Thursday, 19 December 2013

Is Archaeology a Science?

Who'd have thought I'd find myself as co-convener for a third year Theoretical Archaeology module? Such is the situation I find myself in towards the end of my first year at the University of Edinburgh. I used to be one of those people who thought theory was all a bit confusing with no relevance to 'real' archaeology. This is an attitude I have found especially of researchers in archaeology who have a background in the sciences. What is the point of theory? Or I'm a scientist, I don't need theory! As an undergraduate I had a compulsory Philosophy of Science module, but I'm not sure how common this is for most science degrees. I think sometimes we don't realise that even as scientists with 'hard data', we have to interpret our data - and in archaeology especially, these data are always flawed in some way, and our interpretations steeped in our own experiences. It's a myth that scientific results can only have one interpretation. The way we use averages, choose our sample sets etc all impact the end results and skew them slightly in favour of one interpretation or another. Working on the Catalhoyuk project as a PhD student I couldn't really avoid theory, and the more I actually sat down and made the effort to make sense of it, the more it did make sense. It's one of those things that once it clicks, and you 'get it', you wonder how you ever did without it.
I am currently writing a power-point which includes a bit about deductive versus inductive reasoning. As I revise the topic I am reminded of a quote which is nicely relevant to my teaching next semester for two reasons, firstly it highlights the problem of inductive reasoning and ethnographic analogy which is sometimes invoked in archaeological interpretation, and secondly it is by David Hume, who happens to be from Edinburgh! Ok I confess, reading philosophical texts can be mighty confusing. I guess it will be a test of my teaching skills whether I can digest this into an easy to understand format for students!


Monday, 16 December 2013

Cracking archaeology Christmas present!

What a fab Christmas present idea for that special archaeologist in your life, a Catalhoyuk themed 2014 calendar! Stunning photography by the site photographer Jason Quinlan. Alas I doubt he decided to include any photos of coprolites. Still worth a look though, despite this obvious omission, there are many photos of lovely lesser features such as intricate wall paintings, Neolithic burials and exceptionally well preserved mud-brick architecture etc ;)

To Order: http://www.magcloud.com/browse/issue/674617 



Friday, 13 December 2013

Middens and microfauna

There was a nice surprise in the post for me this morning - a copy of a new book by Professor Terry O'Connor, Animals as Neighbours: the Past and Present of Commensal Species. I contributed an image for one of the figures, of midden deposits built up around Neolithic buildings at Catalhoyuk, Turkey. As O'Connor notes, Catalhoyuk is one of the earliest human settlements to have been colonized by house mice! Not surprising, considering the sheer volume of domestic waste deposits that accumulated in such close proximity to where people were living, and the density of human occupation. This also goes to show how useful it is to integrate different lines of evidence in archaeological research - my own work on middens at Catalhoyuk has shown they contain abundant human and animal dung, which also has interesting implications for understanding human health. Dr Emma Jenkins, who works on the microfauna at Catalhoyuk, has also identified large quantities of digested microfaunal material in burials, and suggests scats containing these may have been deliberately placed there for ritualistic purposes! Despite working there for almost a decade, I still find Catalhoyuk a fascinating place. How different these people were in many ways, but the lives of mice have not changed so much!

Sunday, 8 December 2013

The Earliest Neolithic of Iran

The long awaited CZAP volume is out at the end of this month, published by Oxbow. This is the first project monograph from the Central Zagros Archaeological Project (CZAP), and includes 2 (and a half) chapters co-authored by myself, on the biomolecular analysis of coprolites (oh that old chestnut!) and phytolith analysis. Dr Wendy Matthews coordinated the micromorphology analysis and directed sampling, and in the monograph she provides an excellent integration of micromorphology, phytolith and geochemical analysis to address questions about resource use and animal management at this early pre pottery Neolithic site.

I also did the chapter on molluscs - though I am in no way an expert on this, I was the most qualified person on the 2008 excavation team (having worked on a shell midden as an undergrad!), and as we unexpectedly ended up with an incredibly large volume of molluscs from the excavation, a brief preliminary report was needed (hence half a chapter - would make a great project for someone in the future!). I was part of the 2008 team, and headed out to the field literally the day after submitting my PhD. To this day it qualifies as one of the best excavations I've ever worked on (despite spending 2 months sleeping on the floor of a school classroom!). Iran is a wonderful country with a fascinating history and rich archaeological heritage, I feel incredibly lucky to have been able to take part in the project and spend time there. Sheikh-e Abad is a fantastic site, I met some wonderful people, and we made some really exciting discoveries! But you'll have to read the book to find out more about that!


