultural contact with other North African and Arabic cultures, the monumental palimpsest portrays how the funerary habits of this millennia-old society persisted almost undisturbed, valuing location and kinship over external influences.
How to cite: Costanzo, S., Brandolini, F., Ahmed, H. I., Zerboni, A., and Manzo, A.: Bedrock, foothills and kinship: reconstructing the funerary landscape of Eastern Sudan, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-470, https://doi.org/10.5194/egusphere-egu21-470, 2021.
We present a multi-proxy approach to reconstruct Middle Bronze Age (MBA, 1600-1250 BCE) land use practices in the north-western Alpine foreland (SW Germany, Hegau). We combined biogeochemical proxies from multi-layered colluvial deposits and archaeobotanical and archaeozoological data within and in the surrounding of the archaeologically well-documented settlement site of Anselfingen. Offsite pollen data from two peat bogs were used to place the onsite and near-site vegetation and land use data to a regional context.
Phases of colluvial deposition were reconstructed by optically stimulated luminescence (OSL) and radiocarbon (AMS 14C) dating. The first phase of major colluviation could be correlated with MBA land use followed by phases of colluvial deposition during the Iron Age, the Medieval period, and modern times. Charcoal spectra from colluvial deposits and archaeological structures indicate MBA forest management favoring Quercus in the surrounding area north of the settlement. The analysis of faecal biomarker (5ß-stanols up to 40 %) and excavated pig bones (up to 14 %) suggest the presence of a forest pasture mainly used for pig farming. In the surrounding area south of the settlement, an arable field with a buried MBA plough horizon (2Apb) could be verified by soil micromorphological features such as very dusty clay coatings and a banded microstructure and by high concentrations of grass phytoliths from leaves and stems. Agricultural practices (e.g. ploughing) focused on five staple cereal crops (Hordeum distichon/vulgare, Triticum dicoccum, Triticum monococcum, Triticum spelta, Triticum aestivum/turgidum) as indicated by the onsite archaeobotanical records. Stilted pantries, reconstructed from MBA post-holes, were interpreted as storage facilities, while excavated heat stones are likely to indicate post-harvest processing of cereal crops and other agrarian products. Higher levels of urease activity compared to microbial biomass carbon (up to 2.1 µg N µg Cmic-1), and input of herbivorous animal faeces indicate livestock husbandry on fallow land or manuring practices. The suites of polycyclic aromatic hydrocarbons (PAHs) and their spatial distribution indicate the use of fire for various purposes, e.g. for landscape opening and maintenance, for domestic burning and for technical applications. The offsite pollen data support the onsite and near-site vegetation change. During the MBA, fire played a major role in shaping the landscape (peak of micro-charcoal during the MBA in the offsite pollen records) and anthropogenic activities promoted oak dominated forest vegetation at the expense of natural beech forests. This approves a broad regional human influence in the north-western Alpine foreland during the MBA.
Our data allow in-depth insights into the MBA subsistence economy on a local and regional scale, which was not limited to settlements at lakeshore sites. The MBA in the north-western Alpine foreland was a period of establishing settlements with sophisticated land management and land use practices also at low and mid altitude inland sites. We could further show that colluvial deposits are promising archives for the reconstruction of past land use practices.
How to cite: Scherer, S., Höpfer, B., Deckers, K., Fischer, E., Fuchs, M., Kandeler, E., Lehndorff, E., Lomax, J., Marhan, S., Marinova, E., Lechterbeck, J., Meister, J., Poll, C., Rahimova, H., Rösch, M., Wroth, K., Zastrow, J., Knopf, T., Scholten, T., and Kühn, P.: Middle Bronze Age land use practices in the north-western Alpine foreland – A multi-proxy study of colluvial deposits, archaeological features and peat bogs, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15578, https://doi.org/10.5194/egusphere-egu21-15578, 2021.
