202 research outputs found
late Pleistocene-Holocene African Humid Period as Evident in Lakes
From the end of the last glacial stage until the mid-Holocene, large areas of arid and semi-arid North Africa were much wetter than present, during the interval that is known as the African Humid Period (AHP). During this time, large areas were characterized by a marked increase in precipitation, an expansion of lakes, river systems, and wetlands, and the spread of grassland, shrub land, and woodland vegetation into areas that are currently much drier. Simulations with climate models indicate that the AHP was the result of orbitally forced increase in northern hemisphere summer insolation, which caused the intensification and northward expansion of the boreal summer monsoon. However, feedbacks from ocean circulation, land-surface cover, and greenhouse gases were probably also important.
Lake basins and their sediment archives have provided important information about climate during the AHP, including the overall increases in precipitation and in rates, trajectories, and spatial variations in change at the beginning and the end of the interval. The general pattern is one of apparently synchronous onset of the AHP at the start of the Bølling-Allerød interstadial around 14,700 years ago, although wet conditions were interrupted by aridity during the Younger Dryas stadial. Wetter conditions returned at the start of the Holocene around 11,700 years ago covering much of North Africa and extended into parts of the southern hemisphere, including southeastern Equatorial Africa. During this time, the expansion of lakes and of grassland or shrub land vegetation over the area that is now the Sahara desert, was especially marked. Increasing aridity through the mid-Holocene, associated with a reduction in northern hemisphere summer insolation, brought about the end of the AHP by around 5000–4000 years before present. The degree to which this end was abrupt or gradual and geographically synchronous or time transgressive, remains open to debate. Taken as a whole, the lake sediment records do not support rapid and synchronous declines in precipitation and vegetation across the whole of North Africa, as some model experiments and other palaeoclimate archives have suggested. Lake sediments from basins that desiccated during the mid-Holocene may have been deflated, thus providing a misleading picture of rapid change. Moreover, different proxies of climate or environment may respond in contrasting ways to the same changes in climate. Despite this, there is evidence of rapid (within a few hundred years) termination to the AHP in some regions, with clear signs of a time-transgressive response both north to south and east to west, pointing to complex controls over the mid-Holocene drying of North Africa
Ein Beitrag zur Entwicklungsgeschichte eines Landschaftsschutzgebietes
Neben der Kartierung und Darstellung der Sedimente konnte die spätglaziale bis holozäne Entwicklungsgeschichte des Untersuchungsgebietes diskutiert werden. Diese Ergebnisse beruhen auf über 100 Sondierungen, sowie auf sedimentologischen und geochemischen Analysen einer mittels des Livingstonbohrverfahrens ungestört beprobten Sedimentsequenz.
Das Untersuchungsgebiet liegt auf der Grundmoränenplatte des Teltow, die dem Brandenburger Stadium der Weichseleiszeit zuzuordnen ist, dessen subglaziale Schmelzwässer die Buschgrabentalung genutzt und geprägt haben.
Nach dem Abtauen des die Rinnen bedeckenden Eises, bleiben diese zunächst mit Stagnierendem Eis und später mit Toteis verfüllt. Aufgrund der geringen Sedimentüberdeckung des Toteises von schätzungsweise maximal 10 m in der Buschgrabentalung - bei einer maximalen Rinneneintiefung von 15 m gegenüber der umliegenden Geschiebemergelflächen – kommt es bereits im ausgehenden Hochglazial und insbesonere in dessen Interstadialen (Blankenberginterstadial, Meiendorfintervall) zum Austauen des Toteises.
Nach einer längeren Ruhepause, bedingt durch ältestdryaszeitlichen, trockenen Klimabedingungen und der erhöhten Wasserpermeabilität der die Rinnen unterlagernden sandig bis kiesigen Substrate, beginnt im Bölling-Komplex (vor 13 000 B.P.) die limnische Sedimentation und damit die Auffüllung der Becken. Die limnische Fazies beginnt mit einer sandhaltigen Kalkmudde, die im Alleröd in eine rhythmitische, kalkig bis sideritische Fazies übergeht. Aufgrund der Analysenwerte und der für die Rhythmitbildung erforderlichen Rahmenbedingungen kann in diesem Abschnitt mit einem meromiktischen See mit hohem Nährtstoffangebot und zeitweiligen Phasen anaerober Verhältnisse (Sideritbildung) am Seeboden gerechnet werden. Die Rhythmitbildung wird durch den stratigraphischen Leithorizont der allerödzeitlichen Tephralage der Eruption des Laacher Maares aus der Eifel begrenzt.