Zagros archaeology - it's all about looking cool in the shades

Sunrise in the Zagros




Wednesday, 4 December 2013

Micrograph of the Month - Waterlogged Wood

Here are two examples of waterlogged wood, in deposits from Medieval Riga, currently being analysed as part of the Ecology of Crusading project. It's been almost a year since I started on these slides, which were prepared in December last year - there are so many of them it is taking me quite a while to get through. It's a fascinating set of samples, such a mix of materials with some interesting post-depostional processes going on. In the upper image you can see a fragment of wood preserved entirely through waterlogging, within a mixed deposit containing charred material. This little fragment of wood has been stained orange, which is typical of waterlogging and mineralisation. In the lower image you can see a fragment of wood which has been preserved through a mix of partial burning (as seen by the black colour in the lower part of the wood), whilst the non-charred part has been preserved through waterlogging. Waterlogged deposits are relatively rare - most plant material in the archaeological record is preserved by charring. It will be interesting to see what other types of materials have been preserved in these conditions, as we work through the slides. Hopefully it will provide insights into the use of plant resources as well as the activities that were occurring in this part of the medieval city.

Tuesday, 3 December 2013

Blogging Archaeology - the Good the Bad and the Ugly

It's December! That means I need to be thinking about a new micrograph of the month for your viewing pleasure, but for now here is my response to the second round of questions for the Blogging Archaeology blog carnival. Click here for more info and my response to the first round in November. Very interesting to see the range of responses to the last lot. I recognised a few of the blogs taking part, as well discovering some new ones to add to my reading list.


The Good- what has been good about blogging? 

I love writing and putting together images, and my blog is a great way to keep up with that in a way that is less time consuming and stressful than writing articles and lectures. Aside from the pleasure of simply writing, it's also great fun looking at my viewer statistics. It is quite satisfying to see where my audience comes from. Sometimes I can guess who it is, for example when my relatives in Oregon have been reading, and I also get a lot of views from Edinburgh, York and Reading, the three places where I have worked, which I assume is from friends and colleagues who find my blog posts when I link to them on Facebook. And then there are the totally random views - Malaysia, South Korea, the Dominican Republic! Keywords people have searched for are also great fun - one of the funniest being Who is the Queen of Coprolites? Let's just hope they weren't actually searching for me with that one.

The Bad (and the Ugly!)

I've been lucky, no bad experiences so far. For the future I hope that I will get more interaction on my blog. I have started doing 'critique' posts where I share my thoughts on recently published articles, with the aim of getting a discussion going. Despite getting between 40 - 100 views per post (according to Blogger stats), I've only ever had 1 or 2 comments, from people I know. Most of the time I don't get any response. Maybe I am not interesting enough, or maybe I am not reaching the right audience? It's a little frustrating, but it doesn't bother me too much. For now I am blogging for my own pleasure, and hopefully over time I will get some good discussions going!

I wonder if one reason for the lack of interaction is that many people are unsure about posting opinions publicly? Unlike anonymous peer review, you are putting your name to your comments, and that can be quite daunting. I was in two minds at first whether to start my critique posts (e.g "Phytoliths don't cut the mustard?"). But if I am willing to critique papers during peer review, I should be willing to support my views publicly, right? Constructive criticism is a very necessary part of academic pursuit. I do worry that anything 'negative' I say could receive a bad reaction, but I would hope most people are willing to have an objective discussion. I think having a blog-based dialogue between opposing views could actually be more effective than blind peer review?

Tuesday, 26 November 2013

Blogging Archaeology



I was invited today to take part in a blogging carnival, related to a Blogging in Archaeology session at the upcoming SAA conference. Quite handy actually as I can't attend the conference in person this year due to teaching commitments. What is a blogging carnival you may ask? Check out the original post on Doug's Archaeology here. Each month leading up to the session, a question is posted, and participants can choose to answer it via their blog. The answers are then all summarised at the end of the month. Hopefully this will highlight some new archaeology blogs to add to the long list I already follow (maybe I should do a post about that!).

Anyhoo. Here are my answers to the first set of questions:

Why did you start a blog?

