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Digital Geoarchaeology pp Cite as. GIS has become an indispensable tool for archaeologists to organize, explore and analyse spatial data. In this introductory chapter, an historical overview of the development of GIS use in archaeology is given. It focuses on three major fields of application: site location analysis, modelling movement and transport and visibility analysis.
This state of the art is illustrated by discussing three different case studies. Finally, some thoughts on the future of GIS in archaeology are presented.
GIS and spatial analysis are now seen by most archaeologists as essential tools to explore, analyse and interpret spatial data and have become standard ingredients in many archaeological research projects. In this chapter, I will give a condensed overview of the current state of GIS use in archaeology and attempt to sketch the current role of GIS and spatial analysis for archaeological interpretation and show its potential for changing theoretical perspectives and research traditions, drawing on examples from recent research.
And lastly, I will try to look into the crystal ball and set a tentative agenda for future research. If we would have to describe the history of the use of GIS in archaeology in a nutshell, it could be summarized as a cycle of initial enthusiasm and proliferation in the s and early s, followed by severe criticism and partial disillusionment in the late s, only to be reappraised again and rapidly gaining momentum in the late s, leading to its current status as an almost indispensable research tool—or rather methodology—for dealing with spatial archaeological data.
The main trends in this development have been described by, e.
However, when reading the academic literature on the subject which has the tendency of being a rather slow detector of longer-term trendswe could be under the impression that archaeologists are still reluctant and hesitant in their appreciation and adoption of GIS-based spatial analysis. Theoretically oriented archaeologists were seriously concerned about these issues in the s and early s when thinking about how to deal with digital technologies in general.
However, archaeological practice has certainly moved on since then, and currently archaeologists have generally embraced geographical database management, digital cartography and spatial analysis, if only for reasons of efficiency. To a lesser extent, they have also gradually adopted computer-based modelling as a research tool, although acceptance here has been a Exploring The Role Of Analytical Scale In Archaeological Interpretation British Archaeological Repor slower, due to the fact that it has stood in the middle of the processual versus post-processual controversy see also Verhagen and Whitley She distinguishes between two views of understanding the past, the representational and non-representational.
In the representational view, the past is supposed to have an objective reality. This is a reality, however, that we cannot touch. For this reason we can only use representations to understand the past. This leads to a dualistic approach to research, separating, e.
Digital cartography suddenly allowed researchers not just in archaeology to take mapping to a much higher level and to collect and manipulate geographical data in a much more sophisticated way.
The preoccupation of post-processual researchers with bodily understanding as the preferred way to study the past, and in this way to come closer to the mindset of human beings long dead, shows that they were looking for new ways of representation, albeit in a different form than what cartography and other techniques of data complexity reduction could achieve see, e.
Tilley What the early practitioners of GIS and their critics did not perceive is that GIS and other computer-based methods enable pluralism, rather than enforce reductionism.
Using these tools, a multitude of representations can be created with little effort, in which there is no longer an easy way to distinguish between right and wrong and between more and less plausible.
Because of this, cartography has been effectively democratized, and mapping these days is, more than ever, an exercise in scientific rhetoric. In this view, the past is not something that can be understood in a static and definitive way, but rather something that continually changes and is repeatedly reconstructed in the present. It is therefore a plea for eclecticism in using GIS and to consider it more as a constantly changing research practice than as a technology-driven instant solution that can be applied to all forms of spatial data and all archaeological research questions.
We might even go one step further and ask ourselves whether spatial analysis and modelling could not be just one of many approaches, but perhaps constitute a leitmotiv for doing archaeological research in the twenty-first century.
An important characteristic of computer-based techniques that sets them apart from all other approaches is their ability to deal with data sets that are too big and complex to handle by human minds. GIS can deal with big data that also have a spatial dimension and in this way help to discern patterns and to simulate theories of human behaviour over large areas. In the following sections, I will introduce examples of the use of GIS-based spatial analysis that I believe illustrate current research trends, as well as its utility and limitations in practice.
The main applications of GIS in archaeology can be classified into site location analysismodelling movement and transport and visibility analysisand I will provide examples of applications of all of them. In many cases these approaches are also used in conjunction—although we can suspect that this is partly because they are all available in the same toolbox and are therefore relatively easy to combine.
