Archaeological Computing Newsletter

Archaeometry, 2008

Geophysical survey techniques are a highly visible part of the scientific toolkit that is now used by archaeologists. In this paper, the history of the use of geophysical techniques in archaeology will be discussed, as will significant research themes associated with the most widely used prospecting devices. It is apparent that while the use of geophysical techniques is at an all-time high, there are many key areas where prospecting is rapidly developing. Some of the advances relate to fundamental aspects of the techniques, while others dictate how we undertake survey in the future. There is a movement away from pre-gridded survey areas towards real-time GPS for navigation. This allows greater integration, or fusion, of disparate data sources using visualization techniques derived from associated disciplines. The analysis of landscapes has become a major component of the application of new technology and there are many challenges to be tackled, including how to analyse and interpret significant archaeology within large-scale, data-rich, multi-technique investigations. The reflective nature of the review acknowledges the important role of Archaeometry in the development of archaeological geophysics.

Archaeology & Anthropology: Open Access, 2017

Today, there is almost no new archaeological discovery in which geophysical investigation tools do not play a key role. In fact, looking onto the past century, one could argue that geophysics, in a way, has rescued archaeology and revived it from its old-style techniques involving hard labor and timeconsuming digging and trenching. Today, thanks to geophysics, archaeology utilizes state-of the-art technologies, takes advantage of the most recent data management and processing techniques, and benefits from the latest image processing protocols. However, archaeology is not the only beneficiary from this successful coupling between archaeology and geophysics. Many of the advances in shallow and high-resolution geophysical techniques as well as data processing and interpretation capabilities can be indirectly attributed to the needs, demands and feedbacks of archaeologists. This successful exchange of benefits has resulted in a new scientific term that is commonly used nowadays; that is Archaeogeophysics or Archaeological Geophysics.

The state of art of archeological geophysics, from the sidelines, by way of a review of “Handbook of Geophysics and Archaeology” by Alan J. Witten and “Revealing the Buried Past: Geophysics for Archaeologists” by Chris Gaffney and John Gater.