I had been meaning to start one for years before I actually did. I have been a big user of social media since I was an undergrad, but always for personal rather that professional purposes. I eventually started my blog at the beginning of 2012 after organising my first conference. I found it to be quite an effort to advertise a conference and get people to submit papers, even one that had been around for several years, and I realised that having a blog for my professional activities could actually be quite useful.

Why are you still blogging?

After the first few posts I sort of got addicted to updating it and making it look pretty with pictures. But not just that, as I was halfway through my first postdoc and increasingly thinking about the academic job market and how to stand out from the crowd, it became apparent that the use of social media is one way of doing this. Blogging is becoming a useful tool for promoting research both within and beyond the academic sphere, and for having discussions. At some point I realised that it was also a great medium for sharing microscope photographs. I have a huge collection of images that I use for teaching, and only a fraction of them have ever been published. When I was learning micromorphology, it was sometimes very difficult to get good reference images, and I figured by posting these online it might inspire others to take up micromorphology, or at least to make the subject less of a mystery to non-specialists.

Friday, 1 November 2013

Micrograph of the Month: Starch inside a waterlogged seed

Here we have a series of micrographs showing a seed, embedded within waterlogged midden deposits at Neolithic Catalhoyuk. These are the earliest deposits from the Deep Sounding in the South Area, and are some of the only waterlogged contexts at the site. These deposits make a particularly interesting comparison to the later middens at the site, as we can look at the differences between waterlogged and non-waterlogged versions of similar deposit types.

In the many sections I have looked at, getting sections through seeds like this does not occur too often. I have see larger seeds from Celtis (hackberry) more frequently. This teeny little seed looks like it might be a Chenopod (the little bump on the left of the seed is a feature of Chenopods), though I'd have to ask an archaeobotanist to confirm.

The exciting thing about this is you can see the organic part of the seed still preserved within the endocarp - the orangey colour is typical of mineralised organic remains. In the lowermost image you can see the seed in cross polarised light, and the particles within the seed look like yellowish spheres with crosses. These are starch grains, which are often extracted from archaeological sediments to investigate plant use. This is a rare example of these microfossils in situ, both within the seed and within their archaeological context.

Thursday, 24 October 2013

International Archaeology Day 2013

October 19th was International Archaeology Day, not to be confused with Day of Archaeology which I have participated in in the past (2012 and 2013). Whereas Day of Archaeology is a blog based event, where people blog about their day as an archaeologist, International Archaeology Day is more a series of events organised by different groups and institutions. I was a bit late finding out about it so didn't have time to organise any events, but by browsing some of the online activities I discovered Wikipedia edit-a-thons. Specifically I came across Ada Lovelace and Trowelblazers edit-a-thons, which aim to celebrate women in archaeology, palaeontology and geology, by creating and improving Wikipedia articles. What a great idea! Wikipedia often gets bashed for being a poor source of information for academic work, but as a first stopping point to get your head around a subject it's really not that bad. As with any source, the ability to judge the quality of the information on there is essential, and of course it should not be a substitute for more in depth reading. But that's where the bibliographies and referencing comes in.

I've never done much with Wikipedia before, but I decided to sign up and give it a go in the spirit of International Archaeology Day. My first contribution has been quite humble - going through the list of renowned archaeologists and making sure all the women are classified under women archaeologists - but it's a start. The start of a terrible addiction I fear. There are many great articles on Wikipedia but a lot of it is not well referenced or organised systematically. These happen to be two areas which I am slightly obsessive about (as anyone who has asked me to review or mark work will know...), and I have now become addicted to improving Wikipedia archaeology articles! I'll post every so often with a summary of what I've been working on for anyone who is interested and/or would like to join me in my mission!

Wednesday, 23 October 2013

Catalhoyuk monographs

Just a quick update, it looks like the new Catalhoyuk monographs will be out in the next month! This set of volumes describes work at the site from 2000-2008 and includes a huge amount of new and exciting data. I have two chapters in Volume 8 summarising my PhD research on midden formation processes and our pilot study on coprolite and burial residues. These chapters include extra data, images and samples that were not included in the journal articles from 2011 that were published on these studies. 

Volume 8 details here.

