Understanding how data are generated is important for any archaeological research project: is what we see a ‘real’ pattern reflecting past reality, or is the picture distorted by more ‘modern’ processes? These are important questions with far-reaching consequences for the conclusions that we, as archaeologists, can draw. The EngLaId team, in particular our GIS expert Chris Green, has explored the implications of this issue on a national level on previous occasions, both in the context of PAS finds (https://englaid.wordpress.com/2014/03/17/pas-affordances/) and sites and monuments (https://englaid.wordpress.com/2014/08/19/affordances2/). This blog explores some additional considerations in understanding regional differences in the archaeological record between case study regions.
Although significant effort is made in by archaeological professionals in England to attain certain levels of nationwide standardisation, regional differences nevertheless exist. In his previous blog post on affordances relating to the survival and recognition of archaeological sites and monuments on a nationwide scale, Chris Green identified the following affordances: first, the opportunity (or not) to undertake archaeological excavation, and second, modern land use and obscurance (https://englaid.wordpress.com/2014/08/19/affordances2/). A further level of refinement one might add to this, and one determined to a large degree by the same factors that Chris flagged up, is the question what type of archaeological investigations take place in different regions.
To give a simple example: prehistoric field systems survive better in upland areas that have seen little arable exploitation. But what is more, prehistoric field systems are also more easily recognised through large-scale landscape or aerial/remote sensing surveys than through keyhole investigations such as watching briefs – more typical of built-up areas – which are more likely to identify individual ditch sections, requiring a further level of interpretation and extrapolation before these can be ‘glued’ together into more extensive landscapes.
The EngLaId project database currently contains more than 900,000 records, and it is both beyond our scope and outside of our remit to recreate such past landscapes; instead, we aim to base our research entirely on already existing digital data. (A very good discussion of this issue, written by my colleagues Anwen Cooper and Chris Green, has just been published in the Journal of Archaeological Method and Theory: http://link.springer.com/article/10.1007/s10816-015-9240-4). Nonetheless, a broad awareness of differences in investigation types between the different case study regions is important. For that reason, we carried out a comparison of archaeological investigation types across the country as a whole and in the various case study areas.
Two relevant datasets that record archaeological ‘events’ (rather than ‘monuments’) on a nationwide scale were identified, the AIP and the EI (http://archaeologydataservice.ac.uk/archives/view/304/). As the AIP was closed down not long after the EngLaId project started, and the EI is actively in the process of incorporating all AIP records, it was decided the EI was the most complete source (also see Evans 2013). Only records from 1990 onwards were incorporated, to reflect the situation since the implementation of PPG16.
As the EI incorporated a large variety of events, a simplified classification was devised into broad ‘types’ of events that were thought most likely to affect the nature of the archaeological record. These were: 1) intrusive (open area), incorporating both open area excavation and strip, map and sample investigations; 2) intrusive (keyhole), incorporating trial trenching, test pitting and watching briefs; 3) survey (geophysical/aerial/earthwork); 4) field walking/metal detecting; 5) other; whereby 1) and 3) were considered most likely to result in the identification of large-scale archaeological landscapes. Records not fitting any of these categories were deleted.
Simplification was automated, and therefore by definition broad-brush (for more information about the methodology, please contact Letty at firstname.lastname@example.org). (As a control to test this broad-brush methodology, a more detailed characterisation of AIP investigations in selected case study areas was carried out, using the same methodology; comparison with the broad-brush EI investigation types characterisation revealed slightly different patterns, but the overall picture between case study regions remained broadly the same.) The results are plotted in the two charts below.
EngLaId simplified investigation types: 1) intrusive (open area) – brown; 2) intrusive (keyhole) – pinkish brown; 3) survey (geophysical/aerial/earthwork) – yellow; 4) field walking/metal detecting – blue.
The implications of the results have not been fully thought through, but the resulting patterns will be taken into account in our assessments of the archaeological patterns that emerge from our analyses of the archaeological sites and monuments in our database. Some emerging patterns are immediately obvious, such as the much higher density of fieldwork of any kind in our two southeastern case study regions – the Lea Valley and Kent – especially when compared to Cornwall, Cumbria, Devon and North Northumberland. Also of interest is the lower occurrence of recorded metaldetecting/fieldwalking events in western and northern case study areas, such as Cornwall, Cumbria, Devon, the Marches and North Northumberland, areas with large swathes of land use types that are not conducive to successful metal-detecting and which are traditionally associated with low numbers of archaeological ‘finds’. Finally, North Northumberland, the Mendips/Somerset Levels, the Marches and the Isle of Wight have the largest relative percentages of non-intrusive surveys, and therefore may produce ‘good’ data for prehistoric field systems or extensive settlement complexes.
Any feedback at this stage is very welcome – please contact us if you have any comments or questions!
Cooper, A. and Green, C. 2015, ‘Embracing the Complexities of ‘Big Data’ in Archaeology: the Case of the English Landscape and Identities Project’, Journal of Archaeological Method and Theory 22 (1). DOI 10.1007/s10816-015-9240-4
Evans, T. 2013, ‘Holes in the archaeological record? A comparison of national event databases for the historic environment in England’, The Historic Environment: Policy & Practice 4: 19–34.