Thứ Bảy, 19 tháng 9, 2009

Aerial archaeology method in the face of theory (phần I)

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


Contemporary archaeology is undergoing dynamic changes. The process is largely a result of new theoretical concepts being constantly developed but also a product of disappearing limitations in international scientific exchange and easier access to
up-to-date publications. Consequently, there are favourable conditions in many countries to abandon the principles of the widely criticized cultural-historical approach to archaeology. A number of new works published apply novel methods and models which are developed on the basis of new paradigms (specifically within
processual archaeology). Those methods and models are often supposed to be a sign of the author’s original approach to archaeology but, in reality, they merely mask the traditional approach. Empiricism, inductionism and objectivity reappear in disguise.
This practice reveals lack of theoretical and methodological reflection. Thus, it seems crucial that relation between method and theory in archaeology is identified. The opinions on theory and its role have undergone many significant changes. The same applies to the method. Divergent concepts on the relations between theory and method and a widespread belief among archaeologists that the
choice of method automatically presupposes the choice of theoretical orientation, outline the important problem of the role method plays in theoretical approaches.
Questions about the reciprocal relationships between theory and method remain ever topical. In scientific research there is a broad variety of methodological options because the number of methods used in archaeology seems virtually unlimited. There are methods of ground prospection, methods of excavation, methods of describing and recording of archaeological material, methods of explication and interpretation of past events, methods of studying site formation processes, and many others. It is widely accepted that some methods have no connection with theoretical thought whatsoever – they are so to speak “theoretically neutral”. In my opinion, showing the
mutual relations between “theoretically neutral” aerial photographs and various archaeological approaches may shed some light on the relationship between theory and method.
Three conditions had to be fulfilled before aerial photographs could become a useful tool for archaeologists. Two of them were of technical nature: to be airborne and able to record the surface of the ground from an elevated position. The third condition required new thinking, recognition of the fact that archaeological features and sites could be observed from certain altitude and that these observations could be useful in addressing research problems. The two first conditions had already been met by the time when archaeology emerged as a science, which was in the middle of the 19th century, though the scientists of that time did not recognise the usefulness of aerial photographs in the study of the past. The dominating theory of cultural evolution steered archaeological thinking of the past and its interpretations and it limited the
scope of interest, scientific problems and solutions. Applying the basic ideas of evolutionism, archaeologists fully accepted the evolutionary-comparative method, i.e. the comparison of cultural forms and states, and blatantly disregarded their context.
Consequently, they focused on chronological problems, endeavouring to place cultural forms and phenomena within some evolutional sequence. Aerial photographs could not be used for that purpose.
The military, however, showed an early interest in “bird’s eye” views. From the very beginning they focused on aerial photographs taken from balloons and used them for survey purposes. The invention of the aeroplane in the early 20th century soon put balloons in the shade. The First World War saw further development in terms of
aircraft and camera technology. Military air reconnaissance made the number of aerial photographs taken explode. Undoubtedly, archaeological objects must have been accidentally recorded at least on some of them. The First World War also marks the beginning of first and modest experiments with aerial photographs in archaeology (e.g. L. Rey, T. Wiegand, G.A. Beazley, A. Poidebard), though it is widely accepted in the literature of the subject that it was
O.G.S. Crawford who played the leading role in forming and formulating the principles of aerial photography and making it known. Crawford’s recognition of aerial photographs was based on theoretical foundations he had adopted in the first years of the 20th century. At the beginning of his scientific career, Crawford came under the influence of two mainstream trends in archaeology of his times: evolutionism and diffusionism. The lecture he gave in 1911, The Distribution of Early Bronze Age Settlements in Britain, clearly reflected his theoretical thinking. Among the scholars who helped shape Crawford’s ideas were P.J. Wiliams-Freeman, H. Peake and Mortillet.
It is also widely accepted that Crawford’s next lecture, entitled Air Survey and Archaeology and held on 12 March 1923, was the first scientific rendition of the new method. The main point of the lecture was to establish the age and origin of lynchets he thought to be of Celtic origin . The study was based on a detailed analysis of stratigraphic data relations between a number of objects whose chronology had been known . Crawford concluded that lynchets forming a mosaic of square or rectangular fields had been introduced at the beginning of the La Téne period (or even late Bronze Age) just after the first wave of Celtic migration. The system was used until
the Roman invasion. Narrow and stretched lynchets were introduced by Saxon tribes and used until the end of the 18th century. Crawford made some general remarks on aerial photography only towards the end of his presentation, but he managed to show the benefits of the new method and its applicability in solving research problems. The
lecture was on Celtic lynchets and aerial photographs provided for a penetrating analysis of the issue. In sum, Crawford demonstrated the potential of this method for archaeology presenting case study.