The economy of Roman cities in Baetica, was largely diversified and depending on the city for example specialized in olive oil, halieutic or metallurgical production. The economy of the Hispano-Roman city Munigua (municipium Flavium Muniguense) was particularly based on mining and in the 1st and 2nd centuries CE Munigua was the largest producer of copper and iron in the Sierra Morena. This contribution focuses on the evaluation of soil potential for practicing agriculture and evidences for prehistoric and historic land use in the vicinity of Munigua. It aims to provide new information to the food supply strategy of Munigua and furthermore a geoarchaeological few on the diversification debate of the urban economy in the conventus Hispalensis. Applying a pedo-geomorphic approach the present study i) shows that the landscape around Munigua has the potential for an agricultural use in larger areas and would have certainly allowed a production of agricultural goods in Roman times. Additionally, the study ii) provides clear evidence for prehistoric and historic land use in region documented by multi-layered colluvial deposits and a preserved Roman hortic soil. Hence, the results pointing to a local cultivation of agricultural products as an active contribution to the food supply of Munigua. Moreover, the study provides geoarchaeological evidences supporting the concept of an economic diversification of Roman cities in Baetica province and Hispania.
How to cite: Kirchner, A., Herrmann, N., Matras, P., Müller, I., and Meister, J.: A geoachaeological view on the Roman economy of Baetica – The case study Munigua (Seville, SW-Spain)., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9499, https://doi.org/10.5194/egusphere-egu21-9499, 2021.
Stones have been essential to protect humans from weather conditions since the beginning of humanity in escarpments, caves and other dwellings. In addition, they have been used as prehistoric tools, amulets, support for rock art and inscriptions of events or laws. They have also been used for the construction of houses, warehouses, pavements, dikes, funerary monuments and sanctuaries. Foundation stones are laid at the moment when construction of the building or structure that they support starts. The dating of this moment provides useful information about the past history of human activities.
The archaeological site of Touças is located 500 meters to the northeast of Garganta village, in São Martinho de Anta, municipality of Sabrosa (North of Portugal). It consists of about 70 standing stones of granite, several granite sarcophagi, a twin carved grave in the outcropping granite, historical quarries, a well-preserved landmark of Malta military order. In addition, a historical document indicates the previous existence of a chapel in this site.
Fieldwork was carried out to determine the type of building stones used at the archaeological site. Building granite has been identified and sampled for an in-depth analytical study. Two thin sections were prepared and characterised under a Leica DM-4500-P polarisation microscope equipped with a Leica DFC290-HD digital camera and LAS-4.9 software. Eight cubic samples with dimensions of 5×5×5±0.5 cm were tested for the petrophysical characterisation of the granite (effective porosity, water absorption and bulk density) using the Natural Stone Test Method described in European standard UNE-EN 1936. Ultrasonic pulse velocity of the granite cubes was taken with a CNS Electronics PUNDIT equipment following European standard UNE-EN 14579.
Optically stimulated luminescence (OSL) was applied to the granite foundation stones of the standing stones, sarcophagi, and walls to determine their chronology. This was done by measuring the OSL signal of the surface layer of buried granite stones. The sampling was performed at night, under red light. In the lab, slides of 5 mm layer from each stone surface was removed by sawing with a diamond-impregnated wheel. The samples were crushed in a vice and crystals with a diameter in the range of 90-250 mm were extracted by sieving. All measurements were taken with an automated Risø TL/OSL-DA15 reader and a Lexsyg Research device.
The main building granite of the archaeological site is a coarse-crystal-size granite with elongated pseudo-oriented feldspars. This building granite is the same as the outcropping granite, where there is a historical quarry.
OSL dating can be applied to obtain the absolute age from the burial of stones containing quartz. The archaeological excavations carried out in 2020 revealed that the standing stones may predate the use of the site as a medieval necropolis. The foundations of a wall that could belong to the Hermes chapel have also been found.
This archaeological site presents extremely relevant evidence for the understanding of human occupation in Trás-os-Montes e Alto Douro territory.
Acknowledgements: Fundação para a Ciência e a Tecnologia (FCT) of Portugal. Stimulus of Scientific Employment, Individual Support 2017. CEECIND/03568/2017.
How to cite: Freire-Lista, D., Sanjurjo-Sánchez, J., and Vidal Gonçalves, G.: Granite Characterisation and Chronology of the Archaeological Site of Touças (North of Portugal), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4816, https://doi.org/10.5194/egusphere-egu21-4816, 2021.
