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Papers by machteld bats

Recent excavations in the harbour of Ghent revealed new evidence of Mesolithic occupation in the ... more Recent excavations in the harbour of Ghent revealed new evidence of Mesolithic occupation in the sandy lowlands of northern Belgium. The preliminary data suggests several small occupation areas inhabited during the Early and/ or Middle Mesolithic. Indications of older habitation during the Final Palaeolithic, probably dated at the transition of the Younger Dryas to the early Preboreal, have been found as well. The importance of both sets of material is, by the good preservation in situ, already apparent.

Samenvatting Bij opgravingen te Evergem -De Nest kwamen 14 vroeg/midden-mesolithische concentrati... more Samenvatting Bij opgravingen te Evergem -De Nest kwamen 14 vroeg/midden-mesolithische concentraties aan het licht waarvan er zeven werden gedateerd aan de hand van radiokoolstofdateringen verricht op verkoolde hazelnootschelpen. De resultaten van deze dateringen lijken er op te wijzen dat de locatie van de staalname een belangrijke rol speelt: vooral hazelnootfragmenten die niet geassocieerd waren met clusters van (zwaar) verbrand lithisch materiaal (i.e. potentiële haarden) leverden afwijkende dateringen op. In de toekomst lijkt het dan ook aangewezen om de selectie van 14 C-stalen pas te realiseren na ruimtelijke analyse dewelke nodig is om potentiële haarden te detecteren. Trefwoorden: Oost-Vlaanderen, Evergem -De Nest, mesolithicum, 14 C-staalnamestrategie, ruimtelijke analyse.

The presented research is part of a multi-disciplinary project, entitled "Prehistoric settlement ... more The presented research is part of a multi-disciplinary project, entitled "Prehistoric settlement and land-use systems in Sandy Flanders (NW Belgium): a diachronic and geoarchaeological approach".

Journal of Archaeological Science, 2013

ABSTRACT This paper reports the results of a study into the effectiveness of core sampling for di... more ABSTRACT This paper reports the results of a study into the effectiveness of core sampling for discovering Palaeolithic and Mesolithic hunter-gatherer sites in the Netherlands and northwestern Belgium. Earlier work established optimal sampling strategies for use in archaeological heritage management survey in the Netherlands. However, the statistical model used for this was based on a limited amount of data on the distribution of lithic artefacts in Palaeolithic and Mesolithic sites. For the current study we have analyzed the distribution of artefacts in a selected number of excavated sites, and estimated discovery probabilities of these sites through simulation. The simulation results indicate that discovery probabilities are lower than expected due to the effect of clustering of finds. Furthermore, the density of flints in Palaeolithic and Mesolithic sites is generally lower than the estimates that were used for setting up the optimal sampling strategies, and a substantial number of sites is very small. This means that, in order to discover Palaeolithic and Mesolithic sites with sufficient reliability, we will have to apply more intensive survey strategies than have been recommended up to now.

ABSTRACT Reconstruction of past topography is an essential step towards the understanding of past... more ABSTRACT Reconstruction of past topography is an essential step towards the understanding of past landscapes in terms of biophysical patterns and processes and man–landscape interactions by archaeologists, geomorphologists, geologists and soil scientists. Landscape reconstructions can be based on process knowledge, on data, or on a combination of both. In this case study we focus on a data-based approach, where knowledge on the geological history is used to interpret and exploit legacy data. As part of a landscape reconstruction of a large area of 584 km2 a map of the elevation near 10 000 BC was produced. Starting from a present-day grid digital elevation model (GDEM) that was filtered for human influences, we identified the thickness of accumulated sediments over the Holocene, mapped these and corrected the GDEM. To map the thickness of Holocene sediments we used 72 (OSL and 14C) dated sediment samples, 731 recent profile descriptions and 3288 legacy profile descriptions. Protocols were formulated based on literature and local correlative studies to convert the legacy profile descriptions into estimates of the thickness of Holocene sediments, with an estimate of the precision. The method of Kriging with uncertain data was applied to obtain a map. Validation at 200 independent test locations with certain data showed a mean error of –6 cm and a standard deviation or error of 16 cm, which was in accordance with the estimated precision of 16 cm. The resulting map indicated zones with marked change that could be studied in more detail. Future reconstructions could employ both process knowledge and data by combining landscape genesis models with legacy data to mapmodel errors and thus increase the quality of the reconstruction. Copyright © 2013 JohnWiley & Sons, Ltd.