Over the last few years, however, we can see that researchers are becoming more and more interested in coupling GIS to other techniques, such as social network analysis, advanced statistical methods and agent-based modelling. Without site location analysis, GIS might not have caught on as quickly as it did in archaeology. The earliest Exploring The Role Of Analytical Scale In Archaeological Interpretation British Archaeological Repor of GIS-based site location analysis can already be found in the early s in the USA, and it is has never left the scene since then.
At the time, it met a strongly felt need for more efficiently analysing site location preferences, a field of study which had received an enormous boost in the mids through site catchment analysis Higgs and Vita-Finzi ; Findlow and Ericson The closely related practice of predictive modelling followed in its wake, responding to a demand from Cultural Resources Management to predict the distribution of archaeological remains in areas under threat of destruction Kvamme; Judge and Sebastian However, both methods quickly came under severe attack when post-processual theory made its way into archaeology in the late s and early s.
To the post-processualists, site location analysis and predictive modelling were prime examples of how the processualists had chosen to ignore the human dimension in the study of the past.
The first and foremost of these criticisms was the accusation of environmental determinism. The comparison of site locations to various environmental characteristics such as soil type, slope or distance to natural resources will inevitably favour environmental-deterministic explanations of site location patterns Wheatley, ; Gaffney and van Leusen And even when the method can hardly be blamed for lack of data or for flawed archaeological-theoretical perspectives on site location, in practice it has proved to be very difficult to deal with non-environmental variables in site location analysis, although some real progress has been made in this respect over the last decade Whitley et al.
In the early days, many GIS practitioners were well aware of the pitfalls of using and interpreting statistical analyses see, e. Judge and Sebastian However, the backlash against quantitative methods in the early s led to a general distrust in the use of statistics and a loss of proficiency amongst archaeologists that is still evident in university curricula these days.
More importantly, dealing with field survey data for site location analysis has proved to be one of the trickier statistical issues in archaeology, since we usually have little control over the representativeness of sampling, and there are no established procedures for dealing with uneven representation see, e.
Orton ; Verhagen : — Thirdly, site location analysis and predictive modelling have been criticized for being static, and not taking into account the temporal dimension of human behaviour. Again, this is much more a question of the availability of suitable data rather than of flawed methodology—temporal dynamics of site location patterns can only be studied fruitfully if we have sufficiently reliable dating of archaeological sites and if we have sufficiently detailed palaeogeographical reconstructions.
At a deeper level, this debate shows the everlasting struggle between the application and development of scientific theory. We cannot expect a method or technique to operate in a theory-neutral environment; our choice of research questions, study regions, methods and data sets is governed by what we think we know about the past and by what we think we need to do to expand our knowledge.
So if we really did not think that the environment influences site location choice, then we would never choose to analyse it. And on the other hand, patterns that suggest themselves to us, for example, while performing site location analysis, will find their way back into existing theoretical frameworks and either reinforce or challenge established opinions. Basically, we are still looking for answers to the question of what made people settle where at a particular point in time. For this, site location analysis is not the only possible tool, but it remains a versatile, powerful and relatively straightforward way to explore site location preferences over large areas, to detect patterns and anomalies in settlement distribution, to compare these between areas and time periods and to place these in perspective together with other sources of information.
The establishment of a standardized hierarchical classification of archaeological settlements. The selection of a reduced number of relevant environmental variables for analysis that could be standardized for all regions.
The analysis of not just the location of the site itself but also its immediate surroundings. The results of the site location analysis clearly showed how the rhythms of occupation and abandonment of settlement changed between study areas and over the southeast of France as a whole.
Instead of a political and economic crisis coupled to land abandonment and environmental degradation, it reflects a process of restructuration and stabilization of the settlement pattern, Exploring The Role Of Analytical Scale In Archaeological Interpretation British Archaeological Repor which settlement is contracting into fewer locations, but not necessarily exploiting smaller areas Favory et al. At the time, performing the necessary calculations was a considerable task.
The method however proved successful enough to be repeated in various other areas in France during the Archaedyn Project Gandini et al. Invariably, the site location analyses showed a different story of occupation pattern dynamics than was previously assumed on the basis of local studies. However, the analysis was limited to a comparison of environmental preferences.
