Magnetic prospecting of burial grounds is still a great challenge in the field of archaeological geophysics. Some graves appear as positive anomalies, whereas others do not generate any traces or even show up by negative anomalies. This study involves ground magnetic survey, rock magnetic and magnetic mineralogy examinations of soils to determine factors responsible for the formation of magnetic anomalies on Late Roman time burial grounds of Chernyakhiv–Sântana de Mureş archaeological culture located in the forest‐steppe of Ukraine. We surveyed these sites by a total magnetic field caesium magnetometer in order to target the archaeological excavations. We sampled infill from graves excavated under positive anomalies and profiles of background soils to analyse the enhancement of induced and remanent magnetization. In the laboratory, we examined magnetic mineralogy and measured various magnetic parameters and ratios characterizing concentration and granulometry of ferrimagnetic phase of soils. For further explanations of the magnetic anomalies, we created 3D synthetic magnetic models of the studied objects and compared the calculated total field anomalies with field measurements by their intensity and size. Here, we show how positive magnetic anomalies of destroyed burials are generated when a destruction pit remains open and later topsoil material gradually refilled it with aid of precipitation water. In this case, the infill layers acquire detrital remanence of the same intensity as the topsoil. Such burials are the best targets for magnetic survey. However, archaeological excavations revealed both intact and destroyed inhumations that caused no magnetic disturbance. Obviously, they were refilled immediately after digging/destruction, so that natural remanence of the infill remains mechanically destroyed. The study of this specific category of archaeological monuments brought us closer in the understanding the formation of magnetic anomalies in soil‐filled features and showed the potential and limitations of magnetic prospection.
– New approach to mineral-magnetic characterization. – Evaluation of factors influencing geophysical results. – Origin of a fringe without magnetic contrast explained by waterlogging.
For the interpretation of archaeological geophysical data as archaeological features, it is essential that the recorded anomalies can be clearly delineated and analyzed, and therefore, care has been taken to obtain the best possible data. However, as with all measurements, data are degraded by unwanted components, or noise. This review clarifies the terminology, discusses the four major sources of noise (instrument, use of instrument, external, soil), and demonstrates how it can be characterized using geostatistical and wavenumber methods. It is important to recognize that even with improved instruments, some noise sources, like soil noise, may persist and that degraded data may be the result of unexpected sources, for example, global positioning system synchronization problems. Suggestions for the evaluation and recording of noise levels are provided to allow estimation of the limit of detection for archaeological geophysical anomalies.
Within and beyond development-led archaeological frameworks, strategizing archaeological prospection approaches that incorporate geophysical methods remains a daunting task for many archaeologists and managing agencies. While national and international guidelines provide useful support, decisions on a site-specific level often remain difficult to make, particularly in regions with complex and heterogeneous geologies. Although data such as soil and geological maps, and general information about land-use and the archaeology of studied areas help more robust decision-making, the leap to assessing geophysical discrimination potential remains large, particularly when only so-called ‘negative’ features are targeted (e.g. ditches or pits). To provide a more robust framework, we conceptualized a practical approach that starts from the current implementation of Malta-archaeology. As part of a collaboration between the universities of Ghent (BE) and Leiden (NL) and two commercial archaeological units: Archol (NL) and GATE Archaeology (BE), an in-situ geophysical measurement programme has been set up. During trial trenching and test pitting campaigns, measurements of geophysical properties are conducted on excavated profiles. Hereby, the electrical conductivity, dielectric permittivity, and magnetic susceptibility are recorded on characteristic (‘negative’) archaeological features in these profiles, along with recording these properties on governing natural profiles within the studied area. Our aim is to expand this approach to regional and national scales, with reference frameworks for understanding geophysical soil properties of governing geologies and frequently occurring archaeological features. Alongside the field methodology, here we present the first results of this approach.
This poster gives an overview of the aims and structure of the SAGA cost action. It details the key aims of the working groups, along with the structure of SAGA and means to fulfill the key deliverables.
Archaeological sites can be discovered and recorded in a high-resolution and non-invasive manner using geophysical methods. These measure the spatial variation of a range of physical properties of the soil which may be representative proxies of the subsurface archaeology. Less-invasive and cost-effective field procedures have become top-priority to mitigate the destructive effects on our cultural heritage from intensified land use, climate change and the current conflict panorama. At a time when many organisations are investing in advanced geophysical equipment, a major problem is that our ability to fully interpret the information available from geophysical datasets is still very limited. This deficiency prevents geophysical survey moving beyond basic prospection and becoming a significant tool for answering nuanced questions about archaeology and their host landscapes. This limitation arises from an incomplete understanding of the relationship between soil properties and geophysical measurements. Bridging this gap requires multi-disciplinary teams, testing novel methods, plus scholarly discussion to collate the outcomes of projects on this topic. Overcoming these challenges is a prerequisite for maximising the costeffectiveness of geophysical methods, realising the expected benefits of technological investment and allowing broader utility of geophysical methods in the cultural heritage sector. SAGA will build an international network of geophysicists, archaeologists, soil scientists and other experts to develop our capability to interpret geophysical data and promote research collaborations. Our vision is that after four years, SAGA will have created an environment within which emerging field procedures, enhanced data interpretation and a broader understanding of integrated geophysical methods can flourish.
Contribution towards the workshop 'How to overcome the fragmentation in Cultural Heritage research and funding in the context of Horizon Europe?' organised by COST Association