Geological and environmental conditions that influence local topography also affect indirectly the location of human settlement dynamics. Understanding those relationships plays an important role in archaeological research related to the evolution of settlement dynamics. In the lower Tyrrhenian Islands, an important parameter is also the volcanic landscape evolution. This work aims to study the patterns of Neolithic, Cooper and Bronze Age settlements, based on known archaeological sites at the Low Tyrrhenian Islands, and to generate hypotheses about the relations of settlement patterns with the volcanic landscape. To that end, a Web-GIS database was created, which was fed with topographic, geological, geomorphological data and Earth Observation data. Geomorphological analysis, derived from digital elevation models, and earth observation products such as the SENTINEL missions, can provide useful estimations into the processes shaping landscapes and insight into the location and evolution of settlements. The analysis includes a series of different data correlation, from geomorphologic to socioeconomic, integrated by an indicator analysis. A series of thematic maps were developed to interpret why areas were selected to host settlements. Through the use of the database that was developed during the project, a set of indexes have been applied. Those included exposure and vulnerability indices for the inland and coastal areas, but also location and defensibility indices for the archaeological sites. Moreover, baseline maps for future risk estimations through a Multi-Criteria Decision Analysis System (MCDA), have been produced. The Volcanic Islands of the lower Tyrrhenian coast have a volcanic origin and were influenced, and partly still are, by explosive and effusive eruptions of various energy and types, by more or less intense deformational events, often connected with the dynamics of the volcano, and quiescent periods of varying duration. The areas under investigation present different characteristics in their geomorphological but also their societal evolution. Geomorphological data further analyzed in a ternary diagram that indicated the relative influence of each of the parameters in each area. From the diagram, it can be seen that the locations of human activities are strongly affected by past and recent volcanic activity.
Acknowledgement: This work is part of the Brains2Islands “INDAGINE MULTIDISCIPLINARE NEI CONTESTI INSULARI BASSO TIRRENICI” project Funded by FONDAZIONE CON IL SUD project number 2015-0296
How to cite: Alexandrakis, G., Nomi, F., Speciale, C., De Vita, S., and Di Vito, M. A.: Analysis between ancient human settlements and volcanic landscapes using earth observation and archaeological data, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10556, https://doi.org/10.5194/egusphere-egu21-10556, 2021.
Mercury (Hg) was used in gilding techniques since ancient times. This metal gilding technique consisted of applying an amalgam of Au and Hg to the surface of a metallic object and then removing the Hg to achieve adhesion of the Au to the support. The traditional preparation of amalgam was a mixture of Au with Hg (in a ratio of 1/8). After this preparation, the mixture usually was ground in a mortar, heated, and then cooled by pouring it into water. The paste was applied to the areas to be browned and then the piece was subjected to mild temperatures so that the Hg evaporated, leaving a thin layer of Au on the surface of the object.
The origin of this work is the discovery of an evident quantity of liquid Hg on a site under construction, near the old wall of the city of Murcia, at a level identified as from medieval times. To elucidate the origin of this Hg, a sampling of medieval materials has been carried out throughout the site, including both the area with liquid Hg, the entire area what appears to be the work room and the adjacent rooms. The sampling has been carried out using an Ejkelkamp sampler at various depths. These soil samples were analysed by Energy Dispersion X-Ray Fluorescence using a PanAlytical device. Total Hg and Hg speciation data were obtained by Atomic Absorption Spectrometry using a Lumex equipment. In addition to this, a gaseous mercury monitoring has been carried out using a portable atomic absorption equipment to search Hg sources and gaseous Hg dispersion in the atmosphere of the studied site. Results of the survey has shown an evident and intense soil Hg pollution in a small area of 2x2 m. This affected area was located near the outer wall of the medieval building and was very restricted, which suggests that it was a storage place for liquid Hg for later use in other areas. The degassing of these recently uncovered materials produced a significant dispersion of the Hg gas throughout the enclosure. In addition to this, samples of medieval materials have shown very high concentrations of Hg in the vicinity of the contaminated area, and high concentrations in the rest of the enclosure. Speciation analysis have shown that the Hg in this part of the enclosure is in the form of metacinnabar and Hg bound to humic acids, which suggests the presence of an atmosphere with extremely high concentration of gaseous Hg in medieval times that was later deposited in the soil, being fixed to its organic phase. Multielemental analysis has shown additional high concentrations of Pb, Cu and Sn, suggesting that the artisanal works in the enclosure involved these elements too. While waiting for more specific archaeology works that can corroborate it, the origin of this Hg in the area could be the storage for the realization of gilding work on metals with this element.
This work was funded by the company “Obras y Proyectos Soyma”.