…, Jan 1, 2010

A major problem in palaeolandscape reconstruction is that basic data useable for inference are sc... more A major problem in palaeolandscape reconstruction is that basic data useable for inference are scattered in both the temporal and spatial sense. To improve the understanding of occupational patterns by means of landscape reconstruction methods, we propose the application of different process-models in the soil-water-landscape reconstruction in an interdisciplinary approach. These process-models include a digital elevation model, a hydrological model, a pedogenesis model and a land evaluation model. Due to the multiple disciplines involved, no single model can be used but a model framework is defined in which the various discipline-specific models are integrated. In this paper, each of these models is explained and illustrated for a case-study in Flanders (Belgium) and difficulties occurring when integrating the different models, e.g. grain, extent, coverage, are discussed. . In situations where data collection possibilities are limited because of the available time and funds, dealing with issues (iii) to (v) of the above list appears to offer the best perspective to improve understanding of occupational patterns. In this paper we focus on landscape reconstruction methods and the derivation of relevant landscape attributes to tackle (iii) and (iv). Although the post-processual approach (v) is not discussed here, it should not be excluded, however not without bearing in mind the recent critiques formulated by . These landscape reconstruction methods will be applied to the area of Sandy Flanders (NW Belgium). This area is situated at the southern limit of the lowland cover sand region of the NW European plain

Geomorphology, Mar 25, 2011

Field methods to map and reconstruct the morphology of buried river systems are highly dependent ... more Field methods to map and reconstruct the morphology of buried river systems are highly dependent on spatial interpolation. Conventional methods, such as standard borehole survey, allow a detailed vertical reconstruction of the shallow subsurface but leave lateral connections between sample locations open to interpretation. Geophysical survey techniques have recently introduced more detail. Mobile electromagnetic induction (EMI) survey combines high density sampling with full lateral coverage but fails to produce detailed information about vertical facies changes. Recently, multicoil EMI survey added vertical discrimination potential to this lateral continuity. In this study, we present an integrated approach for reconstructing the morphology of a known palaeochannel segment by modelling the depth to the sandy substrate. In addition, a calibration method based on a limited number of auger data is proposed. In a first phase, the modelling procedure was evaluated along two transects on a test site, showing palaeochannel depths ranging from 1 to > 4 m beneath the surface. In a second phase, the morphology of the entire site was reconstructed. These three resulting depth models were then compared with auger observations and electrical resistivity tomography (ERT) data. The high correlation coefficients (> 0.9) between observed and modelled depths showed that even in complex pedological environments, palaeochannel morphology could be predicted precisely using multicoil EMI data. Therefore, we concluded that a multicoil EMI survey proves to be an efficient and reliable solution for mapping and reconstructing the morphology of the shallow subsurface.

NOTAE …, Jan 1, 2009

The prehistoric settlement and land-use systems in the area of Sandy Flanders are being studied i... more The prehistoric settlement and land-use systems in the area of Sandy Flanders are being studied in a multidisciplinary research project. In this article, some preliminary results of recent fieldwork along a major Late Glacial palaeolake, called the Depression of the Moervaart, is described, including the excavation of a trench in the deepest part of the fossil lake, manual and mechanical coring and sampling and geophysical survey.

