Geophysical-assisted landscape archaeology of the the Vallum of Hadrian’s Wall (North England)

Overview

Non-invasive geological and geophysical investigations are conducted in areas of archaeological interest to (1) determine how parts of the soil were eroded/deposited in recent history (2) reconstruct the ancient landscape and how people interacted with it in the past (3) determine which soils are more likely to preserve artefacts of a given age and (4) plan further surveys in target areas. One specific tool used to assist in such deposit modelling is electrical resistivity tomography (ERT).
In this project the student will conduct a 3D ERT survey of portions of the Vallum associated with Hadrian’s Wall (North England). The Vallum is a large, linear earthwork, around 36 m wide, which was comprised of a ditch flanked by two “mounds” (linear earthen banks) set back around 9 m from the edges of the ditch. It was an important part of the frontier defences, and, according to one current interpretation, it was designed to enforce a no-access frontier zone.
The data collected will be used to produce tomographic images of the underground resistivity. These images can be interpreted in terms of the structure and nature of the underlying soil, rocks and geology. This will allow the student to reconstruct the original topography, geology, and environment (e.g. rivers, wetlands) encountered by the Romans, and infer how they used it or adapted to it.

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Image Captions

Down Hill, Halton. A site where the Vallum profile is visible (hill top) in the landscape topography. Grazing sheep are included for approximate scale. Courtesy of Rob Collins.

Methodology

Use of TIGRE unit with 64 electrodes for the acquisition of geophysical data (electrical resistivity). Python GIMLI and BERT software libraries for tomography imaging and inversion of the data will produce 3D resistivity models and tomographic images.
The resistivity model will be interpreted in terms of geology, geomorphology and recent erosion / deposit history. The findings will be put in the context of the historical use of the land, geology and landscape, with possible inferences on the Roman monuments and their use. The results of the PhD investigation will assist with the planning of future studies and development of the target area of archaeological and historical interest.

Project Timeline

Year 1

The student will conduct a literature review of (1) the archaeologic regional aspects and hypotheses, (2) the recent geomorphological evolution (3) the bedrock and geological structure (4) the geophysical method and how it is used to interpret the underground structure and composition. Recent examples of ERT-assisted deposit modelling in archaeological target areas will be studied.
Specific target areas will be identified by the student in collaboration with Northumberland National Park and the supervisors. Preliminary 2D acquisition surveys will be conducted to help in the selection of the areas for detailed analysis.

Year 2

High-resolution 3D surveys of the designed target areas will be conducted. This will be done in a series of trips to the Vallum, which is within a little more than one hour from Durham by car. Processing and modelling of the data will be performed using 3D inversion codes (pygimli, python).
The results will be interpreted, in light of regional geology and historical information. Inferences will be made on the historic geomorphology, how it influenced the Roman use of the landscape, and how it was modified by them.

Year 3

Most of the the final year will be dedicated to organise and classify the acquired material, and start working on the dissemination of the findings. This includes presentation of the results at conferences and the preparation of drafts for publications to submit to journals or publish in book chapters and collections. The student will meet with possible stakeholders (Northumberland National Park, Historical England, National Trust) to illustrate the results and to help design further steps in the development/conservation of the target area. Eventual short additional trips to the field would be conducted between y2 and y3, if it the findings reveal some particular areas of interest where a detailed, high resolution survey within a smaller area may be of support. The writing of archaeological thesis typically takes up to one full year, as a consequence sufficient time in the third year will be made for adequate manuscript writing.

Year 3.5

The additional six months will be mostly dedicated to the completion of the PhD writing and the dissemination of the material, including submission of publications.

Training
& Skills

The student will receive training in the following areas: Geophysical tomography, inverse problems, python programming. The student will acquire advance knowledge of regional geology and geomorphology, historical and archaeological context, and methods used to interpret and acquire data for archaeological studies. He/she will develop skills in interpretation of soil and geological 3D structures, and how to relate them with the historical background and human archaeological artefacts. He/she will acquire experience in interacting with stakeholders as trusts, land cooperatives, and other non-profit cultural institutions and organisations. Practical experience will also be acquired regarding the logistics of fieldwork surveys.

References & further reading
  • Deposit Modelling and Archaeology. Edited by C. Carey, A.J. Howard, D. Knight,
    J. Corcoran and J. Heathcote. ISBN 978-1-5272-2244-1. Short Run Press Ltd, Exeter, Devon, 2018. https://www.brighton.ac.uk/_pdf/research/set-groups/deposit-modelling-and-archaeology-volume.pdf
  • Using geoarchaeological deposit modelling as a framework for archaeological evaluation and mitigation in alluvial environments C. Carey, A.J. Howard, R. Jackson, A. Brown. Journal of Archaeological Science: Reports 11, pp 658-673, 2017.
  • Joint probabilistic inversion of DC resistivity and seismic refraction data applied to bedrock/regolith interface delineation. G. de Pasquale, N. Linde , A. Greenwood. Journal of Applied Geophysics, 170, 103839, 2019. DOI:10.1016/j.jappgeo.2019.103839.
  • Data acquisition, processing and filtering for reliable 3D resistivity and time‐domain induced polarisation tomography in an urban area: field example of Vinsta, Stockholm. M.Rossi, T. Dahlin, P.‐I. Olsson, T. Günther. Near Surface Geophysics, 16:23, pp. 220–229, 2018. DOI:10.3997/1873-0604.2018014
  • Breeze, DJ 2015. The Vallum of Hadrian’s Wall, Archaeologia Aeliana, 5th series, 44, 1-29.
  • Wilmott, T. and Bennett, J. 2000. The linear elements of the Hadrian’s Wall complex: four investigations 1983-200, in T. Wilmott, Hadrian’s Wall: Archaeological Research by English Heritage 1976-2000, London: English Heritage
Further Information

Please feel free to contact stefan.nielsen@durham.ac.uk for any question related to the application or the project.

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