How to cite: Esbrí, J. M., Mansilla-Plaza, L., Sanchez-Gonzalez, M. J., and Higueras, P.: Finding of artisanal uses of elemental mercury in the city of Murcia in medieval times, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7647, https://doi.org/10.5194/egusphere-egu21-7647, 2021.
The proposal to introduce a new geological epoch, the Anthropocene, has led to an increasingly intensive discourse on the concrete evidence of anthropogenic interventions in nature, their extent and exact beginning in Geosciences and neighboring disciplines, as well as on questions of a fundamental change in man-environmental relations especially in the humanities. The concept of the Anthropocene thus has become a socio-political relevance with regard to global environmental changes and their management.
The paper uses a conceptual model to illustrate the various proposals for formalizing the Anthropocene from the geoscientific perspective on the one hand and the complex interlinking of human-nature relationships on the other hand on the base of the Harz Region (Lower Saxony, Germany) and selected type localities for the Anthropocene. The Harz and its foreland possess numerous key localities in geological, geomorphological, vegetation and cultural-historical research as well as important geoarchaeological and settlement-historical sites. At a comparatively small spatial segment of the earth surface, the transitions from a natural to a human-dominated world can be demonstrated on different spatio-temporal scales from the Paleo-Anthropocene to the current modern Anthropocene based on a broad spectrum of Quaternary paleo-archives and cultural evidences. In the northern Harz foreland, there are significant geoarchaeological sites from the Paleolithic and in the southern Harz foreland from the Middle Paleolithic, including caves and settlement relics, with far-reaching implications for early human intervention in nature. Since the Bronze Age, the Harz Region was used for mining mineral resources. Since the Middle Ages and Modern Age at the latest, the Harz Mountains have been systematically developed for mining, and not least because of the rich silver ore deposits, they have been converted into an industrial landscape. Mining landscapes with special landform assemblages emerged at the local level, which not only changed the geological underground and geomorphological relief surface partly irreversibly, but also the vegetation and the hydrological system was profoundly changed with consequences for the future ecological system. The environmental impact, but above all the indirect consequences of mining activities in the context of the import and export of goods, the migrations of workers and exchange of knowledge extended far beyond the region to the global level.
In this regard the St. Andreasberg Mining District with the UNESCO World Heritage site of the Samson Pit, one of the centers of silver mining in the Harz Mountains, was selected as a key site for demonstrating the human impact since the times of the Columbian Exchange. It shows in a paradigmatic way the anthropogenic transformation of the natural landscape in the context of regional and global environmental changes in their complex human-nature interplay. At the same time, the recent change from a mining to a tourism landscape as well as approaches of sustainable development strategies in form of modern wilderness-concepts and the use of regenerative energies based on a century old water management system provide the base for future-oriented man-environment concepts.
How to cite: Iturrizaga, L.: The Harz Mountains and the St. Andreasberg Mining District (Germany) as a key region for an interdisciplinary Anthropocene discourse, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15808, https://doi.org/10.5194/egusphere-egu21-15808, 2021.
The Malagasy highlands are scattered with large inverse teardrop-shaped gullies called lavaka, which are by many considered as the prime indication of a currently ongoing human-induced environmental crisis. Yet, these gullies are known to have existed long before human arrival on the island, resulting in the highly debated role of anthropogenic disturbances on their formation. Here, we assess the dynamics of 700 lavaka in the lake Alaotra region from 1949 to the 2010s by using historical aerial pictures and present day satellite imagery. An overall birth to stabilization ratio of 6.1 indicates a currently rapid growing lavaka population. Observed growth-, birth- and stabilization rates allowed us to calculate a mean lavaka population age of 410 ± 40 years, and estimate that the current crisis started at 943 ± 430 cal. yr BP. This timeframe corresponds well with the “subsistence-shift”, where people move from hunting and foraging to farming and herding practices upon the introduction of cattle in the region. These findings were integrated into a novel, temporally explicit lavaka population model - building upon the observed lavaka growth-, birth- and stabilization rates and lavaka size distributions - where different environmental pressure scenarios were tested. Modelling outcomes show that the currently observed lavaka crisis largely results from a rapid increase in environmental pressure over the last centuries, likely caused by the combined effects of deforestation and overgrazing related to human population growth and the introduction of cattle. With this study we show the potential of an integrated data-modeling approach, where demographic concepts are applied to geomorphological features, allowing to link their evolution with past anthropogenically driven environmental changes.
