Thứ Hai, 21 tháng 9, 2009

Aerial archaeology method in the face of theory (Phần II)

Włodzimierz Rączkowski
Archeologia lotnicza - metoda wobec teorii
Wydawnictwo Naukowe UAM, Poznań 2002
ISBN: 83-232-1194-9

Classification is a ubiquitous practice in aerial archaeology. While analysing aerial photographs, we have to order, group and identify cropmarks, soilmarks or shadows. Few classifications refer directly to the postulates formulated by processual archaeology. The efforts undertaken may be divided into two groups:
i. classifications which are stages of scientific procedures or studies of the past and
ii. database classifications in institutions which are responsible for collecting and disseminating information on objects from the past.
Solutions suggested by R. Palmer, R. Whimster and D. Riley belong to the first group. In the version proposed by Palmer and Riley, there is a clearly visible tendency to build a classification for the purpose of solving a research problem. It does not differ much from traditional ways of classifying (e.g. intuitive criteria, mixture of morphologic and functional criteria) and does not aim at being universal. The other group of classifications includes efforts at recording and ordering the vast sets of information included in aerial photograph collections and archives and making
them available. For years the objects visible in the photographs have been classified according to intuitive functional and morphologic criteria. In the changing circumstances a need arose to introduce a new set of objective categories that could be used to describe new sites. The approach was necessitated by the pplication of computers which allow building databases and by the requirement of data standardization. In the solutions suggested for classifications of large collections there are a lot of elements postulated by processual archaeology like: objective class
identification, isolation of a maximum number of features allowing for “feature relation” analyses or numerical taxonomy and the description of objects by means of metric data. The postulate that this type of classification is indeed universal does not contradict the opinion that there are no universal classifications. This type of classification remains a certain standard of constructing and managing huge databases and supplies us with pre-ordered material. It can be subjected to further classifications when addressing a particular research problem.
Processual archaeology introduced the term “model” being convinced that it could be applied as a tool in scientific explication. Models are usually idealised representations of reality. They serve as tools to present the results of observations or hypotheses. They can also help visualise relations and structures of elements, compare states of systems, inner structure of systems, explication procedures and the construction and development of theories. Hypotheses play an important part in explication procedures. They are generated on the basis of model-formulated theories. Archaeologists must often choose which site or part of a site is to be excavated. They have to decide what is going to be analysed and why. It is no wonder that processual archaeology stresses the importance of statistical sampling. Sampling enables a more
economical disposal of resources and time in preparation and execution of research studies. Still more important is the belief that even a small fraction of a system is representative of the whole since there are many regularities within any cultural
The limitations of processual archaeology influenced the American attitude towards sampling to a much greater extent than the British archaeologists using aerial photographs. A correct method of distinguishing test areas in regional studies was a necessary condition for detailed analyses and allowed the results to be extrapolated on the entire area of the study. Various sampling methods were applied in different projects (e.g. Cedar Mesa Project, Lower Chaco River Project) and opened up the
possibilities for so-called predictive modelling. In both sampling and predictive modelling, aerial photographs and satellite images were used mainly to identify environmental and ecological factors. In each case environmental variables were treated as independent. In this way they could be measured and used in statistical
analyses and the results could be generalised. A systematic approach to culture enabled making conclusions (on the basis of environmental variables) about cultural behaviours, especially with relation to economic subsystems.
Predictive modelling was used in many different ways. To a large degree it was connected with the intensification and expansion of ground prospection. This had theoretical validity because one needed to study several sites at a time to be able to
understand the intricate relations between human behaviours from the past. Efficient explanation of past cultural systems requires that one studies the relations between different places of human activity and residence at the time when the system under
consideration was functioning. The process that shaped the arrangement of places of past activity was closely related to the adaptation of the cultural system to geographical location. Thus, the spatial distribution of sites, being the remains of economic behaviours in a given geographical environment, may inform us of the organizational foundations of a past cultural system. This theoretical approach directed the research towards studies on individual settlements or camps (e.g. site catchment analyses) or settlement studies (landscape studies) in the context of environmental resources.