Sunday, 13 October 2013

The Ness in Progress

Micromorphology block being impregnated with resin. Photo by Earthslides.
Not too much to report on my own activities this week, apart from the neverending email stream that has to be tackled on a daily basis. Sometimes I think it would be nice to declare an email bankruptancy and just delete them all and start anew. More exciting than the contents of my inbox however, are the updates from Earthslides on the progress of my micromorphology samples from the Ness of Brodgar. Julie Boreham from Earthslides runs a page called Hidden Worlds, Off the Bench, where she posts updates of her daily goings on in the lab. This week she has been working on the Ness samples, which are currently being impregnanted in resin, the first step in the process of turning them into slides. Check out her page here for more details!


Tuesday, 1 October 2013

Micrograph of the Month: Fabulous Fired Clay

Here is a nice series of micrographs from a little experiment I did many years ago, back when I was a research assistant at the University of Reading, shortly after finishing my PhD. Professor John Allen had collected a clay sample associated with the Roman town of Silchester, and conducted a series of firing sessions in a kiln, each in increments of 100°C, to provide a collection of reference slides for fired clays in thin section. As I had been working on infra red spectroscopy at the time, I used the same fired samples to produce a series of reference FT-IR spectra to compare with the micrographs. We presented this as a poster at the 5th Experimental Archaeology conference in Reading 2011, though I never really took the work further, as I became more interested in developing the use of organic geochemical techniques rather than inorganic. FT-IR is a great technique for certain materials, but archaeological samples tend to be so mixed and hetergeneous it can be hard to get definitive data with FT-IR. The raw clay was heated from 100 to 1200°C. Distinct colour changes and alterations in the fine fabric can be seen in thin section around 300°C, 500°C, 900°C and 1100°C, coresponding with structural changes in the clay as it becomes more crystalline.


Thursday, 5 September 2013

Hidden Worlds at the EAA 2013 - Pilsen, Czech Republic

Today was the first day of the 2013 EAA conference, held this year in Pilsen, Czech Republic. I've been to quite a few of the EAAs now, and they are always great for catching up with colleagues from across Europe and beyond, and this year is no exception. I've probably spend more of the conference today discussing work over coffee than seeing papers! So far I've met colleagues from Bristol, Reading and York as well as some Edinburgh folk.
This year, rather than giving a paper, I'm doing something a little different. Together with Julie Boreham from Earthslides, UK, I have put together a photographic exhibition of micromorphology slides from Paisley Caves. Julie did a similar exhibition a few years ago for the WAC 2008 conference in Dublin, which was a great success. The idea is to showcase 'Hidden Worlds' of archaeology under the microscope, and to communicate thin section micromorphology to a non-specialist archaeological audience. The large poster sized photos mean that viewers can look at all of the little details that we can see under the microscope, with a text commentary of the important archaeological features. Julie suggested we do an exhibiton focussing on a new set of slides from Paisley Caves - I talked about these a few weeks ago for the Day of Archaeology, and if you are interested you can click on the keywords for some older blog posts with snippets of Paisley info too. In the Paisley Caves exhibition, which was presented today, the analysis is an introductory overview of some of the key features that can be seen in the slides, and how they help reconstruct the sedimentary formation processes at the site.
I used to prefer giving papers at conferences, but they are often so short it is difficult to fit much in, and there is not always much time for questions and discussion. Posters offer a chance to get into more detailed discussions with people about the research. Not too many questions today unfortunately, but we did get a lot of people looking at the exhibition as we were handily located at the top of the main staircase next to the coffee break area!

Hidden Worlds at the EAA 2013

Monday, 2 September 2013

Phytoliths don't cut the mustard?

All over my news feed last week were links to news articles reporting on the 'earliest use of spices in Europe', specifically the use of garlic mustard seed (Alliaria petiolata) by Neolithic people. The evidence used to support this is our old favourite microfossil, the phytolith (frequent readers will know they come up in this blog quite frequently), which archaeologists have recovered from burnt food crusts inside Neolithic pots. The original research article is open access in PLoS ONE and can be read here: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0070583

I have been debating with myself whether to post these thoughts, as I know the team that did the work, and have great respect for them. But the subject is one I feel strongly about (as anyone who has discussed phytolith analysis with me will know!). So the aim here is to open discussion about the problems with microfossil analysis in general, and this happens to be a case study which illustrates many of these problems very well. It also makes for a great blog title! On a more serious note, I find myself once again feeling uneasy at the way phytoliths are increasingly being used in archaeology to support these big theories (earliest domestication of plant xx, earliest human use of plant yy, Neanderthals were master chefs etc), when phytolith analysis as a discipline still has so many flaws that need to be addressed. I recently reviewed some of these problems here (if you don't have access and would like a copy get in touch!).