Durch die stetige Aufsedimentation eine dimiktische Phase über, angezeigtdurch die Sedimentation einer ungeschichteten, kalkfreien Feindetritusmudde, um im beginnenden älteren Atlantikum (7 500 B.P.) in eine Algen- bzw. Torfmudde überzugehen, die in die telmatische Sedimentation überleitet. Es bildet sich ein eutrophes Niedermoor aus, das im obersten Meter in einen Ried- bis Farntorf übergeht. Weite Bereiche des Untersuchungsgebietes sind rezent von mächtigen anthropogenen Aufschüttungen überprägt worden, die z. T. mit der Trockenlegung des Feuchtgebietes während der Nutzung des Geländes als Gärtnerei zusammenhängen
A new device to mount portable energy-dispersive X-ray fluorescence spectrometers (p-ED-XRF) for semi-continuous analyses of split (sediment) cores and solid samples
Portable energy-dispersive X-ray fluorescence spectrometers (p-ED-XRF) have
become increasingly popular in sedimentary laboratories to quantify the
chemical composition of a range of materials such as sediments, soils, solid
samples, and artefacts. Here, we introduce a low-cost, clearly arranged unit
that functions as a sample chamber (German industrial property rights no. 20
2014 106 048.0) for p-ED-XRF devices to facilitate economic, non-destructive,
fast, and semi-continuous analysis of (sediment) cores or other solid samples.
The spatial resolution of the measurements is limited to the specifications of
the applied p-ED-XRF device – in our case a Thermo Scientific Niton XL3t p-ED-
XRF spectrometer with a maximum spatial resolution of 0.3 cm and equipped with
a charge-coupled device (CCD) camera to document the measurement spot. We
demonstrate the strength of combining p-ED-XRF analyses with this new sample
chamber to identify Holocene facies changes (e.g. marine vs. terrestrial
sedimentary facies) using a sediment core from an estuarine environment in the
context of a geoarchaeological investigation at the Atlantic coast of southern
Spain
Coupling spectral imaging and laboratory analyses to digitally map sediment parameters and stratigraphic layers in Yeha, Ethiopia
Quantitative analyses of soil and sediment samples are often used to complement stratigraphic interpretations in archaeological and geoscientific research. The outcome of such analyses often is confined to small parts of the examined profiles as only a limited number of samples can be extracted and processed. Recent laboratory studies show that such selectively measured soil and sediment characteristics can be spatially extrapolated using spectral image data, resulting in reliable maps of a variety of parameters. However, on-site usage of this method has not been examined. We therefore explore, whether image data (RGB data and visible and near infrared hyperspectral data), acquired under regular fieldwork conditions during an archaeological excavation, in combination with a sampling strategy that is close to common practice, can be used to produce maps of soil organic matter, hematite, calcite, several weathering indices and grain size characteristics throughout complex archaeological profiles. We examine two profiles from an archaeological trench in Yeha (Tigray, Ethiopia). Our findings show a promising performance of RGB data and its derivative CIELAB as well as hyperspectral data for the prediction of parameters via random forest regression. By including two individual profiles we are able to assess the accuracy and reproducibility of our results, and illustrate the advantages and drawbacks of a higher spectral resolution and the necessary additional effort during fieldwork. The produced maps of the parameters examined allow us to critically reflect on the stratigraphic interpretation and offer a more objective basis for layer delineation in general. Our study therefore promotes more transparent and reproducible documentation for often destructive archaeological fieldwork
On-Site VIS-NIR Spectral Reflectance and Colour Measurements - A Fast and Inexpensive Alternative for Delineating Sediment Layers Quantitatively? A Case Study from a Monumental Bronze Age Burial Mound (Seddin, Germany)
Quantitative sediment analyses performed in the laboratory are often used throughout archaeological excavations to critically reflect on-site stratigraphic delineation. Established methods are, however, often time-consuming and expensive. Recent studies suggest that systematic image analysis can objectivise the delineation of stratigraphic layers based on fast quantitative spectral measurements. The presented study examines how these assumptions prevail when compared to modern techniques of sediment analysis. We examine an archaeological cross-section at a Bronze Age burial mound near Seddin (administrative district Prignitz, Brandenburg, Germany), consisting of several layers of construction-related material. Using detailed on-site descriptions supported by quantitatively measured sediment properties as a measure of quality, we compare clustering results of (i) extensive colour measurements conducted with an RGB and a multispectral camera during fieldwork, as well as (ii) selectively sampled sedimentological data and (iii) visible and near infrared (VIS-NIR) hyperspectral data, both acquired in the laboratory. Furthermore, the influence of colour transformation to the CIELAB colour space (Commission Internationale de l’Eclairage) and the possibilities of predicting soil organic carbon (SOC) based on image data are examined. Our results indicate that quantitative spectral measurements, while still experimental, can be used to delineate stratigraphic layers in a similar manner to traditional sedimentological data. The proposed processing steps further improved our results. Quantitative colour measurements should therefore be included in the current workflow of archaeological excavations
Towards timing and stratigraphy of the Bronze Age burial mound royal tomb (Königsgrab) of Seddin (Brandenburg, northeastern Germany)
