Sunday, 26 March 2017

Micrograph of the Month: Roman floors

I haven't posted a micrograph for ages, but this one is so pretty I just had to share it. I'm in the middle of doing an analysis of Roman occupation deposits for the Lufton Roman Villa project. I don't know too much about the wider context yet, but my initial observations of this particular sample suggests we are looking at an old floor surface. There are 3 distinct layers, and the uppermost layer is composed of a calcareous material, in which are embedded lots of tiny crushed up ceramic fragments. The middle layer is a sandy aggregate with the occasional bit of soil/clay and charcoal, and there is a very thin lowermost layer (thin because of the sample size, not sure yet how thick it was in the field) which has a lot of organic material including wood and grass charcoal, and possibly fungal spores. I will be writing more on this as the analysis progresses, but for now here is a nice image of one of the ceramic fragments (the orangey-red rectangular inclusion) embedded in the grey calcareous/lime layer. This also shows the boundary between the lime layer and the underlying sandy aggregate.




Wednesday, 8 March 2017

Teaching archaeological sediment micromorphology part 2

This semester I've been teaching archaeological sediment micromorphology, as part of a third year module in geoarchaeology. I mentioned a few weeks ago how hard it was to teach a subject this complex in only 2 hours per week, and that in future I was thinking of removing it from Geoarchaeology and turning it into a stand alone module. I still haven't decided whether to do this, as I think it's important to have some teaching of it at UG level, but a module focusing entirely on micromorphology is probably more suitable for Masters level.

Related to my frustrations, I made an offhand comment on Facebook that despite it being one of my specialist subjects, sediment micromorphology is very boring to teach. More than any other method I have studied, micromorphology is definitely the one filled with the most jargon. Don't get me wrong, I think jargon is important. We need the specialist language to describe the many complex features and processes that we see in thin section, and to make that description as objective as possible. But it does pose challenges, both in teaching the subject, and in presenting research results. In the former, you just can't get away from the fact that there is a lot of repetitive rote learning involved. In the latter, it is no use simply giving a huge table of dense terminology that means nothing to non-specialists - people must rely on your interpretation rather than being able to see for themselves how you arrived at that interpretation.

I'm not sure if I annoyed or offended anyone with the post. It was more a sign of my own frustration, wanting to be a good and interesting teacher, and also knowing that it is just a difficult subject that takes a lot of time to master. A fellow micormorphologist made a comment for example that it was unfair that students doing dissertation projects on say isotopes, got higher marks than those doing micromorphology projects. This is a genuine concern - whilst isotope analysis isn't easy, it is definitely more straightforward as it is much more focused, and data collection is relatively easy (assuming the mass spectrometer is behaving itself). Micromorphology on the other hand is highly variable, requires a huge input of time (even more so for students who are very new to it), and it would be very difficult for a UG student doing it as part of a dissertation in a restricted period of time to come up with an analysis that was comprehensive and publishable. I'm not saying it's impossible, but it would be much more difficult than with isotope data. And to get the highest first class marks, most mark schemes say that the work should be of publishable quality.

I've been trying to work around this as part of the Geoarchaeology module, by focusing students on a limited set of criteria (the ones I think are the most basic/essential), and identifying common archaeological materials (bone, charcoal, ash etc). Whilst the analyses the students do won't be 'comprehensive', at least this way it will be clear whether they have understood the criteria we focused on in class. The classes are structured with an introductory lecture, going through a set of terminology using case studies, and explaining why these criteria are important. The students have a microscope in front of them at the same time, with slides that I have chosen that best illustrate the features we are discussing that week, and after I finish talking, they have an exercise to go through and apply the descriptive criteria to their slides.

I am wondering whether I should put together all the class materials as a sort of 'teaching handbook', and get feedback from the workshop participants at the DIG2017 conference in September?



Friday, 3 March 2017

Thin sections related to pyrotechnology in Bronze Age Sicily

The arrival of new thin sections is always exciting, but always daunting at the same time. Sediment micromorphology has to be one of the more challenging geoarchaeological techniques, simply because of the huge variety in the types of material you can encounter, and a deposit from one site never quite looks the same as one from another, even when they are related to similar activities. The samples from Case Bastione were collected to investigate formation processes and activities of a number of features in the Bronze Age settlement, including a large 'burnt' layer, and some strange pit deposits. The most striking thing about all the samples is the ubiquitous presence of these teeny tiny little creatures - my educated guess is that these are tiny foraminifera of some sort, present within limestone/chalk or another carbonate material (I need to do some research on Sicilian geology!). What is slightly confusing is the presence of a spherulite like appearance within the shells in cross polarised light. This isn't something I have seen before and I am not entirely sure what it means!