There are very few phytoliths that researchers would agree are identifiable beyond genus, yet here we have the exact species being identified, with no explanation except that the sample most closely resembled garlic mustard out of the 120 reference species examined. I can't help but feel that the only reason this species was chosen is because it is the one that happened to be in the reference collection. Other phytolith studies that claim a species level identification (see my review for references) have spent a very long time doing work on modern reference samples, defining the criteria that make the phytoliths distinctive to species.

It is difficult to assess as I cannot find any published reference images of Alliaria petiolata phytoliths apart from the single image in this paper. Personally I am not convinced that the reference image bears much similarity to the archaeological phytoliths. Image A. in particular looks to be a smooth sphere (and about half the size) rather than the distinct pitted apearance in C (the archaeological example). The reference image, B. is similar but by no means (in my opinion) identical. We know from other phytolith studies (rice, maize, wheat) that these details of the phytolith 'decoration' can be subtle, and are essential in distinguishing different types.

This could be a matter of poor image quality. I've looked at enough phytoliths to know that they are often much clearer down the microscope (and in this study the samples were mounted in glycerol, which is not the best refractive index for observing phytoliths). But even if they are similar, this does not preclude other possibilities for their origin. I've seen too many other spherical phytoliths to be convinced (but I do want to be convinced!). How morphologically consistent are these within Alliaria petiolata? How morphologically consistent are these within a single plant? (not very, looking at the large size range in the reference specimen, 4.8 - 11.2 microns). How frequently do they occur within the plant? Although 120 references might seem like a lot, any botanist can tell you this is a fraction of the species present in Europe.

A plus point in the study is that the phytoliths were recovered from within a burnt crust rather than the soil, which narrows down the depositional pathways through which they entered the archaeological record. It is very reasonable to assume that they come from something that was in the pot when the food crust was formed. But whatever the species identification, the very small number recovered does not support the conclusion of the study that "it is demonstrated beyond doubt that the use of spice was practised regularly" (my emphasis).

These are just some of the questions that need to be addressed, not just in this study but phytolith studies in general. This is especially important when research makes the popular news. This is the way that things move from the world of academia into real world 'fact', and it is our responsibility as researchers to be careful in how we present data. Possibilities and suggestions should not become unequivocal and definitive.

On a related but different note, this paper does make a great suggestion that could be tested using experimental archaeology - garlic mustard and marine fats? Yum yum? And ending on a positive note, trying to address cuisine, and the way that plants were prepared and consumed, is an exciting avenue of research, a refreshing change from the endless studies on the nature and timing of domestication.

Please feel free to comment!

Detail from Saul et al. 2013 Figure 1 (original image here)

Sunday, 1 September 2013

Micrograph of the Month: Modern roots

In your sediments, post-depositionally disturbing your stratigraphy. Here we have examples of roots from modern plants that have grown into the archaeological deposits. They are easily distinguishable from archaeological plant remains as the tissue is fresh, organic and well preserved. Photo A shows a root that has grown into soft, ashy, compact midden at Boncuklu, Turkey. You can see clearly the void that has been created from the root's growth, which is the same shape as the root itself (3). We can also see a fragment of shell (1) and some small crushed bone fragments (2) embedded in the deposits. Photos B and C show close ups of modern root from Cesis Hillfort, Latvia. In B you can see where the root is divided into two rootlets whilst C shows the cell structure very clearly. Each of those 'jigsaw' shapes is an individual cell - it is cells like this that become infilled with silica during the growth of the plant, to produce phytoliths. This example of 'jigsaw' shapes within a root is interesting, as jigsaw shapes have been associated with woody dicots, rather than roots - another example of the multiplicity of phytoliths, with similar shapes occuring in diverse plants/plant parts. Photo D shows a root growing into looser, sandy deposits at Biala Gora, Poland. Here the void space is still root shaped (2), but less obviously so than the compacted Boncuklu sediments, which retain their structure better than the sand grains (1).



