GM12.7

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.

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 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-13^th 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 7^th to early-9^th century CE and the mid-14^th to mid-16^th 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.

“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.

Reference:

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.