Journal of Archaeological Science

Understanding palaeotopographical variability forms the basis for understanding prehistoric socie... more Understanding palaeotopographical variability forms the basis for understanding prehistoric societies. Alluvial and lacustrine environments, in particular, are key areas with both a high archaeological and palaeoecological potential. However, the often deep stratification of these sites, the high water table and the complex sedimentological variations can hamper a detailed reconstruction of the spatial relationship between prehistoric settlement and their environment. Combining different remote and proximal sensing techniques and coring data, can offer detailed insight into such landscapes. More specifically, the integration of mobile geophysical methods allows the collection of unprecedented continuous information on large-scale palaeolandscape variability. In this study we present a combined approach in order to map and model prehistoric landscapes and river systems in and around a Late Glacial palaeolake in north-western Belgium. Based on filtered and unfiltered digital elevation models, a survey area of 60 ha was selected, in which detailed mobile multi-receiver electromagnetic induction survey was conducted. The results allowed for the delineation of palaeochannels in the area and enabled modelling the depth of these features in the survey area, providing insight into their flow characteristics. 14C sampling enabled the dating of the evolving river system to the transition between the Late Glacial and the Early Holocene. Through additional coring, this river system could be traced further through the palaeolake area. Based on these results a detailed reconstruction was made of the palaeotopography that harboured the Final Palaeolithic and Early Mesolithic occupation of the study site.

Geomorphology

Topographic position index (TPI) is an algorithm increasingly used to measure topographic slope p... more Topographic position index (TPI) is an algorithm increasingly used to measure topographic slope positions and to automate landform classifications. We applied TPI to a geoarchaeological research project in northwestern Belgium but its use led to erroneous landform classifications in this heterogeneous landscape. We asked whether deviation from mean elevation (DEV) was a better method for landform classification than TPI. We found that it enabled more accurate geomorphological assessment when using northwestern Belgium as a case study.

Archeologische verkenning, kartering en waardering van een uitgestrekt afgedekt prehistorisch lan... more Archeologische verkenning, kartering en waardering van een uitgestrekt afgedekt prehistorisch landschap te Verrebroek

Based on radiocarbon and optically stimulated luminescence (OSL) results obtained in the last 5 y... more Based on radiocarbon and optically stimulated luminescence (OSL) results obtained in the last 5 yr, this paper discusses the absolute chronology of the formation of one of the largest sand dunes within NW Belgium, the Great Ridge of Maldegem-Stekene. Multiproxy analysis of 6 sedimentary sequences points to a complex formation history covering the entire Late Glacial. Dry phases, characterized by eolian deflation and sedimentation, alternated with wet phases in which numerous mostly shallow dune slacks were filled with freshwater. The latter reached their highest water level during the first half of the Allerød, attracting both animals (e.g. European elk) and humans (Federmesser hunter-gatherers). Near the end of the Allerød, all dune slacks finally disappeared as they were filled in with windblown sand ("coversand"), likely forcing prehistoric hunter-gatherers to leave the area.

The area of Sandy Flanders, situated between the North Sea coast and the lower course of the Sche... more The area of Sandy Flanders, situated between the North Sea coast and the lower course of the Scheldt River in NW Belgium, is a relatively flat and low-lying area situated at the southern limit of the lowland cover sand region of the NW European plain. During the Late Pleniglacial and the Late Glacial, numerous, generally small but elongated sand dunes,

Journal of Archaeological Science, 2013

…, Jan 1, 2010

Geomorphology, Mar 25, 2011

NOTAE …, Jan 1, 2009

Journal of Archaeological Science

Geomorphology

Archaeological practice within the European context of heritage management is facing huge challen... more Archaeological practice within the European context of heritage management is facing huge challenges in ways of recording and reproduction of ex-situ preserved sites. As a consequence of the Valletta-treaty, numbers of archived images and drawings of excavated structures as prime sources of past human activity, are exponentially growing. Contrarily to portable remains however, their future study and revision is biased by the two-dimensional character of the recorded data, rendering difficult their future reconstruction for new study or public dissemination. A more realistic three-dimensional (3D) way of recording and archiving should be pursued. In this paper the possibilities for 3D registration of archaeological features are examined in a computer vision-based approach using the PhotoScan software package (Agisoft LCC). It proved to be a scientific and cost-effective improvement compared to traditional documentation methods. Advantages can be found in the high accuracy and straightforwardness of the methodology. The extraction of an orthophoto or a Digital Terrain Model from the 3D model makes it feasible to integrate detailed and accurate information into the digital archaeological excavation plan. The visual character of 3D surface modeling offers enhanced output-possibilities allowing a better documentation of in-situ structures for future research and a higher public participation and awareness for the archaeological heritage."