Sunday, 11 August 2013

Investigations at the Ness of Brodgar Days 4 and 5

Ben Chan discusses this week's progress on the site tour
This week has gone by so quickly, but we have managed to collect some great sets of samples, more than we can get made into slides at the moment! The first lot have already been sent off to Earthslides to get made into thin sections. An important lesson from the field - if you get over enthusiastic about collecting blocks of soil that weigh >1kg each, they will not fit in your luggage and will incur hefty postage fees. And lesson 2, blocks of soil wrapped in tissue and tape look very odd on the airport X ray and your bags will likely be searched. I ended up taking about 20 block samples in all, and spent much of my last day in Orkney panicking about how to transport them back.

 Friday was my last day on site, and the day started with a site tour with each supervisor summarising what has been going on in the building/trench that week. A week is just not long enough to get my head around everything going on at the Ness; I think I've just about come to grips with the major buildings and how my midden samples fit in. Luckily I have been working with a great team of archaeologists who have been incredibly helpful with explaining the current thinking for what is going on, and advising on the best areas to sample. Dan Lee and Dave Reay from ORCA deserve a special mention for putting up with my questions and putting multiple holes in their nice sections.
Midden after micromorphology sampling

I hope to return to Orkney at some point when the analysis of the slides is underway so we can discuss how the results fit in with the macrostratigraphy, and get further information on the different contexts. It's easy to get bogged down in the microscopic details with micromorphology, but it is important to remember that we are just looking at a snapshot from the bigger picture. I like to think of it as a two way team process, where fieldwork provides hypotheses that inform the micromorphology sampling strategy, and micromorphology provides information which clarifies what's going on in different contexts, especially helping to resolve finely stratified deposits that are impossible to excavate as true single contexts. The best bit will be seeing all the results come together, then we can get on with the difficult bit - interpretation! What will these midden deposits tell us about the Neolithic people at the Ness?

Friday, 9 August 2013

Investigations at the Ness of Brodgar Days 2 and 3


Planning sampling strategy with Jo

After planning the sampling strategy, the next few days have been spent collecting samples. I decided to focus on two areas of nicely stratified midden for the main sampling, and have collected overlapping sample blocks to provide an overview of the entire sequence. Already it's possible to see some quite ashy areas, so hopefully we will be able to get some nice information on resource use, and hopefully what activities the fuels relate to. We decided on a further 4 areas as secondary sample sets with a smaller number of samples, testing specific hypotheses from the excavations. More on those later this week.

As well as the Orkney students, we also have a team here from Willamette University, Oregon, led by Professor Scott Pike. Professor Pike has a background in geology and expertise in pXRF (portable X-ray fluorescence). In brief this involves using a piece of kit that looks like a ray gun to fire X rays at material, which then reflects the energy back. Different elements reflect the energy in different ways, and can be identified on this basis. His team have been conducting analysis of floor deposits to identify activity areas from chemical signals, which fits in really well with our micromorphology.  Certain elements are associated with human activity, for example phosphorus, and by mapping the concentrations across the floors we can get a good idea of the intensity of activity in different parts of a building. Yesterday Scott and his students took readings from the 2 main sequences of midden deposits I have sampled, with the aim of providing a complementary set of geochemical data that can be linked to the micromorphology observations. This way we can provide both a visual and chemical characterisation of the deposits, and hopefully a more secure interpretation of the formation processes and activities that are represented.

Sample block ready for removal
It's been great working here over the past few days. Perhaps not suprisingly, there have been quite a few familiar faces at the site, and it's been great to catch up with a few people. Professor Mark Edmonds from the University of York is here helping out with excavations and providing his expertise on the lithics (some amazing stuff coming out whilst I've been here, again check out the site blog!), and Dr Ben Chan, who I worked with on the Feeding Stonehenge project, is also here running one of the excavation trenches. I also got to meet a few people who I've only ever spoken to by email, including Dr Roy Towers, the pottery specialist who sent me the samples for the pottery residue pilot study I did last year at York, as a side project to the Feeding Stonehenge analysis. I just wish I was able to spend more time on site this year - one of the great things about fieldwork is getting the chance to spend time with like minded folk who share your excitement about ancient rubbish heaps.