As in many other aspects, the application of aerial photographs by American and British processual archaeology differed substantially. R. Bewley, representing the British approach to processual archaeology, uses aerial photographs in site catchment analyses to determine the forms of ground exploitation by people from different settlements and to build a model of settlement transformations and ground exploitation methods. F. Findlow and L. Confeld (American version of processual archaeology) have tried to establish the effects of settlement pattern influence on environment close to an archaeological site by analysing LANDSAT satellite images.
The conclusions of the analysis point to the differences in soil colours around sites and in places where there are no sites at all. In this way one can define the criteria past societies adopted while choosing areas for settlement. In regional settlement studies led by American archaeologists, aerial photographs serve to identify the features of natural environment which past cultures adapted to. In the British approach to regional studies (landscape archaeology), though also inspired by processual archaeology, aerial photographs have a different function. The British
approach to landscape shows that aerial photographs and pieces of information derived from them are used to build social-economic models within the system theory. This necessitates precise mapping of all archaeological features distinguished on photographs. And though archaeologists’ attention was still focused on the analysis of sites in a settlement pattern, the results often showed that one should not limit the analysis to a single site. The breakthrough work by R. Palmer, Danebury. An Iron Age Hillfort in Hampshire: an aerial photographic interpretation of its environs shows the change in thinking and the transition to landscape studies. This change also brought new reflection on the role of aerial photographs in the protection and management of archaeological heritage.
Processual inspirations has also found their way to conservation problems and, at least in some cases, they were solved by means of aerial photographs. As in other aspects of processual archaeology the American approach to the application of aerial photographs in conservation activities was different from the British one. There are multiple examples of how aerial photographs and satellite images were used in conservation projects (Chaco Canyon, Green River Basin, Cedar Mesa, San Juan Basin). Predictive models were used to plan conservation activities on vast and weakly surveyed areas. Aerial photographs and satellite images were applied to the
classification of ecological zones, the choice of statistically significant test areas and map making (also as layers in GIS software). The strong relation between the concept of cultural resource management and the concept of cultural ecosystems is
deeply rooted in processual archaeology.
Less visible are the relations between British archaeological heritage management and processual archaeology. They manifest themselves in different activities and concepts,though they are not unambiguously inspired by processual thought. Interesting in this
respect is the discussion on classification in aerial photography. It stresses the belief that no classification is objective and correct and that classification should be problem-oriented. This concept, however, contradicts the need of data standardization, which is an obvious requirement in conservation. The issue awoke
warm discussions, specifically at the time when the guidelines for the National Mapping Programme for England were being worked out. The programme is perhaps the most obvious example of the influence of processual thought on conservation policy in Britain. Projects done within the framework of the programme put into practice those postulates of processual archaeology that stressed the importance of precise spatial localisation of all observable traces of human activities.
In consequence, the maps made within the programme are a splendid point of departure for all spatial analyses and processual studies on past landscape. Reflecting on the application of aerial photographs in processual archaeology, one sees clearly that aerial photographs are slowly being removed from the sphere of interest of academic archaeology and taken over by institutions responsible for the protection and management of archaeological heritage. The symptoms of this process were already visible in the 1960s. It can be assumed that this was mostly due to the participation of aerial archaeologists in theoretical discussions. As long as O.G.S. Crawford stayed active, the main thoughts discussed in the circles of academic archaeology were also reflected in aerial archaeology. In the 1960s, 1970s and 1980s Crawford’s followers did not take up the discussion and, in turn, aerial archaeology found itself outside the mainstream of theoretical reflection. On the other
hand, A Matter of Time moved the stress of the application of aerial photography towards field archaeology and conservation institutions. And theses aspects of archaeology were widely considered theoretically neutral.