Crawford represented the evolutionist-diffusionist school of thought in British archaeology, which was brought into being in the early 20th century. It is not a difficult task to identify elements of both theories in his work. Crawford aimed at establishing chronologies of objects and arranging them in a chronological sequence. He made wide use of metaphors, which was typical evolutionism. He stressed the importance of analogy in the interpretation of spatial arrangements and in his
explications he referred to cause-and-effect relations. Discontinuity in the emergence of new cultural forms was often explained in terms of migration. The geographicalmethod makes it possible to determine the origins, spread and boundaries of a culture. In this approach opinions of a general nature were formed on the basis ofsource archaeological data. The empirical nature of Crawford’s scientific procedure let us believe that he fully accepted the positivist notion: the greater number of sources(record, data), the better and more complete our knowledge about the past.
Crawford’s treatment of sources (archaeological record , data) was very characteristic. He regarded archaeological sources (record , data) as objective and physical objects in which past world was preserved. The source (archaeological record, data) is independent of the researcher who uses it to reconstruct past events
and cultures. It is static and passive like a fossil alaeontologists understood it then.
In this context Crawford considered aerial photographs to be an objective representation of objectively existing archaeological sources (record, data). In other words, he believed in what he saw and treated photographs as a true rendition of the real world. He claimed that a photograph registered everything an archaeologist could see with the naked eye. The process of the reconstruction of the past world by means of photographs requires the archaeologist to be passive and uninvolved. Observation is reduced to ‘pure’ visual perception. The archaeologist is equipped with an ‘innocent’ eye and ‘pure visual perception’ belongs to the canon of empiricism. In such an approach to archaeology, an aerial photograph has the same validity as otherarchaeological sources (record, data),.
Owing to Crawford’s propagating skills, many followed in his footsteps Crawford’s activity soon gained many adherents. They were both pilots, fascinated by the romanticism of the journey into the past, and professional archaeologists. Since the very beginning some tendencies dominated and influenced the future development of
the method and the ways it was perceived by archaeologists. Researchers were divided into two groups: those who practised aerial archaeology, i.e. the taking of aerial photographs, and those who used photographs in their archaeological research.
The first group consisted of amateurs who became fascinated by the new method.They had enough financial resources, time and flying skills to be able to make archaeological discoveries and “compete” with professionals. Academic research owes to them a number of extraordinary discoveries and scores of information on new archaeological sites. The joy of discovery was accompanied by the reflection on the nature of soilmarks, cropmarks and shadows. They played decisive part in developing improving the methods of regular air reconnaissance and taking aerial photographs. They behaved like collectors or antique dealers. Flights made it possible to discover new sites and taking pictures of the sites was like collecting
Academic archaeologists soon accepted aerial photographs as a tool of discovering and registering archaeological sites. Field archaeology made aerial photographs one of the main methods of site recognition applied prior to excavations. However, aerial
photographs were not regarded as equally important in solving research problems. Questions archaeologists asked were limited to the chronology and spatial structure of the site – the latter solely for the purpose of planning the excavations.
It seems that this qualified success of aerial archaeology influenced the scope of the research questions asked. The belief that archaeological material directly informs of the past limited the archaeologist’s main interest to pure documentation of the site and establishment of chronology. This sufficed to place the object in chronological order and to “reconstruct” the past. Aerial photographs were gradually limited to the initialphase of source requisition, i.e. to ground survey. Suggestions to use photographs for map-making and problem-solving were put in the shade.
The positivist approach to archaeology limited the scope of questions that could be asked on the basis of aerial photographs. On the other hand, aerial archaeology brought some new questions with it and proposed new interpretations of traditional scientific problems. In a series of spectacular discoveries new sites were identified (e.g. Woodhenge), which made archaeologists reinterpret their views on many issues related to the past. Aerial photographs also introduced a new perspective to the studies of past agriculture: an analysis of the changeability of field systems. C. Fox clearly inspired by Crawford, gave rise to a new trend called landscape archaeology,which chose aerial photographs to be its key source of information.