Tuesday, 6 August 2013

Investigations at the Ness of Brodgar, Day 1

ORCA project officer Dan explains what's going on with middens
Marvelous midden at the Ness of Brodgar - check out those ashy layers!
Earlier this year I was fortunate enough to be awarded 2 small grants from the Society of Antiquaries of Scotland and the Orkney Archaeological Society, to carry out a pilot microarchaeology study at the Ness of Brodgar site in Orkney. The Ness of Brodgar is part of the Heart of Neolithic Orkney World Heritage Site, and excavations are directed by Nick Card of ORCA/UHI. The site is one of the finest examples of Neolithic archaeology in the UK (along with the rest of Orkney!), and the extent of preservation of the buildings and middens provides a rare opportunity to study the subsistence activities of the inhabitants.
The architecture here is some of the most impressive I've ever seen. It's interesting to note that the dates for the Neolithic here go to around 2500BC - roughly the same date that the Great Pyramid of Giza was constructed. We don't always realise that people were doing equally as impressive things closer to home at this time!
Although much of my previous work has been on Near Eastern Neolithic sites, my interest in the British Neolithic has grown since working on the Feeding Stonehenge project for 2 years, and it is very exciting to have the opportunity to apply my methodological expertise at the Ness.
Yesterday was my first day on site, assessing the deposits and planning a sampling strategy alongside fellow micromorphologist Jo Mackenzie. Jo will be working on building floors, looking at variations in their construction, whilst I will be working on the middens, looking at formation processes and activities. Already in the field we can see some ashy layers in both the middens and building hearths - these will be targeted for phytolith analysis, with the aim of identifying different fuel types that were being utilised. The excavation has its own blog which details daily activities and finds which you can read here. More updates on fieldwork and sampling at this amazing site will follow over the next week!

Thursday, 1 August 2013

Micrograph of the Month: Varieties of Gypsum 1

A: gypsum plaster (Tell Brak, building) B. microcrystalline gypsum (Catalhoyuk, midden) C. gypsum rosette (Kamiltepe, building) D. microcrystalline gypsum (Kamiltepe, external area)
This month we have some micrographs showing examples of some different ways you might encounter gypsum in archaeological thin sections, part 1 as there are a few other forms that I don't have photos of yet but will aquire at some point. Gypsum (aka calcium sulphate) often occurs in Near Eastern samples as a post-depositional feature, where the calcium sulphate salt, dissolved in water, precipitates as the water evaporates. The growth of the crystals can often cause a lot of damage to intact deposits, as the growth of the crystals pushes apart the material. The crystals can have a widely variable morphology, as a result of different formation mechanisms. As well as precipitation from water evaporation, the salts can precipitate due to the solution becoming saturated (i.e. there is so much present no more can be held in the solution), and the type of gypsum crystals has been used in environmental studies as an indicator of aridity. 
In micrographs B and D we can see microcrystalline gypsum, where the individual crystals are very small, and have precipitated within void spaces (in B the void is a crack, in D a plant void). In micrograph C we can see an example of a small 'gyspum rose', where the crystals form a rosette pattern. 
Another type which can be seen in last month's blog is called prismatic gypsum, unsuprisingly due to the single crystals being prism shaped. Similar to this is lenticular gypsum, where the crystals are more rounded and 'lens' shaped. According to Cody (1979), lenticular crystals form in the presence of plant organic matter under alkaline conditions. 
Perhaps the most interesting of these images is A, which shows a layer of gypsum plaster in a building at the site of Tell Brak, Syria in cross polarised light (micromorphology studied by Dr Wendy Matthews, University of Reading). It is very similar in appearance to microcrystalline gypsum, but you can see that it has been prepared as a surface - the pale grey-brown in the lower part of the image shows layers of plaster 'wash' over the thicker gypsum surface.

Cody, R.D., 1979. Lenticular gypsum: occurrences in nature and experimental determinations of effects of soluble green plant material on its formation. Journal of Sedimentary Petrology 49: 1015-1028

Friday, 26 July 2013

Day of Archaeology 2013

Paisley Caves – a view from the microscope

Today's post is for the Day of Archaeology 2013, go check out their website for lots of great posts about the diverse things archaeologists get up to on a day to day basis.

Wednesday, 24 July 2013

A dung debate?

I never imagined I would end up being a specialist on the subject of archaeological poop, but there you go. Coprolites, animal dung, palaeofaeces you name it. So I was very intrigued by an article published in the Proceedings of the National Academy of Sciences last week, claiming evidence for the earliest use of manure by European farmers 8000 years ago.

