Thursday, 28 February 2013

Middens from the Mound of Beads

Ashy midden deposits in thin section.
Since starting my new job as a Research Fellow, I feel like the amount of actual research I have done is limited! But I have spent plenty of time applying for money to do research. It must be nice being a researcher in a subject that doesn't require expensive laboratory work or sample processing. I have daydreams about spending all my time just reading and writing in a nice quiet library somewhere, preferably overseas and sunny. On the plus side, the more funding applications I write, the quicker it gets, and sometimes I even get the money! I just found out recently I was awarded a University of Edinburgh Munro Research Grant to complete the pilot work I've been doing on material from Boncuklu Hoyuk ('the place of beads') in Turkey. I started working there after finishing my PhD, I think the first samples I collected were in 2009, but due to the expense of producing thin sections, I was not able to get them processed at the time. As part of my ongoing work at Catalhoyuk I managed to get 2 Boncuklu slides made at the end of 2011, but this new grant will enable me to get the rest of the pilot samples processed so I can write up the results. Better late than never!

Collecting micromorph blocks from a sub-floor burial at Boncuklu
Boncuklu Hoyuk is a possible predecessor to Catalhoyuk, and so it makes a great case study to take my research further back in time, and look at human activities, resource use and disposal in the earlier Neolithic of Anatolia. As I mentioned in my previous blog on the site, it is also very interesting from a methodological perspective, as the midden deposits are much shallower than many of the deposits I've looked at from Catalhoyuk. On initial observation they look more similar to Catal's external area deposits and exposed midden deposits from the late Neolithic TP Area - it seems the earlier deposits are much better preserved due to their deep burial, whereas the younger deposits are much more bioturbated. The opposite of what is normally expected.

So another large box of soil will be making it's way to Julie Boreham at Earthslides.com, who produced the first 2 slides from the site and produced the lovely slide scan above. This is a curious sample - a thick ashy midden with limited evidence of fine layering at the macroscale. Is this a single event or multiple episodes of deposition that have become more homogenised due to the shallow stratigraphy? And there are many, many phytoliths! Now just to check if they are coming from the ash itself or if there's any evidence of animal dung burning...


Tuesday, 19 February 2013

Layers of time


Natasha K. Loeblich's winning image

I rarely make more than one post per day, but I just had to share this amazing image by researcher Natasha K. Loeblich, which was awarded a distinction in the 2008 Nikon Small World Photography competition. The image shows layers of paints in a colonial townhouse building, and Natasha's work has helped understand what the townhouse looked like during different periods of occupation, which can then be used for repairing historic buildings in an authentic style. You can read more about the research project here. The image was posted recently on io9 website, and many of the reader comments remarked how 'sparkly' the paint looks - it's suprising how materials can appear very different when viewed at the microscopic scale, and materials such as paints which may appear smooth and homogenous, are actually made up of different types of particles. Natasha is an art conservator and paint analyst with a background in architectural history, and her work demonstrates how much archaeology can learn from other disciplines. The techniques she uses (such as cross section analysis, SEM, FT-IR) are identical to those we use in archaeology, and even the application in this particular example is very similar. Her image shows a 'thick' section through the paint, whereas the Catalhoyuk image is a 'thin' section - the same thing really, except the thin section can be analysed using transmitted light, whereas a thick section is examined with reflected light. Both can be analysed further using chemical techniques if they are left without a glass coverslip.


