The end of the excavations

Week 3 – brief summary

Much has happened on the site during this week. Most importantly, we started soil stripping with the machine and managed to uncover roughly half of the intended area on and around the longhouse structure as seen on the aerial photo. Many different features appeared and even more become visible through meticulous manual cleaning. However, it is also apparent that the site is disturbed and we can clearly distinguish the effect of the plow which often has cut through archaeological features… At this stage, it is hard to tell which features are to be related to the Iron Age use of the area and the hall building(s), but it will certainly become clearer as we investigate further. Some nice finds surfaced this week as well, but these will be presented at a later stage 😛

Also, at the end of this week we are sad to say good-bye to a number of excellent people who had to return to their everyday lives. Thank you Hannele (and what a wonderful piece of art!), Kåre, Linnéa, Markus and Thomas – you all made a fantastic effort and you all will be missed!

It has not been just work though – the vikings from the Fornföreningen Fibula invited us to the kick-off dinner on Wednesday for this year’s Viking Market. Clothes were provided by Fibula and we looked spectacular with our mix of jeans, sneakers and linen tunics 😉 They (together with many visiting vikings) became our guests on Friday evening when the excavations were presented on the site.

To the left: we are visiting the vikings and thanks to Michaela, almost dressed up as vikings as well 😀 (Anton photographed with Thomas phone). To the right: vikings visiting us (Peter photographed with his own phone)

Test pits deliver!

I am very happy to end the first week of excavation with noting that the digging of test pits in the plow layer has already resulted in finds clearly connected to the Iron Age phase. Besides pottery (including ornate pieces), the two glass beads found, are clearly among my personal favourites 🙂 This in combination with good signs of underlying features in a number of pits, bode well for the weeks to come. Stay tuned for more thorough presentations!

Archaeologists on the field

This year’s excavations at the Kvarnbo Hall site commenced yesterday. During the very first week, there are only professional archaeologists working at the site. And I am very lucky to have Frands Herschend, Jan-Henrik “Henke” Fallgren and Kim Darmark in my team. There is hardly a better team to wish for: Frands, who is an archaeology professor at Uppsala University, is -among many other things- the man behind the definition of a hall, Henke has profound knowledge about the Iron Age settlement and archaeology in the North, and Kim, who is actually a Stone Age archaeologist, has such a vast experience in field archaeology combined with a scientific mind that it is difficult to parallel. I am pretty certain that the Åland Islands have never had so qualified group of archaeologists working at the same site at the same time 😉

This first week of the excavations was planned as a set-up week. The intention is to prepare the effective routines before the volunteers join the excavations as well as to get the “feel” of the site in calmer conditions. The excavations are planned as a two-stage study: we start with the investigation of the plow layer (i.e the surface layer of the soil which is affected by agricultural plowing (and in the case of Kvarnbo, we are talking about several hundreds of years of plowing, since the area has been under agricultural use from the middle ages onward)). It is pretty unusual to study layers disturbed by plow, as the archaeologically interesting material in these layers has been so disturbed, that many archaeologists consider it too difficult to say anything meaningful about it. At the same time, there are some studies that have shown that plowing might not disperse artefacts at a site so greatly. So, one of our intentions is to study the spatial distribution of the material. I am also interested in getting a comprehensive overview of the material at the site in general, especially, of the material that is impossible to track down by other means, such as metal detecting. In order to do this, we have laid out a grid on the field and plan to excavate 1 m squares in the plow layer on top of the longhouse as well as in the surrounding areas. Therefore, there are many iron rods with yellow flags on the field right now, but there will probably be even more. The second stage of the excavations is more commonplace when it comes to the study of sites in agriculturally plowed areas – the plow layer will be stripped away with the help of an excavator in order to study archaeological features in situ, i.e. features that have not been disturbed by plow.

Site report

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).

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.

Site reporting

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?

CAA-SE workshop

Last week, the photogrammetric work during the excavations at Kvarnbohall was presented by me, Frands and Daniel at CAA-SE workshop in Stockholm. CAA-SE as in Computer Applications & Quantitative Methods in Archaeology – Swedish Chapter. Half an hour felt hardly enough in order to be very specific, but I do think that our presentation went well as we managed to cover everything we wanted to talk about. In general, it felt like unlike the other cases presented, our photogrammetric work at Kvarnbohall was much more daring as deriving measurements from 3D models was already initially part of the method employment (i.e. total station was practically ditched) and we were not using the method parallel to traditional archaeological documentation. The visually attractive representation of site, trenches and features (something that seemed to be emphasized by others at the workshop)  is obviously very important as well, but it is the possibility of taking accurate measurements from the photographs  that seduced me in regard to photogrammetry. Well, I appreciate this hybridized documentation technique as a whole!

(but I should seriously start working with other aspects of the site-report as well…. (although, I am not yet tired of exploring the models created – there is something very meditative to view the post-holes – you can try it yourself 😉 by following this link) ).

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.