Firstly let's consider the different methods that we can use to identify dung in the archaeological record. These can be divided into direct and indirect methods. The former include definitive evidence for the presence of dung, that is actual dung pellets, or lipid biomarkers which are found exclusively in dung (i.e. faecal sterols and bile acids from the gut). The latter include evidence which is suggestive of dung, for example weed seed assemblages. Although indirect indicators are often the only thing available in archaeology, in my opinion one cannot make definitive statements based on indirect evidence. The best we can do is suggest likely possibilities, or hypotheses that can be further tested. The PNAS article uses a new indirect indicator - nitrogen isotope values of crops - to suggest the addition of dung to the plants (specifically an increase in N 15 in manured crops - Bogaard et al. 2007, Fraser et al. 2011). I am not an isotope expert, so cannot comment too much on the reliability of this new method, though the comparison of 'inferred' values of forrage to show enriched levels in cereals seems problematic. Herbivore forrage values were only estimated for 6 of the 13 sites studied, using a very indirect method of taking herbivore bone collagen values and subtracting an estimated 4‰ average to compensate for trophic shift. I would much prefer to see real values measured on actual forrage plants.

Let's also consider archaeological evidence for the presence of agriculture - crop remains (preferably domestic forms), farming tools, crop processing tools. To say that agriculture is present at a site, we would like to see a number of these indicators. Multiple lines of evidence are better than one. Likewise, in order to say manuring was taking place, we would like to see definitive evidence for the presence of dung, and also evidence that it was being deliberately applied to crops. There is no mention in the PNAS article of any other evidence that would support the hypothesis of manuring at the sites investigated. Although it is a reasonable interpretation to make, I would prefer to see more direct evidence of manuring practise rather than relying on something as indirect as nitrogen isotopes in crops. Even in the case of sterol biomarkers, which provide direct evidence of the presence of dung, or even when actual dung pellets are observed, it seems to me a bit of a leap to say that this indicates deliberate manuring of crops. Another possibility is that animals simply wandered around in the same area as crops were being grown, adding their dung deposits without intention.

How can we say for sure that people were deliberately and consistently manuring these crops? This would require 'manuring markers' to be present in the majority of crops over time. Unfortunately it is impossible to determine this, as the istope analysis was conducted on bulk samples i.e. multiple individual grains (this number varied from 2 to 'at least 10' according to the paper) were combined together for analysis, giving an average signal for all the crops from a single stratigraphic unit. How do we know what the variation in manure presence was across these individual plants and across different periods? And are 2-10 individual grains really representative of agricultural practises? These are very low numbers of samples which always makes me a little uneasy, even if it is sometimes the case in archaeology that we just have to work with what we have rather than having statistically significant numbers of samples.

The article mentions significant diversity in N values within some of the sites, interpreted as local variation in manuring rates, comparable to modern 'traditional' farming regimes. Couldn't this just be local variation in the presence of manure? Just some random thoughts - I actually really like the article, and the hypothesis is a good one. I'm just not keen on making definitive statements when there are other possible explanations. Hopefully further testing of the hypotheses will provide other lines of evidence in support!

Comments welcome as always.

Changing perspectives

July appears to be whizzing by nicely. Unusually for me, I am still in the UK. For the past 10 years (has it really been that long?!) I have spent every summer abroad doing fieldwork, and for most of those summers at least a few weeks have been spent collecting samples at Catalhoyuk in Turkey. This year will be the second year that I have been unable to go - last year I was coming to the end of my contract on the Feeding Stonehenge project and had to stay in the lab, and this year I have too many teaching commitments and writing to complete. Depsite this I will still be doing some UK based fieldwork in the next couple of weeks, more on that as it happens. Lucky for me in the age of social media and blogging, I can keep up to date with the latest news from Catalhoyuk as it happens via Scott Haddow's blog, A Bone to Pick. Scott is a member of the osteoarchaeology team at Catalhoyuk and has been posting regular updates, including an amazing find of intact woven textile in a baby burial. It is funny how much more emotive such finds are now that I am a parent. Up until this point I have always had quite a sense of detachment when working with human remains. I guess in some ways it can only be useful to have a sense of empathy during interpretation, though of course it is important to maintain a sense of objectivity.

Honeycomb weathering at Tynemouth Priory
And in entirely unrelated news, here is a lovely example of honeycomb weathering for your geoarchaeological viewing pleasure, from a recent visit to Tynemouth Priory on the Northeast coast of England. You can see examples of this distinctive weathering pattern concentrated in specific parts of the priory and surrounding walls, presumably due to the direction of prevailing winds.