This study uses an integrated multi-method geoarcheological and geochronological approach to contribute to the understanding of the timing and stratigraphy of the monumental burial mound royal tomb (Königsgrab) of Seddin. We show that the hitherto established radiocarbon-based terminus post quem time frame for the construction of the burial mound of 910–800 BCE is supported by optically stimulated luminescence (OSL) dating. The radiocarbon samples were obtained from a substrate directly underneath the burial mound which supposedly represents the late glacial/Holocene soil that was buried below the structure. We use sedimentological (grain-size analyses) and geochemical analyses (element analyses, carbon, pH, and electric conductivity determinations) to reassess and confirm this hypothesis. In addition to the burial age associated with the last anthropogenic reworking during construction of the burial mound, the OSL dating results provide new insights into the primary deposition history of the original substrates used for the structure. In combination with regional information about the middle and late Quaternary development of the environment, our data allow us to provide a synoptic genetic model of the landscape development and the multiphase stratigraphy of the royal tomb of Seddin within the Late Bronze Age cultural group “Seddiner Gruppe” of northern Germany. Based on our initial experiences with OSL dating applied to the sediments of a burial mound – to the best of our knowledge the first attempt in Europe – we propose a minimal invasive approach to obtain datable material from burial mounds and discuss related opportunities and challenges
The landscape of the Late Bronze Age royal tomb of Seddin (NE Germany): linking geomorphology, archaeology, and historic evidence
The monumental Late Bonze Age royal tomb of Seddin is located in the old morainic landscape of the Prignitz region, northeastern Germany. Together with other richly equipped burials and a row of stone pits in its direct vicinity, it provides evidence for the presence of an elite from the nineth to sixth centuries BCE in this region. Our map emphasizes the well-chosen location of the royal tomb in relation to the spatial arrangement of other archaeological monuments that together form an ensemble of a ritual landscape. We trace legacies of land use from the Bronze Age to the present against the backdrop of Late Quaternary landscape evolution. These include the Bronze Age landscape (re-)organization for ritual and economic purposes, its medieval use for arable farming, its economic use and settlement history in historic times, and modern times melioration of agricultural areas that together form the palimpsest of the present-day landscape
Coupling of Geomorphological, Geophysical, Geochemical and Archaeological Spatial Data for a Study of the Interface of the Latène and Przeworsk Cultures in NE Germany
The Aesthetic Responsiveness Assessment (AReA): A screening tool to assess individual differences in responsiveness to art in English and German
People differ in how they respond to artworks. Measuring such individual differences is helpful for explaining response variability and selecting particularly responsive subsamples. On the basis of a sample of items indicating relevant behavior and experience, we exploratively constructed the Aesthetic Responsiveness Assessment (AReA), a screening tool for the assessment of individual differences in responsiveness to art in English and German. Exploratory and confirmatory factor analyses suggested three first-order factors labeled aesthetic appreciation, intense aesthetic experience, and creative behavior, and a second-order factor aesthetic responsiveness. Aesthetic responsiveness was assessed in N= 781 participants from the United States and Germany, and measurement invariance analysis demonstrated full metric and partial scalar invariance across language versions. AReA scale scores yielded good reliability estimates. Validation studies confirmed expected associations between AReA scale scores and measures of related constructs, as well as continuously and retrospectively recorded responses to music, visual art, and poetry. In summary, the AReA is a promising, psychometrically evaluated instrument to assess aesthetic responsiveness built on a mixture of exploratory and confirmatory construction strategies. It can be used as a screening tool both in English and German speaking samples
Zur Archäologie und Landschaftsentwicklung im Turano-Tal (Sabiner Berge), Italien
Ein archäologisch-geographisches Kooperationsprojekt im Turano-Tal,
nordöstlich von Rom, untersuchte die Landschafts- und Besiedlungsgeschichte.
Die mächtigen Talverfüllungen des Untersuchungsgebietes, die in den letzten
5500 Jahren gebildet wurden, dokumentieren die Verzahnung von kolluvialen und
fluvialen Sedimenten. Um 2200 BC zeigt sich eine deutliche Veränderung der
fluvialen Systeme mit einer stetigen Zunahme der Sedimentmächtigkeiten. Die
kumulierten 14C-Datierungen zeigen Intervalle verstärkter Sedimentverlagerung,
die die historische Landnutzung sowie soziale UmbrĂĽche widerspiegeln. Der
archäologische Fokus der Untersuchung lag auf Zeugnissen der römischen
Besiedlung. In diesem Zusammenhang ist ein römischer Tempel besonders
bedeutungsvoll, der unter der Kirche auf dem Berg San Giovanni liegt und eine
Zentralortfunktion auf das umgebende Tal ausĂĽbte. Zudem wurde eine
Dokumentation zu einer bereits bekannten monumentalen Grabinschrift
durchgeführt. Zentral-Apennin; Alt-Sabiner Land; Spät-Holozän;
Landschaftsentwicklung; Besiedlungsgeschichte; Historische Landnutzung;
Römische Besiedlung. A joint project of archaeologists and geographers
investigated the landscape development and settlement history of the Turano
valley, NE of Rome. The valley fills in the area were deposited during the
last 5500 years and show an interlocking of colluvial and fluvial sediments.
From c. 2200 BC onwards a continuous increase in sediment thickness attests to
modifications of the fluvial systems. The distribution of C-dates exhibits
intervals of intense sediment dislocation representing changes in land use and
society. Archaeological research focused on evidence of Roman settlement
activities. In this context a Roman temple situated in the basement of the
medieval church on Mount San Giovanni is of particular interest, as it served
the surrounding valley as a central place. Additionally, an already known
monumental grave inscription was documented
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