The emergence of some thoughts of processual archaeology in aerial archaeology is an interesting phenomenon showing the process of enriching archaeology with new ideas and reflections without being directly connected with theoretical foundations.
British aerial archaeologists of the 1970s and 1980s were not completely isolated from the world of academic archaeology where the main theoretical discussion continued. The discussion brought about numerous works written in the spirit of processual archaeology and the atmosphere within the science slowly changed
gradually influencing researchers working with aerial photographs. The selective way in which processual reflection penetrated aerial photography caused new ideas,methods and solutions to develop independently of theoretical foundations. They were included in and enriched general commonsense knowledge. Consequently, publications conceived within the framework of aerial archaeology presented a
mixture of ideas derived from both cultural-historical and processual archaeology.
The most characteristic trait of these publications works was the application of various methods (without theoretical reflection), also derived from processual archaeology (a phenomenon specifically typical of cultural-historical archaeology). In effect, despite the application of methods borrowed from processual archaeology, the
final conclusions were formulated in the spirit of traditional archaeology.
The picture of British archaeology in the 1970s and 1980s, i.e. in the period when processual archaeology was developing, is not uniform. Aerial archaeology had many “faces” at that time. The tradition of collectors and antique dealers was still continued; there were many works closely related to the cultural-historical trend and some works and activities inspired by processual archaeology. Processual archaeology directed researchers’ attention towards theory and this must be considered its great merit. Paradoxically, it became the source of serious criticism
of its main assumptions. By applying various philosophical theories born within a wide stream called postmodernism, archaeologists registered the limitations of processual archaeology. Modern theoretical and philosophical inspirations in postprocessual
archaeology are so varied that they cannot be linked into a uniform theory.
Postprocessual archaeologists have shown little interest in aerial archaeology. It seems however that there is a hidden potential in it which entitles it to a broader participation in scientific discussion. Postmodern thought can help us discover new layers of scientific issues and fields of study in aerial archaeology. Aerial archaeology must take a stand on the problems which are discussed by postprocessual archaeology – the questions like a picture being text, the language of aerial archaeology, and the problems of power and the concept of landscape.
In a traditional vision of the world it is undisputable that we can only believe in what we see. “Pure” visual perception is one of the canons of empiricism which is the dominating trait of positivism. In postmodern thought, however, there is a belief that what we see and what we do to perceive does not constitute part of innate and
natural abilities but rather is interrelated with the methods societies shape knowledge forms, power strategies and systems of needs. The essence of a photograph is to confirm what it is depicting. One may have an impression that photography (including aerial photography) is an ideal medium for an archaeologist. It gives a direct image of the past and, outwardly, enables direct
contact with the past. But a photograph also immobilises our thinking of the past and imposes a certain framework one can hardly avoid. We must also be aware that aerial photographs are of a specific nature and they must be looked at from that perspective. It is important to stress out that aerial photographs do not (!) offer direct contact with the past understood as the reality of past societies which are studied by the archaeologist. The past recorded on the photograph is the past of air reconnaissance, a “fixed”, historical image of soilmarks, cropmarks and shadows.
The complexity of photographing processes and photograph interpretation can be looked upon from the perspective suggested by R. Barthes. A photograph may be interpreted on the phenomenological or semiotic plane. From the phenomenological point of view, the ability of a photograph to authenticate is more important than the
ability to depict. A photograph is an image without codes and therefore it can be analysed on the level of perception. However, the photograph is read through codes which are culturally formed. The cultural functioning of a photograph is only possible
when it has been read. This is where the semiotic plane comes in. Photographs do not include any “neutral” parts or elements which are deprived of meaning. According to J. Piaget, there is no perception without instant categorisation. A photograph is
verbalised/narrativised at every stage of perception. Moreover, it is perceived through verbalisation. It means that a photograph is entangled in linguistic categories and this statement has far-reaching consequences. One has to abandon the long-lasting belief of cultural and theoretical “neutrality” of an aerial photograph.