In history and prehistory artefacts and structures are often concealed beneath the surface of the earth as a result of geological processes and perhaps more frequently as a result of human activity. A key aspect of landscape archaeology lies in the identification and interpretation of this hidden evidence or in the broader sense of the buried landscape. Recent decades have seen landscape archaeologists concentrating mainly on the collection of vast numbers of sites, for the most part in isolation from one another. We might call this a site-based approach. But neither present-day nor past landscapes consist only of houses, settlements, cemeteries, industrial areas and the like. More recently archaeologists have become aware that there is a great range of evidence (on-site as well off-site or non-site), from scatters of artefacts to road systems, plough-marks and field boundaries, that can provide important information, not only about human exploitation of the environment but also about cultural, social and economic developments. This has created a ‘new’ challenge. We are called to face the inherent complexity of landscapes and their internal relationships—often hidden beneath or between ‘sites’ and for the most part represented by relatively ‘weak’ evidence. We might call this a landscape-based approach. The site-based approach has produced limited results in landscape terms, not least because the main investigative method has been restricted to surface collection. Reconnaissance survey of this kind is of course essential, and can be very productive, but like every other method it has its limitations. We would point particularly to its inadequacies in the identification of structures, features, chronological phases and social groupings. It goes without saying that some archaeological phases are more readily ‘visible’ than others and that some cultures, such as those of mobile hunter-gatherers or pastoralists, leave a very different imprint on the landscape than those of agricultural or urban societies. It is equally obvious that surface artefact collection allows us to recognise only a small range of the potentially available evidence. In Mediterranean landscapes, for instance, the definable site typologies are limited to such things as ‘grave’, ‘farm’, ‘roman villa’, ‘industrial area’, ‘off-site finds’ etc. On the basis of reconnaissance survey it is virtually impossible to collect a wider range of evidence or to achieve a more precise and detailed classification of site typology. We are in no sense averse to field-walking survey, which we see as probably the best available method in regional studies for detecting sites that produce surface evidence in the form of artefact scatters, building material and the like. We are, on the other hand, convinced that the limitations of each and every research method should be openly acknowledged. It is our contention that without the integration of a variety of information-recovery techniques we cannot begin to confront and comprehend the inherent complexity of past landscapes. Remote sensing, and in particular aerial reconnaissance, can play a crucial role in the discovery, recording, interpretation and monitoring of sites. Satellite imagery, airborne scanning (multi-spectral, LiDAR), vertical air photography and exploratory aerial survey have developed into some of the archaeologist’s most valued tools. But, just like field-walking survey, these sources and techniques have their own particular limitations—LiDAR and multi-spectral sensors, for instance, each pose different kinds of problems. Post-depositional processes can also affect the results because of thickness, weakness and size of evidence. And with all techniques there is also the imponderable affect of ‘serendipity’—good fortune (or otherwise) in the local situation or in the luck of the moment. Any non-destructive method capable of reducing or offsetting the uncertainness of field-walking survey, trial excavation or the varying capacities of different types of remote sensing should be greeted with open arms by archaeologists if it leads to an increased probability of informationrecovery. One such method, now the subject of new or revived attention, is near-surface geophysical survey. In recent years a wide range of scientific disciplines have provided useful tools for an integrated approach to data-collection, interpretation and conservation in the field of the cultural heritage. In this context archaeological prospection presents a whole range of non-invasive techniques, including various kinds of geophysical survey, satellite imagery and aerial photography, as well as a variety of digital site-recording systems and numerical techniques for processing, analysing and representing the different data-sets that can be collected through ground-based survey. The last twenty years have seen great technological advances in these non-invasive methods. New instruments, data-acquisition techniques, geophysical methods and processing strategies have made the fieldwork much faster, more sophisticated and more effective. From a site-based outlook, geophysical prospection increases the visibility of features but also greatly enhances the complexity and sophistication of site interpretation, providing high-resolution maps of the subsoil—not merely the surface—and, depending on the technique applied, even maps at different depths. The capacity to see the sub-surface pattern of archaeological features makes it possible to refine the generalised types of site classification achievable through traditional field survey, and gives the opportunity to draw a wider variety of conclusions about questions of cultural, social and economic background. Equally important is the increase in the speed of measurement achieved by a small number of pioneer scholars—many of them represented in this volume—making it possible to move geophysical survey from a site-based to a landscape-based approach. This sort of perspective is not entirely new. We should recall, for instance, the extraordinary revelations of John Bradford on the Foggia plain in Apulia, Sothern Italy (Bradford 1957), where he discovered probably one of the most outstanding stratified landscapes visible from the air. Nearly sixty years ago he wrote in the British journal Antiquity: ‘We can now go towards peopling this landscape, not in a sand-table world of theory, but in a stetting of actual fields and farms which provide unrivalled opportunities for the direct study of roman agriculture” (Bradford 1949). But it must be recognised that it is the geological and land-use character of the Foggia plain, rather than its cultural pattern, that gives it an extremely high archaeological visibility when viewed from the air. The main innovation and advance offered by large-scale continuous geophysical survey within a landscape-based approach lies in the opportunity to overcome or circumvent the limitations of archaeological visibility caused by such things as clay soils, unfavourable land-use or unhelpful cultivation patterns— along, of course, with the ‘vagaries of the moment’ that affect the success or otherwise of aerial survey. Bradford said about the roman landscape on the Foggia plain: “Never before has the actual landscape of the Roman farmer, described in the Georgics, been better preserved for direct study. One can walk along the grassy roman roads from one farmstead to the next and enter up its ditchflanked drive bordered by vines or trees” (Bradford 1949). In the present day this could be said, too—despite inevitable cultural differences—about the Vale of Pickering in north-east England, studied over the past thirty years by Dominic Powlesland, another contributor to this volume. Of course we are not maintaining that geophysical prospection provides the ultimate panacea for the archaeologist concerned with the cultural heritage. In some ways it is, but like all other techniques it can fail in some circumstances to spot significant archaeology—features that are too small, too deeply buried or too weak in the signals or reflections that they produce. It is in our view fair to claim that the results achieved in the last decade through the development and application of geophysics should be acknowledged by the archaeological community as amongst the most important methodological changes of recent times. It is our hope that, through this book, these developments can be more fully understood by archaeologists, who often approach ‘new technology’ with a degree of suspicion. There is a striking paradox here. Archaeologists define society and the major phases of prehistory from an explicitly technological point of view: Stone Age, Bronze Age, Iron Age etc. Moreover, the most important cultural revolutions in the history of humanity have been defined on the basis of technological developments: the introduction of agriculture, the Industrial Revolution and now the advent of computer science. How can we deny the extraordinary contribution of geophysical science, and more generally of technology, in the search for archaeological understanding?

Long Beach advocate the use of geoscientific and other disciplines to advance archaeological endeavour and provide some graphic examples from their research.

Taking the lessons learned from early technological advances in archaeological geophysics prospection, and examining the reasons many recent technologies have failed to live up to the hype, and attempting to apply Occam's Razor to a modern enhancement to the collection, storage, and processing of geophysical data.

2007

Long Beach advocate the use of geoscientific and other disciplines to advance archaeological endeavour and provide some graphic examples from their research.