Grand Challenges of Geoarchaeology?
I have a very important deadline tomorrow, hence it's the perfect time to do a blog post for Doug's Archaeology Blogging Carnival. Last year I took part in a series of posts about the purpose of blogging. This time the theme is Grand Challenges facing archaeology, specifically the participant's archaeology. In my case of course this is geoarchaeology. It's a good theme for me, as it's something I've been reflecting on a lot recently. I am writing a paper on investigating 'use of space', and multi-proxy approaches in archaeology. It's half review, half critique, and is turning into a bit of a monster. What follows is some of the central thoughts I am discussing in that paper, so actually any comments and feedback would be much appreciated!
One of the major challenges that I see facing geoarchaeology, is the integration of data from different scales. How do we use data collected for example at the microscale (such as geochemical patterning of floors, sediment micromorphology), and link this back to activities and processes at larger scales? I first started thinking about this over a decade ago, during my PhD, in relation to the landscape surrounding Catalhoyuk. There has been a long running idea (though recently this is changing), that the land surrounding Catalhoyuk was a big marshy swamp. This was based on a series of sediment cores that identified 'backswamp' deposits. One problem I always had with this was how we extrapolate from a small number of cores, to what is a very large landscape. How representative are these cores - are they telling us about the wider landscape, or something very localised?
This got me thinking about sample sizes in general. When studying individual skeletons (as an example), how many do we need to look at before we can make generalisations about the population? And when we are studying buildings, how many buildings do we need to study to understand the patterns of use of space within a settlement? At Catalhoyuk we have seen an impressive suite of science applied to building floors, in an attempt to reconstruct activity patterns. This has included thin section micromorphology, microartefact patterning and geochemical analyses, phytoliths and starch, alongside artefact studies, macrobotanical and zooarchaeological analysis. In order to understand activity, it is important that we look at all of these lines of evidence together. An activity does not always (often?) leave a single material trace. The integration of different lines of evidence is what is meant by multi-proxy archaeology. The potential of a multi-proxy approach is that it provides a more complete characterisation of the material record, and thus focuses the range of possible interpretations (in theory!). By bringing together multiple lines of evidence, we can better define specific activities which produce an ‘assemblage’ of signals.
But how do we do this in reality? Samples and data are collected by different specialists at different scales, and though it may seem easy enough to go back and compare data afterwards, it can be surprisingly difficult. Micromorphology for example can rarely be directly integrated with microartefact patterning. Whilst microartefacts represent cumulative deposition (palimpsests of activity), micromorphology looks at single (or close to single) events sequentially. For multi-proxy archaeology to work properly, samples must be collected together, and analysed together (ideally with the same aims). In theory, the reflexive methodology that was proposed for Catalhoyuk is supposed to overcome this problem. Rather than looking at different categories of material in isolation, a reflexive methodology 'keeps finds in their context'. But again, how? It's a question of scale, and a question of focus. Multi-proxy archaeology works well in hypothesis-led analysis, but often archaeology works in a more exploratory fashion.
In the end, what we have with Catalhoyuk (from a microanalysis perspective) is a small number of buildings studied in an incredible level of detail, but without the analyses being comparable a lot of the time. How representative are they of the settlement as a whole? Sometimes what we have is not even a reflection of activity within the building, but a reflection of variations in building materials. How much time (and money) should we spend on obtaining such an incredible level of detail? I think the grand challenge for my archaeology, is resolving this problem of scale, and defining the relationship between the details of microanalysis, and the bigger picture.
One of the major challenges that I see facing geoarchaeology, is the integration of data from different scales. How do we use data collected for example at the microscale (such as geochemical patterning of floors, sediment micromorphology), and link this back to activities and processes at larger scales? I first started thinking about this over a decade ago, during my PhD, in relation to the landscape surrounding Catalhoyuk. There has been a long running idea (though recently this is changing), that the land surrounding Catalhoyuk was a big marshy swamp. This was based on a series of sediment cores that identified 'backswamp' deposits. One problem I always had with this was how we extrapolate from a small number of cores, to what is a very large landscape. How representative are these cores - are they telling us about the wider landscape, or something very localised?
This got me thinking about sample sizes in general. When studying individual skeletons (as an example), how many do we need to look at before we can make generalisations about the population? And when we are studying buildings, how many buildings do we need to study to understand the patterns of use of space within a settlement? At Catalhoyuk we have seen an impressive suite of science applied to building floors, in an attempt to reconstruct activity patterns. This has included thin section micromorphology, microartefact patterning and geochemical analyses, phytoliths and starch, alongside artefact studies, macrobotanical and zooarchaeological analysis. In order to understand activity, it is important that we look at all of these lines of evidence together. An activity does not always (often?) leave a single material trace. The integration of different lines of evidence is what is meant by multi-proxy archaeology. The potential of a multi-proxy approach is that it provides a more complete characterisation of the material record, and thus focuses the range of possible interpretations (in theory!). By bringing together multiple lines of evidence, we can better define specific activities which produce an ‘assemblage’ of signals.
But how do we do this in reality? Samples and data are collected by different specialists at different scales, and though it may seem easy enough to go back and compare data afterwards, it can be surprisingly difficult. Micromorphology for example can rarely be directly integrated with microartefact patterning. Whilst microartefacts represent cumulative deposition (palimpsests of activity), micromorphology looks at single (or close to single) events sequentially. For multi-proxy archaeology to work properly, samples must be collected together, and analysed together (ideally with the same aims). In theory, the reflexive methodology that was proposed for Catalhoyuk is supposed to overcome this problem. Rather than looking at different categories of material in isolation, a reflexive methodology 'keeps finds in their context'. But again, how? It's a question of scale, and a question of focus. Multi-proxy archaeology works well in hypothesis-led analysis, but often archaeology works in a more exploratory fashion.
In the end, what we have with Catalhoyuk (from a microanalysis perspective) is a small number of buildings studied in an incredible level of detail, but without the analyses being comparable a lot of the time. How representative are they of the settlement as a whole? Sometimes what we have is not even a reflection of activity within the building, but a reflection of variations in building materials. How much time (and money) should we spend on obtaining such an incredible level of detail? I think the grand challenge for my archaeology, is resolving this problem of scale, and defining the relationship between the details of microanalysis, and the bigger picture.
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