Durham at War Lidar Landscapes Project Report
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Durham at War Lidar Landscapes Project Report December 2017 Front cover. Lidar image of the site of Deerbolt Training Camp, now occupied by Deerbolt Prison, just west of Barnard Castle (Area 1 in this survey). Little if any sign of the First World War camp survives above ground, though earthworks of a contemporary rifle range do survive, and have been recorded on lidar, on the south bank of the Deepdale Beck, to the west. This image demonstrates something of the time-depth of the historic landscape here, with ridge- and-furrow field-systems, some of which date from medieval times, clearly visible. Durham at War Lidar Landscapes Project Report Contents Acknowledgements 1. Introduction 2. Methodology 3. Results 4. Discussion Appendix References 1 Durham at War Lidar Landscapes Project Report Acknowledgements First and foremost, thanks are due to the volunteers who undertook the survey work: D Armstrong, Chris and Audrey Battersby, Barbara Chipchase, Paul Cordes, David Donkin, John Goldsborough, and J P Merrington. This report has been written by Project Consultant, Paul Frodsham (ORACLE Heritage Services). The Project Management Team for Durham County Council was Victoria Oxberry (Durham at War Project Officer), Liz Bregazzi (County Archivist) and Nick Boldrini (County Durham Historic Environment Record Officer). 2 Durham at War Lidar Landscapes Project Report 1. Introduction This project was completed as part of Durham County Council’s HLF-funded Durham at War project (www.durhamatwar.org.uk), which works with local volunteers to commemorate the centenary of the First World War. It was designed to serve two purposes. First, to enable volunteers with an interest in landscape archaeology to familiarise themselves with lidar and its use in archaeological survey. Second, to examine a series of areas where it was known or suspected that features relating to the First World War survived, and to carefully study the lidar in order to record any remnants of these sites, and any other features of potential archaeological importance, that survive above ground. The project was designed by Project Consultant Paul Frodsham (ORACLE Heritage Services) working in close consultation with a Project Management Team consisting of Victoria Oxberry (Durham at War Project Officer), Liz Bregazzi (County Archivist) and Nick Boldrini (County Durham Historic Environment Record Officer). Working in partnership with Professor Stewart Ainsworth of Chester University (an expert on lidar survey, best known for his role as landscape archaeologist with TV’s Time Team), the Project Consultant has recently overseen the design and delivery of large-scale lidar landscape surveys of Upper Teesdale, Weardale and the Upper Derwent Valley in County Durham, along with Hexhamshire and the Allen Valleys in south-west Northumberland (Ainsworth 2015; Frodsham 2017). These projects, managed by the North Pennines AONB Partnership, involved the participation of some 200 volunteers, and resulted in the discovery of several hundred previously unknown archaeological sites within the often complex historic landscapes of the North Pennines. This First World War project differs from these projects in that it was not aimed at blanket coverage of large landscapes, but at survey of smaller areas with specific targets in mind. The appropriateness of the methodology employed in this project, which is based on that of the North Pennines surveys, will be considered in the Discussion towards to the end of this report. ALSM (or ‘airborne laser swath mapping’) data, more commonly referred to as ‘lidar’ (originally a portmanteau of ‘light’ and ‘radar’) is a relatively new information source being used by archaeologists to discover, interpret and record archaeological sites (Crutchley & Crow 2009). The data for this project, provided free of charge by the Environment Agency, was gathered using sensors mounted on an aircraft. This data can be processed to make a computerised 3D model of the ground and all the features on it at the time of capture and can be precisely referenced to the OS National Grid, in effect producing what is termed a ‘lidarmap’. For this project the 3D data collected has been processed to produce 2D ‘hillshaded’ images which replicate the 3D data; this technique emphasises features on the ground, including surviving earthworks of archaeological sites and allows the data to be used as image files which can be viewed on home computers. Although the images look like aerial photographs they are not – they are computer models of everything on 3 Durham at War Lidar Landscapes Project Report the ground that the laser pulses hit. For the lidar to be used in this project the 3D coordinates of approximately 5 million points were collected in each km square. The degree of detail revealed about the historic landscape by this technique can be staggering, often far more informative than aerial photography, but it still needs human eyes to spot it and interpret it. This is the role of the project volunteers. Only two skills were required to make a contribution