Photo Interpretation for Archaeologists by D.R. WILSON
This is an up-dated version of the Batsford 1982 publication (Wilson 1982) of what has become known as the air photo interpreters’ bible. In fact the book contains absolutely essential information for all archaeologists, be they students, professionals or interested amateurs. So often archaeology is seen to be synonymous with excavation and the text books focus on this activity; here is a source to redress the balance and show the potential of information derived from the air.
The twentieth century saw the development, rise and expansion of the subject of aerial survey, especially in obtaining photographs – a data collection episode – which has not finished. This book helps all of us to understand the impact of this work by focussing on the interpretation of the information visible on aerial photographs.
The book was published at an appropriate time; the expansion of aerial survey in Europe began with the end of the Cold War and there have been many training schools, (in Hungary 1996, Poland 1998, Italy in 2000 and 2003). Having Wilson’s expertise and knowledge so well illustrated has made the task of communicating the subject so much easier.
Chapters 2, 3, 4 and 5 provide the basic guidance for anyone wishing to develop their expertise in this subject. The inclusion of a chapter on non-archaeological features is crucial; so much of what is seen from the air is not of archaeological interest or even man-made in origin. Filtering this information out from an archaeological point of view is important but equally important is the understanding it provides for the geological history of the country.
It is interesting to compare the differences between the 1982 and the 2000 editions. The former is totally black and white, with very sharp contrasts in the images; the fashion at the time. With digital technology the images in the 2000 version are more subtle, with less contrast. This may not seem as appealing initially, but on close inspection there is more information visible than on the higher contrast images. The colour section is a real bonus, even if the colour matching is at times below its usual high standard (especially the false colour infra-red image).
Other differences are the new sections on the developments since 1982, not least the references to the National Mapping Programme (an English Heritage project to map all the archaeological sites visible on aerial photographs to improve our understanding of the historic environment). The final section on Transcription and Data retrieval is new and even in the short space of four years, there have been even more developments. This is perhaps the weakest section of the book, as the purpose of air photo interpretation is to communicate the information – and what better medium than through a series of maps? However, to have dwelt too long on mapping would have changed the emphasis of the book, and this second edition has stuck to the original principles of explaining the potential and pitfalls of air photo interpretation.
The geographical and chronological range of the book is very good from the UK perspective, with the exception of the archaeology of the twentieth century. This is a subject enjoying rapid growth which aerial photography and interpretation is making some significant contributions (see Cocroft & Thomas 2003). Even in the four years since its publication another up-date would not be out of place in another year or two.
There is a small point of terminology and the use of the term cropmarks. For simplicity’s sake I have preferred the use of the terms cropmarks, parchmarks, and soilmarks to be one word – as in earthworks. However Wilson uses the two word variant, with a hyphen as in crop-mark. If my memory serves me correctly it was David Wilson who explained his interpretation of the use of these terms; crop mark as two words unless used adjectivally when it was hyphenated as in ‘crop-mark photography’. Having followed this for a number of years and edited so many reports for consistency I decided that using these terms as one word was the most simple without losing any accuracy. Sadly this text has the hyphenated version throughout.
The author suggests four purposes for aerial photography: Illustration, Research, Excavation and fieldwork, and Conservation. Although the order of these should not be significant the use of ‘Illustration’ as the primary role is worthy of debate. One’s view will depend upon the type of job or the organisation you work for. My experience suggests that it is research that is the most important aspect of aerial survey, as it helps to develop Excavation and fieldwork projects as well as providing invaluable information for Conservation. This is not to denigrate, in any way, the use of aerial photographs for illustration – a picture can speak a thousand words – but for the subject to develop and grow its potential for research, as it is the most cost-effective and productive means of discovering new sites and monitoring existing sites, building and landscapes which form part of the historic environment.
A change which the author should have made was to move the section on modern military features (page 193) to Chapter 3 (as he hints himself) but he takes the view that archaeologists see these as ‘modern intrusions’; since 1982 I think this view has changed dramatically. In the new edition figure 112 (in the chapter on Non-archaeological features) still describes the 1939-1945 search-light battery as if it is not archaeology.
Although the book does not list the address of Cambridge University Committee of Aerial Photography (CUCAP), the organisation which created most of the images in the book, it is worth noting that CUCAP no longer exists but has been transformed into the Unit for Landscape Modelling (ULM). This is now part of the Department of Geography and maintains a flying capability, mainly for commercial surveys taking vertical images but also engaged in some Research and Development, especially in doing trials for Lidar (Holden, Horne & Bewley 2002). This technique, which has come to archaeologists attention since 2000, may have as much impact as aerial photographs did in the 1920s.
The good news is that aerial survey is still developing and expanding; the contribution of this book is that it forms the solid foundation for interpretation of remotely sensed images be they photographs, satellite images or those derived from new remote sensing techniques (Shell 2002).
Review Submitted: April 2004
The views expressed in this review are not
necessarily those of the Society or the Reviews Editor.
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