How to cite: Brosens, L., Campforts, B., Jacobs, L., Razanamahandry, V. F., Van Moerbeke, Q., Broothaerts, N., Razafimbelo, T., Rafolisy, T., Bouillon, S., and Govers, G.: Is there an environmental crisis in Madagascar’s highlands? Insights from the spatio-temporal evolution and demographic modelling of lavaka (large gullies), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4354, https://doi.org/10.5194/egusphere-egu21-4354, 2021.
The transition to the Late Mesolithic (c. 8.4-7 ka) in SW Iberia has been characterized as a period of profound reorganization of human settlement. Such reorganization affected various aspects of cultural behaviour and was reflected by a tendency toward a more permanent settlement, changes in the mobility patterns of the human groups and the creation of the first burial grounds. These changes were concomitant with the apparent abandonment of coastal areas and the displacement of people toward the interior of newly formed large estuaries. The motivation behind such changes has been traditionally related to environmental conditions, in particular to the occurrence of the 8.2 ka cooling event whose impact in the landscape and the availability of resources would have been abrupt in these southern latitudes. Here, we revisit all the existing archaeological evidence for the time interval encompassing 11 and 7 ka in order to environmentally frame this behavioural change, paying particular attention to the settlement spatial distribution with regard to the configuration and position of the ancient shoreline and combining this information with environmental reconstructions available for this time interval. The integration of this information suggests that after 8.5 ka the sediment depleted coast north of Lisbon seems to have been abandoned, while the SW Alentejo coast continued to be occupied during the Late Mesolithic. The occurrence of abundant top-cliff dunes along this southern littoral fringe suggests a less sediment starved coast than the northern one that could accommodate wide sandy coastal plains, inviting human communities to continue exploiting sea resources. Conversely, the northern coast appears to have been abandoned due to the rapid sea-level rise that would have flooded the coastal plain, forcing the rapid retreat of this starved and unstable coastline. Simultaneously, the inundation of the coast between 11 and 7 ka created optimal conditions in the innermost areas of the large estuaries, attracting people to these rich and more stable environments. Such circumstances would invite people to gradually move to these new locations and to use coastal settlements mostly for logistic purposes where accommodation space for their activities was available. The latter also suggests that the perception that these communities had in relation to the coastline was completely oppose to ours. For them, the coast was an important element to fulfil their diet, however, the location of their settlements relative to the ancient coast suggests that they perceived the coast as an unstable and unsafe area, which motivated them to always keep a distance or only occupy the area unaffected by such instability. In addition, their occupation attitude, based on adaptation to the landscape rather than the opposite, explains their tendency to retreat from the mobile and unstable coast. It is worth mentioning that the latter hypothesis can be partially biased because of gaps in the archaeological record, in particular because of the lack of underwater archaeological explorations, which may hide an additional and relevant part of this history.
This work was supported by the project PTDC/CTA-GFI/28949/2017 and PTDC/CTA-GEO/28941/2017, funded by the Portuguese Foundation for Science and Technology.
How to cite: Costas, S., Araújo, A. C., Costa, A. M., and Naughton, F.: Changes in human settlement during the Mesolithic of SW Iberia motivated by the rapid inundation of the coast, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12389, https://doi.org/10.5194/egusphere-egu21-12389, 2021.
Rivers and alluvial floodplains are dynamic environments that experience both natural and anthropogenic impacts. Sustainable management of these ecosystems requires a thorough understanding of the functioning of floodplains and their sensitivity to changes in driving forces, including anthropogenic land-cover change. Looking at past human-environment interactions in river catchments can help to develop such sustainable management strategies for the future.
During the Early and Middle Holocene, most floodplains in northeastern Belgium were stable environments, mainly driven by natural forces, resulting in large marshes where peat accumulated and river channels were absent or small. During the Late Holocene, these environments changed completely towards single channel meandering rivers with overbank deposits, impeding peat accumulation. These changes can to a large extent be linked to increasing human activities in the catchment. However, the timing of this change in floodplain geoecology strongly varies within and between different catchments.