The development of British archaeology from the 1930s till 1960s diversified the ways the science was practiced by introducing analytic methods from other sciences but also formed a certain pattern of discourse in which such categories as object
type, archaeological cultures and groups, form of evolution, migration and diffusion played a big part. Numerous discussions led gradually to a synthesis of different theoretical reflections and to the emergence of a cultural-historical trend which manifested itself by a variety of differently stressed elements of functionalism,
neo-evolutionism and Marxism.
The discussion in academic circles had some impact on aerial archaeology. The way aerial photographs were used changed considerably. J. Bradford, M. Beresford and J.K.S. St Joseph took a turn towards the technological and economic interpretation
of facts registered on photographs. It resulted in the recognition of new classification criteria, and consequently, shifted the focus of the debate to interpretation and notdescription alone. Photographs became objects of analysis (equivalent to writtensources and maps in the work by Beresford and St Joseph) and not mere illustrations.
Diffusionism made an important contribution to the cultural-historical approach by introducing maps as a tool of archaeological analysis. Bradford used maps not just for the analysis of distribution but also in the studies of past landscape. A map did notonly include cultural elements from a given period or a given archaeological culture,but also topographic elements important for a certain type of landscape (under the influence of G. Clark’s ecological functionalism). In this way one could study cultural objects in their relation to the past natural environment.
Analysing the fields of interests of academic archaeologists, one can clearly see that they focused on the studies of material culture and the technological and economic aspects of culture. By the force of events aerial photographs were put in the shade,far away from mainstream archaeology. Even Bradford’s, Beresford’s and St
Joseph’s splendid works, which opened up new scientific horizons (e.g. landscape archaeology, medieval archaeology), could not reverse the process. Aerial photographs were, however neither forgotten nor ignored. On the contrary, in all major work on the general aspects of archaeology, aerial photographs are considered
one of the most important methods of prospection. Even Crawford treated them that way towards the end of his scientific career.
It seems, however, that the first years after the Second World War brought some regression in the application of aerial photographs in archaeology. The establishment of the Cambridge University Committee for Aerial Photography (CUCAP) and a collection of aerial photographs in 1948 did not change the situation. St Joseph,
curator of the collection, carried out regular air survey of Great Britain but he focused mainly on the discovery and documentation of archaeological sites and published photographs in a very selective and schematic way. St Joseph’s restrictive attitude towards aerial photographs did not help disseminate the method in academic circles.
Aerial archaeology became less and less attached to the ideas and objectives of academic science.The situation was similar in the USA. Aerial photographs played marginal role and the American reflection was very much the same as the British. Photographs were considered useful in making detailed plans of sites. They were also applied to the identification of field systems and, together with field studies, in the studies of economic aspects of North American archaeological cultures.
Positivist objectivism, empiricism and inductionism dominated archaeological thinking.This was clearly evident in the attitude towards research practice and the separation of archaeological data from their interpretation. The main aim of the archaeologist was a possibly detailed and objective description of data. One needed to collect all data available to be able to know the past. This empirical approach made archaeologists concentrate on information and data collection. In common thinking archaeology was perceived as synonymous to data collecting. That is why so much attention was attached to methods used in field archaeology. The more data one
managed to collect, the better and more complete the knowledge of the past was.
This thinking provided the foundations for archaeological conservation. One of its main aims and activities was the discovery and registration of archaeological sites. This was especially important in the formation of conservation policy after the Second World War.
The period after WW2 brought dynamic economic activity aimed, among others, at the restoration and building of cities, industrial facilities and roads. Consequently,many archaeological sites came under threat. From the objectivist viewpoint, which was predominating in archaeology, the destruction of sites was considered irrevocable loss of information. The threat was recognized and expressed for the first time in A Matter of Time. It offers a careful analysis of threats that archaeologicalsites face due to the development of industry, communication, building and agriculture and formulates the policy of the protection of archaeological heritage. There was nocontroversy that protection of archaeological heritage requires first of all a precise record of sites, their localisation, function, chronology and state of preservation.