Verhagen et al. Source: Verhagen et al. One of the techniques offered by GIS that has attracted much interest in archaeology is least-cost path analysis see, e.
Bell and Lock ; Llobera ; Bell et al. It is a method to find the optimal path between two or more locations. In a landscape that is characterized by differential accessibility, finding the most efficient route is a non-trivial task that requires determining the trade-off between distance travelled and obstacles on the route. These obstacles can be of a physical nature, like steep slopes, water bodies or vegetation hindering free movement, thus making detours potentially more attractive than taking the straight line.
But we can also think of obstacles of a social nature, such as the presence of enemies, toll roads or even taboos on entering certain areas. Tools for finding the most efficient route are implemented in all GIS software. First, a cost surface is defined that determines the costs of crossing one grid cell, usually specified in time or energy units spent.
Slope is amongst the most common cost factors considered, and a number of methods have been developed to determine movement costs associated with slope Herzog Different types of costs monetary, social could be included as well, but this will make things more complicated since we then cannot use the same cost units anymore.
(Archaeology South-East); the development control archaeologists who .. on post-excavation analysis, in particular on the analysis and reporting of artefacts. The Rural Settlement of Roman Britain project and in particular the including the context and scale of projects, and the types, quantities and dates of artefacts.
Finally, we can then determine the least-cost path between the starting location and any other location, giving us some idea on where transport and movement may have taken place see, e. The accumulated cost surface can also be used to find the area that can be reached within a certain amount of time or by spending a maximum amount of energy. This is often used to analyse the size, location and environmental characteristics of Exploring The Role Of Analytical Scale In Archaeological Interpretation British Archaeological Repor territories see, e.
These can be used to analyse the relative accessibility of a certain location. The definition of the cost surfaces is seen as the main obstacle in least-cost path modelling. Furthermore, different modes of transport can lead to different optimal paths: carts carrying heavy loads will have more difficulty negotiating steep slopes see, e. Bevan The optimal path in such a situation may not be the one that takes least time or energy, but one that also uses the existing infrastructure.
In practice, therefore, least-cost path analyses have only been moderately successful in reconstructing past routes and movement see, e. Furthermore, validation of the models will be problematic in most cases since most prehistoric roads are difficult to detect—if they have survived at all.
The application of least-cost path modelling is therefore more fruitfully seen in the light of hypothesis development and testing of where people might have moved in the past and what factors may have been influencing movement and transport. More recently, it is acknowledged that social network analysis SNA techniques can be helpful to better understand the interaction between settlements and other transport nodes and to analyse patterns of communication at the regional scale Verhagen et al.
The Kromme Rijn study area is located on the south bank of the river Rhine, where differential accessibility is mainly due to differences in wetness: the low-lying floodplains are more prone to flooding than the levees, and thus movement is spatially constrained by the location of palaeo-channels in the area.
By combining data from physiological experiments and specifying different costs for different modes of transport on foot—unburdened and burdened—and by mule cartit was possible to create LCP models connecting all Roman settlements in the area for different modes of transport and for different time slices, departing from a detailed palaeo-geographical reconstruction and a comprehensive site database.
Betweenness centrality measurements of Early Roman sites in the Kromme Rijn area, the Netherlands, based on least-cost paths calculated for mule cart transport. Source: Groenhuijzen and Verhagen The analysis results indicate that the sites showing signs of higher status as derived from the presence of stone building remains are relatively well connected, which might indicate that their position in the network may have contributed to them becoming more important during the Roman period.
It is also noteworthy that the network configuration, as well as the importance of settlements, changes with different modes of transport, since the options for mule cart transport are much more limited than for movement on foot. Furthermore, the military limes road, located close to the Rhine, and which has been the subject of most research on transport in the Dutch limesis not very important as a connection between settlement sites.
Obviously, this road did serve to connect the castella on the Rhine, but the lack of settlements on the Rhine banks means that it may not have been used frequently for local transport; the castella and adjoining vici were therefore peripheral to the local transport network. The third major branch of GIS methods that made its way into archaeology is the calculation of lines of sight and viewsheds.