Five river catchments in northeastern Belgium with varying soil properties, topographies, and durations and intensities of human impact were selected in this study, to uncover regional differences in land-cover evolution. The catchments of Dijle (750 km²), Grote Gete (300 km²) and Mombeek (90 km²) are located in the central Belgian loess belt, whereas the Grote Nete (525 km²) and Zwarte Beek catchments (50 km²) are situated in the sandy Campine region. A multi-proxy approach, including sedimentological proxies, pollen, and macrobotanical remains, was chosen to reconstruct alluvial floodplain characteristics and anthropogenic land-cover changes. We constructed a database of 27 records for these five catchments (of which 9 containing pollen, 4 containing macrobotanical remains, and 14 containing both) for which 132 radiocarbon dates in total provide a chronostratigraphic framework.
Qualitative, semi-quantitative (NMDS) and quantitative (REVEALS) analyses of the palynological data revealed regional differences in the initiation and intensity of human impact. From the Neolithic period onwards, deforestation is detected in both the loess and sandy region, although the loess belt underwent a more rapid and severe reduction of woodland. While this deforestation is accompanied by an increase in cropland in the loess region from the Bronze Age onwards, the sandy region only starts to show limited agriculture from the Iron Age onwards, related to its later and less dense human occupation.
While the amount of records and their resolution is rather low in the sandy region, the numerous and detailed records of the loess belt also allow detection of more local and short-term effects (< 200 years) of changes in human impact. A decrease in human impact during the Dark Ages, which can be related to the decreased population density in Europe during the first millennium AD, is visible: hillslope–floodplain connectivity reduced due to the regeneration of vegetation barriers, in turn lowering sediment input, which facilitated local reactivation of peat growth and regrowth of the natural alder-carr floodplain vegetation. After this temporary decrease, human impact on floodplain geoecology started to increase again up till modern times. The impact also got more direct, as peat extraction from the floodplains became common practice, especially in the sandy Campine region.
How to cite: Hoevers, R., Broothaerts, N., Swinnen, W., and Verstraeten, G.: Holocene alluvial floodplains in Belgium: from natural to human-dominated environments, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3986, https://doi.org/10.5194/egusphere-egu21-3986, 2021.
The Aral Sea basin in Central Asia and its major rivers the Amu Darya and Syr Darya were the center of advanced river civilizations, and a principal hub of the Silk Roads trade network. The region’s decline has been traditionally attributed to the Mongol invasion of the early-13th century CE. In this study, we demonstrate the role of changing hydroclimatic conditions on the development of these culturally influential potamic societies that were depending on floodwater farming. Radiometric dating of irrigation canal abandonment and an investigation of regional river channel dynamics at Otrār oasis, a UNESCO World Heritage site located at the confluence of the Syr Darya and Arys rivers in southern Kazakhstan, revealed that major phases of fluvial aggradation occurred between the 7th to early-9th century CE and the mid-14th to mid-16th century CE. These periods coincide with economic flourishing of the oasis, facilitated by NAO-induced wet climatic conditions and higher river flows that favored floodwater farming. Periods of abandonment of the irrigation network and cultural decline primarily correlate with fluvial entrenchment during periods of drought. As the decline of the region seems to have initiated before the arrival of Ghenghis Khan and his armies, climate change has to be considered as a pivotal factor in the region's final demise.
How to cite: Toonen, W., Macklin, M., Dawkes, G., and Durcan, J.: A hydromorphic re-evaluation of Central Asia's Medieval floodwater farming civilizations , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8647, https://doi.org/10.5194/egusphere-egu21-8647, 2021.