Aerial photographs seemed to be the most effective tool for that purpose. When the Royal Commission on the Historical Monuments of England ranked aerial archaeology as one of the most important methods in its programme of conservation,the science gained momentum. The organisational structure was extended, enabling
air reconnaissance on a much larger scale and creating conditions for storing and accessing photographs. It was also the next step in limiting the application of the method to field archaeology. And since the conviction of the theoretical neutrality of field studies was never questioned, aerial photography separated itself from the
methodological reflection in British archaeology.
It is widely assumed that New Archaeology, later called processual archaeology,initiated a broad discussion on theory and explication procedures in archaeology. The 1960s and 1970s, when processual archaeology came into being, brought also a wide spectrum of technological achievements into the humanities. The standardization
of methods and the repeatability of procedures fitted well into the belief of cognitive objectivity and the possibility of formulating universal laws and general theories.Methods borrowed from natural sciences were to guarantee the objectivity of cognition.
Since the turn of 1960s and 1970s aerial archaeology has been undergoing dramatic technological changes, practically in every aspect. Aerial photography has been included into a group of remote sensing methods. Remote sensing encompasses a variety of registration platforms including satellites but also applies cheaper methodsof launching electromagnetic radiation registering devices (kites, model planes,balloons). New devices have been designed to fulfil the need to register different ranges of electromagnetic radiation. New methods of data processing have been developed and computers have become indispensable.
This technological “revolution” in aerial photography was possible mainly (though not exclusively) thanks to processual archaeology. Processual archaeology stressed the necessity of precise measurements of cultural and natural features and the objectivity of the process, and thus opened up new possibilities to apply the potential of aerialarchaeology and import methods and equipment from other fields of science (e.g.computers, GIS, satellite images). Processual archaeology also viewed scientific problems from a new angle and helped formulate new research proposals. New
technology was supposed to serve the modern way of practising archaeology.
Consequently, the technological aspect is still widely discussed among aerial archaeologists. The variety of scientific issues inspired by processual archaeology has resulted in asubstantial widening of the field of archaeological research. It has also influenced the way aerial photographs are used in archaeology and how they are applied to solvingresearch issues. In aerial archaeology processual inspirations (accepted more or less knowingly) have initiated dynamic and multi-faceted discussions on various aspects of the method. It seems that processual thought has substantially influenced such issues as a the concept of archaeological source (record), the problems of classification and construction of models describing the relation between cultural systems and natural environment, and the application of technological achievements. Processual ideas are also reflected in the issues connected with the protection and management of archaeological heritage.
In aerial archaeology one can see a continuation of fixed and widely accepted (in the cultural-historical approach) patterns of thinking about the aerial photograph as an archaeological source (record). Numerous publications on aerial photographs and on their application in studies of the past treat photographs as equal to other source
categories. Though being specific in the way they are acquired, aerial photographs undergo the same procedures as ceramic material found during field survey or excavations. This, however, does not prevent archaeologists from looking for distinguishing features that could help recognize archaeological features or sites in the pictures. The basic indicators were already identified by O.G.S. Crawford, Major Allen, D. Riley and J. Bradford. In the 1970s, a need arose for a more precise explanation and systematisation of phenomena that cause the appearance of cropmarks and soilmarks. There is a clear relation between this requirement and
Schiffer’s concept of formation processes. Among aerial archaeologists, this way of thinking could have been inspired by Schiffer’s ideas though it could also have resulted from the intensification of aerial survey and the emerging research issues. Itremains a fact that within the realms of aerial archaeology, site formation processes were vividly discussed. The reflection on the processes influencing the appearance of distinguishing features that help recognize archaeological features and sites on aerial photographs concentrated on three aspects: 1) role of moisture, type of soil and plant species in the process of revealing cropmarks, 2) forming of soilmarks and 3)discrepancy between research results obtained by means of different methods (aerial survey, fieldwalking survey, excavation).
The discussion on the factors forming the appearance of archaeological features through cropmarks or soilmarks and geomorphologic processes points to the growing awareness of postdepositional processes. British archaeology concentrated on the
processes which had decisive importance for the formation of cropmarks and soilmarks. In American archaeology, focus was put on the processes related to natural and cultural phenomena which had an influence on the quality of archaeological material.
Classification plays a key function in research process. The way classification was understood in cultural-historical archaeology could not be accepted within the paradigm of New Archaeology. The idea of a single, unique and ultimate classification of objects and events was rejected. In fact, an archaeologist can apply many different classifications. It depends on the problems and hypotheses he puts forward.

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