to the project – interest and inquisitiveness (coupled with access to a computer). Involvement in the project not only allowed volunteers to develop new archaeological and recording skills, but also provided them with opportunities to understand more about the development of the often complex archaeological landscapes of parts of County Durham. As noted above, the project methodology was developed during recent volunteer projects in the North Pennines, derived ultimately from that used in the Miner-Farmer project on Alston Moor undertaken by English Heritage (Oakey et al 2012). It was designed to enable volunteers with little or no archaeological background to make meaningful contributions to the recording and understanding of the historic landscape, while providing the tantalising prospect of significant, even spectacular, new discoveries. The recording method used software that is either commonly available on most home computers or is freely available on the internet, enabling contributors to work at home at a pace that suits their own circumstances. The project provided training for volunteers in the process of interpretation and recording using digital lidarmap images on home computers with commonly available programs such as Microsoft Paint and Word. The project was designed to be as paperless as possible and all file exchanges were by email. After participation in this project, the volunteers now have the skills necessary to continue to explore the use of lidar as an aid to landscape analysis, interpretation and recording. The project archive will be incorporated into the County Durham (in a couple of cases Tyne and Wear) Historic Environment Record (HER). Here, it will be available for anyone planning new research projects, while also potentially contributing to future landscape management. In some cases it has not been possible to state the form or age of a site with any degree of certainty. Volunteers were encouraged to try and identify all sites by reference to a standard ‘site type’ list; in some cases such identifications might be certain, while in others they may be little more than informed guesses. In all cases, sites have been recorded in outline, enabling closer analysis later where appropriate. Many different types of site were discussed at the project workshops, helping volunteers to improve their general knowledge of the types of site that survive throughout County Durham, in addition to sites relating directly to the First World War. 4 Durham at War Lidar Landscapes Project Report 2. Methodology The basic methodology is based on that developed for recent lidar surveys of large landscape areas undertaken by teams of volunteers in the North Pennines (Ainsworth 2015; Frodsham 2017). This project is different in that it covers several small areas rather than a large continuous landscape area. However, the basic approach, enabling volunteers to undertake useful survey work with only minimal initial training, was considered appropriate. 2.1 Survey areas Ten separate survey areas were chosen by the Project Management Team eight in County Durham and two in Tyne and Wear. These vary in size from a single km sq to 5 km sqs. Each was chosen because of the known or suspected presence of features relating to the First World War, such as training camps, PoW camps or training trenches. There were several other potential sites which unfortunately had no Environment Agency lidar coverage, so could not be featured in the project. The ten areas are: 1. West of Barnard Castle. 2 sq kms. 2. Weardale, south of Wolsingham. 5 sq kms. 3. Weardale, Old Park / Heights Quarry. 1 sq km. 4. Weardale, East of Stanhope. 1 sq km. 5. Cocken Hall. 4 sq kms. 6. South Shields. 3 sq kms. (Tyne & Wear). 7. Whitburn. 4 sq kms. (Tyne & Wear). 8. Easington Colliery. 2 sq kms. 9. West of Peterlee. 1 sq km. 10.East of Peterlee. 1 sq km. 2.2 Lidar processing Processed lidar data for the ten project areas was commissioned from an appropriately experienced consultant. The background to the processing methodology is discussed at some length in the recent Allen Valleys and Hexhamshire Lidar Landscapes project report (Ainsworth 2016) so will not be repeated here. In short, the data was processed to produce Digital Surface Model (DSM – showing all surfaces including trees, buildings, walls etc) and Digital Terrain Model (DTM – with above-ground features such as trees, buildings walls etc removed) tiles for each km sq within the project area. The lidar was processed using Principal Components Analysis (PCA) tools to produce 8-direction hillshade models as single greyscale images that could be easily circulated to volunteers as jpegs. These images provided the basis on which the volunteers undertook their survey work. 2.3 Volunteer training and guidance Effective volunteer training was an essential element of the project. An introduction to lidar and its use in archaeological survey, an outline of the project and its methodology, and practical training exercises were provided at 5 Durham at War Lidar Landscapes Project Report an initial ‘start-up’ workshop at which there was ample opportunity for people to ask questions.