We present a 700-year reconstruction of the environmental changes in the Colesdalen, Svalbard, inferred from a sediment core retrieved from lake Tenndammen (N 78°06.118; E 15°02.024). A comparison of modern and old maps revealed that the lake was artificially connected to its western tribute that now inputs additional water and sediment into the lake, but earlier lake Tenndammen was mainly fed by discharge and groundwater from the main valley. A multi-proxy approach was applied involving sedimentary ancient DNA (sedaDNA), pollen, spores, plant macrofossils, sedimentology and biogeochemistry. Establishing a chronology for this core was problematic as nine of the fourteen AMS dates were revered. However, core imaging as well as X-ray fluorescence (XRF) demonstrated clear stratification and undisturbed sediment layers. This is supported by the clear and coherent data obtained from the plant palaeo-proxies in terms of vegetation and environmental changes indicated by all proxies at the same core depths. From these observations, we inferred that lake Tenndammen experienced a number of floods which brought older sediments into the lake and produced a high proportion of the reversed dates. In order to test this hypothesis, portable optically stimulated luminescence (pOSL) and infrared stimulated luminescence (pIRSL) was employed. The pIRSL, pOSL and pIRSL/pOSL profiles suggested a series of 15 flooding and 8 drying events occurring at the depths associated with the reversed dates. However, relatively high amount of spheroidal carbonaceous particles (SCP, up to 1300 per gram of dried sediment mass) helped to improve the core chronology through a comparison with the calendar dates of the history of the coal mining and power production in Svalbard. SCP record allowed to find three tie points for the age-depth model at (1) the construction time of the power plant in 1911-1913 in Colesdalen, (2) the abrupt decrease in SCPs associated with the Second World War in 1941-1946, and (3) the highest output of the power plant in Colesdalen in the middle of the 1950s. When combined with the earlier non-reversed dates this provides an age-depth model with the basal age of the core at c. 730 cal. yr. BP and with the upper sediments deposited at c. 1950-1980s. Using this revised age-depth model, four chrono-stratigraphic units were described and, according to the data on luminescence profiling, the most intensive floods were associated with the second unit, which corresponded with the most intensive ice melting in the study area (c. 1670 - 1420 BP). The strongest drying events took place at the end of the second unit and in the first part of the third unit (c. 1655 BP). This was supported by the plant proxies with an abundance of the aquatic and swamp bryophyta Warnstorfia exannulata/Warnstorfia fluitans, algae (i.e. Closterium littorale, Cosmarium botrytis and Staurastrum punctulatum) both in the non-pollen microfossils record and the sedaDNA. This study shows that a combination of biological proxies, sedimentology and pOSL can detect flood and desiccation events, and that lake Tenndammen was a highly sensitive fluvio-lacustrine systems during the late Holocene/Anthropocene.
How to cite: Poliakova, A., Brown, A. G., Sanderson, D. C. W., and Alsos, I. G.: Flood and desiccation events reconstructed based on luminescence profiles and palaeobotanical proxies from the High Arctic lake Tenndammen, Svalbard, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4518, https://doi.org/10.5194/egusphere-egu21-4518, 2021.
“Plot-and-Berm” (P&B) agroecosystems consist of sophisticated agricultural utilization of a high-water table within loose sand sheets, situated in agricultural hinterlands. Sunken agricultural plots between 3-6 m high sand berms coated with anthropogenic refuse/fines protect them from erosion. The plot level enables easy access to the groundwater for crop roots and shallow well construction, while refuse and organic material enrich the inert sand forming distinct grey sand-loam anthrosols. The agroecosystems require significant resources for construction and maintenance. The earliest recognized P&B agroecosystems are Early Islamic to early Crusader (9th-early 12th centuries a.d.) within several coastal sand bodies of Israel that were abandoned by unclear reasons. Similar agroecosystems in Iberia and Algeria and the southeastern Mediterranean (mawasi) coast historically date to the Middle Ages and early modern period.
Here we reexamine the unpublished data of the only previous excavation (Porath, 1975) and present field and artifactual finds along with pulsed-photon portable luminescence (PPSL) profiling from our 2020 research excavation of the agroecosystem, at the southern outskirts of ancient Caesarea in order to refine understandings on construction materials, structure types and roles, and agroecosystem function, maintenance and timespan.
Berms are found to be constructed from over 3 m thick anthropogenic-mixed sand while their grey sand-loam anthrosol coat is differentially distributed. The ~30 cm thick grey sand-loam anthrosols of the plots still possess distinct contacts with the over- and under-lying sand. Probes in the eastern margins of the agroecosystem reveal sand with Roman sherds. Structural remains include short stand-alone walls, small storage/watching structures, and a unique structure on the western-most berm overlooking the beach with a 3 m deep stone wall and grey sand loam substrate. All of the structures and earthworks possess Early Islamic ceramics along with remains from Roman-Byzantine Caesarea.
How to cite: Taxel, I. and Roskin, J.: Revision and preliminary excavation finds of the Early Islamic Plot-and-Berm groundwater harvesting agroecosystem by ancient Caesarea, Israel, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9542, https://doi.org/10.5194/egusphere-egu21-9542, 2021.
