Well, it took its time, but the report of the archaeological investigations in 2014 is now finally ready 🙂 You can read it or look at the pictures in it here: Ilves Kvarnbohall 2014 (although there is a short abstract in English, the main text is in Swedish).
Category Archives: Site report
Results from the geochemical analysis
Finally, the results of the soil analyses are tripping in! In autumn, I sent quite a lot of soil from the longhouse site in Kvarnbo to Sweden to be analysed for plant macrofossils as well as for different geochemical properties of the soil; and, now, I have received the report from Samuel Eriksson from the Environmental Archaeology Laboratory at Umeå University. Samuel analysed 10 samples, ca 20 gram each, for parameters such as MS, MS550, CitP, CitPOI and LOI 😀 (you just got to love the abbreviations instead of lengthy explanations, don’t you!) – In any case, MS stands for magnetic susceptibility of soil, which reflects the presence of magnetic iron-oxide minerals resulting by burning, meaning that fire increases the magnetic susceptibility of soil. MS values are for the “natural” magnetic susceptibility of the soil in the original sample, while MS5500 values stand for the results after heating the original samples at 550 °C in the laboratory. Laboratory-induced heating is executed since the magnetic susceptibility of soil may be naturally high or low without connection to anthropogenic processes and laboratory ignition is kind of reference to the original samples. Simply put – this analysis tries to find out if the site/feature has been affected by fire. CitP and CitPOI are related to phosphates – both the organic and inorganic fractions, where CitPOI gives a reading of the sum of inorganic and organic phosphate. LOI stands for the amount of soil organic matter. Basically, these analyses try to find out if lots of organic waste has been deposited on the site or in a certain feature. And, below, you can see the results:
What does these “pillars” say? Well, one of my main questions while sending in the soil for the geochemical analysis was to find out which features have been affected by fire and which haven’t, in order to, among other things, separate different features from one another and find out if the longhouse has been burned or not. And the answer is in the MS values – features connected to the structure of the house interpreted as a feasting hall do not show traces of being burned! However, as you can see, two features deviate from the general MS pattern and can be seen affected by fire and at least in case of one of these features, I do wonder if it represents the bottom of a hearth? These and LOI values will be interesting to relate to plant macrofossile analysis results when I get hold on that report as well.
Feature sections’ overkill
I’m a bit sorry for posting this picture, but, these sections, the digitalized versions of these do look kind of nice (?) 🙂 and digitalizing these arcaeological features from 3D models (and not from the photos on this picture) is what has occupied me for the past few days. But, now, this work is done (wohoo!) and I am determined to get my site report largely finished by the end of this week.
After having been digging and writing tens-and-tens of technical site reports for the past 10 month, how much fun do you think it is to write another site report?? Even if it is a site report on the archaeological investigations at “my own site” of Kvarnbohall? Well, let me be frank, not so much fun… or, maybe, just marginally fun. Site reports are, after all, quite boring to write as it is mostly about technical data. Although, site reports are, at the same time, also, one of the most important kinds of archaeological writing. Anyway, I am back to working with the excavation data from the investigations at Sa 14.9. When it comes to this particular site reporting, I managed to do a lot during the autumn already, but, apparently, I then started from the simpler end and have to deal with all the complex issues now… Todays “headache”, for example, is the section below – the cut was placed through two features, feature 3 = the wall and feature 4 = post-hole, but the section revealed at least 4 different features, which I had, in fact, documented during the excavations already, but digitalizing the data was, nevertheless, not easy; despite the fact that I had my 3D models and a quite a number of photographs and my own excavation diary entries to aid the work… 11 sections digitalised… 10 sections to go… sigh?
My very own photogrammetric revolution
Lately, I have spent so many hours in front of my computer that I have no such thing as free time anymore and I hardly know what is happening outside, especially, as this sitting in front of the computer can only be done after my regular work at the Museum of Åland. My obsession is connected to photogrammetry 🙂 As I have written here before, during the excavations at the longhouse site in Kvarnbo, we chose photogrammetry as a main documentation method and totally skipped time-consuming hand-drawn recording (yep! totally!). Photogrammetry is a process that produces spatially accurate images from ordinary 2D photographs – with these images being georectified one can produce photographic plans of the site or a feature and its stratigraphy and one can take accurate measurements directly from the photo. And, the 3D models created from the same photographs create a visually very rich final product that you can go back to again and again. As there were quite a lot of features discovered and I am pretty new to the method, you can imagine that much of the time is spent just testing around, but the more time I spend to this, the more I am convinced that photogrammetry is the thing for future fieldwork. Especially, as it is also a very good basis for creating the usual site plans and feature drawings. The models created have been exported to ArcGIS platform for digitalization done from the photogrammetry and – Voilà! – the plan or a section drawing as you are used to see in archaeology is there as well! With one major improvement = you can always go back to the uninterpreted view.