Wall plasters from Building 1 at Catalhoyuk
The image reminded me of one of Dr Wendy Matthews' slides from a Neolithic building in Catalhoyuk (Building 1 for those of you who are familiar with the site); her research into wall plasters has helped understand how long buildings were occupied, how often they were redecorated, how clean they were kept, and how this changed over time. In the image to the right you can see how the layers vary from less frequent thicker, pale brown layers, interspersed with multiple sequences of fine 'grey' layers. These grey layers are actually marl based plaster, and appear much whiter at the macroscale. The large white areas in the thick layer are voids - spaces in the plaster matrix where there was once plant material (used as a temper), that has now decayed. These thick layers represent resurfacing of the walls, whilst the fine layers are plaster 'washes'. Check out Wendy's 2005 publication in the Catalhoyuk monograph for more info:

Matthews, W. (2005) Life-cycle and life-course of buildings. In: Hodder, I. (ed.) Catalhoyuk Perspectives: Themes from the 1995-9 Seasons. McDonald Institute for Archaeological Research and British Institute of Archaeology at Ankara, Cambridge

On a technical note, the Catalhoyuk image is presented the 'wrong way up' - as it is from a wall it should be at 90 degrees, but I wanted to show the similarity with Natasha's image.




Reunited at last!

I will sort them into subject areas at some point
Not too much to report from February. There are lots of things in progress, but I've spent a lot of time getting the facilities set up at Edinburgh, with relatively little time spent on new research. Hopefully now that most of the new lab kit has been ordered I can get going with all of the projects that have been put on hold during the moving process. Speaking of moving, having been based at three different universities over the past few years, my belongings have become somewhat spread out across the country, and I thought now would be the time to try and consolidate everything - mostly books! I had a parcel arrive from the University of Reading a few days ago, containing a whole load of books that I forgot to take when I moved to York in 2010 (I say forgot, most likely I didn't have the energy to pack up another two shelves of books from the office after clearing out everything at home). Mostly books on analytical chemistry, but also my beloved copy of Mellaart's Catalhoyuk a Neolithic Town in Anatolia.
The chemistry books are largely inorganic. I used a combination of inorganic and organic geochemical methods during my PhD, but as the research I was doing at York was entirely organic chemistry, I haven't really needed any of these for a while. But hopefully now that I am able to spend more time on near eastern inorganic materials, these will come in handy again.
The infra-red reference manual by Farmer was one of my most used books during my PhD, though since then an excellent online reference collection has been made available by the Kimmel Centre for Archaeological Science here. Fourier Transform Infra-red spectroscopic analysis (FT-IR) can be used for analysing organic and inorganic materials, but in archaeology is largely applied to inorganic materials such as ashes and plasters. FT-IR tells you the types of bonds present, and can also give a 'fingerprint' for the whole compound. However, as the same types of bonds can be present in multiple molecules, we have to be very careful to interpret these correctly. This is especially true in archaeological samples, which are often a mix of multiple different materials, making interpretation even more difficult. For organic materials, GC-MS has the advantage that it seperates out all the different components, making identification easier.

Friday, 8 February 2013

Micrograph of the Month - Glauconite Grains

I've been working on and off on these samples from Biała Góra (Poland) as part of the Ecology of Crusading project. We collected them back in June 2011 along with a coring transect survey to assess the nature and extent of the 'cultural layer' at the site. It's a very shallow deposit containing lots of broken ceramics and animal bones etc. The sediment itself looks similar to 'dark earth' deposits in the field, of which there have been many micromorphology studies, largely led in the UK by Dr Richard MacPhail

The micrograph shows the lowermost 'natural' deposits (upper in PPL and lower in XPL), which consist of a silty sand deposit which becomes coarser further down the profile. The pretty greenish grains are glauconite, an iron potassium silicate mineral, which is thought to be indicative of a marine depositional environment. They can be seen especially clearly in XPL in the lower image. 

The geology is this part of Poland (as I found out after many hours of searching through obscure journals) consists of fluvio-glacial Pleistocene sediments associated with the Vistula River. But as you can see in the upper micrograph, there is some fine organic material clustering between some of the sand grains. This is the beginning of the upper unit, where the abundance of organic material and degraded anthropogenic inclusions increases dramatically. It is these components of the deposit that give it the 'dark' colour, compared to the bright yellow of the underlying sands. For more info on Biała Góra check out the 2011 project gallery article in Antiquity.