The necessity of sustainable development for landscapes has emerged as an important theme in recent decades. Moreover, past landscape reconstruction enables a better understanding of human resilience to climatic and environmental changes in different periods and locations, and illustrates examples of sustainable development in the past. Free and open-source (FOSS) datasets of satellite imagery offer considerable opportunities for landscape heritage stakeholders both for recording and monitoring activities. In this research, a completely FOSS-cloud procedure to enhance the detection of palaeo-landscape features is presented. Sentinel - 2 satellite imagery has been retrieved in the Google Earth Engine dataset collection and analysed through a Python script code realized in Google Colaboratory. A multi-temporal approach has been adopted to investigate the potential of satellite imagery to detect buried features along with Spectral Index (i.e., RGB, False Short Wave Infrared Colour and Bare Soil Index) and Spectral Decomposition analysis (i.e., Hue, Saturation and Value, Tasselled Cap Transformation and Principal Component Analysis). This procedure has been tested in the Po Plain (Northern Italy), chosen because it is characterized by human-landscape interaction since the Mid-Holocene. Thanks to its complex settlement and land-management history, the Po Plain represents an ideal laboratory to assess the potentiality of satellite imagery to enhance riverscapes’ palaeo-features. The outputs obtained can be visualized directly in the Google Colaboratory browser or downloaded via Google Drive for further graphical applications or spatial analysis. The buried features detected have been checked through the available geomorphological and archaeological literature; published case studies interpreting the occurrence of buried features served as a benchmark to validate the script code developed. This research represents one of the first applications of the GEE Python API in landscape studies. The main advantages of this procedure consist of: i) being FOSS, all the software used here are open-licensed; ii) working in cloud, no powerful hardware is necessary to run the script code; iii) high adaptability, changing the ROI is possible to calculate SI and SD outputs for any area of the world; iv) very basic coding skills are required to adapt the code to a ROI with different environmental characteristics. The development of FOSS-cloud procedures could support the identification, conservation and management of cultural and natural heritage anywhere around the world. In remote areas or where local heritage is threatened as a result of political instability, climate change or other factors, FOSS-cloud protocols can facilitate the application of new scientific methods and enable the dissemination of and access to scientific information.
How to cite: Brandolini, F., Domingo-Ribas, G., Zerboni, A., and Turner, S.: Enhancing the detection of buried anthropogenic features thought a cloud-computing Python procedure, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-579, https://doi.org/10.5194/egusphere-egu21-579, 2021.
This paper presents the application of machine-learning techniques on pXRF data to establish a chronology for sediment cores around Tell Buto (Tell el-Fara´in) in the northwestern Nile Delta. As modern laboratories for dating techniques like OSL or 14C are rare in Egypt and sample export is restricted, we are facing a lack of opportunities to create a robust chronology, which is indispensable in modern Geoarchaeology.
Therefore, we present a new approach to transfer archaeological age information gained at the excavation at Buto to corings of the wider Buto area. Sediments of archaeological outcrops and pits with known age are measured using pXRF to create a geochemical “fingerprint” for several historic eras. Afterwards, these “fingerprints” are transferred to corings of the surrounding areas using machine-learning algorithms.
This paper presents 1) the application of three different machine-learning approaches (Neuronal Net, Random Forest, and C5.0 decision tree) to check if archaeological age information can be transferred to sediments far off the settlement mounds using pXRF data, 2) the comparison of all approaches and the evaluation if the easily anticipated decision tree and Random Forest show similar results as the “black-box system” Neuronal Net, and finally, 3) a case study that provides the results of Altmeyer et al. (in review) for Kom el-Gir, a further settlement mound little north of Buto, with a chronostratigraphic framework based on this approach.
Altmeyer, M., Seeliger, M., Ginau, A., Schiestl, R. & J. Wunderlich (in review): Reconstruction of former channel systems in the northwestern Nile Delta (Egypt) based on corings and electrical resistivity tomography (ERT). (Submitted to E & G Quaternary Science Journal).
How to cite: Seeliger, M., Altmeyer, M., Ginau, A., Schiestl, R., and Wunderlich, J.: Machine Learning (Neuronal Net, Random Forest, and C5.0 single decision tree) based on pXRF data as a tool to date sediment layers of the Nile Delta, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15296, https://doi.org/10.5194/egusphere-egu21-15296, 2021.
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