Soil from the longhouse site in Kvarnbo continues to travel abroad 🙂 Comparing to the first batch of soil sent to travel, in much smaller amounts in terms of weight, but in much larger amounts in terms of numbers. 10 samples, ca 20 gram each, with their own special and necessary permit to leave Åland, are at the present moment already travelling (by ordinary mail service) to Umeå, Sweden, in order to be analyzed in the Environmental Archaeology Laboratory at Umeå University for the geochemical properties. I decided for soil chemistry as this method of analysis can help me to interpret, among other things, which post-holes have been affected by fire and which post-holes have not been affected by fire. As there was quite a number of post-holes documented in the trench of rather modest size, it is reasonable to suggest that several phases of building are represented in the archaeological material. By determining which post-holes have been affected by fire and which haven’t, I am much closer to separating these different phases of construction and determining which post-holes might be related to each other. Another question I am trying to find answer to by means of soil chemistry is, if there are traces that might indicate of metal object(s) having been deposited in the post-holes. Theoretically, the method is suitable for answering this question; however, the possibility of unclear patterns is very real as well….
10 soil-samples for plant-macrofossil analysis were collected from 9 features related to the longhouse at Kvarnbo; and 5 samples – 4 from different post-holes and 1 from the wall construction – will this weekend travel to Uppsala in Sweden, where these will be analysed for plant-macrofossils at the Department of Archaeology and Ancient History, Uppsala University.
In general, plant macrofossil analysis (i.e. looking at the parts of plants preserved in the soil) is used in order to build up a picture of past environments, reconstruct past vegetation and, thereby, gain insight into past landscapes and their development; but this method can also provide important information about the use of structures in archaeology. The purpose of the plant-macrofossil analysis of Kvarnbo material is, however, first and foremost, to find datable material with low own age (for radiocarbon dating) such as, charred seeds – these can remain preserved in soil for a considerable time span and can sometimes be found in the absence of all other organic remains. Yet, using macrofossils for dating of features such as post-holes, it is important that the sample would come from the secondary fill of the post-hole, because only then there is a hope for the fill containing residues from the floor level of the construction and, thereby, be contemporary to the construction. The primary fill is the material that surrounds and supports the post once it has been installed, i.e. it is the backfilled earth connected to the installation of the post, and this fill is therefore not containing structure-contemporary plant-macrofossils (but might contain older material). In any case, post-holes are pretty good traps for macrofossils – after the post is removed from the construction, the hole is normally filled pretty fast again with the material from the surrounding. Inside a house, this fill-after-removing-the-post is often consisting of the floor; therefore, the analysis of the material from the post-hole might provide not only datable material, but also insight into the activities that have been going on in the vicinity of the post-holes.
Although only the very bottom of the post-hole features are preserved at the longhouse site in Kvarnbo, the samples sent to Sweden are all representative in terms of the amount of soil needed in order to run the analysis (every sample contains ca 2 liters of soil), also, all the samples were collected from the uncontaminated contexts meaning that these should not be corrupted by younger material from the subsequent use of the area. Now, it is only to hope that these will contain at least some plant-macrofossils, too (because, you know, these could be empty of such material as well………).
The excavations are past. Right now, reporting is the center of my everyday life. Or, at least, it should be. I have managed to write and submit a report to one of the foundations who supported the archaeological fieldwork at Sa 14.9 – Birgit and Gad Rausings Stiftelse för Humanistisk Forskning. And I have started to build up the body of my excavation report. But as it tends to be with writing, in the head everything is great, but when you open the actual document, you block… It has been difficult to get back in the swing of writing after finishing fieldwork. Despite the fact that I wrote something every day during the excavations, somehow, “real writing” is a different type of writing – the mental activity required is of different kind and, therefore, for the past few weeks, I really have had to push myself to open my PC. But I do feel the change coming!
Yesterday, however, I had much more pleasurable kind of reporting in my agenda – local historical society, Ålandsforskarna, invited me to present my project and the results of the archaeological investigations implemented so far. We were out in the field where the location of trenches was still visible in the vegetation and thanks to the nice weather, everyone survived my hour-long talk about how archaeological investigations often include walking back and forth on plowed fields and investigating dark spots 🙂