Barthes’s views point to the cultural-social context of aerial photographs. The social implications of aerial photographs are related to: (1) the stage of taking photographs (especially oblique photographs), (2) interpretation of the contents (both oblique and
vertical photographs), (3) the use of photographs (or rather their contents) to address research problems, (4) the realisation of conservation policy and archaeological heritage protection programmes, and (5) dissemination of the knowledge about the
Aerial photographs are closely connected with text, in fact they are text. Their role as archaeological sources (record) must be redefined. There is a need to create a special language to analyse and interpret aerial photographs. This “language” is constituted socially and changes in time and cultural context. One can say that “the language of aerial archaeology” has been created since the times of Crawford. Crawford was the first to tie the changeability of phototones in photographs with the presence of archaeological sites on ground and then transformed the information onto a map. This marked the beginning of the “language” which has been undergoing constant changes since then and has been enriched with new elements. This “language” constitutes our “reading” of the photographs. Postprocessual archaeology has noticed the social context of the archaeologist, his/her entanglement in his/her own culture and his/her influence on the image of the past. The division between the subject and the object of study has been questioned. Archaeologists became interested in the relation between the past and their thinking of the past. Since the notion of “truth” has also been questioned one could not apply
the criteria used by academic archaeology usurping the right to form the only “correct” knowledge of the past. For a recipient, the “true” image of the past is the one which is convincing and generally concurrent with his/her ideas on the past.
Can aerial archaeology offer its own “alternative” version of the past? It seems plausible. As far as popular science is concerned, the output of aerial photography is considerable. The market for popular books on the past has exploded and aerial archaeology has found a niche for itself in the book trade. Aerial photographs are the most valuable elements of such books enhancing the beauty of landscape and historical monuments. They appeal to readers’ imagination. A photograph seems to convey a neutral and objective message. In addition, it represents reality and for the recipient it is the reality of past societies. As a kind of archaeological source (record), it offers metaphorical contact with past reality.
Let us conclude this review of the methods of treating aerial photographs in different trends of archaeology by answering the question of theory and method in archaeology. The examples shown so far indicate that the concept of theory and method being independent of each other must be rejected. There is a relation
between theory and method and this relation is not symmetrical. Research problems are formed on the basis of theory and the problems are solved by means of different methods. Thus, theory has a major influence on the place method takes in research process. The questions we ask about method (inspired by our theoretical knowledge)also influence the answers we receive. A method introduced to archaeological studies at a certain point in time undergoes constant modifications. It becomes more “specialised” and starts “living its own life”. Still it is burdened with theory and
practice it was “born” with. Many assumptions remain deeply concealed. A certain model of interpretation is created from the very beginning and hardly ever changes.
Though method (and its results) may occasionally influence theoretical assumptions, it is theory which, to a much greater extent, governs the ways and the scope of method application. Method cannot impose any theoretical approach but rather strengthen the existing attitude or help develop a new one.
It seems necessary to analyse the research process within archaeology. The process has changed through years but it has shaped some standards of practising the science which, in turn, are based on theoretical foundations (accepted more or less knowingly). An analysis of theses processes may help us understand why scientific practice has evolved the way it has evolved. It may lead to the deconstruction of existing ideas, tasks and methods and may become the basis on which new ideas, tasks and methods are formed. This can be called “metaarchaeology” – a study of the discipline, its theories, methods and objectives. Methodological selfreflection and deconstruction of existing standards are not synonymous with negation. “Metaarchaeology” may rather widen our horizons by removing limitations. We can enrich our understanding of the past by applying various trends within archaeology.Cultural-historical, processual and postprocessual archaeologies open up new fields
of scientific exploration and deliver multi-faceted images of the past. Nothing should make us think about the past in the same and obligatory way. We must, however, understand the methodological and theoretical foundations which influence our research processes. This includes a careful selection of methods and adequate interpretation of data we acquire.

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