Full-coverage maps for several specific soil characteristics were produced at particular time-int... more Full-coverage maps for several specific soil characteristics were produced at particular time-intervals over a time span of 12,716 years for a 584 km2 large study area located in Belgium. The pedogenetic process model SoilGen2 was used to reconstruct the evolution of several soil variables at specific depths in the soil profile at various point locations (96 in total). The time span covered by the simulations encompassed the final part of the Younger Dryas and the Holocene up till the present. Time series on climate, organisms and groundwater table were reconstructed and supplied to the model as boundary conditions. Model quality optimization was performed by calibrating the solubility constant of calcite by a comparison of the simulated time necessary for decarbonization with literature values and evaluating the calibrated value over a wide range of precipitation surpluses representative for the regarded time period. The simulated final state was evaluated against measurements collected in a database representing the historic state of the soil at 1950. The simulated specific soil characteristics at the point locations were then used to produce full-coverage maps at the particular time-intervals by regression kriging. Such maps are believed to provide useful information for geoarcheological studies and archeological land evaluations.

Intensive archaeological investigations in Sandy Flanders (Belgium) revealed sites dating from th... more Intensive archaeological investigations in Sandy Flanders (Belgium) revealed sites dating from the Final Paleolithic to the Neolithic, showing a discontinuous spatial and temporal distribution. To improve the understanding of these occupational patterns, a paleolandscape reconstruction is proposed. A major problem in paleolandscape reconstruction is that basic data are scattered in the temporal and spatial sense. Therefore, we propose an interdisciplinary approach to the application of different process models to soil–water–landscape reconstruction. The process models used include a digital elevation model, a hydrological, a pedogenetic, and a land-evaluation model. The result is a modeling framework in which these discipline-specific models, which provide input to each other, are integrated. Outcomes of the different models are still preliminary, because of the ongoing calibration and application of the models. The paper focuses on the methodological aspects of constructing the modeling framework and the questions one needs to answer in advance to facilitate the integration of the model results. Furthermore, errors within each individual model need to be accounted for and ideally are propagated into the next modeling step. Because of model complexity and runtime this is presently unfeasible. Alternatively, we propose to repeat the last step of the model framework (the land-evaluation procedure) for perturbations of the parameters reflecting the estimated model errors. We emphasize the difficulties occurring when integrating these different models, such as those relating to scale differences and error propagation. © 2010 Wiley Periodicals, Inc.

Archaeological distribution patterns are often biased by cultural and environmental processes. Th... more Archaeological distribution patterns are often biased by cultural and environmental processes. These processes influence the preservation of archaeological phenomena in the landscape. Their impact starts when the site and structures are left or abandoned or objects are deposited or disposed of. However, in archaeological landscape research, these processes are seldom incorporated. Therefore, the potential impact of both environmental and cultural processes on the preservation of archaeological phenomena needs to be understood and their influence on the observed archaeological site distribution patterns needs to be measured. Furthermore the history, intensity and methodology of the archaeological research in the region influence the known archaeological distribution pattern and therefore an understanding of the archaeological practice in the region is necessary in the study of the past landscapes of that region. This paper presents a case study on the distribution pattern of Bronze Age barrows in the highly urbanised landscape of north-western Belgium. By integrating natural, cultural and archaeological processes in archaeological landscape research, the completeness and reliability of the archaeological dataset can be estimated. Efforts to estimate completeness and reliability of any dataset should be an integral part of every archaeological landscape research project, especially as biases or hiatuses in datasets can lead to serious misinterpretations or circular reasoning. Furthermore, knowledge of the biography of landscapes is not only important in the study and understanding of past archaeological landscapes, but also in the preservation of these landscapes and our ability to incorporate hidden past landscapes into the actual sustainable management of its cultural–historical heritage.

Expert Systems with …, 2011

This paper discusses the generation of a high precision DEM (Digital Elevation Model) based on hi... more This paper discusses the generation of a high precision DEM (Digital Elevation Model) based on high density airborne LiDAR (Light Detection and Ranging) data for an interdisciplinary landscape archaeological study concerning the settlement history and environment in Sandy Flanders, a region to the north of Ghent (Belgium). The objective was to create a detailed topographical surface free of artificial features and topographical artefacts, in the form of a DEM, visualizing the natural and current topography through the implementation of true ground points only. The semi-automatical removal of these features and artefacts was based on topographical vector data, visual interpretations and slope analysis. Ultimately two DEM’s were constructed (1) a TIN (Triangulated Irregular Network) model, whereby the inherent large file format restricts the usability to large scale and (2) a grid model which can be used for small-, medium- and large-scale applications. Both datasets were used as an image that is interpreted using ancillary data from historical sources. Its usefulness is illustrated in a case of field pattern and microfield topography. Starting from this DEM, the approach of this landscape historical study is mainly retrogressive, i.e. starting from the landscape structures and elements that are still present in the contemporary landscape and moving into the past.

The complex debate on prehistoric settlement decisions is no longer tackled from a purely archaeo... more The complex debate on prehistoric settlement decisions is no longer tackled from a purely archaeological perspective but from a more landscape-oriented manner combined with archaeological evidence. Therefore, reconstruction of several components of the former landscape is needed. Here, we focus on the reconstruction of the groundwater table based on modeling. The depth of the phreatic aquifer influences, for example, soil formation processes and vegetation type. Furthermore, it directly influences settlement by the wetness of a site. Palaeogroundwater modeling of the phreatic aquifer was carried out to produce a series of full-coverage maps of the mean water table depth between 12.7 ka and the middle of the 20th century (1953) in Flanders, Belgium. The research focuses on the reconstruction of the input data and boundary conditions of the model and the model calibration. The model was calibrated for the 1924–1953 time period using drainage class maps. Archaeological site data and podzol occurrence data act as proxies for local drainage conditions over periods in the past. They also served as a control on the simulated phreatic palaeogroundwater levels. Model quality testing on an independent validation data set showed that the model predicts phreatic water table levels at the time of soil mapping well (mean error of 1.8 cm; root mean square error of 65.6 cm). Simulated hydrological conditions were in agreement with the occurrence of archaeological sites of Mesolithic to Roman age at 96% of the validation locations, and also with the occurrence of well-drained podzols at 97% of the validation locations.

Local topography is an important parameter determining the erection of a certain type of site on ... more Local topography is an important parameter determining the erection of a certain type of site on a certain location in the landscape. Despite the importance of topography in archaeological landscape research, the role of local topography has remained rather unexplored compared to other specific topographic parameters such as slope, aspect, curvature or visibility. Therefore, three methods to assess the relative topographic position of sites are applied and discussed here. The Bronze Age barrow dataset of northwest Belgium acts as the subject for this methodological case study. First, elevation percentile calculates the area that is lower than the central point within a predetermined neighborhood. Secondly, difference from mean elevation measures the relative topographic position of the central point as the difference between the elevation of this central point and the mean elevation within a predetermined neighborhood. And finally, deviation from mean elevation calculates the relative topographic position of the central point as the difference from mean elevation divided by the standard deviation of elevation, within a predetermined neighborhood. These three methods, each with their advantages and disadvantages, prove to be an added value for archaeological landscape research.

The area of the Late Glacial Moervaart lake is currently the subject of a multi-disciplinary stud... more The area of the Late Glacial Moervaart lake is currently the subject of a multi-disciplinary study. This article presents some preliminary research results from GIS-based historic-geographical research, auger survey, geophysical survey and palaeoecological analyses.